Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the
LoongArch architecture that add support for the kexec re-boot mechanis
(CONFIG_KEXEC) on LoongArch platforms.
Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
PE format.
I tested this on LoongArch 3A5000 machine and works as expected,
$ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
$ sudo kexec -e
Signed-off-by: Youling Tang <[email protected]>
---
arch/loongarch/Kconfig | 11 ++
arch/loongarch/include/asm/kexec.h | 58 ++++++++
arch/loongarch/kernel/Makefile | 2 +
arch/loongarch/kernel/head.S | 7 +-
arch/loongarch/kernel/machine_kexec.c | 178 ++++++++++++++++++++++++
arch/loongarch/kernel/relocate_kernel.S | 125 +++++++++++++++++
6 files changed, 380 insertions(+), 1 deletion(-)
create mode 100644 arch/loongarch/include/asm/kexec.h
create mode 100644 arch/loongarch/kernel/machine_kexec.c
create mode 100644 arch/loongarch/kernel/relocate_kernel.S
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 45364cffc793..903c82fa958d 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -409,6 +409,17 @@ config FORCE_MAX_ZONEORDER
The page size is not necessarily 4KB. Keep this in mind
when choosing a value for this option.
+config KEXEC
+ bool "Kexec system call"
+ select KEXEC_CORE
+ help
+ kexec is a system call that implements the ability to shutdown your
+ current kernel, and to start another kernel. It is like a reboot
+ but it is independent of the system firmware. And like a reboot
+ you can start any kernel with it, not just Linux.
+
+ The name comes from the similarity to the exec system call.
+
config SECCOMP
bool "Enable seccomp to safely compute untrusted bytecode"
depends on PROC_FS
diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
new file mode 100644
index 000000000000..5c9e7b5eccb8
--- /dev/null
+++ b/arch/loongarch/include/asm/kexec.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * kexec.h for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef _ASM_KEXEC_H
+#define _ASM_KEXEC_H
+
+#include <asm/stacktrace.h>
+#include <asm/page.h>
+
+/* Maximum physical address we can use pages from */
+#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
+/* Maximum address we can reach in physical address mode */
+#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
+ /* Maximum address we can use for the control code buffer */
+#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
+
+/* Reserve a page for the control code buffer */
+#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
+
+/* The native architecture */
+#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
+
+static inline void crash_setup_regs(struct pt_regs *newregs,
+ struct pt_regs *oldregs)
+{
+ if (oldregs)
+ memcpy(newregs, oldregs, sizeof(*newregs));
+ else
+ prepare_frametrace(newregs);
+}
+
+#define ARCH_HAS_KIMAGE_ARCH
+
+struct kimage_arch {
+ unsigned long boot_flag;
+ unsigned long fdt_addr;
+};
+
+typedef void (*do_kexec_t)(unsigned long boot_flag,
+ unsigned long fdt_addr,
+ unsigned long first_ind_entry,
+ unsigned long jump_addr);
+
+struct kimage;
+extern const unsigned char relocate_new_kernel[];
+extern const size_t relocate_new_kernel_size;
+
+#ifdef CONFIG_SMP
+extern atomic_t kexec_ready_to_reboot;
+extern const unsigned char kexec_smp_wait[];
+extern void kexec_reboot(void);
+#endif
+
+#endif /* !_ASM_KEXEC_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index a213e994db68..20b64ac3f128 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU) += fpu.o
obj-$(CONFIG_MODULES) += module.o module-sections.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
+obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
+
obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_SMP) += smp.o
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index 01bac62a6442..22bdf4928325 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -20,7 +20,12 @@
_head:
.word MZ_MAGIC /* "MZ", MS-DOS header */
- .org 0x3c /* 0x04 ~ 0x3b reserved */
+ .org 0x8
+ .quad 0 /* Image load offset from start of RAM */
+ .dword _end - _text /* Effective size of kernel image */
+ .quad 0
+ .dword kernel_entry /* Kernel entry point */
+ .org 0x3c /* 0x28 ~ 0x3b reserved */
.long pe_header - _head /* Offset to the PE header */
pe_header:
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
new file mode 100644
index 000000000000..4ffcd4cd9c8c
--- /dev/null
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * machine_kexec.c for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <linux/compiler.h>
+#include <linux/cpu.h>
+#include <linux/kexec.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/libfdt.h>
+#include <linux/of_fdt.h>
+
+#include <asm/bootinfo.h>
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+
+/* 0x100000 ~ 0x200000 is safe */
+#define KEXEC_CTRL_CODE TO_CACHE(0x100000UL)
+#define KEXEC_BLOB_ADDR TO_CACHE(0x108000UL)
+
+static unsigned long reboot_code_buffer;
+#ifdef CONFIG_SMP
+void (*relocated_kexec_smp_wait)(void *);
+atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
+#endif
+
+static unsigned long jump_addr;
+static unsigned long first_ind_entry;
+static unsigned long boot_flag;
+static unsigned long fdt_addr;
+
+static void kexec_image_info(const struct kimage *kimage)
+{
+ unsigned long i;
+
+ pr_debug("kexec kimage info:\n");
+ pr_debug("\ttype: %d\n", kimage->type);
+ pr_debug("\tstart: %lx\n", kimage->start);
+ pr_debug("\thead: %lx\n", kimage->head);
+ pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
+
+ for (i = 0; i < kimage->nr_segments; i++) {
+ pr_debug("\t segment[%lu]: %016lx - %016lx", i,
+ kimage->segment[i].mem,
+ kimage->segment[i].mem + kimage->segment[i].memsz);
+ pr_debug("\t\t0x%lx bytes, %lu pages\n",
+ (unsigned long)kimage->segment[i].memsz,
+ (unsigned long)kimage->segment[i].memsz / PAGE_SIZE);
+ }
+}
+
+int machine_kexec_prepare(struct kimage *kimage)
+{
+ int i;
+ void *dtb = (void *)KEXEC_BLOB_ADDR;
+
+ kexec_image_info(kimage);
+
+ /* Find the Flattened Device Tree */
+ for (i = 0; i < kimage->nr_segments; i++) {
+ if (!fdt_check_header(kimage->segment[i].buf)) {
+ memcpy(dtb, kimage->segment[i].buf, SZ_64K);
+ kimage->arch.boot_flag = fw_arg0;
+ kimage->arch.fdt_addr = (unsigned long) dtb;
+ break;
+ }
+ continue;
+ }
+
+ /* kexec need a safe page to save reboot_code_buffer */
+ kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
+
+ reboot_code_buffer =
+ (unsigned long)page_address(kimage->control_code_page);
+ memcpy((void *)reboot_code_buffer, relocate_new_kernel,
+ relocate_new_kernel_size);
+
+ /* All secondary cpus now may jump to kexec_smp_wait cycle */
+ relocated_kexec_smp_wait = reboot_code_buffer +
+ (void *)(kexec_smp_wait - relocate_new_kernel);
+
+ return 0;
+}
+
+void machine_kexec_cleanup(struct kimage *kimage)
+{
+}
+
+#ifdef CONFIG_SMP
+void kexec_reboot(void)
+{
+ do_kexec_t do_kexec = NULL;
+
+ /* All secondary cpus go to kexec_smp_wait */
+ if (smp_processor_id() > 0) {
+ relocated_kexec_smp_wait(NULL);
+ unreachable();
+ }
+
+ do_kexec = (void *)reboot_code_buffer;
+ do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr);
+
+ unreachable();
+}
+
+static void kexec_shutdown_secondary(void *)
+{
+ local_irq_disable();
+ while (!atomic_read(&kexec_ready_to_reboot))
+ cpu_relax();
+
+ kexec_reboot();
+}
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+#endif
+
+void machine_shutdown(void)
+{
+ smp_call_function(kexec_shutdown_secondary, NULL, 0);
+}
+
+void machine_kexec(struct kimage *image)
+{
+ unsigned long entry;
+ unsigned long *ptr;
+ struct kimage_arch *internal = &image->arch;
+
+ boot_flag = internal->boot_flag;
+ fdt_addr = internal->fdt_addr;
+
+ jump_addr = (unsigned long)phys_to_virt(image->start);
+
+ first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
+
+ /*
+ * The generic kexec code builds a page list with physical
+ * addresses. they are directly accessible through XKPRANGE
+ * hence the phys_to_virt() call.
+ */
+ for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
+ ptr = (entry & IND_INDIRECTION) ?
+ phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
+ if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
+ *ptr & IND_DESTINATION)
+ *ptr = (unsigned long) phys_to_virt(*ptr);
+ }
+
+ /* Mark offline before disabling local irq. */
+ set_cpu_online(smp_processor_id(), false);
+
+ /* we do not want to be bothered. */
+ local_irq_disable();
+
+ pr_notice("Will call new kernel at %lx\n", jump_addr);
+ pr_notice("FDT image at %lx\n", fdt_addr);
+ pr_notice("Bye ...\n");
+
+ /* Make reboot code buffer available to the boot CPU. */
+ flush_cache_all();
+
+ atomic_set(&kexec_ready_to_reboot, 1);
+
+ /*
+ * We know we were online, and there will be no incoming IPIs at
+ * this point.
+ */
+ set_cpu_online(smp_processor_id(), true);
+
+ /* Ensure remote CPUs observe that we're online before rebooting. */
+ smp_mb__after_atomic();
+
+ kexec_reboot();
+}
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..d1f242f74ea8
--- /dev/null
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * relocate_kernel.S for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kexec.h>
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/regdef.h>
+#include <asm/loongarch.h>
+#include <asm/stackframe.h>
+#include <asm/addrspace.h>
+
+#define IPI_REG_BASE 0x1fe01000
+
+SYM_CODE_START(relocate_new_kernel)
+ /*
+ * s0: Boot flag passed to the new kernel
+ * s1: Virt address of the FDT image
+ * s2: Pointer to the current entry
+ * s3: Virt address to jump to after relocation
+ */
+ move s0, a0
+ move s1, a1
+ move s2, a2
+ move s3, a3
+
+process_entry:
+ PTR_L s4, s2, 0
+ PTR_ADDI s2, s2, SZREG
+
+ /* destination page */
+ andi s5, s4, IND_DESTINATION
+ beqz s5, 1f
+ li.w t0, ~0x1
+ and s6, s4, t0 /* store destination addr in s6 */
+ b process_entry
+
+1:
+ /* indirection page, update s2 */
+ andi s5, s4, IND_INDIRECTION
+ beqz s5, 1f
+ li.w t0, ~0x2
+ and s2, s4, t0
+ b process_entry
+
+1:
+ /* done page */
+ andi s5, s4, IND_DONE
+ beqz s5, 1f
+ b done
+1:
+ /* source page */
+ andi s5, s4, IND_SOURCE
+ beqz s5, process_entry
+ li.w t0, ~0x8
+ and s4, s4, t0
+ li.w s8, (1 << _PAGE_SHIFT) / SZREG
+
+copy_word:
+ /* copy page word by word */
+ REG_L s7, s4, 0
+ REG_S s7, s6, 0
+ PTR_ADDI s6, s6, SZREG
+ PTR_ADDI s4, s4, SZREG
+ LONG_ADDI s8, s8, -1
+ beqz s8, process_entry
+ b copy_word
+ b process_entry
+
+done:
+ dbar 0
+
+ move a0, s0
+ move a1, s1
+ /* jump to the new kernel */
+ jr s3
+SYM_CODE_END(relocate_new_kernel)
+
+#ifdef CONFIG_SMP
+/*
+ * Other CPUs should wait until code is relocated and
+ * then start at entry (?) point.
+ */
+SYM_CODE_START(kexec_smp_wait)
+ li.d t0, IPI_REG_BASE
+ li.d t1, UNCACHE_BASE
+ or t0, t0, t1
+
+ /*
+ * s1:initfn
+ * t0:base t1:cpuid t2:node t3:core t4:count
+ */
+ csrrd t1, LOONGARCH_CSR_CPUID
+ andi t1, t1, CSR_CPUID_COREID
+ andi t3, t1, 0x3
+ slli.w t3, t3, 8 /* get core id */
+ or t0, t0, t3
+ andi t2, t1, 0x3c
+ slli.d t2, t2, 42 /* get node id */
+ or t0, t0, t2
+
+1: li.w t4, 0x100 /* wait for init loop */
+2: addi.w t4, t4, -1 /* limit mailbox access */
+ bnez t4, 2b
+ ld.w s1, t0, 0x20 /* check PC as an indicator */
+ beqz s1, 1b
+ ld.d s1, t0, 0x20 /* get PC via mailbox */
+ ld.d sp, t0, 0x28 /* get SP via mailbox */
+ ld.d tp, t0, 0x30 /* get TP via mailbox */
+
+ li.d t0, CACHE_BASE
+ or s1, s1, t0
+ jr s1 /* jump to initial PC */
+SYM_CODE_END(kexec_smp_wait)
+#endif
+
+relocate_new_kernel_end:
+
+SYM_DATA_START(relocate_new_kernel_size)
+ PTR relocate_new_kernel_end - relocate_new_kernel
+SYM_DATA_END(relocate_new_kernel_size)
--
2.36.0
Hi, Youling,
On 08/29/2022 12:37 PM, Youling Tang wrote:
> Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the
> LoongArch architecture that add support for the kexec re-boot mechanis
> (CONFIG_KEXEC) on LoongArch platforms.
>
> Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
> PE format.
>
> I tested this on LoongArch 3A5000 machine and works as expected,
>
> $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
> $ sudo kexec -e
>
> Signed-off-by: Youling Tang <[email protected]>
> ---
> arch/loongarch/Kconfig | 11 ++
> arch/loongarch/include/asm/kexec.h | 58 ++++++++
> arch/loongarch/kernel/Makefile | 2 +
> arch/loongarch/kernel/head.S | 7 +-
> arch/loongarch/kernel/machine_kexec.c | 178 ++++++++++++++++++++++++
> arch/loongarch/kernel/relocate_kernel.S | 125 +++++++++++++++++
> 6 files changed, 380 insertions(+), 1 deletion(-)
> create mode 100644 arch/loongarch/include/asm/kexec.h
> create mode 100644 arch/loongarch/kernel/machine_kexec.c
> create mode 100644 arch/loongarch/kernel/relocate_kernel.S
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 45364cffc793..903c82fa958d 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -409,6 +409,17 @@ config FORCE_MAX_ZONEORDER
> The page size is not necessarily 4KB. Keep this in mind
> when choosing a value for this option.
>
> +config KEXEC
> + bool "Kexec system call"
> + select KEXEC_CORE
> + help
> + kexec is a system call that implements the ability to shutdown your
> + current kernel, and to start another kernel. It is like a reboot
> + but it is independent of the system firmware. And like a reboot
> + you can start any kernel with it, not just Linux.
> +
> + The name comes from the similarity to the exec system call.
> +
> config SECCOMP
> bool "Enable seccomp to safely compute untrusted bytecode"
> depends on PROC_FS
> diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
> new file mode 100644
> index 000000000000..5c9e7b5eccb8
> --- /dev/null
> +++ b/arch/loongarch/include/asm/kexec.h
> @@ -0,0 +1,58 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * kexec.h for kexec
> + *
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef _ASM_KEXEC_H
> +#define _ASM_KEXEC_H
> +
> +#include <asm/stacktrace.h>
> +#include <asm/page.h>
> +
> +/* Maximum physical address we can use pages from */
> +#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
> +/* Maximum address we can reach in physical address mode */
> +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
> + /* Maximum address we can use for the control code buffer */
> +#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
> +
> +/* Reserve a page for the control code buffer */
> +#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
> +
> +/* The native architecture */
> +#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
> +
> +static inline void crash_setup_regs(struct pt_regs *newregs,
> + struct pt_regs *oldregs)
> +{
> + if (oldregs)
> + memcpy(newregs, oldregs, sizeof(*newregs));
> + else
> + prepare_frametrace(newregs);
> +}
> +
> +#define ARCH_HAS_KIMAGE_ARCH
> +
> +struct kimage_arch {
> + unsigned long boot_flag;
> + unsigned long fdt_addr;
> +};
> +
> +typedef void (*do_kexec_t)(unsigned long boot_flag,
> + unsigned long fdt_addr,
> + unsigned long first_ind_entry,
> + unsigned long jump_addr);
> +
> +struct kimage;
> +extern const unsigned char relocate_new_kernel[];
> +extern const size_t relocate_new_kernel_size;
> +
> +#ifdef CONFIG_SMP
> +extern atomic_t kexec_ready_to_reboot;
> +extern const unsigned char kexec_smp_wait[];
> +extern void kexec_reboot(void);
> +#endif
> +
> +#endif /* !_ASM_KEXEC_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index a213e994db68..20b64ac3f128 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU) += fpu.o
> obj-$(CONFIG_MODULES) += module.o module-sections.o
> obj-$(CONFIG_STACKTRACE) += stacktrace.o
>
> +obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
> +
> obj-$(CONFIG_PROC_FS) += proc.o
>
> obj-$(CONFIG_SMP) += smp.o
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index 01bac62a6442..22bdf4928325 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -20,7 +20,12 @@
>
> _head:
> .word MZ_MAGIC /* "MZ", MS-DOS header */
> - .org 0x3c /* 0x04 ~ 0x3b reserved */
> + .org 0x8
> + .quad 0 /* Image load offset from start of RAM */
> + .dword _end - _text /* Effective size of kernel image */
> + .quad 0
> + .dword kernel_entry /* Kernel entry point */
> + .org 0x3c /* 0x28 ~ 0x3b reserved */
> .long pe_header - _head /* Offset to the PE header */
>
> pe_header:
> diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
> new file mode 100644
> index 000000000000..4ffcd4cd9c8c
> --- /dev/null
> +++ b/arch/loongarch/kernel/machine_kexec.c
> @@ -0,0 +1,178 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * machine_kexec.c for kexec
> + *
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +#include <linux/compiler.h>
> +#include <linux/cpu.h>
> +#include <linux/kexec.h>
> +#include <linux/mm.h>
> +#include <linux/delay.h>
> +#include <linux/libfdt.h>
> +#include <linux/of_fdt.h>
> +
> +#include <asm/bootinfo.h>
> +#include <asm/cacheflush.h>
> +#include <asm/page.h>
> +
> +/* 0x100000 ~ 0x200000 is safe */
> +#define KEXEC_CTRL_CODE TO_CACHE(0x100000UL)
> +#define KEXEC_BLOB_ADDR TO_CACHE(0x108000UL)
> +
> +static unsigned long reboot_code_buffer;
> +#ifdef CONFIG_SMP
> +void (*relocated_kexec_smp_wait)(void *);
> +atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
> +#endif
> +
> +static unsigned long jump_addr;
> +static unsigned long first_ind_entry;
> +static unsigned long boot_flag;
> +static unsigned long fdt_addr;
> +
> +static void kexec_image_info(const struct kimage *kimage)
> +{
> + unsigned long i;
> +
> + pr_debug("kexec kimage info:\n");
> + pr_debug("\ttype: %d\n", kimage->type);
> + pr_debug("\tstart: %lx\n", kimage->start);
> + pr_debug("\thead: %lx\n", kimage->head);
> + pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
> +
> + for (i = 0; i < kimage->nr_segments; i++) {
> + pr_debug("\t segment[%lu]: %016lx - %016lx", i,
> + kimage->segment[i].mem,
> + kimage->segment[i].mem + kimage->segment[i].memsz);
> + pr_debug("\t\t0x%lx bytes, %lu pages\n",
> + (unsigned long)kimage->segment[i].memsz,
> + (unsigned long)kimage->segment[i].memsz / PAGE_SIZE);
> + }
> +}
> +
> +int machine_kexec_prepare(struct kimage *kimage)
> +{
> + int i;
> + void *dtb = (void *)KEXEC_BLOB_ADDR;
> +
> + kexec_image_info(kimage);
> +
> + /* Find the Flattened Device Tree */
> + for (i = 0; i < kimage->nr_segments; i++) {
> + if (!fdt_check_header(kimage->segment[i].buf)) {
> + memcpy(dtb, kimage->segment[i].buf, SZ_64K);
> + kimage->arch.boot_flag = fw_arg0;
> + kimage->arch.fdt_addr = (unsigned long) dtb;
> + break;
> + }
> + continue;
> + }
> +
> + /* kexec need a safe page to save reboot_code_buffer */
> + kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
> +
> + reboot_code_buffer =
> + (unsigned long)page_address(kimage->control_code_page);
> + memcpy((void *)reboot_code_buffer, relocate_new_kernel,
> + relocate_new_kernel_size);
It copys same content to KEXEC_CTRL_CODE each time, could we do this at
boot time?
BTW, our system always keep the low-2MB no used, on mips-loongson or
LoongArch. Is that necessary on LoongArch? We cannot use parameter
'mem=YYM' normally but 'mem=YYM@2M' is ok. And the low-2MB is not
in virtual memory management, although we can get it in kernel.
In kexec/kdump process, we can follows kimage_alloc_control_pages().
When the boot cpu copy complete the second-kernels, all cpus can jump
to a kernel-entry-trampoline which is in kernel image. Then we don't
worry about the code can be destroyed. The kernel-entry-trampoline
get its cpuid, keep non-boot cpus do as kexec_smp_wait and let boot
cpu go kernel-entry. In this way we can drop the low-2MB IMO.
> +
> + /* All secondary cpus now may jump to kexec_smp_wait cycle */
> + relocated_kexec_smp_wait = reboot_code_buffer +
> + (void *)(kexec_smp_wait - relocate_new_kernel);
> +
> + return 0;
> +}
> +
> +void machine_kexec_cleanup(struct kimage *kimage)
> +{
> +}
> +
> +#ifdef CONFIG_SMP
> +void kexec_reboot(void)
> +{
> + do_kexec_t do_kexec = NULL;
> +
> + /* All secondary cpus go to kexec_smp_wait */
> + if (smp_processor_id() > 0) {
> + relocated_kexec_smp_wait(NULL);
> + unreachable();
> + }
> +
> + do_kexec = (void *)reboot_code_buffer;
> + do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr);
> +
> + unreachable();
> +}
> +
> +static void kexec_shutdown_secondary(void *)
> +{
> + local_irq_disable();
> + while (!atomic_read(&kexec_ready_to_reboot))
> + cpu_relax();
> +
> + kexec_reboot();
> +}
> +
> +void machine_crash_shutdown(struct pt_regs *regs)
> +{
> +}
> +#endif
> +
> +void machine_shutdown(void)
> +{
> + smp_call_function(kexec_shutdown_secondary, NULL, 0);
> +}
> +
> +void machine_kexec(struct kimage *image)
> +{
> + unsigned long entry;
> + unsigned long *ptr;
> + struct kimage_arch *internal = &image->arch;
> +
> + boot_flag = internal->boot_flag;
> + fdt_addr = internal->fdt_addr;
> +
> + jump_addr = (unsigned long)phys_to_virt(image->start);
> +
> + first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
> +
> + /*
> + * The generic kexec code builds a page list with physical
> + * addresses. they are directly accessible through XKPRANGE
> + * hence the phys_to_virt() call.
> + */
> + for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
> + ptr = (entry & IND_INDIRECTION) ?
> + phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
> + if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
> + *ptr & IND_DESTINATION)
> + *ptr = (unsigned long) phys_to_virt(*ptr);
> + }
> +
> + /* Mark offline before disabling local irq. */
> + set_cpu_online(smp_processor_id(), false);
> +
> + /* we do not want to be bothered. */
> + local_irq_disable();
> +
> + pr_notice("Will call new kernel at %lx\n", jump_addr);
> + pr_notice("FDT image at %lx\n", fdt_addr);
> + pr_notice("Bye ...\n");
> +
> + /* Make reboot code buffer available to the boot CPU. */
> + flush_cache_all();
> +
> + atomic_set(&kexec_ready_to_reboot, 1);
> +
> + /*
> + * We know we were online, and there will be no incoming IPIs at
> + * this point.
> + */
> + set_cpu_online(smp_processor_id(), true);
> +
> + /* Ensure remote CPUs observe that we're online before rebooting. */
> + smp_mb__after_atomic();
> +
> + kexec_reboot();
> +}
> diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
> new file mode 100644
> index 000000000000..d1f242f74ea8
> --- /dev/null
> +++ b/arch/loongarch/kernel/relocate_kernel.S
> @@ -0,0 +1,125 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * relocate_kernel.S for kexec
> + *
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#include <linux/kexec.h>
> +
> +#include <asm/asm.h>
> +#include <asm/asmmacro.h>
> +#include <asm/regdef.h>
> +#include <asm/loongarch.h>
> +#include <asm/stackframe.h>
> +#include <asm/addrspace.h>
> +
> +#define IPI_REG_BASE 0x1fe01000
> +
> +SYM_CODE_START(relocate_new_kernel)
> + /*
> + * s0: Boot flag passed to the new kernel
> + * s1: Virt address of the FDT image
> + * s2: Pointer to the current entry
> + * s3: Virt address to jump to after relocation
> + */
> + move s0, a0
> + move s1, a1
> + move s2, a2
> + move s3, a3
> +
> +process_entry:
> + PTR_L s4, s2, 0
> + PTR_ADDI s2, s2, SZREG
> +
> + /* destination page */
> + andi s5, s4, IND_DESTINATION
> + beqz s5, 1f
> + li.w t0, ~0x1
> + and s6, s4, t0 /* store destination addr in s6 */
> + b process_entry
> +
> +1:
> + /* indirection page, update s2 */
> + andi s5, s4, IND_INDIRECTION
> + beqz s5, 1f
> + li.w t0, ~0x2
> + and s2, s4, t0
> + b process_entry
> +
> +1:
> + /* done page */
> + andi s5, s4, IND_DONE
> + beqz s5, 1f
> + b done
> +1:
> + /* source page */
> + andi s5, s4, IND_SOURCE
> + beqz s5, process_entry
> + li.w t0, ~0x8
> + and s4, s4, t0
> + li.w s8, (1 << _PAGE_SHIFT) / SZREG
> +
> +copy_word:
> + /* copy page word by word */
> + REG_L s7, s4, 0
> + REG_S s7, s6, 0
> + PTR_ADDI s6, s6, SZREG
> + PTR_ADDI s4, s4, SZREG
> + LONG_ADDI s8, s8, -1
> + beqz s8, process_entry
> + b copy_word
> + b process_entry
> +
> +done:
> + dbar 0
ibar, too?
> +
> + move a0, s0
> + move a1, s1
> + /* jump to the new kernel */
> + jr s3
> +SYM_CODE_END(relocate_new_kernel)
> +
> +#ifdef CONFIG_SMP
> +/*
> + * Other CPUs should wait until code is relocated and
> + * then start at entry (?) point.
> + */
> +SYM_CODE_START(kexec_smp_wait)
> + li.d t0, IPI_REG_BASE
> + li.d t1, UNCACHE_BASE
> + or t0, t0, t1
> +
> + /*
> + * s1:initfn
> + * t0:base t1:cpuid t2:node t3:core t4:count
> + */
> + csrrd t1, LOONGARCH_CSR_CPUID
> + andi t1, t1, CSR_CPUID_COREID
> + andi t3, t1, 0x3
> + slli.w t3, t3, 8 /* get core id */
> + or t0, t0, t3
> + andi t2, t1, 0x3c
> + slli.d t2, t2, 42 /* get node id */
> + or t0, t0, t2
> +
> +1: li.w t4, 0x100 /* wait for init loop */
> +2: addi.w t4, t4, -1 /* limit mailbox access */
> + bnez t4, 2b
> + ld.w s1, t0, 0x20 /* check PC as an indicator */
Can we do this with iocsr*?
Thanks,
Jinyang
> + beqz s1, 1b
> + ld.d s1, t0, 0x20 /* get PC via mailbox */
> + ld.d sp, t0, 0x28 /* get SP via mailbox */
> + ld.d tp, t0, 0x30 /* get TP via mailbox */
> +
> + li.d t0, CACHE_BASE
> + or s1, s1, t0
> + jr s1 /* jump to initial PC */
> +SYM_CODE_END(kexec_smp_wait)
> +#endif
> +
> +relocate_new_kernel_end:
> +
> +SYM_DATA_START(relocate_new_kernel_size)
> + PTR relocate_new_kernel_end - relocate_new_kernel
> +SYM_DATA_END(relocate_new_kernel_size)
Hi, Jinyang
On 08/30/2022 09:53 AM, Jinyang He wrote:
> Hi, Youling,
>
>
> On 08/29/2022 12:37 PM, Youling Tang wrote:
>> Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to
>> the
>> LoongArch architecture that add support for the kexec re-boot mechanis
>> (CONFIG_KEXEC) on LoongArch platforms.
>>
>> Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
>> PE format.
>>
>> I tested this on LoongArch 3A5000 machine and works as expected,
>>
>> $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
>> $ sudo kexec -e
>>
>> Signed-off-by: Youling Tang <[email protected]>
>> ---
>> arch/loongarch/Kconfig | 11 ++
>> arch/loongarch/include/asm/kexec.h | 58 ++++++++
>> arch/loongarch/kernel/Makefile | 2 +
>> arch/loongarch/kernel/head.S | 7 +-
>> arch/loongarch/kernel/machine_kexec.c | 178 ++++++++++++++++++++++++
>> arch/loongarch/kernel/relocate_kernel.S | 125 +++++++++++++++++
>> 6 files changed, 380 insertions(+), 1 deletion(-)
>> create mode 100644 arch/loongarch/include/asm/kexec.h
>> create mode 100644 arch/loongarch/kernel/machine_kexec.c
>> create mode 100644 arch/loongarch/kernel/relocate_kernel.S
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index 45364cffc793..903c82fa958d 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -409,6 +409,17 @@ config FORCE_MAX_ZONEORDER
>> The page size is not necessarily 4KB. Keep this in mind
>> when choosing a value for this option.
>> +config KEXEC
>> + bool "Kexec system call"
>> + select KEXEC_CORE
>> + help
>> + kexec is a system call that implements the ability to shutdown
>> your
>> + current kernel, and to start another kernel. It is like a reboot
>> + but it is independent of the system firmware. And like a reboot
>> + you can start any kernel with it, not just Linux.
>> +
>> + The name comes from the similarity to the exec system call.
>> +
>> config SECCOMP
>> bool "Enable seccomp to safely compute untrusted bytecode"
>> depends on PROC_FS
>> diff --git a/arch/loongarch/include/asm/kexec.h
>> b/arch/loongarch/include/asm/kexec.h
>> new file mode 100644
>> index 000000000000..5c9e7b5eccb8
>> --- /dev/null
>> +++ b/arch/loongarch/include/asm/kexec.h
>> @@ -0,0 +1,58 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * kexec.h for kexec
>> + *
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +
>> +#ifndef _ASM_KEXEC_H
>> +#define _ASM_KEXEC_H
>> +
>> +#include <asm/stacktrace.h>
>> +#include <asm/page.h>
>> +
>> +/* Maximum physical address we can use pages from */
>> +#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
>> +/* Maximum address we can reach in physical address mode */
>> +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
>> + /* Maximum address we can use for the control code buffer */
>> +#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
>> +
>> +/* Reserve a page for the control code buffer */
>> +#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
>> +
>> +/* The native architecture */
>> +#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
>> +
>> +static inline void crash_setup_regs(struct pt_regs *newregs,
>> + struct pt_regs *oldregs)
>> +{
>> + if (oldregs)
>> + memcpy(newregs, oldregs, sizeof(*newregs));
>> + else
>> + prepare_frametrace(newregs);
>> +}
>> +
>> +#define ARCH_HAS_KIMAGE_ARCH
>> +
>> +struct kimage_arch {
>> + unsigned long boot_flag;
>> + unsigned long fdt_addr;
>> +};
>> +
>> +typedef void (*do_kexec_t)(unsigned long boot_flag,
>> + unsigned long fdt_addr,
>> + unsigned long first_ind_entry,
>> + unsigned long jump_addr);
>> +
>> +struct kimage;
>> +extern const unsigned char relocate_new_kernel[];
>> +extern const size_t relocate_new_kernel_size;
>> +
>> +#ifdef CONFIG_SMP
>> +extern atomic_t kexec_ready_to_reboot;
>> +extern const unsigned char kexec_smp_wait[];
>> +extern void kexec_reboot(void);
>> +#endif
>> +
>> +#endif /* !_ASM_KEXEC_H */
>> diff --git a/arch/loongarch/kernel/Makefile
>> b/arch/loongarch/kernel/Makefile
>> index a213e994db68..20b64ac3f128 100644
>> --- a/arch/loongarch/kernel/Makefile
>> +++ b/arch/loongarch/kernel/Makefile
>> @@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU) += fpu.o
>> obj-$(CONFIG_MODULES) += module.o module-sections.o
>> obj-$(CONFIG_STACKTRACE) += stacktrace.o
>> +obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
>> +
>> obj-$(CONFIG_PROC_FS) += proc.o
>> obj-$(CONFIG_SMP) += smp.o
>> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
>> index 01bac62a6442..22bdf4928325 100644
>> --- a/arch/loongarch/kernel/head.S
>> +++ b/arch/loongarch/kernel/head.S
>> @@ -20,7 +20,12 @@
>> _head:
>> .word MZ_MAGIC /* "MZ", MS-DOS header */
>> - .org 0x3c /* 0x04 ~ 0x3b reserved */
>> + .org 0x8
>> + .quad 0 /* Image load offset from start of RAM */
>> + .dword _end - _text /* Effective size of kernel image */
>> + .quad 0
>> + .dword kernel_entry /* Kernel entry point */
>> + .org 0x3c /* 0x28 ~ 0x3b reserved */
>> .long pe_header - _head /* Offset to the PE header */
>> pe_header:
>> diff --git a/arch/loongarch/kernel/machine_kexec.c
>> b/arch/loongarch/kernel/machine_kexec.c
>> new file mode 100644
>> index 000000000000..4ffcd4cd9c8c
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/machine_kexec.c
>> @@ -0,0 +1,178 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * machine_kexec.c for kexec
>> + *
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#include <linux/compiler.h>
>> +#include <linux/cpu.h>
>> +#include <linux/kexec.h>
>> +#include <linux/mm.h>
>> +#include <linux/delay.h>
>> +#include <linux/libfdt.h>
>> +#include <linux/of_fdt.h>
>> +
>> +#include <asm/bootinfo.h>
>> +#include <asm/cacheflush.h>
>> +#include <asm/page.h>
>> +
>> +/* 0x100000 ~ 0x200000 is safe */
>> +#define KEXEC_CTRL_CODE TO_CACHE(0x100000UL)
>> +#define KEXEC_BLOB_ADDR TO_CACHE(0x108000UL)
>> +
>> +static unsigned long reboot_code_buffer;
>> +#ifdef CONFIG_SMP
>> +void (*relocated_kexec_smp_wait)(void *);
>> +atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
>> +#endif
>> +
>> +static unsigned long jump_addr;
>> +static unsigned long first_ind_entry;
>> +static unsigned long boot_flag;
>> +static unsigned long fdt_addr;
>> +
>> +static void kexec_image_info(const struct kimage *kimage)
>> +{
>> + unsigned long i;
>> +
>> + pr_debug("kexec kimage info:\n");
>> + pr_debug("\ttype: %d\n", kimage->type);
>> + pr_debug("\tstart: %lx\n", kimage->start);
>> + pr_debug("\thead: %lx\n", kimage->head);
>> + pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
>> +
>> + for (i = 0; i < kimage->nr_segments; i++) {
>> + pr_debug("\t segment[%lu]: %016lx - %016lx", i,
>> + kimage->segment[i].mem,
>> + kimage->segment[i].mem + kimage->segment[i].memsz);
>> + pr_debug("\t\t0x%lx bytes, %lu pages\n",
>> + (unsigned long)kimage->segment[i].memsz,
>> + (unsigned long)kimage->segment[i].memsz / PAGE_SIZE);
>> + }
>> +}
>> +
>> +int machine_kexec_prepare(struct kimage *kimage)
>> +{
>> + int i;
>> + void *dtb = (void *)KEXEC_BLOB_ADDR;
>> +
>> + kexec_image_info(kimage);
>> +
>> + /* Find the Flattened Device Tree */
>> + for (i = 0; i < kimage->nr_segments; i++) {
>> + if (!fdt_check_header(kimage->segment[i].buf)) {
>> + memcpy(dtb, kimage->segment[i].buf, SZ_64K);
>> + kimage->arch.boot_flag = fw_arg0;
>> + kimage->arch.fdt_addr = (unsigned long) dtb;
>> + break;
>> + }
>> + continue;
>> + }
>> +
>> + /* kexec need a safe page to save reboot_code_buffer */
>> + kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
>> +
>> + reboot_code_buffer =
>> + (unsigned long)page_address(kimage->control_code_page);
>> + memcpy((void *)reboot_code_buffer, relocate_new_kernel,
>> + relocate_new_kernel_size);
> It copys same content to KEXEC_CTRL_CODE each time, could we do this at
> boot time?
I think it's possible to have the copy action happen at boot-time or
during the prepare phase. (RISCV in prepare, MIPS in boot-time)
>
> BTW, our system always keep the low-2MB no used, on mips-loongson or
> LoongArch. Is that necessary on LoongArch? We cannot use parameter
> 'mem=YYM' normally but 'mem=YYM@2M' is ok. And the low-2MB is not
> in virtual memory management, although we can get it in kernel.
For existing kernels, the low 2M has been reserved by
memblock_reserve(PHYS_OFFSET, 0x200000), maybe it is acceptable to keep
the low 2M behavior.
Yes, we need to use "mem=YM@2M" if the low 2M is reserved.
>
> In kexec/kdump process, we can follows kimage_alloc_control_pages().
> When the boot cpu copy complete the second-kernels, all cpus can jump
> to a kernel-entry-trampoline which is in kernel image. Then we don't
> worry about the code can be destroyed. The kernel-entry-trampoline
> get its cpuid, keep non-boot cpus do as kexec_smp_wait and let boot
> cpu go kernel-entry. In this way we can drop the low-2MB IMO.
It is also feasible to dynamically allocate control pages, but it is
easier to use a low 2M approach. What do you think, Huacai?
>
>> +
>> + /* All secondary cpus now may jump to kexec_smp_wait cycle */
>> + relocated_kexec_smp_wait = reboot_code_buffer +
>> + (void *)(kexec_smp_wait - relocate_new_kernel);
>> +
>> + return 0;
>> +}
>> +
>> +void machine_kexec_cleanup(struct kimage *kimage)
>> +{
>> +}
>> +
>> +#ifdef CONFIG_SMP
>> +void kexec_reboot(void)
>> +{
>> + do_kexec_t do_kexec = NULL;
>> +
>> + /* All secondary cpus go to kexec_smp_wait */
>> + if (smp_processor_id() > 0) {
>> + relocated_kexec_smp_wait(NULL);
>> + unreachable();
>> + }
>> +
>> + do_kexec = (void *)reboot_code_buffer;
>> + do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr);
>> +
>> + unreachable();
>> +}
>> +
>> +static void kexec_shutdown_secondary(void *)
>> +{
>> + local_irq_disable();
>> + while (!atomic_read(&kexec_ready_to_reboot))
>> + cpu_relax();
>> +
>> + kexec_reboot();
>> +}
>> +
>> +void machine_crash_shutdown(struct pt_regs *regs)
>> +{
>> +}
>> +#endif
>> +
>> +void machine_shutdown(void)
>> +{
>> + smp_call_function(kexec_shutdown_secondary, NULL, 0);
>> +}
>> +
>> +void machine_kexec(struct kimage *image)
>> +{
>> + unsigned long entry;
>> + unsigned long *ptr;
>> + struct kimage_arch *internal = &image->arch;
>> +
>> + boot_flag = internal->boot_flag;
>> + fdt_addr = internal->fdt_addr;
>> +
>> + jump_addr = (unsigned long)phys_to_virt(image->start);
>> +
>> + first_ind_entry = (unsigned long)phys_to_virt(image->head &
>> PAGE_MASK);
>> +
>> + /*
>> + * The generic kexec code builds a page list with physical
>> + * addresses. they are directly accessible through XKPRANGE
>> + * hence the phys_to_virt() call.
>> + */
>> + for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
>> + ptr = (entry & IND_INDIRECTION) ?
>> + phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
>> + if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
>> + *ptr & IND_DESTINATION)
>> + *ptr = (unsigned long) phys_to_virt(*ptr);
>> + }
>> +
>> + /* Mark offline before disabling local irq. */
>> + set_cpu_online(smp_processor_id(), false);
>> +
>> + /* we do not want to be bothered. */
>> + local_irq_disable();
>> +
>> + pr_notice("Will call new kernel at %lx\n", jump_addr);
>> + pr_notice("FDT image at %lx\n", fdt_addr);
>> + pr_notice("Bye ...\n");
>> +
>> + /* Make reboot code buffer available to the boot CPU. */
>> + flush_cache_all();
>> +
>> + atomic_set(&kexec_ready_to_reboot, 1);
>> +
>> + /*
>> + * We know we were online, and there will be no incoming IPIs at
>> + * this point.
>> + */
>> + set_cpu_online(smp_processor_id(), true);
>> +
>> + /* Ensure remote CPUs observe that we're online before rebooting. */
>> + smp_mb__after_atomic();
>> +
>> + kexec_reboot();
>> +}
>> diff --git a/arch/loongarch/kernel/relocate_kernel.S
>> b/arch/loongarch/kernel/relocate_kernel.S
>> new file mode 100644
>> index 000000000000..d1f242f74ea8
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/relocate_kernel.S
>> @@ -0,0 +1,125 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * relocate_kernel.S for kexec
>> + *
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +
>> +#include <linux/kexec.h>
>> +
>> +#include <asm/asm.h>
>> +#include <asm/asmmacro.h>
>> +#include <asm/regdef.h>
>> +#include <asm/loongarch.h>
>> +#include <asm/stackframe.h>
>> +#include <asm/addrspace.h>
>> +
>> +#define IPI_REG_BASE 0x1fe01000
>> +
>> +SYM_CODE_START(relocate_new_kernel)
>> + /*
>> + * s0: Boot flag passed to the new kernel
>> + * s1: Virt address of the FDT image
>> + * s2: Pointer to the current entry
>> + * s3: Virt address to jump to after relocation
>> + */
>> + move s0, a0
>> + move s1, a1
>> + move s2, a2
>> + move s3, a3
>> +
>> +process_entry:
>> + PTR_L s4, s2, 0
>> + PTR_ADDI s2, s2, SZREG
>> +
>> + /* destination page */
>> + andi s5, s4, IND_DESTINATION
>> + beqz s5, 1f
>> + li.w t0, ~0x1
>> + and s6, s4, t0 /* store destination addr in s6 */
>> + b process_entry
>> +
>> +1:
>> + /* indirection page, update s2 */
>> + andi s5, s4, IND_INDIRECTION
>> + beqz s5, 1f
>> + li.w t0, ~0x2
>> + and s2, s4, t0
>> + b process_entry
>> +
>> +1:
>> + /* done page */
>> + andi s5, s4, IND_DONE
>> + beqz s5, 1f
>> + b done
>> +1:
>> + /* source page */
>> + andi s5, s4, IND_SOURCE
>> + beqz s5, process_entry
>> + li.w t0, ~0x8
>> + and s4, s4, t0
>> + li.w s8, (1 << _PAGE_SHIFT) / SZREG
>> +
>> +copy_word:
>> + /* copy page word by word */
>> + REG_L s7, s4, 0
>> + REG_S s7, s6, 0
>> + PTR_ADDI s6, s6, SZREG
>> + PTR_ADDI s4, s4, SZREG
>> + LONG_ADDI s8, s8, -1
>> + beqz s8, process_entry
>> + b copy_word
>> + b process_entry
>> +
>> +done:
>> + dbar 0
> ibar, too?
Will add ibar 0.
>> +
>> + move a0, s0
>> + move a1, s1
>> + /* jump to the new kernel */
>> + jr s3
>> +SYM_CODE_END(relocate_new_kernel)
>> +
>> +#ifdef CONFIG_SMP
>> +/*
>> + * Other CPUs should wait until code is relocated and
>> + * then start at entry (?) point.
>> + */
>> +SYM_CODE_START(kexec_smp_wait)
>> + li.d t0, IPI_REG_BASE
>> + li.d t1, UNCACHE_BASE
>> + or t0, t0, t1
>> +
>> + /*
>> + * s1:initfn
>> + * t0:base t1:cpuid t2:node t3:core t4:count
>> + */
>> + csrrd t1, LOONGARCH_CSR_CPUID
>> + andi t1, t1, CSR_CPUID_COREID
>> + andi t3, t1, 0x3
>> + slli.w t3, t3, 8 /* get core id */
>> + or t0, t0, t3
>> + andi t2, t1, 0x3c
>> + slli.d t2, t2, 42 /* get node id */
>> + or t0, t0, t2
>> +
>> +1: li.w t4, 0x100 /* wait for init loop */
>> +2: addi.w t4, t4, -1 /* limit mailbox access */
>> + bnez t4, 2b
>> + ld.w s1, t0, 0x20 /* check PC as an indicator */
> Can we do this with iocsr*?
OK, I will consider the implementation in the iocsr way.
Thanks,
Youling
>
> Thanks,
> Jinyang
>> + beqz s1, 1b
>> + ld.d s1, t0, 0x20 /* get PC via mailbox */
>> + ld.d sp, t0, 0x28 /* get SP via mailbox */
>> + ld.d tp, t0, 0x30 /* get TP via mailbox */
>> +
>> + li.d t0, CACHE_BASE
>> + or s1, s1, t0
>> + jr s1 /* jump to initial PC */
>> +SYM_CODE_END(kexec_smp_wait)
>> +#endif
>> +
>> +relocate_new_kernel_end:
>> +
>> +SYM_DATA_START(relocate_new_kernel_size)
>> + PTR relocate_new_kernel_end - relocate_new_kernel
>> +SYM_DATA_END(relocate_new_kernel_size)
>
On Tue, Aug 30, 2022 at 11:26 AM Youling Tang <[email protected]> wrote:
>
> Hi, Jinyang
>
> On 08/30/2022 09:53 AM, Jinyang He wrote:
> > Hi, Youling,
> >
> >
> > On 08/29/2022 12:37 PM, Youling Tang wrote:
> >> Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to
> >> the
> >> LoongArch architecture that add support for the kexec re-boot mechanis
> >> (CONFIG_KEXEC) on LoongArch platforms.
> >>
> >> Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
> >> PE format.
> >>
> >> I tested this on LoongArch 3A5000 machine and works as expected,
> >>
> >> $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
> >> $ sudo kexec -e
> >>
> >> Signed-off-by: Youling Tang <[email protected]>
> >> ---
> >> arch/loongarch/Kconfig | 11 ++
> >> arch/loongarch/include/asm/kexec.h | 58 ++++++++
> >> arch/loongarch/kernel/Makefile | 2 +
> >> arch/loongarch/kernel/head.S | 7 +-
> >> arch/loongarch/kernel/machine_kexec.c | 178 ++++++++++++++++++++++++
> >> arch/loongarch/kernel/relocate_kernel.S | 125 +++++++++++++++++
> >> 6 files changed, 380 insertions(+), 1 deletion(-)
> >> create mode 100644 arch/loongarch/include/asm/kexec.h
> >> create mode 100644 arch/loongarch/kernel/machine_kexec.c
> >> create mode 100644 arch/loongarch/kernel/relocate_kernel.S
> >>
> >> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> >> index 45364cffc793..903c82fa958d 100644
> >> --- a/arch/loongarch/Kconfig
> >> +++ b/arch/loongarch/Kconfig
> >> @@ -409,6 +409,17 @@ config FORCE_MAX_ZONEORDER
> >> The page size is not necessarily 4KB. Keep this in mind
> >> when choosing a value for this option.
> >> +config KEXEC
> >> + bool "Kexec system call"
> >> + select KEXEC_CORE
> >> + help
> >> + kexec is a system call that implements the ability to shutdown
> >> your
> >> + current kernel, and to start another kernel. It is like a reboot
> >> + but it is independent of the system firmware. And like a reboot
> >> + you can start any kernel with it, not just Linux.
> >> +
> >> + The name comes from the similarity to the exec system call.
> >> +
> >> config SECCOMP
> >> bool "Enable seccomp to safely compute untrusted bytecode"
> >> depends on PROC_FS
> >> diff --git a/arch/loongarch/include/asm/kexec.h
> >> b/arch/loongarch/include/asm/kexec.h
> >> new file mode 100644
> >> index 000000000000..5c9e7b5eccb8
> >> --- /dev/null
> >> +++ b/arch/loongarch/include/asm/kexec.h
> >> @@ -0,0 +1,58 @@
> >> +/* SPDX-License-Identifier: GPL-2.0 */
> >> +/*
> >> + * kexec.h for kexec
> >> + *
> >> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> >> + */
> >> +
> >> +#ifndef _ASM_KEXEC_H
> >> +#define _ASM_KEXEC_H
> >> +
> >> +#include <asm/stacktrace.h>
> >> +#include <asm/page.h>
> >> +
> >> +/* Maximum physical address we can use pages from */
> >> +#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
> >> +/* Maximum address we can reach in physical address mode */
> >> +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
> >> + /* Maximum address we can use for the control code buffer */
> >> +#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
> >> +
> >> +/* Reserve a page for the control code buffer */
> >> +#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
> >> +
> >> +/* The native architecture */
> >> +#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
> >> +
> >> +static inline void crash_setup_regs(struct pt_regs *newregs,
> >> + struct pt_regs *oldregs)
> >> +{
> >> + if (oldregs)
> >> + memcpy(newregs, oldregs, sizeof(*newregs));
> >> + else
> >> + prepare_frametrace(newregs);
> >> +}
> >> +
> >> +#define ARCH_HAS_KIMAGE_ARCH
> >> +
> >> +struct kimage_arch {
> >> + unsigned long boot_flag;
> >> + unsigned long fdt_addr;
> >> +};
> >> +
> >> +typedef void (*do_kexec_t)(unsigned long boot_flag,
> >> + unsigned long fdt_addr,
> >> + unsigned long first_ind_entry,
> >> + unsigned long jump_addr);
> >> +
> >> +struct kimage;
> >> +extern const unsigned char relocate_new_kernel[];
> >> +extern const size_t relocate_new_kernel_size;
> >> +
> >> +#ifdef CONFIG_SMP
> >> +extern atomic_t kexec_ready_to_reboot;
> >> +extern const unsigned char kexec_smp_wait[];
> >> +extern void kexec_reboot(void);
> >> +#endif
> >> +
> >> +#endif /* !_ASM_KEXEC_H */
> >> diff --git a/arch/loongarch/kernel/Makefile
> >> b/arch/loongarch/kernel/Makefile
> >> index a213e994db68..20b64ac3f128 100644
> >> --- a/arch/loongarch/kernel/Makefile
> >> +++ b/arch/loongarch/kernel/Makefile
> >> @@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU) += fpu.o
> >> obj-$(CONFIG_MODULES) += module.o module-sections.o
> >> obj-$(CONFIG_STACKTRACE) += stacktrace.o
> >> +obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
> >> +
> >> obj-$(CONFIG_PROC_FS) += proc.o
> >> obj-$(CONFIG_SMP) += smp.o
> >> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> >> index 01bac62a6442..22bdf4928325 100644
> >> --- a/arch/loongarch/kernel/head.S
> >> +++ b/arch/loongarch/kernel/head.S
> >> @@ -20,7 +20,12 @@
> >> _head:
> >> .word MZ_MAGIC /* "MZ", MS-DOS header */
> >> - .org 0x3c /* 0x04 ~ 0x3b reserved */
> >> + .org 0x8
> >> + .quad 0 /* Image load offset from start of RAM */
> >> + .dword _end - _text /* Effective size of kernel image */
> >> + .quad 0
> >> + .dword kernel_entry /* Kernel entry point */
> >> + .org 0x3c /* 0x28 ~ 0x3b reserved */
> >> .long pe_header - _head /* Offset to the PE header */
> >> pe_header:
> >> diff --git a/arch/loongarch/kernel/machine_kexec.c
> >> b/arch/loongarch/kernel/machine_kexec.c
> >> new file mode 100644
> >> index 000000000000..4ffcd4cd9c8c
> >> --- /dev/null
> >> +++ b/arch/loongarch/kernel/machine_kexec.c
> >> @@ -0,0 +1,178 @@
> >> +// SPDX-License-Identifier: GPL-2.0-only
> >> +/*
> >> + * machine_kexec.c for kexec
> >> + *
> >> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> >> + */
> >> +#include <linux/compiler.h>
> >> +#include <linux/cpu.h>
> >> +#include <linux/kexec.h>
> >> +#include <linux/mm.h>
> >> +#include <linux/delay.h>
> >> +#include <linux/libfdt.h>
> >> +#include <linux/of_fdt.h>
> >> +
> >> +#include <asm/bootinfo.h>
> >> +#include <asm/cacheflush.h>
> >> +#include <asm/page.h>
> >> +
> >> +/* 0x100000 ~ 0x200000 is safe */
> >> +#define KEXEC_CTRL_CODE TO_CACHE(0x100000UL)
> >> +#define KEXEC_BLOB_ADDR TO_CACHE(0x108000UL)
> >> +
> >> +static unsigned long reboot_code_buffer;
> >> +#ifdef CONFIG_SMP
> >> +void (*relocated_kexec_smp_wait)(void *);
> >> +atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
> >> +#endif
> >> +
> >> +static unsigned long jump_addr;
> >> +static unsigned long first_ind_entry;
> >> +static unsigned long boot_flag;
> >> +static unsigned long fdt_addr;
> >> +
> >> +static void kexec_image_info(const struct kimage *kimage)
> >> +{
> >> + unsigned long i;
> >> +
> >> + pr_debug("kexec kimage info:\n");
> >> + pr_debug("\ttype: %d\n", kimage->type);
> >> + pr_debug("\tstart: %lx\n", kimage->start);
> >> + pr_debug("\thead: %lx\n", kimage->head);
> >> + pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
> >> +
> >> + for (i = 0; i < kimage->nr_segments; i++) {
> >> + pr_debug("\t segment[%lu]: %016lx - %016lx", i,
> >> + kimage->segment[i].mem,
> >> + kimage->segment[i].mem + kimage->segment[i].memsz);
> >> + pr_debug("\t\t0x%lx bytes, %lu pages\n",
> >> + (unsigned long)kimage->segment[i].memsz,
> >> + (unsigned long)kimage->segment[i].memsz / PAGE_SIZE);
> >> + }
> >> +}
> >> +
> >> +int machine_kexec_prepare(struct kimage *kimage)
> >> +{
> >> + int i;
> >> + void *dtb = (void *)KEXEC_BLOB_ADDR;
> >> +
> >> + kexec_image_info(kimage);
> >> +
> >> + /* Find the Flattened Device Tree */
> >> + for (i = 0; i < kimage->nr_segments; i++) {
> >> + if (!fdt_check_header(kimage->segment[i].buf)) {
> >> + memcpy(dtb, kimage->segment[i].buf, SZ_64K);
> >> + kimage->arch.boot_flag = fw_arg0;
> >> + kimage->arch.fdt_addr = (unsigned long) dtb;
> >> + break;
> >> + }
> >> + continue;
> >> + }
> >> +
> >> + /* kexec need a safe page to save reboot_code_buffer */
> >> + kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
> >> +
> >> + reboot_code_buffer =
> >> + (unsigned long)page_address(kimage->control_code_page);
> >> + memcpy((void *)reboot_code_buffer, relocate_new_kernel,
> >> + relocate_new_kernel_size);
> > It copys same content to KEXEC_CTRL_CODE each time, could we do this at
> > boot time?
> I think it's possible to have the copy action happen at boot-time or
> during the prepare phase. (RISCV in prepare, MIPS in boot-time)
>
> >
> > BTW, our system always keep the low-2MB no used, on mips-loongson or
> > LoongArch. Is that necessary on LoongArch? We cannot use parameter
> > 'mem=YYM' normally but 'mem=YYM@2M' is ok. And the low-2MB is not
> > in virtual memory management, although we can get it in kernel.
> For existing kernels, the low 2M has been reserved by
> memblock_reserve(PHYS_OFFSET, 0x200000), maybe it is acceptable to keep
> the low 2M behavior.
>
> Yes, we need to use "mem=YM@2M" if the low 2M is reserved.
>
> >
> > In kexec/kdump process, we can follows kimage_alloc_control_pages().
> > When the boot cpu copy complete the second-kernels, all cpus can jump
> > to a kernel-entry-trampoline which is in kernel image. Then we don't
> > worry about the code can be destroyed. The kernel-entry-trampoline
> > get its cpuid, keep non-boot cpus do as kexec_smp_wait and let boot
> > cpu go kernel-entry. In this way we can drop the low-2MB IMO.
>
> It is also feasible to dynamically allocate control pages, but it is
> easier to use a low 2M approach. What do you think, Huacai?
I prefer to use the low 2MB.
Huacai
>
> >
> >> +
> >> + /* All secondary cpus now may jump to kexec_smp_wait cycle */
> >> + relocated_kexec_smp_wait = reboot_code_buffer +
> >> + (void *)(kexec_smp_wait - relocate_new_kernel);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +void machine_kexec_cleanup(struct kimage *kimage)
> >> +{
> >> +}
> >> +
> >> +#ifdef CONFIG_SMP
> >> +void kexec_reboot(void)
> >> +{
> >> + do_kexec_t do_kexec = NULL;
> >> +
> >> + /* All secondary cpus go to kexec_smp_wait */
> >> + if (smp_processor_id() > 0) {
> >> + relocated_kexec_smp_wait(NULL);
> >> + unreachable();
> >> + }
> >> +
> >> + do_kexec = (void *)reboot_code_buffer;
> >> + do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr);
> >> +
> >> + unreachable();
> >> +}
> >> +
> >> +static void kexec_shutdown_secondary(void *)
> >> +{
> >> + local_irq_disable();
> >> + while (!atomic_read(&kexec_ready_to_reboot))
> >> + cpu_relax();
> >> +
> >> + kexec_reboot();
> >> +}
> >> +
> >> +void machine_crash_shutdown(struct pt_regs *regs)
> >> +{
> >> +}
> >> +#endif
> >> +
> >> +void machine_shutdown(void)
> >> +{
> >> + smp_call_function(kexec_shutdown_secondary, NULL, 0);
> >> +}
> >> +
> >> +void machine_kexec(struct kimage *image)
> >> +{
> >> + unsigned long entry;
> >> + unsigned long *ptr;
> >> + struct kimage_arch *internal = &image->arch;
> >> +
> >> + boot_flag = internal->boot_flag;
> >> + fdt_addr = internal->fdt_addr;
> >> +
> >> + jump_addr = (unsigned long)phys_to_virt(image->start);
> >> +
> >> + first_ind_entry = (unsigned long)phys_to_virt(image->head &
> >> PAGE_MASK);
> >> +
> >> + /*
> >> + * The generic kexec code builds a page list with physical
> >> + * addresses. they are directly accessible through XKPRANGE
> >> + * hence the phys_to_virt() call.
> >> + */
> >> + for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
> >> + ptr = (entry & IND_INDIRECTION) ?
> >> + phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
> >> + if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
> >> + *ptr & IND_DESTINATION)
> >> + *ptr = (unsigned long) phys_to_virt(*ptr);
> >> + }
> >> +
> >> + /* Mark offline before disabling local irq. */
> >> + set_cpu_online(smp_processor_id(), false);
> >> +
> >> + /* we do not want to be bothered. */
> >> + local_irq_disable();
> >> +
> >> + pr_notice("Will call new kernel at %lx\n", jump_addr);
> >> + pr_notice("FDT image at %lx\n", fdt_addr);
> >> + pr_notice("Bye ...\n");
> >> +
> >> + /* Make reboot code buffer available to the boot CPU. */
> >> + flush_cache_all();
> >> +
> >> + atomic_set(&kexec_ready_to_reboot, 1);
> >> +
> >> + /*
> >> + * We know we were online, and there will be no incoming IPIs at
> >> + * this point.
> >> + */
> >> + set_cpu_online(smp_processor_id(), true);
> >> +
> >> + /* Ensure remote CPUs observe that we're online before rebooting. */
> >> + smp_mb__after_atomic();
> >> +
> >> + kexec_reboot();
> >> +}
> >> diff --git a/arch/loongarch/kernel/relocate_kernel.S
> >> b/arch/loongarch/kernel/relocate_kernel.S
> >> new file mode 100644
> >> index 000000000000..d1f242f74ea8
> >> --- /dev/null
> >> +++ b/arch/loongarch/kernel/relocate_kernel.S
> >> @@ -0,0 +1,125 @@
> >> +/* SPDX-License-Identifier: GPL-2.0 */
> >> +/*
> >> + * relocate_kernel.S for kexec
> >> + *
> >> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> >> + */
> >> +
> >> +#include <linux/kexec.h>
> >> +
> >> +#include <asm/asm.h>
> >> +#include <asm/asmmacro.h>
> >> +#include <asm/regdef.h>
> >> +#include <asm/loongarch.h>
> >> +#include <asm/stackframe.h>
> >> +#include <asm/addrspace.h>
> >> +
> >> +#define IPI_REG_BASE 0x1fe01000
> >> +
> >> +SYM_CODE_START(relocate_new_kernel)
> >> + /*
> >> + * s0: Boot flag passed to the new kernel
> >> + * s1: Virt address of the FDT image
> >> + * s2: Pointer to the current entry
> >> + * s3: Virt address to jump to after relocation
> >> + */
> >> + move s0, a0
> >> + move s1, a1
> >> + move s2, a2
> >> + move s3, a3
> >> +
> >> +process_entry:
> >> + PTR_L s4, s2, 0
> >> + PTR_ADDI s2, s2, SZREG
> >> +
> >> + /* destination page */
> >> + andi s5, s4, IND_DESTINATION
> >> + beqz s5, 1f
> >> + li.w t0, ~0x1
> >> + and s6, s4, t0 /* store destination addr in s6 */
> >> + b process_entry
> >> +
> >> +1:
> >> + /* indirection page, update s2 */
> >> + andi s5, s4, IND_INDIRECTION
> >> + beqz s5, 1f
> >> + li.w t0, ~0x2
> >> + and s2, s4, t0
> >> + b process_entry
> >> +
> >> +1:
> >> + /* done page */
> >> + andi s5, s4, IND_DONE
> >> + beqz s5, 1f
> >> + b done
> >> +1:
> >> + /* source page */
> >> + andi s5, s4, IND_SOURCE
> >> + beqz s5, process_entry
> >> + li.w t0, ~0x8
> >> + and s4, s4, t0
> >> + li.w s8, (1 << _PAGE_SHIFT) / SZREG
> >> +
> >> +copy_word:
> >> + /* copy page word by word */
> >> + REG_L s7, s4, 0
> >> + REG_S s7, s6, 0
> >> + PTR_ADDI s6, s6, SZREG
> >> + PTR_ADDI s4, s4, SZREG
> >> + LONG_ADDI s8, s8, -1
> >> + beqz s8, process_entry
> >> + b copy_word
> >> + b process_entry
> >> +
> >> +done:
> >> + dbar 0
> > ibar, too?
>
> Will add ibar 0.
>
> >> +
> >> + move a0, s0
> >> + move a1, s1
> >> + /* jump to the new kernel */
> >> + jr s3
> >> +SYM_CODE_END(relocate_new_kernel)
> >> +
> >> +#ifdef CONFIG_SMP
> >> +/*
> >> + * Other CPUs should wait until code is relocated and
> >> + * then start at entry (?) point.
> >> + */
> >> +SYM_CODE_START(kexec_smp_wait)
> >> + li.d t0, IPI_REG_BASE
> >> + li.d t1, UNCACHE_BASE
> >> + or t0, t0, t1
> >> +
> >> + /*
> >> + * s1:initfn
> >> + * t0:base t1:cpuid t2:node t3:core t4:count
> >> + */
> >> + csrrd t1, LOONGARCH_CSR_CPUID
> >> + andi t1, t1, CSR_CPUID_COREID
> >> + andi t3, t1, 0x3
> >> + slli.w t3, t3, 8 /* get core id */
> >> + or t0, t0, t3
> >> + andi t2, t1, 0x3c
> >> + slli.d t2, t2, 42 /* get node id */
> >> + or t0, t0, t2
> >> +
> >> +1: li.w t4, 0x100 /* wait for init loop */
> >> +2: addi.w t4, t4, -1 /* limit mailbox access */
> >> + bnez t4, 2b
> >> + ld.w s1, t0, 0x20 /* check PC as an indicator */
> > Can we do this with iocsr*?
>
> OK, I will consider the implementation in the iocsr way.
>
> Thanks,
> Youling
> >
> > Thanks,
> > Jinyang
> >> + beqz s1, 1b
> >> + ld.d s1, t0, 0x20 /* get PC via mailbox */
> >> + ld.d sp, t0, 0x28 /* get SP via mailbox */
> >> + ld.d tp, t0, 0x30 /* get TP via mailbox */
> >> +
> >> + li.d t0, CACHE_BASE
> >> + or s1, s1, t0
> >> + jr s1 /* jump to initial PC */
> >> +SYM_CODE_END(kexec_smp_wait)
> >> +#endif
> >> +
> >> +relocate_new_kernel_end:
> >> +
> >> +SYM_DATA_START(relocate_new_kernel_size)
> >> + PTR relocate_new_kernel_end - relocate_new_kernel
> >> +SYM_DATA_END(relocate_new_kernel_size)
> >
>
On 08/30/2022 11:42 AM, Huacai Chen wrote:
> On Tue, Aug 30, 2022 at 11:26 AM Youling Tang <[email protected]> wrote:
>> Hi, Jinyang
>>
>> On 08/30/2022 09:53 AM, Jinyang He wrote:
>>> Hi, Youling,
>>>
>>>
>>> On 08/29/2022 12:37 PM, Youling Tang wrote:
>>>> Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to
>>>> the
>>>> LoongArch architecture that add support for the kexec re-boot mechanis
>>>> (CONFIG_KEXEC) on LoongArch platforms.
>>>>
>>>> Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
>>>> PE format.
>>>>
>>>> I tested this on LoongArch 3A5000 machine and works as expected,
>>>>
>>>> $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
>>>> $ sudo kexec -e
>>>>
>>>> Signed-off-by: Youling Tang <[email protected]>
>>>> ---
>>>> arch/loongarch/Kconfig | 11 ++
>>>> arch/loongarch/include/asm/kexec.h | 58 ++++++++
>>>> arch/loongarch/kernel/Makefile | 2 +
>>>> arch/loongarch/kernel/head.S | 7 +-
>>>> arch/loongarch/kernel/machine_kexec.c | 178 ++++++++++++++++++++++++
>>>> arch/loongarch/kernel/relocate_kernel.S | 125 +++++++++++++++++
>>>> 6 files changed, 380 insertions(+), 1 deletion(-)
>>>> create mode 100644 arch/loongarch/include/asm/kexec.h
>>>> create mode 100644 arch/loongarch/kernel/machine_kexec.c
>>>> create mode 100644 arch/loongarch/kernel/relocate_kernel.S
>>>>
>>>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>>>> index 45364cffc793..903c82fa958d 100644
>>>> --- a/arch/loongarch/Kconfig
>>>> +++ b/arch/loongarch/Kconfig
>>>> @@ -409,6 +409,17 @@ config FORCE_MAX_ZONEORDER
>>>> The page size is not necessarily 4KB. Keep this in mind
>>>> when choosing a value for this option.
>>>> +config KEXEC
>>>> + bool "Kexec system call"
>>>> + select KEXEC_CORE
>>>> + help
>>>> + kexec is a system call that implements the ability to shutdown
>>>> your
>>>> + current kernel, and to start another kernel. It is like a reboot
>>>> + but it is independent of the system firmware. And like a reboot
>>>> + you can start any kernel with it, not just Linux.
>>>> +
>>>> + The name comes from the similarity to the exec system call.
>>>> +
>>>> config SECCOMP
>>>> bool "Enable seccomp to safely compute untrusted bytecode"
>>>> depends on PROC_FS
>>>> diff --git a/arch/loongarch/include/asm/kexec.h
>>>> b/arch/loongarch/include/asm/kexec.h
>>>> new file mode 100644
>>>> index 000000000000..5c9e7b5eccb8
>>>> --- /dev/null
>>>> +++ b/arch/loongarch/include/asm/kexec.h
>>>> @@ -0,0 +1,58 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>> +/*
>>>> + * kexec.h for kexec
>>>> + *
>>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>>>> + */
>>>> +
>>>> +#ifndef _ASM_KEXEC_H
>>>> +#define _ASM_KEXEC_H
>>>> +
>>>> +#include <asm/stacktrace.h>
>>>> +#include <asm/page.h>
>>>> +
>>>> +/* Maximum physical address we can use pages from */
>>>> +#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
>>>> +/* Maximum address we can reach in physical address mode */
>>>> +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
>>>> + /* Maximum address we can use for the control code buffer */
>>>> +#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
>>>> +
>>>> +/* Reserve a page for the control code buffer */
>>>> +#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
>>>> +
>>>> +/* The native architecture */
>>>> +#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
>>>> +
>>>> +static inline void crash_setup_regs(struct pt_regs *newregs,
>>>> + struct pt_regs *oldregs)
>>>> +{
>>>> + if (oldregs)
>>>> + memcpy(newregs, oldregs, sizeof(*newregs));
>>>> + else
>>>> + prepare_frametrace(newregs);
>>>> +}
>>>> +
>>>> +#define ARCH_HAS_KIMAGE_ARCH
>>>> +
>>>> +struct kimage_arch {
>>>> + unsigned long boot_flag;
>>>> + unsigned long fdt_addr;
>>>> +};
>>>> +
>>>> +typedef void (*do_kexec_t)(unsigned long boot_flag,
>>>> + unsigned long fdt_addr,
>>>> + unsigned long first_ind_entry,
>>>> + unsigned long jump_addr);
>>>> +
>>>> +struct kimage;
>>>> +extern const unsigned char relocate_new_kernel[];
>>>> +extern const size_t relocate_new_kernel_size;
>>>> +
>>>> +#ifdef CONFIG_SMP
>>>> +extern atomic_t kexec_ready_to_reboot;
>>>> +extern const unsigned char kexec_smp_wait[];
>>>> +extern void kexec_reboot(void);
>>>> +#endif
>>>> +
>>>> +#endif /* !_ASM_KEXEC_H */
>>>> diff --git a/arch/loongarch/kernel/Makefile
>>>> b/arch/loongarch/kernel/Makefile
>>>> index a213e994db68..20b64ac3f128 100644
>>>> --- a/arch/loongarch/kernel/Makefile
>>>> +++ b/arch/loongarch/kernel/Makefile
>>>> @@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU) += fpu.o
>>>> obj-$(CONFIG_MODULES) += module.o module-sections.o
>>>> obj-$(CONFIG_STACKTRACE) += stacktrace.o
>>>> +obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
>>>> +
>>>> obj-$(CONFIG_PROC_FS) += proc.o
>>>> obj-$(CONFIG_SMP) += smp.o
>>>> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
>>>> index 01bac62a6442..22bdf4928325 100644
>>>> --- a/arch/loongarch/kernel/head.S
>>>> +++ b/arch/loongarch/kernel/head.S
>>>> @@ -20,7 +20,12 @@
>>>> _head:
>>>> .word MZ_MAGIC /* "MZ", MS-DOS header */
>>>> - .org 0x3c /* 0x04 ~ 0x3b reserved */
>>>> + .org 0x8
>>>> + .quad 0 /* Image load offset from start of RAM */
>>>> + .dword _end - _text /* Effective size of kernel image */
>>>> + .quad 0
>>>> + .dword kernel_entry /* Kernel entry point */
>>>> + .org 0x3c /* 0x28 ~ 0x3b reserved */
>>>> .long pe_header - _head /* Offset to the PE header */
>>>> pe_header:
>>>> diff --git a/arch/loongarch/kernel/machine_kexec.c
>>>> b/arch/loongarch/kernel/machine_kexec.c
>>>> new file mode 100644
>>>> index 000000000000..4ffcd4cd9c8c
>>>> --- /dev/null
>>>> +++ b/arch/loongarch/kernel/machine_kexec.c
>>>> @@ -0,0 +1,178 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * machine_kexec.c for kexec
>>>> + *
>>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>>>> + */
>>>> +#include <linux/compiler.h>
>>>> +#include <linux/cpu.h>
>>>> +#include <linux/kexec.h>
>>>> +#include <linux/mm.h>
>>>> +#include <linux/delay.h>
>>>> +#include <linux/libfdt.h>
>>>> +#include <linux/of_fdt.h>
>>>> +
>>>> +#include <asm/bootinfo.h>
>>>> +#include <asm/cacheflush.h>
>>>> +#include <asm/page.h>
>>>> +
>>>> +/* 0x100000 ~ 0x200000 is safe */
>>>> +#define KEXEC_CTRL_CODE TO_CACHE(0x100000UL)
>>>> +#define KEXEC_BLOB_ADDR TO_CACHE(0x108000UL)
>>>> +
>>>> +static unsigned long reboot_code_buffer;
>>>> +#ifdef CONFIG_SMP
>>>> +void (*relocated_kexec_smp_wait)(void *);
>>>> +atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
>>>> +#endif
>>>> +
>>>> +static unsigned long jump_addr;
>>>> +static unsigned long first_ind_entry;
>>>> +static unsigned long boot_flag;
>>>> +static unsigned long fdt_addr;
>>>> +
>>>> +static void kexec_image_info(const struct kimage *kimage)
>>>> +{
>>>> + unsigned long i;
>>>> +
>>>> + pr_debug("kexec kimage info:\n");
>>>> + pr_debug("\ttype: %d\n", kimage->type);
>>>> + pr_debug("\tstart: %lx\n", kimage->start);
>>>> + pr_debug("\thead: %lx\n", kimage->head);
>>>> + pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
>>>> +
>>>> + for (i = 0; i < kimage->nr_segments; i++) {
>>>> + pr_debug("\t segment[%lu]: %016lx - %016lx", i,
>>>> + kimage->segment[i].mem,
>>>> + kimage->segment[i].mem + kimage->segment[i].memsz);
>>>> + pr_debug("\t\t0x%lx bytes, %lu pages\n",
>>>> + (unsigned long)kimage->segment[i].memsz,
>>>> + (unsigned long)kimage->segment[i].memsz / PAGE_SIZE);
>>>> + }
>>>> +}
>>>> +
>>>> +int machine_kexec_prepare(struct kimage *kimage)
>>>> +{
>>>> + int i;
>>>> + void *dtb = (void *)KEXEC_BLOB_ADDR;
>>>> +
>>>> + kexec_image_info(kimage);
>>>> +
>>>> + /* Find the Flattened Device Tree */
>>>> + for (i = 0; i < kimage->nr_segments; i++) {
>>>> + if (!fdt_check_header(kimage->segment[i].buf)) {
>>>> + memcpy(dtb, kimage->segment[i].buf, SZ_64K);
>>>> + kimage->arch.boot_flag = fw_arg0;
>>>> + kimage->arch.fdt_addr = (unsigned long) dtb;
>>>> + break;
>>>> + }
>>>> + continue;
>>>> + }
>>>> +
>>>> + /* kexec need a safe page to save reboot_code_buffer */
>>>> + kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
>>>> +
>>>> + reboot_code_buffer =
>>>> + (unsigned long)page_address(kimage->control_code_page);
>>>> + memcpy((void *)reboot_code_buffer, relocate_new_kernel,
>>>> + relocate_new_kernel_size);
>>> It copys same content to KEXEC_CTRL_CODE each time, could we do this at
>>> boot time?
>> I think it's possible to have the copy action happen at boot-time or
>> during the prepare phase. (RISCV in prepare, MIPS in boot-time)
>>
>>> BTW, our system always keep the low-2MB no used, on mips-loongson or
>>> LoongArch. Is that necessary on LoongArch? We cannot use parameter
>>> 'mem=YYM' normally but 'mem=YYM@2M' is ok. And the low-2MB is not
>>> in virtual memory management, although we can get it in kernel.
>> For existing kernels, the low 2M has been reserved by
>> memblock_reserve(PHYS_OFFSET, 0x200000), maybe it is acceptable to keep
>> the low 2M behavior.
>>
>> Yes, we need to use "mem=YM@2M" if the low 2M is reserved.
>>
>>> In kexec/kdump process, we can follows kimage_alloc_control_pages().
>>> When the boot cpu copy complete the second-kernels, all cpus can jump
>>> to a kernel-entry-trampoline which is in kernel image. Then we don't
>>> worry about the code can be destroyed. The kernel-entry-trampoline
>>> get its cpuid, keep non-boot cpus do as kexec_smp_wait and let boot
>>> cpu go kernel-entry. In this way we can drop the low-2MB IMO.
>> It is also feasible to dynamically allocate control pages, but it is
>> easier to use a low 2M approach. What do you think, Huacai?
> I prefer to use the low 2MB.
>
> Huacai
Low 2MB also is ok for me, like a trick. And should it free
control_code_page here?
>>>> +
>>>> + /* All secondary cpus now may jump to kexec_smp_wait cycle */
>>>> + relocated_kexec_smp_wait = reboot_code_buffer +
>>>> + (void *)(kexec_smp_wait - relocate_new_kernel);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +void machine_kexec_cleanup(struct kimage *kimage)
>>>> +{
>>>> +}
>>>> +
>>>> +#ifdef CONFIG_SMP
>>>> +void kexec_reboot(void)
>>>> +{
>>>> + do_kexec_t do_kexec = NULL;
>>>> +
>>>> + /* All secondary cpus go to kexec_smp_wait */
>>>> + if (smp_processor_id() > 0) {
>>>> + relocated_kexec_smp_wait(NULL);
>>>> + unreachable();
>>>> + }
>>>> +
>>>> + do_kexec = (void *)reboot_code_buffer;
>>>> + do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr);
>>>> +
>>>> + unreachable();
>>>> +}
>>>> +
>>>> +static void kexec_shutdown_secondary(void *)
>>>> +{
>>>> + local_irq_disable();
>>>> + while (!atomic_read(&kexec_ready_to_reboot))
>>>> + cpu_relax();
>>>> +
>>>> + kexec_reboot();
>>>> +}
>>>> +
>>>> +void machine_crash_shutdown(struct pt_regs *regs)
>>>> +{
>>>> +}
>>>> +#endif
>>>> +
>>>> +void machine_shutdown(void)
>>>> +{
>>>> + smp_call_function(kexec_shutdown_secondary, NULL, 0);
>>>> +}
>>>> +
>>>> +void machine_kexec(struct kimage *image)
>>>> +{
>>>> + unsigned long entry;
>>>> + unsigned long *ptr;
>>>> + struct kimage_arch *internal = &image->arch;
>>>> +
>>>> + boot_flag = internal->boot_flag;
>>>> + fdt_addr = internal->fdt_addr;
>>>> +
>>>> + jump_addr = (unsigned long)phys_to_virt(image->start);
>>>> +
>>>> + first_ind_entry = (unsigned long)phys_to_virt(image->head &
>>>> PAGE_MASK);
>>>> +
>>>> + /*
>>>> + * The generic kexec code builds a page list with physical
>>>> + * addresses. they are directly accessible through XKPRANGE
>>>> + * hence the phys_to_virt() call.
>>>> + */
>>>> + for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
>>>> + ptr = (entry & IND_INDIRECTION) ?
>>>> + phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
>>>> + if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
>>>> + *ptr & IND_DESTINATION)
>>>> + *ptr = (unsigned long) phys_to_virt(*ptr);
>>>> + }
>>>> +
>>>> + /* Mark offline before disabling local irq. */
>>>> + set_cpu_online(smp_processor_id(), false);
>>>> +
>>>> + /* we do not want to be bothered. */
>>>> + local_irq_disable();
>>>> +
>>>> + pr_notice("Will call new kernel at %lx\n", jump_addr);
>>>> + pr_notice("FDT image at %lx\n", fdt_addr);
>>>> + pr_notice("Bye ...\n");
>>>> +
>>>> + /* Make reboot code buffer available to the boot CPU. */
>>>> + flush_cache_all();
>>>> +
>>>> + atomic_set(&kexec_ready_to_reboot, 1);
>>>> +
>>>> + /*
>>>> + * We know we were online, and there will be no incoming IPIs at
>>>> + * this point.
>>>> + */
>>>> + set_cpu_online(smp_processor_id(), true);
>>>> +
>>>> + /* Ensure remote CPUs observe that we're online before rebooting. */
>>>> + smp_mb__after_atomic();
>>>> +
>>>> + kexec_reboot();
>>>> +}
>>>> diff --git a/arch/loongarch/kernel/relocate_kernel.S
>>>> b/arch/loongarch/kernel/relocate_kernel.S
>>>> new file mode 100644
>>>> index 000000000000..d1f242f74ea8
>>>> --- /dev/null
>>>> +++ b/arch/loongarch/kernel/relocate_kernel.S
>>>> @@ -0,0 +1,125 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>> +/*
>>>> + * relocate_kernel.S for kexec
>>>> + *
>>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>>>> + */
>>>> +
>>>> +#include <linux/kexec.h>
>>>> +
>>>> +#include <asm/asm.h>
>>>> +#include <asm/asmmacro.h>
>>>> +#include <asm/regdef.h>
>>>> +#include <asm/loongarch.h>
>>>> +#include <asm/stackframe.h>
>>>> +#include <asm/addrspace.h>
>>>> +
>>>> +#define IPI_REG_BASE 0x1fe01000
>>>> +
>>>> +SYM_CODE_START(relocate_new_kernel)
>>>> + /*
>>>> + * s0: Boot flag passed to the new kernel
>>>> + * s1: Virt address of the FDT image
>>>> + * s2: Pointer to the current entry
>>>> + * s3: Virt address to jump to after relocation
>>>> + */
>>>> + move s0, a0
>>>> + move s1, a1
>>>> + move s2, a2
>>>> + move s3, a3
>>>> +
>>>> +process_entry:
>>>> + PTR_L s4, s2, 0
>>>> + PTR_ADDI s2, s2, SZREG
>>>> +
>>>> + /* destination page */
>>>> + andi s5, s4, IND_DESTINATION
>>>> + beqz s5, 1f
>>>> + li.w t0, ~0x1
>>>> + and s6, s4, t0 /* store destination addr in s6 */
>>>> + b process_entry
>>>> +
>>>> +1:
>>>> + /* indirection page, update s2 */
>>>> + andi s5, s4, IND_INDIRECTION
>>>> + beqz s5, 1f
>>>> + li.w t0, ~0x2
>>>> + and s2, s4, t0
>>>> + b process_entry
>>>> +
>>>> +1:
>>>> + /* done page */
>>>> + andi s5, s4, IND_DONE
>>>> + beqz s5, 1f
>>>> + b done
>>>> +1:
>>>> + /* source page */
>>>> + andi s5, s4, IND_SOURCE
>>>> + beqz s5, process_entry
>>>> + li.w t0, ~0x8
>>>> + and s4, s4, t0
>>>> + li.w s8, (1 << _PAGE_SHIFT) / SZREG
>>>> +
>>>> +copy_word:
>>>> + /* copy page word by word */
>>>> + REG_L s7, s4, 0
>>>> + REG_S s7, s6, 0
>>>> + PTR_ADDI s6, s6, SZREG
>>>> + PTR_ADDI s4, s4, SZREG
>>>> + LONG_ADDI s8, s8, -1
>>>> + beqz s8, process_entry
>>>> + b copy_word
>>>> + b process_entry
>>>> +
>>>> +done:
>>>> + dbar 0
>>> ibar, too?
>> Will add ibar 0.
>>
>>>> +
>>>> + move a0, s0
>>>> + move a1, s1
>>>> + /* jump to the new kernel */
>>>> + jr s3
>>>> +SYM_CODE_END(relocate_new_kernel)
>>>> +
>>>> +#ifdef CONFIG_SMP
>>>> +/*
>>>> + * Other CPUs should wait until code is relocated and
>>>> + * then start at entry (?) point.
>>>> + */
>>>> +SYM_CODE_START(kexec_smp_wait)
>>>> + li.d t0, IPI_REG_BASE
>>>> + li.d t1, UNCACHE_BASE
>>>> + or t0, t0, t1
>>>> +
>>>> + /*
>>>> + * s1:initfn
>>>> + * t0:base t1:cpuid t2:node t3:core t4:count
>>>> + */
>>>> + csrrd t1, LOONGARCH_CSR_CPUID
>>>> + andi t1, t1, CSR_CPUID_COREID
>>>> + andi t3, t1, 0x3
>>>> + slli.w t3, t3, 8 /* get core id */
>>>> + or t0, t0, t3
>>>> + andi t2, t1, 0x3c
>>>> + slli.d t2, t2, 42 /* get node id */
>>>> + or t0, t0, t2
>>>> +
>>>> +1: li.w t4, 0x100 /* wait for init loop */
>>>> +2: addi.w t4, t4, -1 /* limit mailbox access */
>>>> + bnez t4, 2b
>>>> + ld.w s1, t0, 0x20 /* check PC as an indicator */
>>> Can we do this with iocsr*?
>> OK, I will consider the implementation in the iocsr way.
>>
>> Thanks,
>> Youling
>>> Thanks,
>>> Jinyang
>>>> + beqz s1, 1b
>>>> + ld.d s1, t0, 0x20 /* get PC via mailbox */
>>>> + ld.d sp, t0, 0x28 /* get SP via mailbox */
>>>> + ld.d tp, t0, 0x30 /* get TP via mailbox */
>>>> +
>>>> + li.d t0, CACHE_BASE
>>>> + or s1, s1, t0
>>>> + jr s1 /* jump to initial PC */
>>>> +SYM_CODE_END(kexec_smp_wait)
>>>> +#endif
>>>> +
>>>> +relocate_new_kernel_end:
>>>> +
>>>> +SYM_DATA_START(relocate_new_kernel_size)
>>>> + PTR relocate_new_kernel_end - relocate_new_kernel
>>>> +SYM_DATA_END(relocate_new_kernel_size)
On 08/29/2022 12:37 PM, Youling Tang wrote:
> Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the
> LoongArch architecture that add support for the kexec re-boot mechanis
> (CONFIG_KEXEC) on LoongArch platforms.
>
> Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
> PE format.
>
> I tested this on LoongArch 3A5000 machine and works as expected,
>
> $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
> $ sudo kexec -e
>
> Signed-off-by: Youling Tang <[email protected]>
> ---
> arch/loongarch/Kconfig | 11 ++
> arch/loongarch/include/asm/kexec.h | 58 ++++++++
> arch/loongarch/kernel/Makefile | 2 +
> arch/loongarch/kernel/head.S | 7 +-
> arch/loongarch/kernel/machine_kexec.c | 178 ++++++++++++++++++++++++
> arch/loongarch/kernel/relocate_kernel.S | 125 +++++++++++++++++
> 6 files changed, 380 insertions(+), 1 deletion(-)
> create mode 100644 arch/loongarch/include/asm/kexec.h
> create mode 100644 arch/loongarch/kernel/machine_kexec.c
> create mode 100644 arch/loongarch/kernel/relocate_kernel.S
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 45364cffc793..903c82fa958d 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -409,6 +409,17 @@ config FORCE_MAX_ZONEORDER
> The page size is not necessarily 4KB. Keep this in mind
> when choosing a value for this option.
>
> +config KEXEC
> + bool "Kexec system call"
> + select KEXEC_CORE
> + help
> + kexec is a system call that implements the ability to shutdown your
> + current kernel, and to start another kernel. It is like a reboot
> + but it is independent of the system firmware. And like a reboot
> + you can start any kernel with it, not just Linux.
> +
> + The name comes from the similarity to the exec system call.
> +
> config SECCOMP
> bool "Enable seccomp to safely compute untrusted bytecode"
> depends on PROC_FS
> diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
> new file mode 100644
> index 000000000000..5c9e7b5eccb8
> --- /dev/null
> +++ b/arch/loongarch/include/asm/kexec.h
> @@ -0,0 +1,58 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * kexec.h for kexec
> + *
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef _ASM_KEXEC_H
> +#define _ASM_KEXEC_H
> +
> +#include <asm/stacktrace.h>
> +#include <asm/page.h>
> +
> +/* Maximum physical address we can use pages from */
> +#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
> +/* Maximum address we can reach in physical address mode */
> +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
> + /* Maximum address we can use for the control code buffer */
> +#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
> +
> +/* Reserve a page for the control code buffer */
> +#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
> +
> +/* The native architecture */
> +#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
> +
> +static inline void crash_setup_regs(struct pt_regs *newregs,
> + struct pt_regs *oldregs)
> +{
> + if (oldregs)
> + memcpy(newregs, oldregs, sizeof(*newregs));
> + else
> + prepare_frametrace(newregs);
> +}
> +
> +#define ARCH_HAS_KIMAGE_ARCH
> +
> +struct kimage_arch {
> + unsigned long boot_flag;
> + unsigned long fdt_addr;
> +};
> +
> +typedef void (*do_kexec_t)(unsigned long boot_flag,
> + unsigned long fdt_addr,
> + unsigned long first_ind_entry,
> + unsigned long jump_addr);
> +
> +struct kimage;
> +extern const unsigned char relocate_new_kernel[];
> +extern const size_t relocate_new_kernel_size;
> +
> +#ifdef CONFIG_SMP
> +extern atomic_t kexec_ready_to_reboot;
> +extern const unsigned char kexec_smp_wait[];
> +extern void kexec_reboot(void);
> +#endif
> +
> +#endif /* !_ASM_KEXEC_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index a213e994db68..20b64ac3f128 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU) += fpu.o
> obj-$(CONFIG_MODULES) += module.o module-sections.o
> obj-$(CONFIG_STACKTRACE) += stacktrace.o
>
> +obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
> +
> obj-$(CONFIG_PROC_FS) += proc.o
>
> obj-$(CONFIG_SMP) += smp.o
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index 01bac62a6442..22bdf4928325 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -20,7 +20,12 @@
>
> _head:
> .word MZ_MAGIC /* "MZ", MS-DOS header */
> - .org 0x3c /* 0x04 ~ 0x3b reserved */
> + .org 0x8
> + .quad 0 /* Image load offset from start of RAM */
> + .dword _end - _text /* Effective size of kernel image */
> + .quad 0
> + .dword kernel_entry /* Kernel entry point */
> + .org 0x3c /* 0x28 ~ 0x3b reserved */
> .long pe_header - _head /* Offset to the PE header */
>
> pe_header:
> diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
> new file mode 100644
> index 000000000000..4ffcd4cd9c8c
> --- /dev/null
> +++ b/arch/loongarch/kernel/machine_kexec.c
> @@ -0,0 +1,178 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * machine_kexec.c for kexec
> + *
> + * Copyright (C) 2022 Loongson Technology Corporation Limited
> + */
> +#include <linux/compiler.h>
> +#include <linux/cpu.h>
> +#include <linux/kexec.h>
> +#include <linux/mm.h>
> +#include <linux/delay.h>
> +#include <linux/libfdt.h>
> +#include <linux/of_fdt.h>
> +
> +#include <asm/bootinfo.h>
> +#include <asm/cacheflush.h>
> +#include <asm/page.h>
> +
> +/* 0x100000 ~ 0x200000 is safe */
> +#define KEXEC_CTRL_CODE TO_CACHE(0x100000UL)
> +#define KEXEC_BLOB_ADDR TO_CACHE(0x108000UL)
> +
> +static unsigned long reboot_code_buffer;
> +#ifdef CONFIG_SMP
> +void (*relocated_kexec_smp_wait)(void *);
> +atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
> +#endif
> +
> +static unsigned long jump_addr;
> +static unsigned long first_ind_entry;
> +static unsigned long boot_flag;
> +static unsigned long fdt_addr;
> +
> +static void kexec_image_info(const struct kimage *kimage)
> +{
> + unsigned long i;
> +
> + pr_debug("kexec kimage info:\n");
> + pr_debug("\ttype: %d\n", kimage->type);
> + pr_debug("\tstart: %lx\n", kimage->start);
> + pr_debug("\thead: %lx\n", kimage->head);
> + pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
> +
> + for (i = 0; i < kimage->nr_segments; i++) {
> + pr_debug("\t segment[%lu]: %016lx - %016lx", i,
> + kimage->segment[i].mem,
> + kimage->segment[i].mem + kimage->segment[i].memsz);
> + pr_debug("\t\t0x%lx bytes, %lu pages\n",
> + (unsigned long)kimage->segment[i].memsz,
> + (unsigned long)kimage->segment[i].memsz / PAGE_SIZE);
> + }
> +}
> +
> +int machine_kexec_prepare(struct kimage *kimage)
> +{
> + int i;
> + void *dtb = (void *)KEXEC_BLOB_ADDR;
> +
> + kexec_image_info(kimage);
> +
> + /* Find the Flattened Device Tree */
> + for (i = 0; i < kimage->nr_segments; i++) {
> + if (!fdt_check_header(kimage->segment[i].buf)) {
> + memcpy(dtb, kimage->segment[i].buf, SZ_64K);
> + kimage->arch.boot_flag = fw_arg0;
> + kimage->arch.fdt_addr = (unsigned long) dtb;
> + break;
> + }
> + continue;
> + }
> +
> + /* kexec need a safe page to save reboot_code_buffer */
> + kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
> +
> + reboot_code_buffer =
> + (unsigned long)page_address(kimage->control_code_page);
> + memcpy((void *)reboot_code_buffer, relocate_new_kernel,
> + relocate_new_kernel_size);
> +
> + /* All secondary cpus now may jump to kexec_smp_wait cycle */
> + relocated_kexec_smp_wait = reboot_code_buffer +
> + (void *)(kexec_smp_wait - relocate_new_kernel);
> +
> + return 0;
> +}
> +
> +void machine_kexec_cleanup(struct kimage *kimage)
> +{
> +}
> +
> +#ifdef CONFIG_SMP
> +void kexec_reboot(void)
> +{
> + do_kexec_t do_kexec = NULL;
> +
> + /* All secondary cpus go to kexec_smp_wait */
> + if (smp_processor_id() > 0) {
> + relocated_kexec_smp_wait(NULL);
> + unreachable();
> + }
> +
> + do_kexec = (void *)reboot_code_buffer;
> + do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr);
> +
> + unreachable();
> +}
self-check,
kexec_reboot() is in! SMP needs to be used, modified as follows:
void kexec_reboot(void)
{
do_kexec_t do_kexec = NULL;
#ifdef CONFIG_SMP
/* All secondary cpus go to kexec_smp_wait */
if (smp_processor_id() > 0) {
relocated_kexec_smp_wait(NULL);
unreachable();
}
#endif
do_kexec = (void *)reboot_code_buffer;
do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr);
unreachable();
}
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