2020-02-26 01:11:19

by Atish Patra

Subject: [RFC PATCH 0/5] Add UEFI support for RISC-V

This series adds UEFI support for RISC-V. Currently, only boot time
services have been added. Runtime services will be added in a separate
series. This series depends on some core EFI patches
present in current in efi-next and following other patches.

U-Boot: Adds the boot hartid under chosen node.
https://lists.denx.de/pipermail/u-boot/2020-February/401227.html

Linux kernel: SBI v0.2 and HSM extension support. This series is a mandatory
pre-requisite for UEFI support as only single core can boot EFI stub and
Linux via UEFI. All other cores are brought up using SBI HSM extension.
http://lists.infradead.org/pipermail/linux-riscv/2020-February/008513.html

OpenSBI: master (commit: ge3f69fc1e934)

Patch 1 just moves arm-stub code to a generic code so that it can be used
across different architecture.

Patch 3 adds fixmap bindings so that CONFIG_EFI can be compiled and we do not
have create separate config to enable boot time services.
As runtime services are not enabled at this time, full generic early ioremap
support is also not added in this series.

Patch 4 and 5 adds the PE/COFF header and EFI stub code support for RISC-V
respectively.

The patches can also be found in following git repo.

https://github.com/atishp04/linux/tree/wip_uefi_riscv

The patches have been verified on Qemu using bootefi command in U-Boot.
Here is a boot log.

Atish Patra (5):
efi: Move arm-stub to a common file
include: pe.h: Add RISC-V related PE definition
RISC-V: Define fixmap bindings for generic early ioremap support
RISC-V: Add PE/COFF header for EFI stub
RISC-V: Add EFI stub support.

arch/arm/Kconfig | 2 +-
arch/arm64/Kconfig | 2 +-
arch/riscv/Kconfig | 21 +++
arch/riscv/Makefile | 1 +
arch/riscv/configs/defconfig | 1 +
arch/riscv/include/asm/Kbuild | 2 +-
arch/riscv/include/asm/fixmap.h | 21 ++-
arch/riscv/include/asm/io.h | 1 +
arch/riscv/include/asm/sections.h | 13 ++
arch/riscv/kernel/Makefile | 4 +
arch/riscv/kernel/efi-header.S | 107 ++++++++++++++
arch/riscv/kernel/head.S | 15 ++
arch/riscv/kernel/image-vars.h | 52 +++++++
arch/riscv/kernel/vmlinux.lds.S | 27 +++-
drivers/firmware/efi/Kconfig | 6 +-
drivers/firmware/efi/libstub/Makefile | 20 ++-
.../efi/libstub/{arm-stub.c => efi-stub.c} | 7 +-
drivers/firmware/efi/libstub/riscv-stub.c | 135 ++++++++++++++++++
include/linux/pe.h | 3 +
19 files changed, 420 insertions(+), 20 deletions(-)
create mode 100644 arch/riscv/include/asm/sections.h
create mode 100644 arch/riscv/kernel/efi-header.S
create mode 100644 arch/riscv/kernel/image-vars.h
rename drivers/firmware/efi/libstub/{arm-stub.c => efi-stub.c} (98%)
create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c

--
2.24.0

2020-02-26 01:11:28

by Atish Patra

Subject: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

Add a RISC-V architecture specific stub code that actually copies the
actual kernel image to a valid address and jump to it after boot services
are terminated. Enable UEFI related kernel configs as well for RISC-V.

Signed-off-by: Atish Patra <[email protected]>
---
arch/riscv/Kconfig | 20 ++++
arch/riscv/Makefile | 1 +
arch/riscv/configs/defconfig | 1 +
drivers/firmware/efi/libstub/Makefile | 8 ++
drivers/firmware/efi/libstub/riscv-stub.c | 135 ++++++++++++++++++++++
5 files changed, 165 insertions(+)
create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 42c122170cfd..68b1d565e51d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -372,10 +372,30 @@ config CMDLINE_FORCE

endchoice

+config EFI_STUB
+ bool
+
+config EFI
+ bool "UEFI runtime support"
+ depends on OF
+ select LIBFDT
+ select UCS2_STRING
+ select EFI_PARAMS_FROM_FDT
+ select EFI_STUB
+ select EFI_GENERIC_ARCH_STUB
+ default y
+ help
+ This option provides support for runtime services provided
+ by UEFI firmware (such as non-volatile variables, realtime
+ clock, and platform reset). A UEFI stub is also provided to
+ allow the kernel to be booted as an EFI application. This
+ is only useful on systems that have UEFI firmware.
+
endmenu

menu "Power management options"

source "kernel/power/Kconfig"
+source "drivers/firmware/Kconfig"

endmenu
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index b9009a2fbaf5..0afaa89ba9ad 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
core-y += arch/riscv/

libs-y += arch/riscv/lib/
+core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a

PHONY += vdso_install
vdso_install:
diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index e2ff95cb3390..0a5d3578f51e 100644
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
# CONFIG_FTRACE is not set
# CONFIG_RUNTIME_TESTING_MENU is not set
CONFIG_MEMTEST=y
+CONFIG_EFI=y
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 2c5b76787126..38facb61745b 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
-fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)
+cflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
+ -fpic

cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) += -I$(srctree)/scripts/dtc/libfdt

@@ -55,6 +57,7 @@ lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) += efi-stub.o fdt.o string.o \
lib-$(CONFIG_ARM) += arm32-stub.o
lib-$(CONFIG_ARM64) += arm64-stub.o
lib-$(CONFIG_X86) += x86-stub.o
+lib-$(CONFIG_RISCV) += riscv-stub.o
CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)

@@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
--prefix-symbols=__efistub_
STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS

+STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
+ --prefix-symbols=__efistub_
+STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
+
+
$(obj)/%.stub.o: $(obj)/%.o FORCE
$(call if_changed,stubcopy)

diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
new file mode 100644
index 000000000000..3935b29ea93a
--- /dev/null
+++ b/drivers/firmware/efi/libstub/riscv-stub.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]>
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ *
+ * This file implements the EFI boot stub for the RISC-V kernel.
+ * Adapted from ARM64 version at drivers/firmware/efi/libstub/arm64-stub.c.
+ */
+
+#include <linux/efi.h>
+#include <linux/libfdt.h>
+#include <linux/libfdt_env.h>
+#include <asm/efi.h>
+#include <asm/sections.h>
+
+#include "efistub.h"
+/*
+ * RISCV requires the kernel image to placed TEXT_OFFSET bytes beyond a 2 MB
+ * aligned base for 64 bit and 4MB for 32 bit.
+ */
+#if IS_ENABLED(CONFIG_64BIT)
+#define MIN_KIMG_ALIGN SZ_2M
+#else
+#define MIN_KIMG_ALIGN SZ_4M
+#endif
+/*
+ * TEXT_OFFSET ensures that we don't overwrite the firmware that probably sits
+ * at the beginning of the DRAM.
+ */
+#define TEXT_OFFSET MIN_KIMG_ALIGN
+
+typedef __attribute__((noreturn)) void (*jump_kernel_func)(unsigned int,
+ unsigned long);
+
+efi_status_t check_platform_features(void)
+{
+ return EFI_SUCCESS;
+}
+
+u64 get_boot_hartid_from_fdt(unsigned long fdt)
+{
+ int chosen_node, len;
+ const fdt64_t *prop;
+ uint64_t hartid = U64_MAX;
+
+ chosen_node = fdt_path_offset((void *)fdt, "/chosen");
+ if (chosen_node < 0)
+ return hartid;
+ prop = fdt_getprop((void *)fdt, chosen_node, "efi-boot-hartid", &len);
+ if (!prop || len != sizeof(u64))
+ return hartid;
+
+ hartid = fdt64_to_cpu(*prop);
+
+ return hartid;
+}
+
+/*
+ * Jump to real kernel here with following constraints.
+ * 1. MMU should be disabled.
+ * 2. a0 should contain hartid
+ * 3. a1 should DT address
+ */
+void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt)
+{
+ unsigned long kernel_entry = entrypoint + _start_kernel - _start;
+ jump_kernel_func jump_kernel = (void (*)(unsigned int, unsigned long))kernel_entry;
+ u64 hartid = get_boot_hartid_from_fdt(fdt);
+
+ if (hartid == U64_MAX)
+ /* We can not use panic or BUG at this point */
+ __asm__ __volatile__ ("ebreak");
+ /* Disable MMU */
+ csr_write(CSR_SATP, 0);
+ jump_kernel(hartid, fdt);
+}
+
+efi_status_t handle_kernel_image(unsigned long *image_addr,
+ unsigned long *image_size,
+ unsigned long *reserve_addr,
+ unsigned long *reserve_size,
+ unsigned long dram_base,
+ efi_loaded_image_t *image)
+{
+ efi_status_t status;
+ unsigned long kernel_size, kernel_memsize = 0;
+ unsigned long preferred_offset;
+
+ /*
+ * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
+ * a KIMG_ALIGN aligned base.
+ */
+ preferred_offset = round_up(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET;
+
+ kernel_size = _edata - _start;
+ kernel_memsize = kernel_size + (_end - _edata);
+
+ /*
+ * Try a straight allocation at the preferred offset.
+ * This will work around the issue where, if dram_base == 0x0,
+ * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
+ * address of the allocation to be mistaken for a FAIL return
+ * value or a NULL pointer). It will also ensure that, on
+ * platforms where the [dram_base, dram_base + TEXT_OFFSET)
+ * interval is partially occupied by the firmware (like on APM
+ * Mustang), we can still place the kernel at the address
+ * 'dram_base + TEXT_OFFSET'.
+ */
+ if (*image_addr == preferred_offset)
+ return EFI_SUCCESS;
+
+ *image_addr = *reserve_addr = preferred_offset;
+ *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
+
+ status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
+ EFI_LOADER_DATA,
+ *reserve_size / EFI_PAGE_SIZE,
+ (efi_physical_addr_t *)reserve_addr);
+
+ if (status != EFI_SUCCESS) {
+ *reserve_size = kernel_memsize + TEXT_OFFSET;
+ status = efi_low_alloc(*reserve_size, MIN_KIMG_ALIGN,
+ reserve_addr);
+
+ if (status != EFI_SUCCESS) {
+ pr_efi_err("Failed to relocate kernel\n");
+ *reserve_size = 0;
+ return status;
+ }
+ *image_addr = *reserve_addr + TEXT_OFFSET;
+ }
+ memcpy((void *)*image_addr, image->image_base, kernel_size);
+
+ return EFI_SUCCESS;
+}
--
2.24.0

2020-02-26 01:11:52

by Atish Patra

Subject: [RFC PATCH 3/5] RISC-V: Define fixmap bindings for generic early ioremap support

UEFI uses early IO or memory mappings for runtime services before
normal ioremap() is usable. This patch only adds minimum necessary
fixmap bindings and headers for generic ioremap support to work.

Signed-off-by: Atish Patra <[email protected]>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/Kbuild | 1 +
arch/riscv/include/asm/fixmap.h | 21 ++++++++++++++++++++-
arch/riscv/include/asm/io.h | 1 +
4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 27bfc7947e44..42c122170cfd 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -65,6 +65,7 @@ config RISCV
select ARCH_HAS_GCOV_PROFILE_ALL
select HAVE_COPY_THREAD_TLS
select HAVE_ARCH_KASAN if MMU && 64BIT
+ select GENERIC_EARLY_IOREMAP

config ARCH_MMAP_RND_BITS_MIN
default 18 if 64BIT
diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
index ec0ca8c6ab64..517394390106 100644
--- a/arch/riscv/include/asm/Kbuild
+++ b/arch/riscv/include/asm/Kbuild
@@ -4,6 +4,7 @@ generic-y += checksum.h
generic-y += compat.h
generic-y += device.h
generic-y += div64.h
+generic-y += early_ioremap.h
generic-y += extable.h
generic-y += flat.h
generic-y += dma.h
diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
index 42d2c42f3cc9..7a4beb7e29a3 100644
--- a/arch/riscv/include/asm/fixmap.h
+++ b/arch/riscv/include/asm/fixmap.h
@@ -25,9 +25,28 @@ enum fixed_addresses {
#define FIX_FDT_SIZE SZ_1M
FIX_FDT_END,
FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
+ FIX_EARLYCON_MEM_BASE,
+
FIX_PTE,
FIX_PMD,
- FIX_EARLYCON_MEM_BASE,
+ /*
+ * Make sure that it is 2MB aligned.
+ */
+#define NR_FIX_SZ_2M (SZ_2M / PAGE_SIZE)
+ FIX_THOLE = NR_FIX_SZ_2M - FIX_PMD - 1,
+
+ __end_of_permanent_fixed_addresses,
+ /*
+ * Temporary boot-time mappings, used by early_ioremap(),
+ * before ioremap() is functional.
+ */
+#define NR_FIX_BTMAPS (SZ_256K / PAGE_SIZE)
+#define FIX_BTMAPS_SLOTS 7
+#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
+
+ FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
+ FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
+
__end_of_fixed_addresses
};

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 0f477206a4ed..047f414b6948 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -14,6 +14,7 @@
#include <linux/types.h>
#include <asm/mmiowb.h>
#include <asm/pgtable.h>
+#include <asm/early_ioremap.h>

/*
* MMIO access functions are separated out to break dependency cycles
--
2.24.0

2020-02-26 01:12:03

by Atish Patra

Subject: [RFC PATCH 1/5] efi: Move arm-stub to a common file

Most of the arm-stub code is written in an architecture independent manner.
As a result, RISC-V can reuse most of the arm-stub code.

Rename the arm-stub.c to efi-stub.c so that ARM, ARM64 and RISC-V can use it.
This patch doesn't introduce any functional changes.

Signed-off-by: Atish Patra <[email protected]>
---
arch/arm/Kconfig | 2 +-
arch/arm64/Kconfig | 2 +-
drivers/firmware/efi/Kconfig | 6 +++---
drivers/firmware/efi/libstub/Makefile | 12 ++++++------
.../firmware/efi/libstub/{arm-stub.c => efi-stub.c} | 7 ++++++-
5 files changed, 17 insertions(+), 12 deletions(-)
rename drivers/firmware/efi/libstub/{arm-stub.c => efi-stub.c} (98%)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 97864aabc2a6..9931fea06076 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1955,7 +1955,7 @@ config EFI
select UCS2_STRING
select EFI_PARAMS_FROM_FDT
select EFI_STUB
- select EFI_ARMSTUB
+ select EFI_GENERIC_ARCH_STUB
select EFI_RUNTIME_WRAPPERS
---help---
This option provides support for runtime services provided
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 0b30e884e088..ae776d8ef2f9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1720,7 +1720,7 @@ config EFI
select EFI_PARAMS_FROM_FDT
select EFI_RUNTIME_WRAPPERS
select EFI_STUB
- select EFI_ARMSTUB
+ select EFI_GENERIC_ARCH_STUB
default y
help
This option provides support for runtime services provided
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index ecc83e2f032c..1bcedb7812da 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -106,12 +106,12 @@ config EFI_PARAMS_FROM_FDT
config EFI_RUNTIME_WRAPPERS
bool

-config EFI_ARMSTUB
+config EFI_GENERIC_ARCH_STUB
bool

-config EFI_ARMSTUB_DTB_LOADER
+config EFI_STUB_DTB_LOADER
bool "Enable the DTB loader"
- depends on EFI_ARMSTUB
+ depends on EFI_GENERIC_ARCH_STUB
default y
help
Select this config option to add support for the dtb= command
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 4d6246c6f651..2c5b76787126 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -22,7 +22,7 @@ cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
-fno-builtin -fpic \
$(call cc-option,-mno-single-pic-base)

-cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
+cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) += -I$(srctree)/scripts/dtc/libfdt

KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
-include $(srctree)/drivers/firmware/efi/libstub/hidden.h \
@@ -44,13 +44,13 @@ lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
skip_spaces.o lib-cmdline.o lib-ctype.o

# include the stub's generic dependencies from lib/ when building for ARM/arm64
-arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
+efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c

$(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
$(call if_changed_rule,cc_o_c)

-lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o \
- $(patsubst %.c,lib-%.o,$(arm-deps-y))
+lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) += efi-stub.o fdt.o string.o \
+ $(patsubst %.c,lib-%.o,$(efi-deps-y))

lib-$(CONFIG_ARM) += arm32-stub.o
lib-$(CONFIG_ARM64) += arm64-stub.o
@@ -72,8 +72,8 @@ CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
# a verification pass to see if any absolute relocations exist in any of the
# object files.
#
-extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y)
-lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y))
+extra-$(CONFIG_EFI_GENERIC_ARCH_STUB) := $(lib-y)
+lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) := $(patsubst %.o,%.stub.o,$(lib-y))

STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
--prefix-symbols=__efistub_
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
similarity index 98%
rename from drivers/firmware/efi/libstub/arm-stub.c
rename to drivers/firmware/efi/libstub/efi-stub.c
index 13559c7e6643..b87c3f70430c 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -15,6 +15,7 @@

#include "efistub.h"

+#if IS_ENABLED(CONFIG_ARM64) || IS_ENABLED(CONFIG_ARM)
/*
* This is the base address at which to start allocating virtual memory ranges
* for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
@@ -27,6 +28,10 @@
* entire footprint of the UEFI runtime services memory regions)
*/
#define EFI_RT_VIRTUAL_BASE SZ_512M
+#else
+#define EFI_RT_VIRTUAL_BASE SZ_2G
+#endif
+
#define EFI_RT_VIRTUAL_SIZE SZ_512M

#ifdef CONFIG_ARM64
@@ -243,7 +248,7 @@ efi_status_t efi_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg)
* 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
* boot is enabled if we can't determine its state.
*/
- if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
+ if (!IS_ENABLED(CONFIG_EFI_STUB_DTB_LOADER) ||
secure_boot != efi_secureboot_mode_disabled) {
if (strstr(cmdline_ptr, "dtb="))
pr_efi("Ignoring DTB from command line.\n");
--
2.24.0

2020-02-26 07:04:43

by Ard Biesheuvel

Subject: Re: [RFC PATCH 1/5] efi: Move arm-stub to a common file

Hi Atish,

On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]> wrote:
>
> Most of the arm-stub code is written in an architecture independent manner.
> As a result, RISC-V can reuse most of the arm-stub code.
>
> Rename the arm-stub.c to efi-stub.c so that ARM, ARM64 and RISC-V can use it.
> This patch doesn't introduce any functional changes.
>
> Signed-off-by: Atish Patra <[email protected]>
> ---
> arch/arm/Kconfig | 2 +-
> arch/arm64/Kconfig | 2 +-
> drivers/firmware/efi/Kconfig | 6 +++---
> drivers/firmware/efi/libstub/Makefile | 12 ++++++------
> .../firmware/efi/libstub/{arm-stub.c => efi-stub.c} | 7 ++++++-
> 5 files changed, 17 insertions(+), 12 deletions(-)
> rename drivers/firmware/efi/libstub/{arm-stub.c => efi-stub.c} (98%)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 97864aabc2a6..9931fea06076 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1955,7 +1955,7 @@ config EFI
> select UCS2_STRING
> select EFI_PARAMS_FROM_FDT
> select EFI_STUB
> - select EFI_ARMSTUB
> + select EFI_GENERIC_ARCH_STUB
> select EFI_RUNTIME_WRAPPERS
> ---help---
> This option provides support for runtime services provided
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 0b30e884e088..ae776d8ef2f9 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1720,7 +1720,7 @@ config EFI
> select EFI_PARAMS_FROM_FDT
> select EFI_RUNTIME_WRAPPERS
> select EFI_STUB
> - select EFI_ARMSTUB
> + select EFI_GENERIC_ARCH_STUB
> default y
> help
> This option provides support for runtime services provided
> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> index ecc83e2f032c..1bcedb7812da 100644
> --- a/drivers/firmware/efi/Kconfig
> +++ b/drivers/firmware/efi/Kconfig
> @@ -106,12 +106,12 @@ config EFI_PARAMS_FROM_FDT
> config EFI_RUNTIME_WRAPPERS
> bool
>
> -config EFI_ARMSTUB
> +config EFI_GENERIC_ARCH_STUB

Let's call it EFI_GENERIC_STUB

> bool
>
> -config EFI_ARMSTUB_DTB_LOADER
> +config EFI_STUB_DTB_LOADER
> bool "Enable the DTB loader"
> - depends on EFI_ARMSTUB
> + depends on EFI_GENERIC_ARCH_STUB

Do you actually need the DTB loader? I feel adding this for ARM was a
mistake, so you may want to make this depend on !RISCV while you're at
it.

> default y
> help
> Select this config option to add support for the dtb= command
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index 4d6246c6f651..2c5b76787126 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -22,7 +22,7 @@ cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> -fno-builtin -fpic \
> $(call cc-option,-mno-single-pic-base)
>
> -cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
> +cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) += -I$(srctree)/scripts/dtc/libfdt
>
> KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
> -include $(srctree)/drivers/firmware/efi/libstub/hidden.h \
> @@ -44,13 +44,13 @@ lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
> skip_spaces.o lib-cmdline.o lib-ctype.o
>
> # include the stub's generic dependencies from lib/ when building for ARM/arm64
> -arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
> +efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
>
> $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
> $(call if_changed_rule,cc_o_c)
>
> -lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o \
> - $(patsubst %.c,lib-%.o,$(arm-deps-y))
> +lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) += efi-stub.o fdt.o string.o \
> + $(patsubst %.c,lib-%.o,$(efi-deps-y))
>
> lib-$(CONFIG_ARM) += arm32-stub.o
> lib-$(CONFIG_ARM64) += arm64-stub.o
> @@ -72,8 +72,8 @@ CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> # a verification pass to see if any absolute relocations exist in any of the
> # object files.
> #
> -extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y)
> -lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-y))
> +extra-$(CONFIG_EFI_GENERIC_ARCH_STUB) := $(lib-y)
> +lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) := $(patsubst %.o,%.stub.o,$(lib-y))
>
> STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
> --prefix-symbols=__efistub_
> diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
> similarity index 98%
> rename from drivers/firmware/efi/libstub/arm-stub.c
> rename to drivers/firmware/efi/libstub/efi-stub.c
> index 13559c7e6643..b87c3f70430c 100644
> --- a/drivers/firmware/efi/libstub/arm-stub.c
> +++ b/drivers/firmware/efi/libstub/efi-stub.c
> @@ -15,6 +15,7 @@
>
> #include "efistub.h"
>
> +#if IS_ENABLED(CONFIG_ARM64) || IS_ENABLED(CONFIG_ARM)
> /*
> * This is the base address at which to start allocating virtual memory ranges
> * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
> @@ -27,6 +28,10 @@
> * entire footprint of the UEFI runtime services memory regions)
> */
> #define EFI_RT_VIRTUAL_BASE SZ_512M
> +#else
> +#define EFI_RT_VIRTUAL_BASE SZ_2G
> +#endif
> +

Can we drop this hunk for now? It should be part of your runtime
services series.

> #define EFI_RT_VIRTUAL_SIZE SZ_512M
>
> #ifdef CONFIG_ARM64
> @@ -243,7 +248,7 @@ efi_status_t efi_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg)
> * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
> * boot is enabled if we can't determine its state.
> */
> - if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
> + if (!IS_ENABLED(CONFIG_EFI_STUB_DTB_LOADER) ||
> secure_boot != efi_secureboot_mode_disabled) {
> if (strstr(cmdline_ptr, "dtb="))
> pr_efi("Ignoring DTB from command line.\n");
> --
> 2.24.0
>

2020-02-26 07:09:52

by Ard Biesheuvel

Subject: Re: [RFC PATCH 3/5] RISC-V: Define fixmap bindings for generic early ioremap support

On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]> wrote:
>
> UEFI uses early IO or memory mappings for runtime services before
> normal ioremap() is usable. This patch only adds minimum necessary
> fixmap bindings and headers for generic ioremap support to work.
>
> Signed-off-by: Atish Patra <[email protected]>

Looks reasonable to me,

Acked-by: Ard Biesheuvel <[email protected]>

although I wonder why it is part of this series?

> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/include/asm/Kbuild | 1 +
> arch/riscv/include/asm/fixmap.h | 21 ++++++++++++++++++++-
> arch/riscv/include/asm/io.h | 1 +
> 4 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 27bfc7947e44..42c122170cfd 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -65,6 +65,7 @@ config RISCV
> select ARCH_HAS_GCOV_PROFILE_ALL
> select HAVE_COPY_THREAD_TLS
> select HAVE_ARCH_KASAN if MMU && 64BIT
> + select GENERIC_EARLY_IOREMAP
>
> config ARCH_MMAP_RND_BITS_MIN
> default 18 if 64BIT
> diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
> index ec0ca8c6ab64..517394390106 100644
> --- a/arch/riscv/include/asm/Kbuild
> +++ b/arch/riscv/include/asm/Kbuild
> @@ -4,6 +4,7 @@ generic-y += checksum.h
> generic-y += compat.h
> generic-y += device.h
> generic-y += div64.h
> +generic-y += early_ioremap.h
> generic-y += extable.h
> generic-y += flat.h
> generic-y += dma.h
> diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
> index 42d2c42f3cc9..7a4beb7e29a3 100644
> --- a/arch/riscv/include/asm/fixmap.h
> +++ b/arch/riscv/include/asm/fixmap.h
> @@ -25,9 +25,28 @@ enum fixed_addresses {
> #define FIX_FDT_SIZE SZ_1M
> FIX_FDT_END,
> FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
> + FIX_EARLYCON_MEM_BASE,
> +
> FIX_PTE,
> FIX_PMD,
> - FIX_EARLYCON_MEM_BASE,
> + /*
> + * Make sure that it is 2MB aligned.
> + */
> +#define NR_FIX_SZ_2M (SZ_2M / PAGE_SIZE)
> + FIX_THOLE = NR_FIX_SZ_2M - FIX_PMD - 1,
> +
> + __end_of_permanent_fixed_addresses,
> + /*
> + * Temporary boot-time mappings, used by early_ioremap(),
> + * before ioremap() is functional.
> + */
> +#define NR_FIX_BTMAPS (SZ_256K / PAGE_SIZE)
> +#define FIX_BTMAPS_SLOTS 7
> +#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
> +
> + FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
> + FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
> +
> __end_of_fixed_addresses
> };
>
> diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
> index 0f477206a4ed..047f414b6948 100644
> --- a/arch/riscv/include/asm/io.h
> +++ b/arch/riscv/include/asm/io.h
> @@ -14,6 +14,7 @@
> #include <linux/types.h>
> #include <asm/mmiowb.h>
> #include <asm/pgtable.h>
> +#include <asm/early_ioremap.h>
>
> /*
> * MMIO access functions are separated out to break dependency cycles
> --
> 2.24.0
>

2020-02-26 07:29:27

by Ard Biesheuvel

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]> wrote:
>
> Add a RISC-V architecture specific stub code that actually copies the
> actual kernel image to a valid address and jump to it after boot services
> are terminated. Enable UEFI related kernel configs as well for RISC-V.
>
> Signed-off-by: Atish Patra <[email protected]>
> ---
> arch/riscv/Kconfig | 20 ++++
> arch/riscv/Makefile | 1 +
> arch/riscv/configs/defconfig | 1 +
> drivers/firmware/efi/libstub/Makefile | 8 ++
> drivers/firmware/efi/libstub/riscv-stub.c | 135 ++++++++++++++++++++++
> 5 files changed, 165 insertions(+)
> create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 42c122170cfd..68b1d565e51d 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -372,10 +372,30 @@ config CMDLINE_FORCE
>
> endchoice
>
> +config EFI_STUB
> + bool
> +
> +config EFI
> + bool "UEFI runtime support"
> + depends on OF
> + select LIBFDT
> + select UCS2_STRING
> + select EFI_PARAMS_FROM_FDT
> + select EFI_STUB
> + select EFI_GENERIC_ARCH_STUB
> + default y
> + help
> + This option provides support for runtime services provided
> + by UEFI firmware (such as non-volatile variables, realtime
> + clock, and platform reset). A UEFI stub is also provided to
> + allow the kernel to be booted as an EFI application. This
> + is only useful on systems that have UEFI firmware.
> +
> endmenu
>
> menu "Power management options"
>
> source "kernel/power/Kconfig"
> +source "drivers/firmware/Kconfig"
>
> endmenu
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index b9009a2fbaf5..0afaa89ba9ad 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
> core-y += arch/riscv/
>
> libs-y += arch/riscv/lib/
> +core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
>
> PHONY += vdso_install
> vdso_install:
> diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
> index e2ff95cb3390..0a5d3578f51e 100644
> --- a/arch/riscv/configs/defconfig
> +++ b/arch/riscv/configs/defconfig
> @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
> # CONFIG_FTRACE is not set
> # CONFIG_RUNTIME_TESTING_MENU is not set
> CONFIG_MEMTEST=y
> +CONFIG_EFI=y
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index 2c5b76787126..38facb61745b 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> -fno-builtin -fpic \
> $(call cc-option,-mno-single-pic-base)
> +cflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> + -fpic
>
> cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) += -I$(srctree)/scripts/dtc/libfdt
>
> @@ -55,6 +57,7 @@ lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) += efi-stub.o fdt.o string.o \
> lib-$(CONFIG_ARM) += arm32-stub.o
> lib-$(CONFIG_ARM64) += arm64-stub.o
> lib-$(CONFIG_X86) += x86-stub.o
> +lib-$(CONFIG_RISCV) += riscv-stub.o
> CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
>
> @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
> --prefix-symbols=__efistub_
> STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
>
> +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
> + --prefix-symbols=__efistub_
> +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
> +
> +
> $(obj)/%.stub.o: $(obj)/%.o FORCE
> $(call if_changed,stubcopy)
>
> diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
> new file mode 100644
> index 000000000000..3935b29ea93a
> --- /dev/null
> +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> @@ -0,0 +1,135 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]>
> + * Copyright (C) 2020 Western Digital Corporation or its affiliates.
> + *
> + * This file implements the EFI boot stub for the RISC-V kernel.
> + * Adapted from ARM64 version at drivers/firmware/efi/libstub/arm64-stub.c.
> + */
> +
> +#include <linux/efi.h>
> +#include <linux/libfdt.h>
> +#include <linux/libfdt_env.h>
> +#include <asm/efi.h>
> +#include <asm/sections.h>
> +
> +#include "efistub.h"
> +/*
> + * RISCV requires the kernel image to placed TEXT_OFFSET bytes beyond a 2 MB
> + * aligned base for 64 bit and 4MB for 32 bit.
> + */
> +#if IS_ENABLED(CONFIG_64BIT)

You can use #ifdef here

> +#define MIN_KIMG_ALIGN SZ_2M
> +#else
> +#define MIN_KIMG_ALIGN SZ_4M
> +#endif
> +/*
> + * TEXT_OFFSET ensures that we don't overwrite the firmware that probably sits
> + * at the beginning of the DRAM.
> + */

Ugh. Really? On an EFI system, that memory should be reserved in some
way, we shouldn't be able to stomp on it like that.

> +#define TEXT_OFFSET MIN_KIMG_ALIGN
> +
> +typedef __attribute__((noreturn)) void (*jump_kernel_func)(unsigned int,
> + unsigned long);
> +
> +efi_status_t check_platform_features(void)
> +{
> + return EFI_SUCCESS;
> +}
> +
> +u64 get_boot_hartid_from_fdt(unsigned long fdt)

static

> +{
> + int chosen_node, len;
> + const fdt64_t *prop;
> + uint64_t hartid = U64_MAX;
> +
> + chosen_node = fdt_path_offset((void *)fdt, "/chosen");
> + if (chosen_node < 0)
> + return hartid;

Just return U64_MAX here

> + prop = fdt_getprop((void *)fdt, chosen_node, "efi-boot-hartid", &len);

Please call this 'boot-hartid' not 'efi-boot-hartid' as the hartid
value is independent of whether you boot via EFI or not.

> + if (!prop || len != sizeof(u64))
> + return hartid;
> +

Return U64_MAX

> + hartid = fdt64_to_cpu(*prop);
> +

and just return the swabbed value, so you can get rid of the local var.

> + return hartid;
> +}
> +
> +/*
> + * Jump to real kernel here with following constraints.
> + * 1. MMU should be disabled.
> + * 2. a0 should contain hartid
> + * 3. a1 should DT address
> + */
> +void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt)

This prototype has changed, and now includes the size of the fdt in param 3.

> +{
> + unsigned long kernel_entry = entrypoint + _start_kernel - _start;

stext_offset ? It has a terrible name though, and I'll probably
propose to change it at some point, for all arches. But you can still
use it here.

> + jump_kernel_func jump_kernel = (void (*)(unsigned int, unsigned long))kernel_entry;
> + u64 hartid = get_boot_hartid_from_fdt(fdt);
> +
> + if (hartid == U64_MAX)
> + /* We can not use panic or BUG at this point */
> + __asm__ __volatile__ ("ebreak");
> + /* Disable MMU */
> + csr_write(CSR_SATP, 0);
> + jump_kernel(hartid, fdt);
> +}
> +
> +efi_status_t handle_kernel_image(unsigned long *image_addr,
> + unsigned long *image_size,
> + unsigned long *reserve_addr,
> + unsigned long *reserve_size,
> + unsigned long dram_base,
> + efi_loaded_image_t *image)
> +{
> + efi_status_t status;
> + unsigned long kernel_size, kernel_memsize = 0;
> + unsigned long preferred_offset;
> +
> + /*
> + * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
> + * a KIMG_ALIGN aligned base.
> + */
> + preferred_offset = round_up(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET;
> +
> + kernel_size = _edata - _start;
> + kernel_memsize = kernel_size + (_end - _edata);
> +
> + /*
> + * Try a straight allocation at the preferred offset.
> + * This will work around the issue where, if dram_base == 0x0,
> + * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
> + * address of the allocation to be mistaken for a FAIL return
> + * value or a NULL pointer). It will also ensure that, on
> + * platforms where the [dram_base, dram_base + TEXT_OFFSET)
> + * interval is partially occupied by the firmware (like on APM
> + * Mustang), we can still place the kernel at the address
> + * 'dram_base + TEXT_OFFSET'.

Better drop this entire last sentence (unless it is relevant, but then
rework it to drop the APM Mustang reference)

> + */
> + if (*image_addr == preferred_offset)
> + return EFI_SUCCESS;
> +
> + *image_addr = *reserve_addr = preferred_offset;
> + *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
> +
> + status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> + EFI_LOADER_DATA,
> + *reserve_size / EFI_PAGE_SIZE,
> + (efi_physical_addr_t *)reserve_addr);
> +
> + if (status != EFI_SUCCESS) {
> + *reserve_size = kernel_memsize + TEXT_OFFSET;
> + status = efi_low_alloc(*reserve_size, MIN_KIMG_ALIGN,
> + reserve_addr);
> +
> + if (status != EFI_SUCCESS) {
> + pr_efi_err("Failed to relocate kernel\n");
> + *reserve_size = 0;
> + return status;
> + }
> + *image_addr = *reserve_addr + TEXT_OFFSET;
> + }
> + memcpy((void *)*image_addr, image->image_base, kernel_size);
> +
> + return EFI_SUCCESS;
> +}
> --
> 2.24.0
>

2020-02-26 23:47:33

by Palmer Dabbelt

Subject: Re: [RFC PATCH 0/5] Add UEFI support for RISC-V

On Tue, 25 Feb 2020 17:10:32 PST (-0800), Atish Patra wrote:
> This series adds UEFI support for RISC-V. Currently, only boot time
> services have been added. Runtime services will be added in a separate
> series. This series depends on some core EFI patches
> present in current in efi-next and following other patches.
>
> U-Boot: Adds the boot hartid under chosen node.
> https://lists.denx.de/pipermail/u-boot/2020-February/401227.html
>
> Linux kernel: SBI v0.2 and HSM extension support. This series is a mandatory
> pre-requisite for UEFI support as only single core can boot EFI stub and
> Linux via UEFI. All other cores are brought up using SBI HSM extension.
> http://lists.infradead.org/pipermail/linux-riscv/2020-February/008513.html
>
> OpenSBI: master (commit: ge3f69fc1e934)
>
> Patch 1 just moves arm-stub code to a generic code so that it can be used
> across different architecture.
>
> Patch 3 adds fixmap bindings so that CONFIG_EFI can be compiled and we do not
> have create separate config to enable boot time services.
> As runtime services are not enabled at this time, full generic early ioremap
> support is also not added in this series.
>
> Patch 4 and 5 adds the PE/COFF header and EFI stub code support for RISC-V
> respectively.
>
> The patches can also be found in following git repo.
>
> https://github.com/atishp04/linux/tree/wip_uefi_riscv
>
> The patches have been verified on Qemu using bootefi command in U-Boot.
> Here is a boot log.
>
> Atish Patra (5):
> efi: Move arm-stub to a common file
> include: pe.h: Add RISC-V related PE definition
> RISC-V: Define fixmap bindings for generic early ioremap support
> RISC-V: Add PE/COFF header for EFI stub
> RISC-V: Add EFI stub support.
>
> arch/arm/Kconfig | 2 +-
> arch/arm64/Kconfig | 2 +-
> arch/riscv/Kconfig | 21 +++
> arch/riscv/Makefile | 1 +
> arch/riscv/configs/defconfig | 1 +
> arch/riscv/include/asm/Kbuild | 2 +-
> arch/riscv/include/asm/fixmap.h | 21 ++-
> arch/riscv/include/asm/io.h | 1 +
> arch/riscv/include/asm/sections.h | 13 ++
> arch/riscv/kernel/Makefile | 4 +
> arch/riscv/kernel/efi-header.S | 107 ++++++++++++++
> arch/riscv/kernel/head.S | 15 ++
> arch/riscv/kernel/image-vars.h | 52 +++++++
> arch/riscv/kernel/vmlinux.lds.S | 27 +++-
> drivers/firmware/efi/Kconfig | 6 +-
> drivers/firmware/efi/libstub/Makefile | 20 ++-
> .../efi/libstub/{arm-stub.c => efi-stub.c} | 7 +-
> drivers/firmware/efi/libstub/riscv-stub.c | 135 ++++++++++++++++++
> include/linux/pe.h | 3 +
> 19 files changed, 420 insertions(+), 20 deletions(-)
> create mode 100644 arch/riscv/include/asm/sections.h
> create mode 100644 arch/riscv/kernel/efi-header.S
> create mode 100644 arch/riscv/kernel/image-vars.h
> rename drivers/firmware/efi/libstub/{arm-stub.c => efi-stub.c} (98%)
> create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c

I'm in favor of adding EFI support, and I'd rather have it sooner than later so
we don't paint ourselves into a corner. I'm not sure what happened to the
RISC-V EFI spec process, though, which would be my only worry here (also I
haven't looked at the code :)). Do we have enough of a spec through the EFI
process that this is all kosher on their end?

Given that this definately isn't for these RCs, I'm going to leave it in my
review queue. It might be best to get the "move stuff to generic" work merged
on its own, as then we can carry less diff around.

Thanks!

2020-02-27 01:17:23

by Atish Patra

Subject: Re: [RFC PATCH 1/5] efi: Move arm-stub to a common file

On Wed, 2020-02-26 at 08:04 +0100, Ard Biesheuvel wrote:
> Hi Atish,
>
> On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> wrote:
> > Most of the arm-stub code is written in an architecture independent
> > manner.
> > As a result, RISC-V can reuse most of the arm-stub code.
> >
> > Rename the arm-stub.c to efi-stub.c so that ARM, ARM64 and RISC-V
> > can use it.
> > This patch doesn't introduce any functional changes.
> >
> > Signed-off-by: Atish Patra <[email protected]>
> > ---
> > arch/arm/Kconfig | 2 +-
> > arch/arm64/Kconfig | 2 +-
> > drivers/firmware/efi/Kconfig | 6 +++---
> > drivers/firmware/efi/libstub/Makefile | 12 ++++++
> > ------
> > .../firmware/efi/libstub/{arm-stub.c => efi-stub.c} | 7 ++++++-
> > 5 files changed, 17 insertions(+), 12 deletions(-)
> > rename drivers/firmware/efi/libstub/{arm-stub.c => efi-stub.c}
> > (98%)
> >
> > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> > index 97864aabc2a6..9931fea06076 100644
> > --- a/arch/arm/Kconfig
> > +++ b/arch/arm/Kconfig
> > @@ -1955,7 +1955,7 @@ config EFI
> > select UCS2_STRING
> > select EFI_PARAMS_FROM_FDT
> > select EFI_STUB
> > - select EFI_ARMSTUB
> > + select EFI_GENERIC_ARCH_STUB
> > select EFI_RUNTIME_WRAPPERS
> > ---help---
> > This option provides support for runtime services
> > provided
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 0b30e884e088..ae776d8ef2f9 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -1720,7 +1720,7 @@ config EFI
> > select EFI_PARAMS_FROM_FDT
> > select EFI_RUNTIME_WRAPPERS
> > select EFI_STUB
> > - select EFI_ARMSTUB
> > + select EFI_GENERIC_ARCH_STUB
> > default y
> > help
> > This option provides support for runtime services
> > provided
> > diff --git a/drivers/firmware/efi/Kconfig
> > b/drivers/firmware/efi/Kconfig
> > index ecc83e2f032c..1bcedb7812da 100644
> > --- a/drivers/firmware/efi/Kconfig
> > +++ b/drivers/firmware/efi/Kconfig
> > @@ -106,12 +106,12 @@ config EFI_PARAMS_FROM_FDT
> > config EFI_RUNTIME_WRAPPERS
> > bool
> >
> > -config EFI_ARMSTUB
> > +config EFI_GENERIC_ARCH_STUB
>
> Let's call it EFI_GENERIC_STUB
>
> > bool
> >
> > -config EFI_ARMSTUB_DTB_LOADER
> > +config EFI_STUB_DTB_LOADER
> > bool "Enable the DTB loader"
> > - depends on EFI_ARMSTUB
> > + depends on EFI_GENERIC_ARCH_STUB
>
> Do you actually need the DTB loader? I feel adding this for ARM was a
> mistake, so you may want to make this depend on !RISCV while you're
> at
> it.
>

Actually we don't need it RISC-V. I think I added that that's a valid
option to have. But your recent cleaup seems otherwise. I will make it
depend on !RISCV. It also doesn't make sense to rename it to
EFI_STUB_DTB_LOADER. So I will just leave EFI_ARMSTUB_DTB_LOADER as it
is.

> > default y
> > help
> > Select this config option to add support for the dtb=
> > command
> > diff --git a/drivers/firmware/efi/libstub/Makefile
> > b/drivers/firmware/efi/libstub/Makefile
> > index 4d6246c6f651..2c5b76787126 100644
> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -22,7 +22,7 @@ cflags-$(CONFIG_ARM) := $(subst
> > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > -fno-builtin -fpic \
> > $(call cc-option,-mno-single-
> > pic-base)
> >
> > -cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
> > +cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > -I$(srctree)/scripts/dtc/libfdt
> >
> > KBUILD_CFLAGS := $(cflags-y)
> > -DDISABLE_BRANCH_PROFILING \
> > -include
> > $(srctree)/drivers/firmware/efi/libstub/hidden.h \
> > @@ -44,13 +44,13 @@ lib-y := efi-
> > stub-helper.o gop.o secureboot.o tpm.o \
> > skip_spaces.o lib-cmdline.o lib-
> > ctype.o
> >
> > # include the stub's generic dependencies from lib/ when building
> > for ARM/arm64
> > -arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c
> > fdt_sw.c
> > +efi-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c
> > fdt_sw.c
> >
> > $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE
> > $(call if_changed_rule,cc_o_c)
> >
> > -lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o string.o \
> > - $(patsubst %.c,lib-%.o,$(arm-
> > deps-y))
> > +lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) += efi-stub.o fdt.o
> > string.o \
> > + $(patsubst %.c,lib-%.o,$(efi-
> > deps-y))
> >
> > lib-$(CONFIG_ARM) += arm32-stub.o
> > lib-$(CONFIG_ARM64) += arm64-stub.o
> > @@ -72,8 +72,8 @@ CFLAGS_arm64-stub.o :=
> > -DTEXT_OFFSET=$(TEXT_OFFSET)
> > # a verification pass to see if any absolute relocations exist in
> > any of the
> > # object files.
> > #
> > -extra-$(CONFIG_EFI_ARMSTUB) := $(lib-y)
> > -lib-$(CONFIG_EFI_ARMSTUB) := $(patsubst %.o,%.stub.o,$(lib-
> > y))
> > +extra-$(CONFIG_EFI_GENERIC_ARCH_STUB) := $(lib-y)
> > +lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) := $(patsubst
> > %.o,%.stub.o,$(lib-y))
> >
> > STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \
> > --prefix-symbols=__efistub_
> > diff --git a/drivers/firmware/efi/libstub/arm-stub.c
> > b/drivers/firmware/efi/libstub/efi-stub.c
> > similarity index 98%
> > rename from drivers/firmware/efi/libstub/arm-stub.c
> > rename to drivers/firmware/efi/libstub/efi-stub.c
> > index 13559c7e6643..b87c3f70430c 100644
> > --- a/drivers/firmware/efi/libstub/arm-stub.c
> > +++ b/drivers/firmware/efi/libstub/efi-stub.c
> > @@ -15,6 +15,7 @@
> >
> > #include "efistub.h"
> >
> > +#if IS_ENABLED(CONFIG_ARM64) || IS_ENABLED(CONFIG_ARM)
> > /*
> > * This is the base address at which to start allocating virtual
> > memory ranges
> > * for UEFI Runtime Services. This is in the low TTBR0 range so
> > that we can use
> > @@ -27,6 +28,10 @@
> > * entire footprint of the UEFI runtime services memory regions)
> > */
> > #define EFI_RT_VIRTUAL_BASE SZ_512M
> > +#else
> > +#define EFI_RT_VIRTUAL_BASE SZ_2G
> > +#endif
> > +
>
> Can we drop this hunk for now? It should be part of your runtime
> services series.
>

Sure. Will do it.

> > #define EFI_RT_VIRTUAL_SIZE SZ_512M
> >
> > #ifdef CONFIG_ARM64
> > @@ -243,7 +248,7 @@ efi_status_t efi_entry(efi_handle_t handle,
> > efi_system_table_t *sys_table_arg)
> > * 'dtb=' unless UEFI Secure Boot is disabled. We assume
> > that secure
> > * boot is enabled if we can't determine its state.
> > */
> > - if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
> > + if (!IS_ENABLED(CONFIG_EFI_STUB_DTB_LOADER) ||
> > secure_boot != efi_secureboot_mode_disabled) {
> > if (strstr(cmdline_ptr, "dtb="))
> > pr_efi("Ignoring DTB from command
> > line.\n");
> > --
> > 2.24.0
> >

--
Regards,
Atish

2020-02-27 02:09:42

by Atish Patra

Subject: Re: [RFC PATCH 0/5] Add UEFI support for RISC-V

On Wed, 2020-02-26 at 15:46 -0800, Palmer Dabbelt wrote:
> On Tue, 25 Feb 2020 17:10:32 PST (-0800), Atish Patra wrote:
> > This series adds UEFI support for RISC-V. Currently, only boot time
> > services have been added. Runtime services will be added in a
> > separate
> > series. This series depends on some core EFI patches
> > present in current in efi-next and following other patches.
> >
> > U-Boot: Adds the boot hartid under chosen node.
> > https://lists.denx.de/pipermail/u-boot/2020-February/401227.html
> >
> > Linux kernel: SBI v0.2 and HSM extension support. This series is a
> > mandatory
> > pre-requisite for UEFI support as only single core can boot EFI
> > stub and
> > Linux via UEFI. All other cores are brought up using SBI HSM
> > extension.
> > http://lists.infradead.org/pipermail/linux-riscv/2020-February/008513.html
> >
> > OpenSBI: master (commit: ge3f69fc1e934)
> >
> > Patch 1 just moves arm-stub code to a generic code so that it can
> > be used
> > across different architecture.
> >
> > Patch 3 adds fixmap bindings so that CONFIG_EFI can be compiled and
> > we do not
> > have create separate config to enable boot time services.
> > As runtime services are not enabled at this time, full generic
> > early ioremap
> > support is also not added in this series.
> >
> > Patch 4 and 5 adds the PE/COFF header and EFI stub code support for
> > RISC-V
> > respectively.
> >
> > The patches can also be found in following git repo.
> >
> > https://github.com/atishp04/linux/tree/wip_uefi_riscv
> >
> > The patches have been verified on Qemu using bootefi command in U-
> > Boot.
> > Here is a boot log.
> >
> > Atish Patra (5):
> > efi: Move arm-stub to a common file
> > include: pe.h: Add RISC-V related PE definition
> > RISC-V: Define fixmap bindings for generic early ioremap support
> > RISC-V: Add PE/COFF header for EFI stub
> > RISC-V: Add EFI stub support.
> >
> > arch/arm/Kconfig | 2 +-
> > arch/arm64/Kconfig | 2 +-
> > arch/riscv/Kconfig | 21 +++
> > arch/riscv/Makefile | 1 +
> > arch/riscv/configs/defconfig | 1 +
> > arch/riscv/include/asm/Kbuild | 2 +-
> > arch/riscv/include/asm/fixmap.h | 21 ++-
> > arch/riscv/include/asm/io.h | 1 +
> > arch/riscv/include/asm/sections.h | 13 ++
> > arch/riscv/kernel/Makefile | 4 +
> > arch/riscv/kernel/efi-header.S | 107 ++++++++++++++
> > arch/riscv/kernel/head.S | 15 ++
> > arch/riscv/kernel/image-vars.h | 52 +++++++
> > arch/riscv/kernel/vmlinux.lds.S | 27 +++-
> > drivers/firmware/efi/Kconfig | 6 +-
> > drivers/firmware/efi/libstub/Makefile | 20 ++-
> > .../efi/libstub/{arm-stub.c => efi-stub.c} | 7 +-
> > drivers/firmware/efi/libstub/riscv-stub.c | 135
> > ++++++++++++++++++
> > include/linux/pe.h | 3 +
> > 19 files changed, 420 insertions(+), 20 deletions(-)
> > create mode 100644 arch/riscv/include/asm/sections.h
> > create mode 100644 arch/riscv/kernel/efi-header.S
> > create mode 100644 arch/riscv/kernel/image-vars.h
> > rename drivers/firmware/efi/libstub/{arm-stub.c => efi-stub.c}
> > (98%)
> > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
>
> I'm in favor of adding EFI support, and I'd rather have it sooner
> than later so
> we don't paint ourselves into a corner. I'm not sure what happened
> to the
> RISC-V EFI spec process, though, which would be my only worry here
> (also I
> haven't looked at the code :)). Do we have enough of a spec through
> the EFI
> process that this is all kosher on their end?
>
The RISC-V platform is already merged in UEFI spec. The latest UEFI
spec can be found here.

https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf

Section 2.3.7: RISC-V Platforms

There are some modification required in the current spec. For example:

The current spec assumes that UEFI will execute in M mode only and
should perform handoff control to OS in M-mode as well. This is not
entirely correct as we can do this in S-mode as well.

We are in the process of creating an ECR so that next release will have
the correct information.

> Given that this definately isn't for these RCs, I'm going to leave it
> in my
> review queue. It might be best to get the "move stuff to generic"
> work merged
> on its own, as then we can carry less diff around.
>
>

Yup. It's definitely not rc material. Given that RISC-V specific
section is already merged in UEFI spec, can we aim for 5.7 merge window?

> Thanks!

--
Regards,
Atish

2020-02-27 19:53:39

by Atish Patra

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote:
> On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> wrote:
> > Add a RISC-V architecture specific stub code that actually copies
> > the
> > actual kernel image to a valid address and jump to it after boot
> > services
> > are terminated. Enable UEFI related kernel configs as well for
> > RISC-V.
> >
> > Signed-off-by: Atish Patra <[email protected]>
> > ---
> > arch/riscv/Kconfig | 20 ++++
> > arch/riscv/Makefile | 1 +
> > arch/riscv/configs/defconfig | 1 +
> > drivers/firmware/efi/libstub/Makefile | 8 ++
> > drivers/firmware/efi/libstub/riscv-stub.c | 135
> > ++++++++++++++++++++++
> > 5 files changed, 165 insertions(+)
> > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 42c122170cfd..68b1d565e51d 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -372,10 +372,30 @@ config CMDLINE_FORCE
> >
> > endchoice
> >
> > +config EFI_STUB
> > + bool
> > +
> > +config EFI
> > + bool "UEFI runtime support"
> > + depends on OF
> > + select LIBFDT
> > + select UCS2_STRING
> > + select EFI_PARAMS_FROM_FDT
> > + select EFI_STUB
> > + select EFI_GENERIC_ARCH_STUB
> > + default y
> > + help
> > + This option provides support for runtime services
> > provided
> > + by UEFI firmware (such as non-volatile variables,
> > realtime
> > + clock, and platform reset). A UEFI stub is also provided
> > to
> > + allow the kernel to be booted as an EFI application. This
> > + is only useful on systems that have UEFI firmware.
> > +
> > endmenu
> >
> > menu "Power management options"
> >
> > source "kernel/power/Kconfig"
> > +source "drivers/firmware/Kconfig"
> >
> > endmenu
> > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > index b9009a2fbaf5..0afaa89ba9ad 100644
> > --- a/arch/riscv/Makefile
> > +++ b/arch/riscv/Makefile
> > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
> > core-y += arch/riscv/
> >
> > libs-y += arch/riscv/lib/
> > +core-$(CONFIG_EFI_STUB) +=
> > $(objtree)/drivers/firmware/efi/libstub/lib.a
> >
> > PHONY += vdso_install
> > vdso_install:
> > diff --git a/arch/riscv/configs/defconfig
> > b/arch/riscv/configs/defconfig
> > index e2ff95cb3390..0a5d3578f51e 100644
> > --- a/arch/riscv/configs/defconfig
> > +++ b/arch/riscv/configs/defconfig
> > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
> > # CONFIG_FTRACE is not set
> > # CONFIG_RUNTIME_TESTING_MENU is not set
> > CONFIG_MEMTEST=y
> > +CONFIG_EFI=y
> > diff --git a/drivers/firmware/efi/libstub/Makefile
> > b/drivers/firmware/efi/libstub/Makefile
> > index 2c5b76787126..38facb61745b 100644
> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) := $(subst
> > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > cflags-$(CONFIG_ARM) := $(subst
> > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > -fno-builtin -fpic \
> > $(call cc-option,-mno-single-
> > pic-base)
> > +cflags-$(CONFIG_RISCV) := $(subst
> > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > + -fpic
> >
> > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > -I$(srctree)/scripts/dtc/libfdt
> >
> > @@ -55,6 +57,7 @@ lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > efi-stub.o fdt.o string.o \
> > lib-$(CONFIG_ARM) += arm32-stub.o
> > lib-$(CONFIG_ARM64) += arm64-stub.o
> > lib-$(CONFIG_X86) += x86-stub.o
> > +lib-$(CONFIG_RISCV) += riscv-stub.o
> > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> >
> > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --
> > prefix-alloc-sections=.init \
> > --prefix-symbols=__efistub_
> > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
> >
> > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
> > + --prefix-symbols=__efistub_
> > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
> > +
> > +
> > $(obj)/%.stub.o: $(obj)/%.o FORCE
> > $(call if_changed,stubcopy)
> >
> > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c
> > b/drivers/firmware/efi/libstub/riscv-stub.c
> > new file mode 100644
> > index 000000000000..3935b29ea93a
> > --- /dev/null
> > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> > @@ -0,0 +1,135 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]>
> > + * Copyright (C) 2020 Western Digital Corporation or its
> > affiliates.
> > + *
> > + * This file implements the EFI boot stub for the RISC-V kernel.
> > + * Adapted from ARM64 version at
> > drivers/firmware/efi/libstub/arm64-stub.c.
> > + */
> > +
> > +#include <linux/efi.h>
> > +#include <linux/libfdt.h>
> > +#include <linux/libfdt_env.h>
> > +#include <asm/efi.h>
> > +#include <asm/sections.h>
> > +
> > +#include "efistub.h"
> > +/*
> > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes
> > beyond a 2 MB
> > + * aligned base for 64 bit and 4MB for 32 bit.
> > + */
> > +#if IS_ENABLED(CONFIG_64BIT)
>
> You can use #ifdef here
>

ok.

> > +#define MIN_KIMG_ALIGN SZ_2M
> > +#else
> > +#define MIN_KIMG_ALIGN SZ_4M
> > +#endif
> > +/*
> > + * TEXT_OFFSET ensures that we don't overwrite the firmware that
> > probably sits
> > + * at the beginning of the DRAM.
> > + */
>
> Ugh. Really? On an EFI system, that memory should be reserved in some
> way, we shouldn't be able to stomp on it like that.
>

Currently, we reserve the initial 128KB for run time firmware(only
openSBI for now, EDK2 later) by using PMP (physical memory protection).
Any acess to that region from supervisor mode (i.e. U-Boot) will result
in a fault.

Is it mandatory for UEFI to reserve the beginning of the DRAM ?

> > +#define TEXT_OFFSET MIN_KIMG_ALIGN
> > +
> > +typedef __attribute__((noreturn)) void
> > (*jump_kernel_func)(unsigned int,
> > + unsigned
> > long);
> > +
> > +efi_status_t check_platform_features(void)
> > +{
> > + return EFI_SUCCESS;
> > +}
> > +
> > +u64 get_boot_hartid_from_fdt(unsigned long fdt)
>
> static
>
> > +{
> > + int chosen_node, len;
> > + const fdt64_t *prop;
> > + uint64_t hartid = U64_MAX;
> > +
> > + chosen_node = fdt_path_offset((void *)fdt, "/chosen");
> > + if (chosen_node < 0)
> > + return hartid;
>
> Just return U64_MAX here
>
> > + prop = fdt_getprop((void *)fdt, chosen_node, "efi-boot-
> > hartid", &len);
>
> Please call this 'boot-hartid' not 'efi-boot-hartid' as the hartid
> value is independent of whether you boot via EFI or not.
>
> > + if (!prop || len != sizeof(u64))
> > + return hartid;
> > +
>
> Return U64_MAX
>
> > + hartid = fdt64_to_cpu(*prop);
> > +
>
> and just return the swabbed value, so you can get rid of the local
> var.
>

Fixed all the above issues. I changed it to u32 as u64 won't work on 32
bit systems.

> > + return hartid;
> > +}
> > +
> > +/*
> > + * Jump to real kernel here with following constraints.
> > + * 1. MMU should be disabled.
> > + * 2. a0 should contain hartid
> > + * 3. a1 should DT address
> > + */
> > +void __noreturn efi_enter_kernel(unsigned long entrypoint,
> > unsigned long fdt)
>
> This prototype has changed, and now includes the size of the fdt in
> param 3.
>

Ahh yes. Fixed.

> > +{
> > + unsigned long kernel_entry = entrypoint + _start_kernel -
> > _start;
>
> stext_offset ? It has a terrible name though, and I'll probably
> propose to change it at some point, for all arches. But you can still
> use it here.
>

Sure. I updated it with stext_offset.

> > + jump_kernel_func jump_kernel = (void (*)(unsigned int,
> > unsigned long))kernel_entry;
> > + u64 hartid = get_boot_hartid_from_fdt(fdt);
> > +
> > + if (hartid == U64_MAX)
> > + /* We can not use panic or BUG at this point */
> > + __asm__ __volatile__ ("ebreak");
> > + /* Disable MMU */
> > + csr_write(CSR_SATP, 0);
> > + jump_kernel(hartid, fdt);
> > +}
> > +
> > +efi_status_t handle_kernel_image(unsigned long *image_addr,
> > + unsigned long *image_size,
> > + unsigned long *reserve_addr,
> > + unsigned long *reserve_size,
> > + unsigned long dram_base,
> > + efi_loaded_image_t *image)
> > +{
> > + efi_status_t status;
> > + unsigned long kernel_size, kernel_memsize = 0;
> > + unsigned long preferred_offset;
> > +
> > + /*
> > + * The preferred offset of the kernel Image is TEXT_OFFSET
> > bytes beyond
> > + * a KIMG_ALIGN aligned base.
> > + */
> > + preferred_offset = round_up(dram_base, MIN_KIMG_ALIGN) +
> > TEXT_OFFSET;
> > +
> > + kernel_size = _edata - _start;
> > + kernel_memsize = kernel_size + (_end - _edata);
> > +
> > + /*
> > + * Try a straight allocation at the preferred offset.
> > + * This will work around the issue where, if dram_base ==
> > 0x0,
> > + * efi_low_alloc() refuses to allocate at 0x0 (to prevent
> > the
> > + * address of the allocation to be mistaken for a FAIL
> > return
> > + * value or a NULL pointer). It will also ensure that, on
> > + * platforms where the [dram_base, dram_base + TEXT_OFFSET)
> > + * interval is partially occupied by the firmware (like on
> > APM
> > + * Mustang), we can still place the kernel at the address
> > + * 'dram_base + TEXT_OFFSET'.
>
> Better drop this entire last sentence (unless it is relevant, but
> then
> rework it to drop the APM Mustang reference)
>

As stated above, RISC-V firmware occupies [dram_base, dram_base +
128K). That's why I thought this comment is useful. I should have
removed the mustand reference. I will update it.

> > + */
> > + if (*image_addr == preferred_offset)
> > + return EFI_SUCCESS;
> > +
> > + *image_addr = *reserve_addr = preferred_offset;
> > + *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
> > +
> > + status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> > + EFI_LOADER_DATA,
> > + *reserve_size / EFI_PAGE_SIZE,
> > + (efi_physical_addr_t
> > *)reserve_addr);
> > +
> > + if (status != EFI_SUCCESS) {
> > + *reserve_size = kernel_memsize + TEXT_OFFSET;
> > + status = efi_low_alloc(*reserve_size,
> > MIN_KIMG_ALIGN,
> > + reserve_addr);
> > +
> > + if (status != EFI_SUCCESS) {
> > + pr_efi_err("Failed to relocate kernel\n");
> > + *reserve_size = 0;
> > + return status;
> > + }
> > + *image_addr = *reserve_addr + TEXT_OFFSET;
> > + }
> > + memcpy((void *)*image_addr, image->image_base,
> > kernel_size);
> > +
> > + return EFI_SUCCESS;
> > +}
> > --
> > 2.24.0
> >

--
Regards,
Atish

2020-02-27 19:59:56

by Atish Patra

Subject: Re: [RFC PATCH 3/5] RISC-V: Define fixmap bindings for generic early ioremap support

On Wed, 2020-02-26 at 08:08 +0100, Ard Biesheuvel wrote:
> On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> wrote:
> > UEFI uses early IO or memory mappings for runtime services before
> > normal ioremap() is usable. This patch only adds minimum necessary
> > fixmap bindings and headers for generic ioremap support to work.
> >
> > Signed-off-by: Atish Patra <[email protected]>
>
> Looks reasonable to me,
>
> Acked-by: Ard Biesheuvel <[email protected]>
>
> although I wonder why it is part of this series?
>

because of CONFIG_EFI. With CONFIG_EFI enabled, all the run time
service memory mapping code is compiled for RISC-V. I could have
createa a separate config for only boot time services or used EFI_STUB
at places where CONFI_EFI. But it seems redundant as we will support
runtime services soon. Let me know if that's a wrong approach.

> > ---
> > arch/riscv/Kconfig | 1 +
> > arch/riscv/include/asm/Kbuild | 1 +
> > arch/riscv/include/asm/fixmap.h | 21 ++++++++++++++++++++-
> > arch/riscv/include/asm/io.h | 1 +
> > 4 files changed, 23 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 27bfc7947e44..42c122170cfd 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -65,6 +65,7 @@ config RISCV
> > select ARCH_HAS_GCOV_PROFILE_ALL
> > select HAVE_COPY_THREAD_TLS
> > select HAVE_ARCH_KASAN if MMU && 64BIT
> > + select GENERIC_EARLY_IOREMAP
> >
> > config ARCH_MMAP_RND_BITS_MIN
> > default 18 if 64BIT
> > diff --git a/arch/riscv/include/asm/Kbuild
> > b/arch/riscv/include/asm/Kbuild
> > index ec0ca8c6ab64..517394390106 100644
> > --- a/arch/riscv/include/asm/Kbuild
> > +++ b/arch/riscv/include/asm/Kbuild
> > @@ -4,6 +4,7 @@ generic-y += checksum.h
> > generic-y += compat.h
> > generic-y += device.h
> > generic-y += div64.h
> > +generic-y += early_ioremap.h
> > generic-y += extable.h
> > generic-y += flat.h
> > generic-y += dma.h
> > diff --git a/arch/riscv/include/asm/fixmap.h
> > b/arch/riscv/include/asm/fixmap.h
> > index 42d2c42f3cc9..7a4beb7e29a3 100644
> > --- a/arch/riscv/include/asm/fixmap.h
> > +++ b/arch/riscv/include/asm/fixmap.h
> > @@ -25,9 +25,28 @@ enum fixed_addresses {
> > #define FIX_FDT_SIZE SZ_1M
> > FIX_FDT_END,
> > FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
> > + FIX_EARLYCON_MEM_BASE,
> > +
> > FIX_PTE,
> > FIX_PMD,
> > - FIX_EARLYCON_MEM_BASE,
> > + /*
> > + * Make sure that it is 2MB aligned.
> > + */
> > +#define NR_FIX_SZ_2M (SZ_2M / PAGE_SIZE)
> > + FIX_THOLE = NR_FIX_SZ_2M - FIX_PMD - 1,
> > +
> > + __end_of_permanent_fixed_addresses,
> > + /*
> > + * Temporary boot-time mappings, used by early_ioremap(),
> > + * before ioremap() is functional.
> > + */
> > +#define NR_FIX_BTMAPS (SZ_256K / PAGE_SIZE)
> > +#define FIX_BTMAPS_SLOTS 7
> > +#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
> > +
> > + FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
> > + FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
> > +
> > __end_of_fixed_addresses
> > };
> >
> > diff --git a/arch/riscv/include/asm/io.h
> > b/arch/riscv/include/asm/io.h
> > index 0f477206a4ed..047f414b6948 100644
> > --- a/arch/riscv/include/asm/io.h
> > +++ b/arch/riscv/include/asm/io.h
> > @@ -14,6 +14,7 @@
> > #include <linux/types.h>
> > #include <asm/mmiowb.h>
> > #include <asm/pgtable.h>
> > +#include <asm/early_ioremap.h>
> >
> > /*
> > * MMIO access functions are separated out to break dependency
> > cycles
> > --
> > 2.24.0
> >

--
Regards,
Atish

2020-02-27 20:01:38

by Ard Biesheuvel

Subject: Re: [RFC PATCH 3/5] RISC-V: Define fixmap bindings for generic early ioremap support

On Thu, 27 Feb 2020 at 20:58, Atish Patra <[email protected]> wrote:
>
> On Wed, 2020-02-26 at 08:08 +0100, Ard Biesheuvel wrote:
> > On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> > wrote:
> > > UEFI uses early IO or memory mappings for runtime services before
> > > normal ioremap() is usable. This patch only adds minimum necessary
> > > fixmap bindings and headers for generic ioremap support to work.
> > >
> > > Signed-off-by: Atish Patra <[email protected]>
> >
> > Looks reasonable to me,
> >
> > Acked-by: Ard Biesheuvel <[email protected]>
> >
> > although I wonder why it is part of this series?
> >
>
> because of CONFIG_EFI. With CONFIG_EFI enabled, all the run time
> service memory mapping code is compiled for RISC-V. I could have
> createa a separate config for only boot time services or used EFI_STUB
> at places where CONFI_EFI. But it seems redundant as we will support
> runtime services soon. Let me know if that's a wrong approach.
>

No that's fine



> > > ---
> > > arch/riscv/Kconfig | 1 +
> > > arch/riscv/include/asm/Kbuild | 1 +
> > > arch/riscv/include/asm/fixmap.h | 21 ++++++++++++++++++++-
> > > arch/riscv/include/asm/io.h | 1 +
> > > 4 files changed, 23 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > index 27bfc7947e44..42c122170cfd 100644
> > > --- a/arch/riscv/Kconfig
> > > +++ b/arch/riscv/Kconfig
> > > @@ -65,6 +65,7 @@ config RISCV
> > > select ARCH_HAS_GCOV_PROFILE_ALL
> > > select HAVE_COPY_THREAD_TLS
> > > select HAVE_ARCH_KASAN if MMU && 64BIT
> > > + select GENERIC_EARLY_IOREMAP
> > >
> > > config ARCH_MMAP_RND_BITS_MIN
> > > default 18 if 64BIT
> > > diff --git a/arch/riscv/include/asm/Kbuild
> > > b/arch/riscv/include/asm/Kbuild
> > > index ec0ca8c6ab64..517394390106 100644
> > > --- a/arch/riscv/include/asm/Kbuild
> > > +++ b/arch/riscv/include/asm/Kbuild
> > > @@ -4,6 +4,7 @@ generic-y += checksum.h
> > > generic-y += compat.h
> > > generic-y += device.h
> > > generic-y += div64.h
> > > +generic-y += early_ioremap.h
> > > generic-y += extable.h
> > > generic-y += flat.h
> > > generic-y += dma.h
> > > diff --git a/arch/riscv/include/asm/fixmap.h
> > > b/arch/riscv/include/asm/fixmap.h
> > > index 42d2c42f3cc9..7a4beb7e29a3 100644
> > > --- a/arch/riscv/include/asm/fixmap.h
> > > +++ b/arch/riscv/include/asm/fixmap.h
> > > @@ -25,9 +25,28 @@ enum fixed_addresses {
> > > #define FIX_FDT_SIZE SZ_1M
> > > FIX_FDT_END,
> > > FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
> > > + FIX_EARLYCON_MEM_BASE,
> > > +
> > > FIX_PTE,
> > > FIX_PMD,
> > > - FIX_EARLYCON_MEM_BASE,
> > > + /*
> > > + * Make sure that it is 2MB aligned.
> > > + */
> > > +#define NR_FIX_SZ_2M (SZ_2M / PAGE_SIZE)
> > > + FIX_THOLE = NR_FIX_SZ_2M - FIX_PMD - 1,
> > > +
> > > + __end_of_permanent_fixed_addresses,
> > > + /*
> > > + * Temporary boot-time mappings, used by early_ioremap(),
> > > + * before ioremap() is functional.
> > > + */
> > > +#define NR_FIX_BTMAPS (SZ_256K / PAGE_SIZE)
> > > +#define FIX_BTMAPS_SLOTS 7
> > > +#define TOTAL_FIX_BTMAPS (NR_FIX_BTMAPS * FIX_BTMAPS_SLOTS)
> > > +
> > > + FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
> > > + FIX_BTMAP_BEGIN = FIX_BTMAP_END + TOTAL_FIX_BTMAPS - 1,
> > > +
> > > __end_of_fixed_addresses
> > > };
> > >
> > > diff --git a/arch/riscv/include/asm/io.h
> > > b/arch/riscv/include/asm/io.h
> > > index 0f477206a4ed..047f414b6948 100644
> > > --- a/arch/riscv/include/asm/io.h
> > > +++ b/arch/riscv/include/asm/io.h
> > > @@ -14,6 +14,7 @@
> > > #include <linux/types.h>
> > > #include <asm/mmiowb.h>
> > > #include <asm/pgtable.h>
> > > +#include <asm/early_ioremap.h>
> > >
> > > /*
> > > * MMIO access functions are separated out to break dependency
> > > cycles
> > > --
> > > 2.24.0
> > >
>
> --
> Regards,
> Atish

2020-02-27 20:01:43

by Ard Biesheuvel

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On Thu, 27 Feb 2020 at 20:53, Atish Patra <[email protected]> wrote:
>
> On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote:
> > On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> > wrote:
> > > Add a RISC-V architecture specific stub code that actually copies
> > > the
> > > actual kernel image to a valid address and jump to it after boot
> > > services
> > > are terminated. Enable UEFI related kernel configs as well for
> > > RISC-V.
> > >
> > > Signed-off-by: Atish Patra <[email protected]>
> > > ---
> > > arch/riscv/Kconfig | 20 ++++
> > > arch/riscv/Makefile | 1 +
> > > arch/riscv/configs/defconfig | 1 +
> > > drivers/firmware/efi/libstub/Makefile | 8 ++
> > > drivers/firmware/efi/libstub/riscv-stub.c | 135
> > > ++++++++++++++++++++++
> > > 5 files changed, 165 insertions(+)
> > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
> > >
> > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > index 42c122170cfd..68b1d565e51d 100644
> > > --- a/arch/riscv/Kconfig
> > > +++ b/arch/riscv/Kconfig
> > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE
> > >
> > > endchoice
> > >
> > > +config EFI_STUB
> > > + bool
> > > +
> > > +config EFI
> > > + bool "UEFI runtime support"
> > > + depends on OF
> > > + select LIBFDT
> > > + select UCS2_STRING
> > > + select EFI_PARAMS_FROM_FDT
> > > + select EFI_STUB
> > > + select EFI_GENERIC_ARCH_STUB
> > > + default y
> > > + help
> > > + This option provides support for runtime services
> > > provided
> > > + by UEFI firmware (such as non-volatile variables,
> > > realtime
> > > + clock, and platform reset). A UEFI stub is also provided
> > > to
> > > + allow the kernel to be booted as an EFI application. This
> > > + is only useful on systems that have UEFI firmware.
> > > +
> > > endmenu
> > >
> > > menu "Power management options"
> > >
> > > source "kernel/power/Kconfig"
> > > +source "drivers/firmware/Kconfig"
> > >
> > > endmenu
> > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > > index b9009a2fbaf5..0afaa89ba9ad 100644
> > > --- a/arch/riscv/Makefile
> > > +++ b/arch/riscv/Makefile
> > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
> > > core-y += arch/riscv/
> > >
> > > libs-y += arch/riscv/lib/
> > > +core-$(CONFIG_EFI_STUB) +=
> > > $(objtree)/drivers/firmware/efi/libstub/lib.a
> > >
> > > PHONY += vdso_install
> > > vdso_install:
> > > diff --git a/arch/riscv/configs/defconfig
> > > b/arch/riscv/configs/defconfig
> > > index e2ff95cb3390..0a5d3578f51e 100644
> > > --- a/arch/riscv/configs/defconfig
> > > +++ b/arch/riscv/configs/defconfig
> > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
> > > # CONFIG_FTRACE is not set
> > > # CONFIG_RUNTIME_TESTING_MENU is not set
> > > CONFIG_MEMTEST=y
> > > +CONFIG_EFI=y
> > > diff --git a/drivers/firmware/efi/libstub/Makefile
> > > b/drivers/firmware/efi/libstub/Makefile
> > > index 2c5b76787126..38facb61745b 100644
> > > --- a/drivers/firmware/efi/libstub/Makefile
> > > +++ b/drivers/firmware/efi/libstub/Makefile
> > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) := $(subst
> > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > cflags-$(CONFIG_ARM) := $(subst
> > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > -fno-builtin -fpic \
> > > $(call cc-option,-mno-single-
> > > pic-base)
> > > +cflags-$(CONFIG_RISCV) := $(subst
> > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > + -fpic
> > >
> > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > -I$(srctree)/scripts/dtc/libfdt
> > >
> > > @@ -55,6 +57,7 @@ lib-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > efi-stub.o fdt.o string.o \
> > > lib-$(CONFIG_ARM) += arm32-stub.o
> > > lib-$(CONFIG_ARM64) += arm64-stub.o
> > > lib-$(CONFIG_X86) += x86-stub.o
> > > +lib-$(CONFIG_RISCV) += riscv-stub.o
> > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > >
> > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --
> > > prefix-alloc-sections=.init \
> > > --prefix-symbols=__efistub_
> > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
> > >
> > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-sections=.init \
> > > + --prefix-symbols=__efistub_
> > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
> > > +
> > > +
> > > $(obj)/%.stub.o: $(obj)/%.o FORCE
> > > $(call if_changed,stubcopy)
> > >
> > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c
> > > b/drivers/firmware/efi/libstub/riscv-stub.c
> > > new file mode 100644
> > > index 000000000000..3935b29ea93a
> > > --- /dev/null
> > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> > > @@ -0,0 +1,135 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]>
> > > + * Copyright (C) 2020 Western Digital Corporation or its
> > > affiliates.
> > > + *
> > > + * This file implements the EFI boot stub for the RISC-V kernel.
> > > + * Adapted from ARM64 version at
> > > drivers/firmware/efi/libstub/arm64-stub.c.
> > > + */
> > > +
> > > +#include <linux/efi.h>
> > > +#include <linux/libfdt.h>
> > > +#include <linux/libfdt_env.h>
> > > +#include <asm/efi.h>
> > > +#include <asm/sections.h>
> > > +
> > > +#include "efistub.h"
> > > +/*
> > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes
> > > beyond a 2 MB
> > > + * aligned base for 64 bit and 4MB for 32 bit.
> > > + */
> > > +#if IS_ENABLED(CONFIG_64BIT)
> >
> > You can use #ifdef here
> >
>
> ok.
>
> > > +#define MIN_KIMG_ALIGN SZ_2M
> > > +#else
> > > +#define MIN_KIMG_ALIGN SZ_4M
> > > +#endif
> > > +/*
> > > + * TEXT_OFFSET ensures that we don't overwrite the firmware that
> > > probably sits
> > > + * at the beginning of the DRAM.
> > > + */
> >
> > Ugh. Really? On an EFI system, that memory should be reserved in some
> > way, we shouldn't be able to stomp on it like that.
> >
>
> Currently, we reserve the initial 128KB for run time firmware(only
> openSBI for now, EDK2 later) by using PMP (physical memory protection).
> Any acess to that region from supervisor mode (i.e. U-Boot) will result
> in a fault.
>
> Is it mandatory for UEFI to reserve the beginning of the DRAM ?
>

It is mandatory to describe which memory is usable and which memory is
reserved. If this memory is not usable, you either describe it as
reserved, or not describe it at all. Describing it as usable memory,
allocating it for the kernel but with a hidden agreement that it is
reserved is highly likely to cause problems down the road.



> > > +#define TEXT_OFFSET MIN_KIMG_ALIGN
> > > +
> > > +typedef __attribute__((noreturn)) void
> > > (*jump_kernel_func)(unsigned int,
> > > + unsigned
> > > long);
> > > +
> > > +efi_status_t check_platform_features(void)
> > > +{
> > > + return EFI_SUCCESS;
> > > +}
> > > +
> > > +u64 get_boot_hartid_from_fdt(unsigned long fdt)
> >
> > static
> >
> > > +{
> > > + int chosen_node, len;
> > > + const fdt64_t *prop;
> > > + uint64_t hartid = U64_MAX;
> > > +
> > > + chosen_node = fdt_path_offset((void *)fdt, "/chosen");
> > > + if (chosen_node < 0)
> > > + return hartid;
> >
> > Just return U64_MAX here
> >
> > > + prop = fdt_getprop((void *)fdt, chosen_node, "efi-boot-
> > > hartid", &len);
> >
> > Please call this 'boot-hartid' not 'efi-boot-hartid' as the hartid
> > value is independent of whether you boot via EFI or not.
> >
> > > + if (!prop || len != sizeof(u64))
> > > + return hartid;
> > > +
> >
> > Return U64_MAX
> >
> > > + hartid = fdt64_to_cpu(*prop);
> > > +
> >
> > and just return the swabbed value, so you can get rid of the local
> > var.
> >
>
> Fixed all the above issues. I changed it to u32 as u64 won't work on 32
> bit systems.
>

If the hart id is only 32 bits max then i guess that will work.

> > > + return hartid;
> > > +}
> > > +
> > > +/*
> > > + * Jump to real kernel here with following constraints.
> > > + * 1. MMU should be disabled.
> > > + * 2. a0 should contain hartid
> > > + * 3. a1 should DT address
> > > + */
> > > +void __noreturn efi_enter_kernel(unsigned long entrypoint,
> > > unsigned long fdt)
> >
> > This prototype has changed, and now includes the size of the fdt in
> > param 3.
> >
>
> Ahh yes. Fixed.
>
> > > +{
> > > + unsigned long kernel_entry = entrypoint + _start_kernel -
> > > _start;
> >
> > stext_offset ? It has a terrible name though, and I'll probably
> > propose to change it at some point, for all arches. But you can still
> > use it here.
> >
>
> Sure. I updated it with stext_offset.
>
> > > + jump_kernel_func jump_kernel = (void (*)(unsigned int,
> > > unsigned long))kernel_entry;
> > > + u64 hartid = get_boot_hartid_from_fdt(fdt);
> > > +
> > > + if (hartid == U64_MAX)
> > > + /* We can not use panic or BUG at this point */
> > > + __asm__ __volatile__ ("ebreak");
> > > + /* Disable MMU */
> > > + csr_write(CSR_SATP, 0);
> > > + jump_kernel(hartid, fdt);
> > > +}
> > > +
> > > +efi_status_t handle_kernel_image(unsigned long *image_addr,
> > > + unsigned long *image_size,
> > > + unsigned long *reserve_addr,
> > > + unsigned long *reserve_size,
> > > + unsigned long dram_base,
> > > + efi_loaded_image_t *image)
> > > +{
> > > + efi_status_t status;
> > > + unsigned long kernel_size, kernel_memsize = 0;
> > > + unsigned long preferred_offset;
> > > +
> > > + /*
> > > + * The preferred offset of the kernel Image is TEXT_OFFSET
> > > bytes beyond
> > > + * a KIMG_ALIGN aligned base.
> > > + */
> > > + preferred_offset = round_up(dram_base, MIN_KIMG_ALIGN) +
> > > TEXT_OFFSET;
> > > +
> > > + kernel_size = _edata - _start;
> > > + kernel_memsize = kernel_size + (_end - _edata);
> > > +
> > > + /*
> > > + * Try a straight allocation at the preferred offset.
> > > + * This will work around the issue where, if dram_base ==
> > > 0x0,
> > > + * efi_low_alloc() refuses to allocate at 0x0 (to prevent
> > > the
> > > + * address of the allocation to be mistaken for a FAIL
> > > return
> > > + * value or a NULL pointer). It will also ensure that, on
> > > + * platforms where the [dram_base, dram_base + TEXT_OFFSET)
> > > + * interval is partially occupied by the firmware (like on
> > > APM
> > > + * Mustang), we can still place the kernel at the address
> > > + * 'dram_base + TEXT_OFFSET'.
> >
> > Better drop this entire last sentence (unless it is relevant, but
> > then
> > rework it to drop the APM Mustang reference)
> >
>
> As stated above, RISC-V firmware occupies [dram_base, dram_base +
> 128K). That's why I thought this comment is useful. I should have
> removed the mustand reference. I will update it.
>
> > > + */
> > > + if (*image_addr == preferred_offset)
> > > + return EFI_SUCCESS;
> > > +
> > > + *image_addr = *reserve_addr = preferred_offset;
> > > + *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
> > > +
> > > + status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> > > + EFI_LOADER_DATA,
> > > + *reserve_size / EFI_PAGE_SIZE,
> > > + (efi_physical_addr_t
> > > *)reserve_addr);
> > > +
> > > + if (status != EFI_SUCCESS) {
> > > + *reserve_size = kernel_memsize + TEXT_OFFSET;
> > > + status = efi_low_alloc(*reserve_size,
> > > MIN_KIMG_ALIGN,
> > > + reserve_addr);
> > > +
> > > + if (status != EFI_SUCCESS) {
> > > + pr_efi_err("Failed to relocate kernel\n");
> > > + *reserve_size = 0;
> > > + return status;
> > > + }
> > > + *image_addr = *reserve_addr + TEXT_OFFSET;
> > > + }
> > > + memcpy((void *)*image_addr, image->image_base,
> > > kernel_size);
> > > +
> > > + return EFI_SUCCESS;
> > > +}
> > > --
> > > 2.24.0
> > >
>
> --
> Regards,
> Atish

2020-02-28 01:06:22

by Atish Patra

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote:
> On Thu, 27 Feb 2020 at 20:53, Atish Patra <[email protected]>
> wrote:
> > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote:
> > > On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> > > wrote:
> > > > Add a RISC-V architecture specific stub code that actually
> > > > copies
> > > > the
> > > > actual kernel image to a valid address and jump to it after
> > > > boot
> > > > services
> > > > are terminated. Enable UEFI related kernel configs as well for
> > > > RISC-V.
> > > >
> > > > Signed-off-by: Atish Patra <[email protected]>
> > > > ---
> > > > arch/riscv/Kconfig | 20 ++++
> > > > arch/riscv/Makefile | 1 +
> > > > arch/riscv/configs/defconfig | 1 +
> > > > drivers/firmware/efi/libstub/Makefile | 8 ++
> > > > drivers/firmware/efi/libstub/riscv-stub.c | 135
> > > > ++++++++++++++++++++++
> > > > 5 files changed, 165 insertions(+)
> > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
> > > >
> > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > > index 42c122170cfd..68b1d565e51d 100644
> > > > --- a/arch/riscv/Kconfig
> > > > +++ b/arch/riscv/Kconfig
> > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE
> > > >
> > > > endchoice
> > > >
> > > > +config EFI_STUB
> > > > + bool
> > > > +
> > > > +config EFI
> > > > + bool "UEFI runtime support"
> > > > + depends on OF
> > > > + select LIBFDT
> > > > + select UCS2_STRING
> > > > + select EFI_PARAMS_FROM_FDT
> > > > + select EFI_STUB
> > > > + select EFI_GENERIC_ARCH_STUB
> > > > + default y
> > > > + help
> > > > + This option provides support for runtime services
> > > > provided
> > > > + by UEFI firmware (such as non-volatile variables,
> > > > realtime
> > > > + clock, and platform reset). A UEFI stub is also
> > > > provided
> > > > to
> > > > + allow the kernel to be booted as an EFI application.
> > > > This
> > > > + is only useful on systems that have UEFI firmware.
> > > > +
> > > > endmenu
> > > >
> > > > menu "Power management options"
> > > >
> > > > source "kernel/power/Kconfig"
> > > > +source "drivers/firmware/Kconfig"
> > > >
> > > > endmenu
> > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > > > index b9009a2fbaf5..0afaa89ba9ad 100644
> > > > --- a/arch/riscv/Makefile
> > > > +++ b/arch/riscv/Makefile
> > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
> > > > core-y += arch/riscv/
> > > >
> > > > libs-y += arch/riscv/lib/
> > > > +core-$(CONFIG_EFI_STUB) +=
> > > > $(objtree)/drivers/firmware/efi/libstub/lib.a
> > > >
> > > > PHONY += vdso_install
> > > > vdso_install:
> > > > diff --git a/arch/riscv/configs/defconfig
> > > > b/arch/riscv/configs/defconfig
> > > > index e2ff95cb3390..0a5d3578f51e 100644
> > > > --- a/arch/riscv/configs/defconfig
> > > > +++ b/arch/riscv/configs/defconfig
> > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
> > > > # CONFIG_FTRACE is not set
> > > > # CONFIG_RUNTIME_TESTING_MENU is not set
> > > > CONFIG_MEMTEST=y
> > > > +CONFIG_EFI=y
> > > > diff --git a/drivers/firmware/efi/libstub/Makefile
> > > > b/drivers/firmware/efi/libstub/Makefile
> > > > index 2c5b76787126..38facb61745b 100644
> > > > --- a/drivers/firmware/efi/libstub/Makefile
> > > > +++ b/drivers/firmware/efi/libstub/Makefile
> > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) :=
> > > > $(subst
> > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > cflags-$(CONFIG_ARM) := $(subst
> > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > -fno-builtin -fpic \
> > > > $(call cc-option,-mno-
> > > > single-
> > > > pic-base)
> > > > +cflags-$(CONFIG_RISCV) := $(subst
> > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > + -fpic
> > > >
> > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > -I$(srctree)/scripts/dtc/libfdt
> > > >
> > > > @@ -55,6 +57,7 @@ lib-
> > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > efi-stub.o fdt.o string.o \
> > > > lib-$(CONFIG_ARM) += arm32-stub.o
> > > > lib-$(CONFIG_ARM64) += arm64-stub.o
> > > > lib-$(CONFIG_X86) += x86-stub.o
> > > > +lib-$(CONFIG_RISCV) += riscv-stub.o
> > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > >
> > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --
> > > > prefix-alloc-sections=.init \
> > > > --prefix-symbols=__efistub_
> > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
> > > >
> > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-
> > > > sections=.init \
> > > > + --prefix-symbols=__efistub_
> > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
> > > > +
> > > > +
> > > > $(obj)/%.stub.o: $(obj)/%.o FORCE
> > > > $(call if_changed,stubcopy)
> > > >
> > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c
> > > > b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > new file mode 100644
> > > > index 000000000000..3935b29ea93a
> > > > --- /dev/null
> > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > @@ -0,0 +1,135 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]
> > > > >
> > > > + * Copyright (C) 2020 Western Digital Corporation or its
> > > > affiliates.
> > > > + *
> > > > + * This file implements the EFI boot stub for the RISC-V
> > > > kernel.
> > > > + * Adapted from ARM64 version at
> > > > drivers/firmware/efi/libstub/arm64-stub.c.
> > > > + */
> > > > +
> > > > +#include <linux/efi.h>
> > > > +#include <linux/libfdt.h>
> > > > +#include <linux/libfdt_env.h>
> > > > +#include <asm/efi.h>
> > > > +#include <asm/sections.h>
> > > > +
> > > > +#include "efistub.h"
> > > > +/*
> > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes
> > > > beyond a 2 MB
> > > > + * aligned base for 64 bit and 4MB for 32 bit.
> > > > + */
> > > > +#if IS_ENABLED(CONFIG_64BIT)
> > >
> > > You can use #ifdef here
> > >
> >
> > ok.
> >
> > > > +#define MIN_KIMG_ALIGN SZ_2M
> > > > +#else
> > > > +#define MIN_KIMG_ALIGN SZ_4M
> > > > +#endif
> > > > +/*
> > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware
> > > > that
> > > > probably sits
> > > > + * at the beginning of the DRAM.
> > > > + */
> > >
> > > Ugh. Really? On an EFI system, that memory should be reserved in
> > > some
> > > way, we shouldn't be able to stomp on it like that.
> > >
> >
> > Currently, we reserve the initial 128KB for run time firmware(only
> > openSBI for now, EDK2 later) by using PMP (physical memory
> > protection).
> > Any acess to that region from supervisor mode (i.e. U-Boot) will
> > result
> > in a fault.
> >
> > Is it mandatory for UEFI to reserve the beginning of the DRAM ?
> >
>
> It is mandatory to describe which memory is usable and which memory
> is
> reserved. If this memory is not usable, you either describe it as
> reserved, or not describe it at all. Describing it as usable memory,
> allocating it for the kernel but with a hidden agreement that it is
> reserved is highly likely to cause problems down the road.
>

I completely agree with you on this. We have been talking to have a
booting guide and memory map document for RISC-V Linux to document all
the idiosyncries of RISC-V. But that has not happend until now.
Once, the ordered booting patches are merged, I will try to take a stab
at it.

Other than that, do we need to describe it somewhere in U-boot wrt to
UEFI so that it doesn't allocate memory from that region ?

>
>
> > > > +#define TEXT_OFFSET MIN_KIMG_ALIGN
> > > > +
> > > > +typedef __attribute__((noreturn)) void
> > > > (*jump_kernel_func)(unsigned int,
> > > > + unsi
> > > > gned
> > > > long);
> > > > +
> > > > +efi_status_t check_platform_features(void)
> > > > +{
> > > > + return EFI_SUCCESS;
> > > > +}
> > > > +
> > > > +u64 get_boot_hartid_from_fdt(unsigned long fdt)
> > >
> > > static
> > >
> > > > +{
> > > > + int chosen_node, len;
> > > > + const fdt64_t *prop;
> > > > + uint64_t hartid = U64_MAX;
> > > > +
> > > > + chosen_node = fdt_path_offset((void *)fdt, "/chosen");
> > > > + if (chosen_node < 0)
> > > > + return hartid;
> > >
> > > Just return U64_MAX here
> > >
> > > > + prop = fdt_getprop((void *)fdt, chosen_node, "efi-boot-
> > > > hartid", &len);
> > >
> > > Please call this 'boot-hartid' not 'efi-boot-hartid' as the
> > > hartid
> > > value is independent of whether you boot via EFI or not.
> > >
> > > > + if (!prop || len != sizeof(u64))
> > > > + return hartid;
> > > > +
> > >
> > > Return U64_MAX
> > >
> > > > + hartid = fdt64_to_cpu(*prop);
> > > > +
> > >
> > > and just return the swabbed value, so you can get rid of the
> > > local
> > > var.
> > >
> >
> > Fixed all the above issues. I changed it to u32 as u64 won't work
> > on 32
> > bit systems.
> >
>
> If the hart id is only 32 bits max then i guess that will work.
>
> > > > + return hartid;
> > > > +}
> > > > +
> > > > +/*
> > > > + * Jump to real kernel here with following constraints.
> > > > + * 1. MMU should be disabled.
> > > > + * 2. a0 should contain hartid
> > > > + * 3. a1 should DT address
> > > > + */
> > > > +void __noreturn efi_enter_kernel(unsigned long entrypoint,
> > > > unsigned long fdt)
> > >
> > > This prototype has changed, and now includes the size of the fdt
> > > in
> > > param 3.
> > >
> >
> > Ahh yes. Fixed.
> >
> > > > +{
> > > > + unsigned long kernel_entry = entrypoint + _start_kernel
> > > > -
> > > > _start;
> > >
> > > stext_offset ? It has a terrible name though, and I'll probably
> > > propose to change it at some point, for all arches. But you can
> > > still
> > > use it here.
> > >
> >
> > Sure. I updated it with stext_offset.
> >
> > > > + jump_kernel_func jump_kernel = (void (*)(unsigned int,
> > > > unsigned long))kernel_entry;
> > > > + u64 hartid = get_boot_hartid_from_fdt(fdt);
> > > > +
> > > > + if (hartid == U64_MAX)
> > > > + /* We can not use panic or BUG at this point */
> > > > + __asm__ __volatile__ ("ebreak");
> > > > + /* Disable MMU */
> > > > + csr_write(CSR_SATP, 0);
> > > > + jump_kernel(hartid, fdt);
> > > > +}
> > > > +
> > > > +efi_status_t handle_kernel_image(unsigned long *image_addr,
> > > > + unsigned long *image_size,
> > > > + unsigned long *reserve_addr,
> > > > + unsigned long *reserve_size,
> > > > + unsigned long dram_base,
> > > > + efi_loaded_image_t *image)
> > > > +{
> > > > + efi_status_t status;
> > > > + unsigned long kernel_size, kernel_memsize = 0;
> > > > + unsigned long preferred_offset;
> > > > +
> > > > + /*
> > > > + * The preferred offset of the kernel Image is
> > > > TEXT_OFFSET
> > > > bytes beyond
> > > > + * a KIMG_ALIGN aligned base.
> > > > + */
> > > > + preferred_offset = round_up(dram_base, MIN_KIMG_ALIGN)
> > > > +
> > > > TEXT_OFFSET;
> > > > +
> > > > + kernel_size = _edata - _start;
> > > > + kernel_memsize = kernel_size + (_end - _edata);
> > > > +
> > > > + /*
> > > > + * Try a straight allocation at the preferred offset.
> > > > + * This will work around the issue where, if dram_base
> > > > ==
> > > > 0x0,
> > > > + * efi_low_alloc() refuses to allocate at 0x0 (to
> > > > prevent
> > > > the
> > > > + * address of the allocation to be mistaken for a FAIL
> > > > return
> > > > + * value or a NULL pointer). It will also ensure that,
> > > > on
> > > > + * platforms where the [dram_base, dram_base +
> > > > TEXT_OFFSET)
> > > > + * interval is partially occupied by the firmware (like
> > > > on
> > > > APM
> > > > + * Mustang), we can still place the kernel at the
> > > > address
> > > > + * 'dram_base + TEXT_OFFSET'.
> > >
> > > Better drop this entire last sentence (unless it is relevant, but
> > > then
> > > rework it to drop the APM Mustang reference)
> > >
> >
> > As stated above, RISC-V firmware occupies [dram_base, dram_base +
> > 128K). That's why I thought this comment is useful. I should have
> > removed the mustand reference. I will update it.
> >
> > > > + */
> > > > + if (*image_addr == preferred_offset)
> > > > + return EFI_SUCCESS;
> > > > +
> > > > + *image_addr = *reserve_addr = preferred_offset;
> > > > + *reserve_size = round_up(kernel_memsize,
> > > > EFI_ALLOC_ALIGN);
> > > > +
> > > > + status = efi_bs_call(allocate_pages,
> > > > EFI_ALLOCATE_ADDRESS,
> > > > + EFI_LOADER_DATA,
> > > > + *reserve_size / EFI_PAGE_SIZE,
> > > > + (efi_physical_addr_t
> > > > *)reserve_addr);
> > > > +
> > > > + if (status != EFI_SUCCESS) {
> > > > + *reserve_size = kernel_memsize + TEXT_OFFSET;
> > > > + status = efi_low_alloc(*reserve_size,
> > > > MIN_KIMG_ALIGN,
> > > > + reserve_addr);
> > > > +
> > > > + if (status != EFI_SUCCESS) {
> > > > + pr_efi_err("Failed to relocate
> > > > kernel\n");
> > > > + *reserve_size = 0;
> > > > + return status;
> > > > + }
> > > > + *image_addr = *reserve_addr + TEXT_OFFSET;
> > > > + }
> > > > + memcpy((void *)*image_addr, image->image_base,
> > > > kernel_size);
> > > > +
> > > > + return EFI_SUCCESS;
> > > > +}
> > > > --
> > > > 2.24.0
> > > >
> >
> > --
> > Regards,
> > Atish

--
Regards,
Atish

2020-02-28 06:57:49

by Ard Biesheuvel

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On Fri, 28 Feb 2020 at 02:05, Atish Patra <[email protected]> wrote:
>
> On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote:
> > On Thu, 27 Feb 2020 at 20:53, Atish Patra <[email protected]>
> > wrote:
> > > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote:
> > > > On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> > > > wrote:
> > > > > Add a RISC-V architecture specific stub code that actually
> > > > > copies
> > > > > the
> > > > > actual kernel image to a valid address and jump to it after
> > > > > boot
> > > > > services
> > > > > are terminated. Enable UEFI related kernel configs as well for
> > > > > RISC-V.
> > > > >
> > > > > Signed-off-by: Atish Patra <[email protected]>
> > > > > ---
> > > > > arch/riscv/Kconfig | 20 ++++
> > > > > arch/riscv/Makefile | 1 +
> > > > > arch/riscv/configs/defconfig | 1 +
> > > > > drivers/firmware/efi/libstub/Makefile | 8 ++
> > > > > drivers/firmware/efi/libstub/riscv-stub.c | 135
> > > > > ++++++++++++++++++++++
> > > > > 5 files changed, 165 insertions(+)
> > > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
> > > > >
> > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > > > index 42c122170cfd..68b1d565e51d 100644
> > > > > --- a/arch/riscv/Kconfig
> > > > > +++ b/arch/riscv/Kconfig
> > > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE
> > > > >
> > > > > endchoice
> > > > >
> > > > > +config EFI_STUB
> > > > > + bool
> > > > > +
> > > > > +config EFI
> > > > > + bool "UEFI runtime support"
> > > > > + depends on OF
> > > > > + select LIBFDT
> > > > > + select UCS2_STRING
> > > > > + select EFI_PARAMS_FROM_FDT
> > > > > + select EFI_STUB
> > > > > + select EFI_GENERIC_ARCH_STUB
> > > > > + default y
> > > > > + help
> > > > > + This option provides support for runtime services
> > > > > provided
> > > > > + by UEFI firmware (such as non-volatile variables,
> > > > > realtime
> > > > > + clock, and platform reset). A UEFI stub is also
> > > > > provided
> > > > > to
> > > > > + allow the kernel to be booted as an EFI application.
> > > > > This
> > > > > + is only useful on systems that have UEFI firmware.
> > > > > +
> > > > > endmenu
> > > > >
> > > > > menu "Power management options"
> > > > >
> > > > > source "kernel/power/Kconfig"
> > > > > +source "drivers/firmware/Kconfig"
> > > > >
> > > > > endmenu
> > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > > > > index b9009a2fbaf5..0afaa89ba9ad 100644
> > > > > --- a/arch/riscv/Makefile
> > > > > +++ b/arch/riscv/Makefile
> > > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
> > > > > core-y += arch/riscv/
> > > > >
> > > > > libs-y += arch/riscv/lib/
> > > > > +core-$(CONFIG_EFI_STUB) +=
> > > > > $(objtree)/drivers/firmware/efi/libstub/lib.a
> > > > >
> > > > > PHONY += vdso_install
> > > > > vdso_install:
> > > > > diff --git a/arch/riscv/configs/defconfig
> > > > > b/arch/riscv/configs/defconfig
> > > > > index e2ff95cb3390..0a5d3578f51e 100644
> > > > > --- a/arch/riscv/configs/defconfig
> > > > > +++ b/arch/riscv/configs/defconfig
> > > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
> > > > > # CONFIG_FTRACE is not set
> > > > > # CONFIG_RUNTIME_TESTING_MENU is not set
> > > > > CONFIG_MEMTEST=y
> > > > > +CONFIG_EFI=y
> > > > > diff --git a/drivers/firmware/efi/libstub/Makefile
> > > > > b/drivers/firmware/efi/libstub/Makefile
> > > > > index 2c5b76787126..38facb61745b 100644
> > > > > --- a/drivers/firmware/efi/libstub/Makefile
> > > > > +++ b/drivers/firmware/efi/libstub/Makefile
> > > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) :=
> > > > > $(subst
> > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > cflags-$(CONFIG_ARM) := $(subst
> > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > -fno-builtin -fpic \
> > > > > $(call cc-option,-mno-
> > > > > single-
> > > > > pic-base)
> > > > > +cflags-$(CONFIG_RISCV) := $(subst
> > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > + -fpic
> > > > >
> > > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > > -I$(srctree)/scripts/dtc/libfdt
> > > > >
> > > > > @@ -55,6 +57,7 @@ lib-
> > > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > > efi-stub.o fdt.o string.o \
> > > > > lib-$(CONFIG_ARM) += arm32-stub.o
> > > > > lib-$(CONFIG_ARM64) += arm64-stub.o
> > > > > lib-$(CONFIG_X86) += x86-stub.o
> > > > > +lib-$(CONFIG_RISCV) += riscv-stub.o
> > > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > > >
> > > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --
> > > > > prefix-alloc-sections=.init \
> > > > > --prefix-symbols=__efistub_
> > > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
> > > > >
> > > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-
> > > > > sections=.init \
> > > > > + --prefix-symbols=__efistub_
> > > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
> > > > > +
> > > > > +
> > > > > $(obj)/%.stub.o: $(obj)/%.o FORCE
> > > > > $(call if_changed,stubcopy)
> > > > >
> > > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > new file mode 100644
> > > > > index 000000000000..3935b29ea93a
> > > > > --- /dev/null
> > > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > @@ -0,0 +1,135 @@
> > > > > +// SPDX-License-Identifier: GPL-2.0
> > > > > +/*
> > > > > + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]
> > > > > >
> > > > > + * Copyright (C) 2020 Western Digital Corporation or its
> > > > > affiliates.
> > > > > + *
> > > > > + * This file implements the EFI boot stub for the RISC-V
> > > > > kernel.
> > > > > + * Adapted from ARM64 version at
> > > > > drivers/firmware/efi/libstub/arm64-stub.c.
> > > > > + */
> > > > > +
> > > > > +#include <linux/efi.h>
> > > > > +#include <linux/libfdt.h>
> > > > > +#include <linux/libfdt_env.h>
> > > > > +#include <asm/efi.h>
> > > > > +#include <asm/sections.h>
> > > > > +
> > > > > +#include "efistub.h"
> > > > > +/*
> > > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes
> > > > > beyond a 2 MB
> > > > > + * aligned base for 64 bit and 4MB for 32 bit.
> > > > > + */
> > > > > +#if IS_ENABLED(CONFIG_64BIT)
> > > >
> > > > You can use #ifdef here
> > > >
> > >
> > > ok.
> > >
> > > > > +#define MIN_KIMG_ALIGN SZ_2M
> > > > > +#else
> > > > > +#define MIN_KIMG_ALIGN SZ_4M
> > > > > +#endif
> > > > > +/*
> > > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware
> > > > > that
> > > > > probably sits
> > > > > + * at the beginning of the DRAM.
> > > > > + */
> > > >
> > > > Ugh. Really? On an EFI system, that memory should be reserved in
> > > > some
> > > > way, we shouldn't be able to stomp on it like that.
> > > >
> > >
> > > Currently, we reserve the initial 128KB for run time firmware(only
> > > openSBI for now, EDK2 later) by using PMP (physical memory
> > > protection).
> > > Any acess to that region from supervisor mode (i.e. U-Boot) will
> > > result
> > > in a fault.
> > >
> > > Is it mandatory for UEFI to reserve the beginning of the DRAM ?
> > >
> >
> > It is mandatory to describe which memory is usable and which memory
> > is
> > reserved. If this memory is not usable, you either describe it as
> > reserved, or not describe it at all. Describing it as usable memory,
> > allocating it for the kernel but with a hidden agreement that it is
> > reserved is highly likely to cause problems down the road.
> >
>
> I completely agree with you on this. We have been talking to have a
> booting guide and memory map document for RISC-V Linux to document all
> the idiosyncries of RISC-V. But that has not happend until now.
> Once, the ordered booting patches are merged, I will try to take a stab
> at it.
>
> Other than that, do we need to describe it somewhere in U-boot wrt to
> UEFI so that it doesn't allocate memory from that region ?
>

It is an idiosyncrasy that the firmware should hide from the OS.

What if GRUB comes along and attempts to allocate that memory? Do we
also have to teach it that the first 128 KB memory of free memory are
magic and should not be touched?

So the answer is to mark it as reserved. This way, no UEFI tools,
bootloaders etc will ever try to use it. Then, in the stub, you can
tweak the existing code to cheat a bit, and make the TEXT_OFFSET
window overlap the 128 KB reserved window at the bottom of memory.
Doing that in the stub is fine - this is part of the kernel so it can
know about crazy RISC-V rules.

2020-03-10 07:10:06

by Atish Patra

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On Thu, Feb 27, 2020 at 10:57 PM Ard Biesheuvel <[email protected]> wrote:
>
> On Fri, 28 Feb 2020 at 02:05, Atish Patra <[email protected]> wrote:
> >
> > On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote:
> > > On Thu, 27 Feb 2020 at 20:53, Atish Patra <[email protected]>
> > > wrote:
> > > > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote:
> > > > > On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> > > > > wrote:
> > > > > > Add a RISC-V architecture specific stub code that actually
> > > > > > copies
> > > > > > the
> > > > > > actual kernel image to a valid address and jump to it after
> > > > > > boot
> > > > > > services
> > > > > > are terminated. Enable UEFI related kernel configs as well for
> > > > > > RISC-V.
> > > > > >
> > > > > > Signed-off-by: Atish Patra <[email protected]>
> > > > > > ---
> > > > > > arch/riscv/Kconfig | 20 ++++
> > > > > > arch/riscv/Makefile | 1 +
> > > > > > arch/riscv/configs/defconfig | 1 +
> > > > > > drivers/firmware/efi/libstub/Makefile | 8 ++
> > > > > > drivers/firmware/efi/libstub/riscv-stub.c | 135
> > > > > > ++++++++++++++++++++++
> > > > > > 5 files changed, 165 insertions(+)
> > > > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
> > > > > >
> > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > > > > index 42c122170cfd..68b1d565e51d 100644
> > > > > > --- a/arch/riscv/Kconfig
> > > > > > +++ b/arch/riscv/Kconfig
> > > > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE
> > > > > >
> > > > > > endchoice
> > > > > >
> > > > > > +config EFI_STUB
> > > > > > + bool
> > > > > > +
> > > > > > +config EFI
> > > > > > + bool "UEFI runtime support"
> > > > > > + depends on OF
> > > > > > + select LIBFDT
> > > > > > + select UCS2_STRING
> > > > > > + select EFI_PARAMS_FROM_FDT
> > > > > > + select EFI_STUB
> > > > > > + select EFI_GENERIC_ARCH_STUB
> > > > > > + default y
> > > > > > + help
> > > > > > + This option provides support for runtime services
> > > > > > provided
> > > > > > + by UEFI firmware (such as non-volatile variables,
> > > > > > realtime
> > > > > > + clock, and platform reset). A UEFI stub is also
> > > > > > provided
> > > > > > to
> > > > > > + allow the kernel to be booted as an EFI application.
> > > > > > This
> > > > > > + is only useful on systems that have UEFI firmware.
> > > > > > +
> > > > > > endmenu
> > > > > >
> > > > > > menu "Power management options"
> > > > > >
> > > > > > source "kernel/power/Kconfig"
> > > > > > +source "drivers/firmware/Kconfig"
> > > > > >
> > > > > > endmenu
> > > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > > > > > index b9009a2fbaf5..0afaa89ba9ad 100644
> > > > > > --- a/arch/riscv/Makefile
> > > > > > +++ b/arch/riscv/Makefile
> > > > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
> > > > > > core-y += arch/riscv/
> > > > > >
> > > > > > libs-y += arch/riscv/lib/
> > > > > > +core-$(CONFIG_EFI_STUB) +=
> > > > > > $(objtree)/drivers/firmware/efi/libstub/lib.a
> > > > > >
> > > > > > PHONY += vdso_install
> > > > > > vdso_install:
> > > > > > diff --git a/arch/riscv/configs/defconfig
> > > > > > b/arch/riscv/configs/defconfig
> > > > > > index e2ff95cb3390..0a5d3578f51e 100644
> > > > > > --- a/arch/riscv/configs/defconfig
> > > > > > +++ b/arch/riscv/configs/defconfig
> > > > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
> > > > > > # CONFIG_FTRACE is not set
> > > > > > # CONFIG_RUNTIME_TESTING_MENU is not set
> > > > > > CONFIG_MEMTEST=y
> > > > > > +CONFIG_EFI=y
> > > > > > diff --git a/drivers/firmware/efi/libstub/Makefile
> > > > > > b/drivers/firmware/efi/libstub/Makefile
> > > > > > index 2c5b76787126..38facb61745b 100644
> > > > > > --- a/drivers/firmware/efi/libstub/Makefile
> > > > > > +++ b/drivers/firmware/efi/libstub/Makefile
> > > > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) :=
> > > > > > $(subst
> > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > > cflags-$(CONFIG_ARM) := $(subst
> > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > > -fno-builtin -fpic \
> > > > > > $(call cc-option,-mno-
> > > > > > single-
> > > > > > pic-base)
> > > > > > +cflags-$(CONFIG_RISCV) := $(subst
> > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > > + -fpic
> > > > > >
> > > > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > > > -I$(srctree)/scripts/dtc/libfdt
> > > > > >
> > > > > > @@ -55,6 +57,7 @@ lib-
> > > > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > > > efi-stub.o fdt.o string.o \
> > > > > > lib-$(CONFIG_ARM) += arm32-stub.o
> > > > > > lib-$(CONFIG_ARM64) += arm64-stub.o
> > > > > > lib-$(CONFIG_X86) += x86-stub.o
> > > > > > +lib-$(CONFIG_RISCV) += riscv-stub.o
> > > > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > > > >
> > > > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --
> > > > > > prefix-alloc-sections=.init \
> > > > > > --prefix-symbols=__efistub_
> > > > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
> > > > > >
> > > > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-
> > > > > > sections=.init \
> > > > > > + --prefix-symbols=__efistub_
> > > > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
> > > > > > +
> > > > > > +
> > > > > > $(obj)/%.stub.o: $(obj)/%.o FORCE
> > > > > > $(call if_changed,stubcopy)
> > > > > >
> > > > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > > b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > > new file mode 100644
> > > > > > index 000000000000..3935b29ea93a
> > > > > > --- /dev/null
> > > > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > > @@ -0,0 +1,135 @@
> > > > > > +// SPDX-License-Identifier: GPL-2.0
> > > > > > +/*
> > > > > > + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]
> > > > > > >
> > > > > > + * Copyright (C) 2020 Western Digital Corporation or its
> > > > > > affiliates.
> > > > > > + *
> > > > > > + * This file implements the EFI boot stub for the RISC-V
> > > > > > kernel.
> > > > > > + * Adapted from ARM64 version at
> > > > > > drivers/firmware/efi/libstub/arm64-stub.c.
> > > > > > + */
> > > > > > +
> > > > > > +#include <linux/efi.h>
> > > > > > +#include <linux/libfdt.h>
> > > > > > +#include <linux/libfdt_env.h>
> > > > > > +#include <asm/efi.h>
> > > > > > +#include <asm/sections.h>
> > > > > > +
> > > > > > +#include "efistub.h"
> > > > > > +/*
> > > > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes
> > > > > > beyond a 2 MB
> > > > > > + * aligned base for 64 bit and 4MB for 32 bit.
> > > > > > + */
> > > > > > +#if IS_ENABLED(CONFIG_64BIT)
> > > > >
> > > > > You can use #ifdef here
> > > > >
> > > >
> > > > ok.
> > > >
> > > > > > +#define MIN_KIMG_ALIGN SZ_2M
> > > > > > +#else
> > > > > > +#define MIN_KIMG_ALIGN SZ_4M
> > > > > > +#endif
> > > > > > +/*
> > > > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware
> > > > > > that
> > > > > > probably sits
> > > > > > + * at the beginning of the DRAM.
> > > > > > + */
> > > > >
> > > > > Ugh. Really? On an EFI system, that memory should be reserved in
> > > > > some
> > > > > way, we shouldn't be able to stomp on it like that.
> > > > >
> > > >
> > > > Currently, we reserve the initial 128KB for run time firmware(only
> > > > openSBI for now, EDK2 later) by using PMP (physical memory
> > > > protection).
> > > > Any acess to that region from supervisor mode (i.e. U-Boot) will
> > > > result
> > > > in a fault.
> > > >
> > > > Is it mandatory for UEFI to reserve the beginning of the DRAM ?
> > > >
> > >
> > > It is mandatory to describe which memory is usable and which memory
> > > is
> > > reserved. If this memory is not usable, you either describe it as
> > > reserved, or not describe it at all. Describing it as usable memory,
> > > allocating it for the kernel but with a hidden agreement that it is
> > > reserved is highly likely to cause problems down the road.
> > >
> >
> > I completely agree with you on this. We have been talking to have a
> > booting guide and memory map document for RISC-V Linux to document all
> > the idiosyncries of RISC-V. But that has not happend until now.
> > Once, the ordered booting patches are merged, I will try to take a stab
> > at it.
> >
> > Other than that, do we need to describe it somewhere in U-boot wrt to
> > UEFI so that it doesn't allocate memory from that region ?
> >
>
> It is an idiosyncrasy that the firmware should hide from the OS.
>
> What if GRUB comes along and attempts to allocate that memory? Do we
> also have to teach it that the first 128 KB memory of free memory are
> magic and should not be touched?
>
> So the answer is to mark it as reserved. This way, no UEFI tools,
> bootloaders etc will ever try to use it.

Sounds good to me. We are currently discussing the best approach to
provide reserved memory
information to U-Boot/EDK2. The idea is to U-Boot/EDK2 may have to
update the DT with
reserved-memory node so that Linux is aware of the reservation as well.

Then, in the stub, you can
> tweak the existing code to cheat a bit, and make the TEXT_OFFSET
> window overlap the 128 KB reserved window at the bottom of memory.
> Doing that in the stub is fine - this is part of the kernel so it can
> know about crazy RISC-V rules.

I am bit confused here. Why does EFI stub need to overlap the reserved memory.
I thought EFI stub just needs to parse the DT to find out the reserved
memory region to make sure
that it doesn't try to access/overwrite that region.

--
Regards,
Atish

2020-03-10 07:39:20

by Anup Patel

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On Tue, Mar 10, 2020 at 12:39 PM Atish Patra <[email protected]> wrote:
>
> On Thu, Feb 27, 2020 at 10:57 PM Ard Biesheuvel <[email protected]> wrote:
> >
> > On Fri, 28 Feb 2020 at 02:05, Atish Patra <[email protected]> wrote:
> > >
> > > On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote:
> > > > On Thu, 27 Feb 2020 at 20:53, Atish Patra <[email protected]>
> > > > wrote:
> > > > > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote:
> > > > > > On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
> > > > > > wrote:
> > > > > > > Add a RISC-V architecture specific stub code that actually
> > > > > > > copies
> > > > > > > the
> > > > > > > actual kernel image to a valid address and jump to it after
> > > > > > > boot
> > > > > > > services
> > > > > > > are terminated. Enable UEFI related kernel configs as well for
> > > > > > > RISC-V.
> > > > > > >
> > > > > > > Signed-off-by: Atish Patra <[email protected]>
> > > > > > > ---
> > > > > > > arch/riscv/Kconfig | 20 ++++
> > > > > > > arch/riscv/Makefile | 1 +
> > > > > > > arch/riscv/configs/defconfig | 1 +
> > > > > > > drivers/firmware/efi/libstub/Makefile | 8 ++
> > > > > > > drivers/firmware/efi/libstub/riscv-stub.c | 135
> > > > > > > ++++++++++++++++++++++
> > > > > > > 5 files changed, 165 insertions(+)
> > > > > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
> > > > > > >
> > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > > > > > index 42c122170cfd..68b1d565e51d 100644
> > > > > > > --- a/arch/riscv/Kconfig
> > > > > > > +++ b/arch/riscv/Kconfig
> > > > > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE
> > > > > > >
> > > > > > > endchoice
> > > > > > >
> > > > > > > +config EFI_STUB
> > > > > > > + bool
> > > > > > > +
> > > > > > > +config EFI
> > > > > > > + bool "UEFI runtime support"
> > > > > > > + depends on OF
> > > > > > > + select LIBFDT
> > > > > > > + select UCS2_STRING
> > > > > > > + select EFI_PARAMS_FROM_FDT
> > > > > > > + select EFI_STUB
> > > > > > > + select EFI_GENERIC_ARCH_STUB
> > > > > > > + default y
> > > > > > > + help
> > > > > > > + This option provides support for runtime services
> > > > > > > provided
> > > > > > > + by UEFI firmware (such as non-volatile variables,
> > > > > > > realtime
> > > > > > > + clock, and platform reset). A UEFI stub is also
> > > > > > > provided
> > > > > > > to
> > > > > > > + allow the kernel to be booted as an EFI application.
> > > > > > > This
> > > > > > > + is only useful on systems that have UEFI firmware.
> > > > > > > +
> > > > > > > endmenu
> > > > > > >
> > > > > > > menu "Power management options"
> > > > > > >
> > > > > > > source "kernel/power/Kconfig"
> > > > > > > +source "drivers/firmware/Kconfig"
> > > > > > >
> > > > > > > endmenu
> > > > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > > > > > > index b9009a2fbaf5..0afaa89ba9ad 100644
> > > > > > > --- a/arch/riscv/Makefile
> > > > > > > +++ b/arch/riscv/Makefile
> > > > > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
> > > > > > > core-y += arch/riscv/
> > > > > > >
> > > > > > > libs-y += arch/riscv/lib/
> > > > > > > +core-$(CONFIG_EFI_STUB) +=
> > > > > > > $(objtree)/drivers/firmware/efi/libstub/lib.a
> > > > > > >
> > > > > > > PHONY += vdso_install
> > > > > > > vdso_install:
> > > > > > > diff --git a/arch/riscv/configs/defconfig
> > > > > > > b/arch/riscv/configs/defconfig
> > > > > > > index e2ff95cb3390..0a5d3578f51e 100644
> > > > > > > --- a/arch/riscv/configs/defconfig
> > > > > > > +++ b/arch/riscv/configs/defconfig
> > > > > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
> > > > > > > # CONFIG_FTRACE is not set
> > > > > > > # CONFIG_RUNTIME_TESTING_MENU is not set
> > > > > > > CONFIG_MEMTEST=y
> > > > > > > +CONFIG_EFI=y
> > > > > > > diff --git a/drivers/firmware/efi/libstub/Makefile
> > > > > > > b/drivers/firmware/efi/libstub/Makefile
> > > > > > > index 2c5b76787126..38facb61745b 100644
> > > > > > > --- a/drivers/firmware/efi/libstub/Makefile
> > > > > > > +++ b/drivers/firmware/efi/libstub/Makefile
> > > > > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) :=
> > > > > > > $(subst
> > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > > > cflags-$(CONFIG_ARM) := $(subst
> > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > > > -fno-builtin -fpic \
> > > > > > > $(call cc-option,-mno-
> > > > > > > single-
> > > > > > > pic-base)
> > > > > > > +cflags-$(CONFIG_RISCV) := $(subst
> > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > > > > > + -fpic
> > > > > > >
> > > > > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > > > > -I$(srctree)/scripts/dtc/libfdt
> > > > > > >
> > > > > > > @@ -55,6 +57,7 @@ lib-
> > > > > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) +=
> > > > > > > efi-stub.o fdt.o string.o \
> > > > > > > lib-$(CONFIG_ARM) += arm32-stub.o
> > > > > > > lib-$(CONFIG_ARM64) += arm64-stub.o
> > > > > > > lib-$(CONFIG_X86) += x86-stub.o
> > > > > > > +lib-$(CONFIG_RISCV) += riscv-stub.o
> > > > > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > > > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> > > > > > >
> > > > > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --
> > > > > > > prefix-alloc-sections=.init \
> > > > > > > --prefix-symbols=__efistub_
> > > > > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
> > > > > > >
> > > > > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-
> > > > > > > sections=.init \
> > > > > > > + --prefix-symbols=__efistub_
> > > > > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
> > > > > > > +
> > > > > > > +
> > > > > > > $(obj)/%.stub.o: $(obj)/%.o FORCE
> > > > > > > $(call if_changed,stubcopy)
> > > > > > >
> > > > > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > > > b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > > > new file mode 100644
> > > > > > > index 000000000000..3935b29ea93a
> > > > > > > --- /dev/null
> > > > > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> > > > > > > @@ -0,0 +1,135 @@
> > > > > > > +// SPDX-License-Identifier: GPL-2.0
> > > > > > > +/*
> > > > > > > + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]
> > > > > > > >
> > > > > > > + * Copyright (C) 2020 Western Digital Corporation or its
> > > > > > > affiliates.
> > > > > > > + *
> > > > > > > + * This file implements the EFI boot stub for the RISC-V
> > > > > > > kernel.
> > > > > > > + * Adapted from ARM64 version at
> > > > > > > drivers/firmware/efi/libstub/arm64-stub.c.
> > > > > > > + */
> > > > > > > +
> > > > > > > +#include <linux/efi.h>
> > > > > > > +#include <linux/libfdt.h>
> > > > > > > +#include <linux/libfdt_env.h>
> > > > > > > +#include <asm/efi.h>
> > > > > > > +#include <asm/sections.h>
> > > > > > > +
> > > > > > > +#include "efistub.h"
> > > > > > > +/*
> > > > > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes
> > > > > > > beyond a 2 MB
> > > > > > > + * aligned base for 64 bit and 4MB for 32 bit.
> > > > > > > + */
> > > > > > > +#if IS_ENABLED(CONFIG_64BIT)
> > > > > >
> > > > > > You can use #ifdef here
> > > > > >
> > > > >
> > > > > ok.
> > > > >
> > > > > > > +#define MIN_KIMG_ALIGN SZ_2M
> > > > > > > +#else
> > > > > > > +#define MIN_KIMG_ALIGN SZ_4M
> > > > > > > +#endif
> > > > > > > +/*
> > > > > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware
> > > > > > > that
> > > > > > > probably sits
> > > > > > > + * at the beginning of the DRAM.
> > > > > > > + */
> > > > > >
> > > > > > Ugh. Really? On an EFI system, that memory should be reserved in
> > > > > > some
> > > > > > way, we shouldn't be able to stomp on it like that.
> > > > > >
> > > > >
> > > > > Currently, we reserve the initial 128KB for run time firmware(only
> > > > > openSBI for now, EDK2 later) by using PMP (physical memory
> > > > > protection).
> > > > > Any acess to that region from supervisor mode (i.e. U-Boot) will
> > > > > result
> > > > > in a fault.
> > > > >
> > > > > Is it mandatory for UEFI to reserve the beginning of the DRAM ?
> > > > >
> > > >
> > > > It is mandatory to describe which memory is usable and which memory
> > > > is
> > > > reserved. If this memory is not usable, you either describe it as
> > > > reserved, or not describe it at all. Describing it as usable memory,
> > > > allocating it for the kernel but with a hidden agreement that it is
> > > > reserved is highly likely to cause problems down the road.
> > > >
> > >
> > > I completely agree with you on this. We have been talking to have a
> > > booting guide and memory map document for RISC-V Linux to document all
> > > the idiosyncries of RISC-V. But that has not happend until now.
> > > Once, the ordered booting patches are merged, I will try to take a stab
> > > at it.
> > >
> > > Other than that, do we need to describe it somewhere in U-boot wrt to
> > > UEFI so that it doesn't allocate memory from that region ?
> > >
> >
> > It is an idiosyncrasy that the firmware should hide from the OS.
> >
> > What if GRUB comes along and attempts to allocate that memory? Do we
> > also have to teach it that the first 128 KB memory of free memory are
> > magic and should not be touched?
> >
> > So the answer is to mark it as reserved. This way, no UEFI tools,
> > bootloaders etc will ever try to use it.
>
> Sounds good to me. We are currently discussing the best approach to
> provide reserved memory
> information to U-Boot/EDK2. The idea is to U-Boot/EDK2 may have to
> update the DT with
> reserved-memory node so that Linux is aware of the reservation as well.

The discussion is happening on Github at:
https://github.com/riscv/riscv-sbi-doc/pull/37

Feel free to share your views in above mentioned Github link.

Regards,
Anup

2020-03-10 13:20:01

by Ard Biesheuvel

Subject: Re: [RFC PATCH 5/5] RISC-V: Add EFI stub support.

On 10/03/2020, Atish Patra <[email protected]> wrote:
> On Thu, Feb 27, 2020 at 10:57 PM Ard Biesheuvel <[email protected]> wrote:
>>
>> On Fri, 28 Feb 2020 at 02:05, Atish Patra <[email protected]> wrote:
>> >
>> > On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote:
>> > > On Thu, 27 Feb 2020 at 20:53, Atish Patra <[email protected]>
>> > > wrote:
>> > > > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote:
>> > > > > On Wed, 26 Feb 2020 at 02:10, Atish Patra <[email protected]>
>> > > > > wrote:
>> > > > > > Add a RISC-V architecture specific stub code that actually
>> > > > > > copies
>> > > > > > the
>> > > > > > actual kernel image to a valid address and jump to it after
>> > > > > > boot
>> > > > > > services
>> > > > > > are terminated. Enable UEFI related kernel configs as well for
>> > > > > > RISC-V.
>> > > > > >
>> > > > > > Signed-off-by: Atish Patra <[email protected]>
>> > > > > > ---
>> > > > > > arch/riscv/Kconfig | 20 ++++
>> > > > > > arch/riscv/Makefile | 1 +
>> > > > > > arch/riscv/configs/defconfig | 1 +
>> > > > > > drivers/firmware/efi/libstub/Makefile | 8 ++
>> > > > > > drivers/firmware/efi/libstub/riscv-stub.c | 135
>> > > > > > ++++++++++++++++++++++
>> > > > > > 5 files changed, 165 insertions(+)
>> > > > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c
>> > > > > >
>> > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> > > > > > index 42c122170cfd..68b1d565e51d 100644
>> > > > > > --- a/arch/riscv/Kconfig
>> > > > > > +++ b/arch/riscv/Kconfig
>> > > > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE
>> > > > > >
>> > > > > > endchoice
>> > > > > >
>> > > > > > +config EFI_STUB
>> > > > > > + bool
>> > > > > > +
>> > > > > > +config EFI
>> > > > > > + bool "UEFI runtime support"
>> > > > > > + depends on OF
>> > > > > > + select LIBFDT
>> > > > > > + select UCS2_STRING
>> > > > > > + select EFI_PARAMS_FROM_FDT
>> > > > > > + select EFI_STUB
>> > > > > > + select EFI_GENERIC_ARCH_STUB
>> > > > > > + default y
>> > > > > > + help
>> > > > > > + This option provides support for runtime services
>> > > > > > provided
>> > > > > > + by UEFI firmware (such as non-volatile variables,
>> > > > > > realtime
>> > > > > > + clock, and platform reset). A UEFI stub is also
>> > > > > > provided
>> > > > > > to
>> > > > > > + allow the kernel to be booted as an EFI application.
>> > > > > > This
>> > > > > > + is only useful on systems that have UEFI firmware.
>> > > > > > +
>> > > > > > endmenu
>> > > > > >
>> > > > > > menu "Power management options"
>> > > > > >
>> > > > > > source "kernel/power/Kconfig"
>> > > > > > +source "drivers/firmware/Kconfig"
>> > > > > >
>> > > > > > endmenu
>> > > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
>> > > > > > index b9009a2fbaf5..0afaa89ba9ad 100644
>> > > > > > --- a/arch/riscv/Makefile
>> > > > > > +++ b/arch/riscv/Makefile
>> > > > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o
>> > > > > > core-y += arch/riscv/
>> > > > > >
>> > > > > > libs-y += arch/riscv/lib/
>> > > > > > +core-$(CONFIG_EFI_STUB) +=
>> > > > > > $(objtree)/drivers/firmware/efi/libstub/lib.a
>> > > > > >
>> > > > > > PHONY += vdso_install
>> > > > > > vdso_install:
>> > > > > > diff --git a/arch/riscv/configs/defconfig
>> > > > > > b/arch/riscv/configs/defconfig
>> > > > > > index e2ff95cb3390..0a5d3578f51e 100644
>> > > > > > --- a/arch/riscv/configs/defconfig
>> > > > > > +++ b/arch/riscv/configs/defconfig
>> > > > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
>> > > > > > # CONFIG_FTRACE is not set
>> > > > > > # CONFIG_RUNTIME_TESTING_MENU is not set
>> > > > > > CONFIG_MEMTEST=y
>> > > > > > +CONFIG_EFI=y
>> > > > > > diff --git a/drivers/firmware/efi/libstub/Makefile
>> > > > > > b/drivers/firmware/efi/libstub/Makefile
>> > > > > > index 2c5b76787126..38facb61745b 100644
>> > > > > > --- a/drivers/firmware/efi/libstub/Makefile
>> > > > > > +++ b/drivers/firmware/efi/libstub/Makefile
>> > > > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) :=
>> > > > > > $(subst
>> > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
>> > > > > > cflags-$(CONFIG_ARM) := $(subst
>> > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
>> > > > > > -fno-builtin -fpic \
>> > > > > > $(call cc-option,-mno-
>> > > > > > single-
>> > > > > > pic-base)
>> > > > > > +cflags-$(CONFIG_RISCV) := $(subst
>> > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
>> > > > > > + -fpic
>> > > > > >
>> > > > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) +=
>> > > > > > -I$(srctree)/scripts/dtc/libfdt
>> > > > > >
>> > > > > > @@ -55,6 +57,7 @@ lib-
>> > > > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) +=
>> > > > > > efi-stub.o fdt.o string.o \
>> > > > > > lib-$(CONFIG_ARM) += arm32-stub.o
>> > > > > > lib-$(CONFIG_ARM64) += arm64-stub.o
>> > > > > > lib-$(CONFIG_X86) += x86-stub.o
>> > > > > > +lib-$(CONFIG_RISCV) += riscv-stub.o
>> > > > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
>> > > > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
>> > > > > >
>> > > > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --
>> > > > > > prefix-alloc-sections=.init \
>> > > > > > --prefix-symbols=__efistub_
>> > > > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS
>> > > > > >
>> > > > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc-
>> > > > > > sections=.init \
>> > > > > > + --prefix-symbols=__efistub_
>> > > > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20
>> > > > > > +
>> > > > > > +
>> > > > > > $(obj)/%.stub.o: $(obj)/%.o FORCE
>> > > > > > $(call if_changed,stubcopy)
>> > > > > >
>> > > > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c
>> > > > > > b/drivers/firmware/efi/libstub/riscv-stub.c
>> > > > > > new file mode 100644
>> > > > > > index 000000000000..3935b29ea93a
>> > > > > > --- /dev/null
>> > > > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c
>> > > > > > @@ -0,0 +1,135 @@
>> > > > > > +// SPDX-License-Identifier: GPL-2.0
>> > > > > > +/*
>> > > > > > + * Copyright (C) 2013, 2014 Linaro Ltd; <[email protected]
>> > > > > > >
>> > > > > > + * Copyright (C) 2020 Western Digital Corporation or its
>> > > > > > affiliates.
>> > > > > > + *
>> > > > > > + * This file implements the EFI boot stub for the RISC-V
>> > > > > > kernel.
>> > > > > > + * Adapted from ARM64 version at
>> > > > > > drivers/firmware/efi/libstub/arm64-stub.c.
>> > > > > > + */
>> > > > > > +
>> > > > > > +#include <linux/efi.h>
>> > > > > > +#include <linux/libfdt.h>
>> > > > > > +#include <linux/libfdt_env.h>
>> > > > > > +#include <asm/efi.h>
>> > > > > > +#include <asm/sections.h>
>> > > > > > +
>> > > > > > +#include "efistub.h"
>> > > > > > +/*
>> > > > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes
>> > > > > > beyond a 2 MB
>> > > > > > + * aligned base for 64 bit and 4MB for 32 bit.
>> > > > > > + */
>> > > > > > +#if IS_ENABLED(CONFIG_64BIT)
>> > > > >
>> > > > > You can use #ifdef here
>> > > > >
>> > > >
>> > > > ok.
>> > > >
>> > > > > > +#define MIN_KIMG_ALIGN SZ_2M
>> > > > > > +#else
>> > > > > > +#define MIN_KIMG_ALIGN SZ_4M
>> > > > > > +#endif
>> > > > > > +/*
>> > > > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware
>> > > > > > that
>> > > > > > probably sits
>> > > > > > + * at the beginning of the DRAM.
>> > > > > > + */
>> > > > >
>> > > > > Ugh. Really? On an EFI system, that memory should be reserved in
>> > > > > some
>> > > > > way, we shouldn't be able to stomp on it like that.
>> > > > >
>> > > >
>> > > > Currently, we reserve the initial 128KB for run time firmware(only
>> > > > openSBI for now, EDK2 later) by using PMP (physical memory
>> > > > protection).
>> > > > Any acess to that region from supervisor mode (i.e. U-Boot) will
>> > > > result
>> > > > in a fault.
>> > > >
>> > > > Is it mandatory for UEFI to reserve the beginning of the DRAM ?
>> > > >
>> > >
>> > > It is mandatory to describe which memory is usable and which memory
>> > > is
>> > > reserved. If this memory is not usable, you either describe it as
>> > > reserved, or not describe it at all. Describing it as usable memory,
>> > > allocating it for the kernel but with a hidden agreement that it is
>> > > reserved is highly likely to cause problems down the road.
>> > >
>> >
>> > I completely agree with you on this. We have been talking to have a
>> > booting guide and memory map document for RISC-V Linux to document all
>> > the idiosyncries of RISC-V. But that has not happend until now.
>> > Once, the ordered booting patches are merged, I will try to take a stab
>> > at it.
>> >
>> > Other than that, do we need to describe it somewhere in U-boot wrt to
>> > UEFI so that it doesn't allocate memory from that region ?
>> >
>>
>> It is an idiosyncrasy that the firmware should hide from the OS.
>>
>> What if GRUB comes along and attempts to allocate that memory? Do we
>> also have to teach it that the first 128 KB memory of free memory are
>> magic and should not be touched?
>>
>> So the answer is to mark it as reserved. This way, no UEFI tools,
>> bootloaders etc will ever try to use it.
>
> Sounds good to me. We are currently discussing the best approach to
> provide reserved memory
> information to U-Boot/EDK2. The idea is to U-Boot/EDK2 may have to
> update the DT with
> reserved-memory node so that Linux is aware of the reservation as well.
>

The efi stub disregards dt memory information entirely, so the
reservation should be made in the efi memory map. For edk2, I don’t
think there is any point in adding these reservations to the dt at
all.


> Then, in the stub, you can
>> tweak the existing code to cheat a bit, and make the TEXT_OFFSET
>> window overlap the 128 KB reserved window at the bottom of memory.
>> Doing that in the stub is fine - this is part of the kernel so it can
>> know about crazy RISC-V rules.
>
> I am bit confused here. Why does EFI stub need to overlap the reserved
> memory.
> I thought EFI stub just needs to parse the DT to find out the reserved
> memory region to make sure
> that it doesn't try to access/overwrite that region.

The efi stub does not use dt memory information, since it has its own
memory map. If some memory exists that may not be used for general
allocation, you have to reserve it.

Then, as an optimization, you may combine the stub’s knowledge about
riscv in particular, and decide to use an allocation at the bottom of
memory that partially overlaps in a way that is known to be safe