This patch series to support kexec/kdump (only 64bit).
Kexec is a system call that enables you to load and boot into another kernel
from the currently running kernel. This is useful for kernel developers or
other people who need to reboot very quickly without waiting for the whole
BIOS boot process to finish.
Kdump uses kexec to quickly boot to a dump-capture kernel whenever a
dump of the system kernel's memory needs to be taken (for example, when
the system panics). The system kernel's memory image is preserved across
the reboot and is accessible to the dump-capture kernel.
For details, see Documentation/admin-guide/kdump/kdump.rst.
User tools kexec-tools see link [1].
TODO:
Currently kdump does not support the same binary image, the production kernel
and the capture kernel will be generated with different configurations. I will
support kernel relocation support in the near future. Then will go to implement
the same binary support based on kernel relocation support.
[1] Link: https://github.com/tangyouling/kexec-tools
Changes in v3:
- Adjust the PE header (note that kexec-tools needs to be updated).
- Add ibar in kexec_reboot().
- boot_flag is replaced by efi_boot.
- Adjust do_kexec parameter passing order.
- Adjust the order of static variables to be consistent with do_kexec.
- Remove a-series register save.
- Some comments and register usage modification.
- Add the opening and closing of the cpu core state.
- Add a call to cpu_device_up to turn it on when the cpu core state is offline.
Changes in v2:
- Add ibar.
- Access via IOCSR.
- Remove the settings of the tp, sp registers.
- Remove the crash.c file and merge the relevant code into machine_kexec.c.
- Adjust the use of CONFIG_SMP macro to avoid build errors under !SMP
configuration.
- Change the default value of PHYSICAL_START of the capture kernel to
0x90000000a0000000.
Youling Tang (3):
LoongArch: Add kexec support
LoongArch: Add kdump support
LoongArch: Enable CONFIG_KEXEC
arch/loongarch/Kconfig | 33 +++
arch/loongarch/Makefile | 4 +
arch/loongarch/configs/loongson3_defconfig | 1 +
arch/loongarch/include/asm/kexec.h | 58 ++++
arch/loongarch/kernel/Makefile | 3 +
arch/loongarch/kernel/crash_dump.c | 19 ++
arch/loongarch/kernel/head.S | 6 +-
arch/loongarch/kernel/machine_kexec.c | 295 +++++++++++++++++++++
arch/loongarch/kernel/mem.c | 6 +
arch/loongarch/kernel/relocate_kernel.S | 111 ++++++++
arch/loongarch/kernel/setup.c | 49 ++++
arch/loongarch/kernel/traps.c | 4 +
12 files changed, 588 insertions(+), 1 deletion(-)
create mode 100644 arch/loongarch/include/asm/kexec.h
create mode 100644 arch/loongarch/kernel/crash_dump.c
create mode 100644 arch/loongarch/kernel/machine_kexec.c
create mode 100644 arch/loongarch/kernel/relocate_kernel.S
--
2.36.0
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 | 6 +-
arch/loongarch/kernel/machine_kexec.c | 209 ++++++++++++++++++++++++
arch/loongarch/kernel/relocate_kernel.S | 105 ++++++++++++
6 files changed, 390 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 9b1f2ab878e9..08e063aaf847 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -422,6 +422,17 @@ config ARCH_IOREMAP
protection support. However, you can enable LoongArch DMW-based
ioremap() for better performance.
+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..e5b022d335c7
--- /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 efi_boot;
+ unsigned long fdt_addr;
+};
+
+typedef void (*do_kexec_t)(unsigned long efi_boot,
+ unsigned long fdt_addr,
+ unsigned long jump_addr,
+ unsigned long first_ind_entry);
+
+struct kimage;
+extern const unsigned char relocate_new_kernel[];
+extern const size_t relocate_new_kernel_size;
+extern void kexec_reboot(void);
+
+#ifdef CONFIG_SMP
+extern atomic_t kexec_ready_to_reboot;
+extern const unsigned char kexec_smp_wait[];
+#endif
+
+#endif /* !_ASM_KEXEC_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 7225916dd378..17dc8ce6b5ce 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 eb3f641d5915..c0d61b29fcaa 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -20,7 +20,11 @@
_head:
.word MZ_MAGIC /* "MZ", MS-DOS header */
- .org 0x3c /* 0x04 ~ 0x3b reserved */
+ .org 0x8
+ .dword kernel_entry /* Kernel entry point */
+ .dword _end - _text /* Effective size of kernel image */
+ .quad 0 /* Image load offset from start of RAM */
+ .org 0x3c /* 0x20 ~ 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..a2f3c3e65130
--- /dev/null
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -0,0 +1,209 @@
+// 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
+static void (*relocated_kexec_smp_wait)(void *);
+atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
+#endif
+
+static unsigned long efi_boot;
+static unsigned long fdt_addr;
+static unsigned long jump_addr;
+static unsigned long first_ind_entry;
+
+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.efi_boot = 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);
+
+#ifdef CONFIG_SMP
+ /* 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);
+#endif
+
+ return 0;
+}
+
+void machine_kexec_cleanup(struct kimage *kimage)
+{
+}
+
+void kexec_reboot(void)
+{
+ do_kexec_t do_kexec = NULL;
+
+ /*
+ * 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();
+
+ /*
+ * Make sure we get correct instructions written by the
+ * machine_kexec_prepare() CPU.
+ */
+ asm volatile ("\tibar 0\n"::);
+
+#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(efi_boot, fdt_addr, jump_addr, first_ind_entry);
+
+ unreachable();
+}
+
+
+#ifdef CONFIG_SMP
+static void kexec_shutdown_secondary(void *)
+{
+ int cpu = smp_processor_id();
+
+ if (!cpu_online(cpu))
+ return;
+
+ /* We won't be sent IPIs any more. */
+ set_cpu_online(cpu, false);
+
+ local_irq_disable();
+ while (!atomic_read(&kexec_ready_to_reboot))
+ cpu_relax();
+
+ kexec_reboot();
+}
+#endif
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+
+void machine_shutdown(void)
+{
+ int cpu;
+
+ /* All CPUs go to reboot_code_buffer */
+ for_each_possible_cpu(cpu)
+ if (!cpu_online(cpu))
+ cpu_device_up(get_cpu_device(cpu));
+
+#ifdef CONFIG_SMP
+ smp_call_function(kexec_shutdown_secondary, NULL, 0);
+#endif
+}
+
+void machine_kexec(struct kimage *image)
+{
+ unsigned long entry;
+ unsigned long *ptr;
+ struct kimage_arch *internal = &image->arch;
+
+ efi_boot = internal->efi_boot;
+ 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();
+
+#ifdef CONFIG_SMP
+ atomic_set(&kexec_ready_to_reboot, 1);
+#endif
+
+ kexec_reboot();
+}
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..0ea8b29242e6
--- /dev/null
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -0,0 +1,105 @@
+/* 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>
+
+SYM_CODE_START(relocate_new_kernel)
+ /*
+ * a0: Boot flag passed to the new kernel
+ * a1: Virt address of the FDT image
+ * a2: Virt address to jump to after relocation
+ * a3: Pointer to the current indirection page entry
+ */
+
+ move s0, a3
+
+process_entry:
+ PTR_L s1, s0, 0
+ PTR_ADDI s0, s0, SZREG
+
+ /* destination page */
+ andi s2, s1, IND_DESTINATION
+ beqz s2, 1f
+ li.w t0, ~0x1
+ and s3, s1, t0 /* store destination addr in s3 */
+ b process_entry
+
+1:
+ /* indirection page, update s0 */
+ andi s2, s1, IND_INDIRECTION
+ beqz s2, 1f
+ li.w t0, ~0x2
+ and s0, s1, t0
+ b process_entry
+
+1:
+ /* done page */
+ andi s2, s1, IND_DONE
+ beqz s2, 1f
+ b done
+1:
+ /* source page */
+ andi s2, s1, IND_SOURCE
+ beqz s2, process_entry
+ li.w t0, ~0x8
+ and s1, s1, t0
+ li.w s5, (1 << _PAGE_SHIFT) / SZREG
+
+copy_word:
+ /* copy page word by word */
+ REG_L s4, s1, 0
+ REG_S s4, s3, 0
+ PTR_ADDI s3, s3, SZREG
+ PTR_ADDI s1, s1, SZREG
+ LONG_ADDI s5, s5, -1
+ beqz s5, process_entry
+ b copy_word
+ b process_entry
+
+done:
+ ibar 0
+ dbar 0
+
+ /*
+ * Jump to the new kernel,
+ * make sure the values of a0, a1 and a2 are not changed.
+ */
+ jr a2
+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)
+1: li.w t0, 0x100 /* wait for init loop */
+2: addi.w t0, t0, -1 /* limit mailbox access */
+ bnez t0, 2b
+ li.w t1, LOONGARCH_IOCSR_MBUF0
+ iocsrrd.w s0, t1 /* check PC as an indicator */
+ beqz s0, 1b
+ iocsrrd.d s0, t1 /* get PC via mailbox */
+
+ li.d t0, CACHE_BASE
+ or s0, s0, t0 /* s0 = TO_CACHE(s0) */
+ jr s0 /* 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
On Thu, 2022-09-15 at 10:53 +0800, Youling Tang wrote:
> +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)) {
Hi Youling,
When I build Huacai's tree
(https://github.com/loongson/linux/commits/loongarch-next), there is a
strange error linking vmlinux:
ld: arch/loongarch/kernel/machine_kexec.o: in function `machine_kexec_prepare':
/home/xry111/git-repos/linux/arch/loongarch/kernel/machine_kexec.c:70: undefined reference to `fdt_check_header'
Not sure why...
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University
Hi, Ruoyao
On 09/22/2022 06:00 PM, Xi Ruoyao wrote:
> On Thu, 2022-09-15 at 10:53 +0800, Youling Tang wrote:
>> +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)) {
>
> Hi Youling,
>
> When I build Huacai's tree
> (https://github.com/loongson/linux/commits/loongarch-next), there is a
> strange error linking vmlinux:
>
> ld: arch/loongarch/kernel/machine_kexec.o: in function `machine_kexec_prepare':
> /home/xry111/git-repos/linux/arch/loongarch/kernel/machine_kexec.c:70: undefined reference to `fdt_check_header'
>
> Not sure why...
This is because of the problem after efistub removes the fdt
modification, I will reimplement kexec/kdump. This build error can be
avoided by turning off CONFIG_KEXEC temporarily, tomorrow I will submit
a new kexec/kdump implementation.
Thanks,
Youling.
>