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crash: split crash dumping code out from kexec_core.c 

Currently, KEXEC_CORE select CRASH_CORE automatically because crash codes
need be built in to avoid compiling error when building kexec code even
though the crash dumping functionality is not enabled. E.g
--------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_KEXEC=y
CONFIG_KEXEC_FILE=y
---------------------

After splitting out crashkernel reservation code and vmcoreinfo exporting
code, there's only crash related code left in kernel/crash_core.c. Now
move crash related codes from kexec_core.c to crash_core.c and only build it
in when CONFIG_CRASH_DUMP=y.

And also wrap up crash codes inside CONFIG_CRASH_DUMP ifdeffery scope,
or replace inappropriate CONFIG_KEXEC_CORE ifdef with CONFIG_CRASH_DUMP
ifdef in generic kernel files.

With these changes, crash_core codes are abstracted from kexec codes and
can be disabled at all if only kexec reboot feature is wanted.

Link: https://lkml.kernel.org/r/20240124051254.67105-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Michael Kelley <mhklinux@outlook.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baoquan He 2024-01-24 13:12:44 +08:00 committed by Andrew Morton
parent 2c44b67e2e
commit 02aff84805
10 changed files with 359 additions and 292 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/base/cpu.c
View File

@ -144,7 +144,7 @@ static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
#endif /* CONFIG_HOTPLUG_CPU */
#ifdef CONFIG_KEXEC_CORE
#ifdef CONFIG_CRASH_DUMP
#include <linux/kexec.h>
static ssize_t crash_notes_show(struct device *dev,
@ -189,14 +189,14 @@ static const struct attribute_group crash_note_cpu_attr_group = {
#endif
static const struct attribute_group *common_cpu_attr_groups[] = {
#ifdef CONFIG_KEXEC_CORE
#ifdef CONFIG_CRASH_DUMP
&crash_note_cpu_attr_group,
#endif
NULL
};
static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
#ifdef CONFIG_KEXEC_CORE
#ifdef CONFIG_CRASH_DUMP
&crash_note_cpu_attr_group,
#endif
NULL

61
include/linux/crash_core.h
View File

@ -6,6 +6,48 @@
#include <linux/elfcore.h>
#include <linux/elf.h>
struct kimage;
#ifdef CONFIG_CRASH_DUMP
int crash_shrink_memory(unsigned long new_size);
ssize_t crash_get_memory_size(void);
#ifndef arch_kexec_protect_crashkres
/*
* Protection mechanism for crashkernel reserved memory after
* the kdump kernel is loaded.
*
* Provide an empty default implementation here -- architecture
* code may override this
*/
static inline void arch_kexec_protect_crashkres(void) { }
#endif
#ifndef arch_kexec_unprotect_crashkres
static inline void arch_kexec_unprotect_crashkres(void) { }
#endif
#ifndef arch_crash_handle_hotplug_event
static inline void arch_crash_handle_hotplug_event(struct kimage *image) { }
#endif
int crash_check_update_elfcorehdr(void);
#ifndef crash_hotplug_cpu_support
static inline int crash_hotplug_cpu_support(void) { return 0; }
#endif
#ifndef crash_hotplug_memory_support
static inline int crash_hotplug_memory_support(void) { return 0; }
#endif
#ifndef crash_get_elfcorehdr_size
static inline unsigned int crash_get_elfcorehdr_size(void) { return 0; }
#endif
/* Alignment required for elf header segment */
#define ELF_CORE_HEADER_ALIGN 4096
@ -31,4 +73,23 @@ struct kexec_segment;
#define KEXEC_CRASH_HP_REMOVE_MEMORY 4
#define KEXEC_CRASH_HP_INVALID_CPU -1U
extern void __crash_kexec(struct pt_regs *regs);
extern void crash_kexec(struct pt_regs *regs);
int kexec_should_crash(struct task_struct *p);
int kexec_crash_loaded(void);
void crash_save_cpu(struct pt_regs *regs, int cpu);
extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
#else /* !CONFIG_CRASH_DUMP*/
struct pt_regs;
struct task_struct;
struct kimage;
static inline void __crash_kexec(struct pt_regs *regs) { }
static inline void crash_kexec(struct pt_regs *regs) { }
static inline int kexec_should_crash(struct task_struct *p) { return 0; }
static inline int kexec_crash_loaded(void) { return 0; }
static inline void crash_save_cpu(struct pt_regs *regs, int cpu) {};
static inline int kimage_crash_copy_vmcoreinfo(struct kimage *image) { return 0; };
#endif /* CONFIG_CRASH_DUMP*/
#endif /* LINUX_CRASH_CORE_H */

45
include/linux/kexec.h
View File

@ -15,7 +15,6 @@
#if !defined(__ASSEMBLY__)
#include <linux/crash_core.h>
#include <linux/vmcore_info.h>
#include <linux/crash_reserve.h>
#include <asm/io.h>
@ -33,6 +32,7 @@ extern note_buf_t __percpu *crash_notes;
#include <linux/module.h>
#include <linux/highmem.h>
#include <asm/kexec.h>
#include <linux/crash_core.h>
/* Verify architecture specific macros are defined */
@ -380,13 +380,6 @@ extern struct page *kimage_alloc_control_pages(struct kimage *image,
static inline int machine_kexec_post_load(struct kimage *image) { return 0; }
#endif
extern void __crash_kexec(struct pt_regs *);
extern void crash_kexec(struct pt_regs *);
int kexec_should_crash(struct task_struct *);
int kexec_crash_loaded(void);
void crash_save_cpu(struct pt_regs *regs, int cpu);
extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
extern struct kimage *kexec_image;
extern struct kimage *kexec_crash_image;
@ -410,24 +403,6 @@ bool kexec_load_permitted(int kexec_image_type);
/* flag to track if kexec reboot is in progress */
extern bool kexec_in_progress;
int crash_shrink_memory(unsigned long new_size);
ssize_t crash_get_memory_size(void);
#ifndef arch_kexec_protect_crashkres
/*
* Protection mechanism for crashkernel reserved memory after
* the kdump kernel is loaded.
*
* Provide an empty default implementation here -- architecture
* code may override this
*/
static inline void arch_kexec_protect_crashkres(void) { }
#endif
#ifndef arch_kexec_unprotect_crashkres
static inline void arch_kexec_unprotect_crashkres(void) { }
#endif
#ifndef page_to_boot_pfn
static inline unsigned long page_to_boot_pfn(struct page *page)
{
@ -484,24 +459,6 @@ static inline int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, g
static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { }
#endif
#ifndef arch_crash_handle_hotplug_event
static inline void arch_crash_handle_hotplug_event(struct kimage *image) { }
#endif
int crash_check_update_elfcorehdr(void);
#ifndef crash_hotplug_cpu_support
static inline int crash_hotplug_cpu_support(void) { return 0; }
#endif
#ifndef crash_hotplug_memory_support
static inline int crash_hotplug_memory_support(void) { return 0; }
#endif
#ifndef crash_get_elfcorehdr_size
static inline unsigned int crash_get_elfcorehdr_size(void) { return 0; }
#endif
extern bool kexec_file_dbg_print;
#define kexec_dprintk(fmt, ...) \

2
init/initramfs.c
View File

@ -642,7 +642,7 @@ void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
"initrd");
}
#ifdef CONFIG_KEXEC_CORE
#ifdef CONFIG_CRASH_RESERVE
static bool __init kexec_free_initrd(void)
{
unsigned long crashk_start = (unsigned long)__va(crashk_res.start);

3
kernel/Makefile
View File

@ -70,7 +70,8 @@ obj-$(CONFIG_KALLSYMS_SELFTEST) += kallsyms_selftest.o
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o elfcorehdr.o
obj-$(CONFIG_CRASH_RESERVE) += crash_reserve.o
obj-$(CONFIG_KEXEC_CORE) += kexec_core.o crash_core.o
obj-$(CONFIG_KEXEC_CORE) += kexec_core.o
obj-$(CONFIG_CRASH_DUMP) += crash_core.o
obj-$(CONFIG_KEXEC) += kexec.o
obj-$(CONFIG_KEXEC_FILE) += kexec_file.o
obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o

256
kernel/crash_core.c
View File

@ -11,9 +11,14 @@
#include <linux/sizes.h>
#include <linux/kexec.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/cpuhotplug.h>
#include <linux/memblock.h>
#include <linux/kmemleak.h>
#include <linux/crash_core.h>
#include <linux/reboot.h>
#include <linux/btf.h>
#include <linux/objtool.h>
#include <asm/page.h>
#include <asm/sections.h>
@ -26,6 +31,131 @@
/* Per cpu memory for storing cpu states in case of system crash. */
note_buf_t __percpu *crash_notes;
#ifdef CONFIG_CRASH_DUMP
int kimage_crash_copy_vmcoreinfo(struct kimage *image)
{
struct page *vmcoreinfo_page;
void *safecopy;
if (!IS_ENABLED(CONFIG_CRASH_DUMP))
return 0;
if (image->type != KEXEC_TYPE_CRASH)
return 0;
/*
* For kdump, allocate one vmcoreinfo safe copy from the
* crash memory. as we have arch_kexec_protect_crashkres()
* after kexec syscall, we naturally protect it from write
* (even read) access under kernel direct mapping. But on
* the other hand, we still need to operate it when crash
* happens to generate vmcoreinfo note, hereby we rely on
* vmap for this purpose.
*/
vmcoreinfo_page = kimage_alloc_control_pages(image, 0);
if (!vmcoreinfo_page) {
pr_warn("Could not allocate vmcoreinfo buffer\n");
return -ENOMEM;
}
safecopy = vmap(&vmcoreinfo_page, 1, VM_MAP, PAGE_KERNEL);
if (!safecopy) {
pr_warn("Could not vmap vmcoreinfo buffer\n");
return -ENOMEM;
}
image->vmcoreinfo_data_copy = safecopy;
crash_update_vmcoreinfo_safecopy(safecopy);
return 0;
}
int kexec_should_crash(struct task_struct *p)
{
/*
* If crash_kexec_post_notifiers is enabled, don't run
* crash_kexec() here yet, which must be run after panic
* notifiers in panic().
*/
if (crash_kexec_post_notifiers)
return 0;
/*
* There are 4 panic() calls in make_task_dead() path, each of which
* corresponds to each of these 4 conditions.
*/
if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
return 1;
return 0;
}
int kexec_crash_loaded(void)
{
return !!kexec_crash_image;
}
EXPORT_SYMBOL_GPL(kexec_crash_loaded);
/*
* No panic_cpu check version of crash_kexec(). This function is called
* only when panic_cpu holds the current CPU number; this is the only CPU
* which processes crash_kexec routines.
*/
void __noclone __crash_kexec(struct pt_regs *regs)
{
/* Take the kexec_lock here to prevent sys_kexec_load
* running on one cpu from replacing the crash kernel
* we are using after a panic on a different cpu.
*
* If the crash kernel was not located in a fixed area
* of memory the xchg(&kexec_crash_image) would be
* sufficient. But since I reuse the memory...
*/
if (kexec_trylock()) {
if (kexec_crash_image) {
struct pt_regs fixed_regs;
crash_setup_regs(&fixed_regs, regs);
crash_save_vmcoreinfo();
machine_crash_shutdown(&fixed_regs);
machine_kexec(kexec_crash_image);
}
kexec_unlock();
}
}
STACK_FRAME_NON_STANDARD(__crash_kexec);
__bpf_kfunc void crash_kexec(struct pt_regs *regs)
{
int old_cpu, this_cpu;
/*
* Only one CPU is allowed to execute the crash_kexec() code as with
* panic(). Otherwise parallel calls of panic() and crash_kexec()
* may stop each other. To exclude them, we use panic_cpu here too.
*/
old_cpu = PANIC_CPU_INVALID;
this_cpu = raw_smp_processor_id();
if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
/* This is the 1st CPU which comes here, so go ahead. */
__crash_kexec(regs);
/*
* Reset panic_cpu to allow another panic()/crash_kexec()
* call.
*/
atomic_set(&panic_cpu, PANIC_CPU_INVALID);
}
}
static inline resource_size_t crash_resource_size(const struct resource *res)
{
return !res->end ? 0 : resource_size(res);
}
int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
void **addr, unsigned long *sz)
{
@ -187,6 +317,130 @@ int crash_exclude_mem_range(struct crash_mem *mem,
return 0;
}
ssize_t crash_get_memory_size(void)
{
ssize_t size = 0;
if (!kexec_trylock())
return -EBUSY;
size += crash_resource_size(&crashk_res);
size += crash_resource_size(&crashk_low_res);
kexec_unlock();
return size;
}
static int __crash_shrink_memory(struct resource *old_res,
unsigned long new_size)
{
struct resource *ram_res;
ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
if (!ram_res)
return -ENOMEM;
ram_res->start = old_res->start + new_size;
ram_res->end = old_res->end;
ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
ram_res->name = "System RAM";
if (!new_size) {
release_resource(old_res);
old_res->start = 0;
old_res->end = 0;
} else {
crashk_res.end = ram_res->start - 1;
}
crash_free_reserved_phys_range(ram_res->start, ram_res->end);
insert_resource(&iomem_resource, ram_res);
return 0;
}
int crash_shrink_memory(unsigned long new_size)
{
int ret = 0;
unsigned long old_size, low_size;
if (!kexec_trylock())
return -EBUSY;
if (kexec_crash_image) {
ret = -ENOENT;
goto unlock;
}
low_size = crash_resource_size(&crashk_low_res);
old_size = crash_resource_size(&crashk_res) + low_size;
new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN);
if (new_size >= old_size) {
ret = (new_size == old_size) ? 0 : -EINVAL;
goto unlock;
}
/*
* (low_size > new_size) implies that low_size is greater than zero.
* This also means that if low_size is zero, the else branch is taken.
*
* If low_size is greater than 0, (low_size > new_size) indicates that
* crashk_low_res also needs to be shrunken. Otherwise, only crashk_res
* needs to be shrunken.
*/
if (low_size > new_size) {
ret = __crash_shrink_memory(&crashk_res, 0);
if (ret)
goto unlock;
ret = __crash_shrink_memory(&crashk_low_res, new_size);
} else {
ret = __crash_shrink_memory(&crashk_res, new_size - low_size);
}
/* Swap crashk_res and crashk_low_res if needed */
if (!crashk_res.end && crashk_low_res.end) {
crashk_res.start = crashk_low_res.start;
crashk_res.end = crashk_low_res.end;
release_resource(&crashk_low_res);
crashk_low_res.start = 0;
crashk_low_res.end = 0;
insert_resource(&iomem_resource, &crashk_res);
}
unlock:
kexec_unlock();
return ret;
}
void crash_save_cpu(struct pt_regs *regs, int cpu)
{
struct elf_prstatus prstatus;
u32 *buf;
if ((cpu < 0) || (cpu >= nr_cpu_ids))
return;
/* Using ELF notes here is opportunistic.
* I need a well defined structure format
* for the data I pass, and I need tags
* on the data to indicate what information I have
* squirrelled away. ELF notes happen to provide
* all of that, so there is no need to invent something new.
*/
buf = (u32 *)per_cpu_ptr(crash_notes, cpu);
if (!buf)
return;
memset(&prstatus, 0, sizeof(prstatus));
prstatus.common.pr_pid = current->pid;
elf_core_copy_regs(&prstatus.pr_reg, regs);
buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
&prstatus, sizeof(prstatus));
final_note(buf);
}
static int __init crash_notes_memory_init(void)
{
/* Allocate memory for saving cpu registers. */
@ -220,6 +474,8 @@ static int __init crash_notes_memory_init(void)
}
subsys_initcall(crash_notes_memory_init);
#endif /*CONFIG_CRASH_DUMP*/
#ifdef CONFIG_CRASH_HOTPLUG
#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt

11
kernel/kexec.c
View File

@ -28,12 +28,14 @@ static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
struct kimage *image;
bool kexec_on_panic = flags & KEXEC_ON_CRASH;
#ifdef CONFIG_CRASH_DUMP
if (kexec_on_panic) {
/* Verify we have a valid entry point */
if ((entry < phys_to_boot_phys(crashk_res.start)) ||
(entry > phys_to_boot_phys(crashk_res.end)))
return -EADDRNOTAVAIL;
}
#endif
/* Allocate and initialize a controlling structure */
image = do_kimage_alloc_init();
@ -44,11 +46,13 @@ static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
image->nr_segments = nr_segments;
memcpy(image->segment, segments, nr_segments * sizeof(*segments));
#ifdef CONFIG_CRASH_DUMP
if (kexec_on_panic) {
/* Enable special crash kernel control page alloc policy. */
image->control_page = crashk_res.start;
image->type = KEXEC_TYPE_CRASH;
}
#endif
ret = sanity_check_segment_list(image);
if (ret)
@ -99,13 +103,14 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
if (!kexec_trylock())
return -EBUSY;
#ifdef CONFIG_CRASH_DUMP
if (flags & KEXEC_ON_CRASH) {
dest_image = &kexec_crash_image;
if (kexec_crash_image)
arch_kexec_unprotect_crashkres();
} else {
} else
#endif
dest_image = &kexec_image;
}
if (nr_segments == 0) {
/* Uninstall image */
@ -162,8 +167,10 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
image = xchg(dest_image, image);
out:
#ifdef CONFIG_CRASH_DUMP
if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
arch_kexec_protect_crashkres();
#endif
kimage_free(image);
out_unlock:

250
kernel/kexec_core.c
View File

@ -54,30 +54,6 @@ bool kexec_in_progress = false;
bool kexec_file_dbg_print;
int kexec_should_crash(struct task_struct *p)
{
/*
* If crash_kexec_post_notifiers is enabled, don't run
* crash_kexec() here yet, which must be run after panic
* notifiers in panic().
*/
if (crash_kexec_post_notifiers)
return 0;
/*
* There are 4 panic() calls in make_task_dead() path, each of which
* corresponds to each of these 4 conditions.
*/
if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
return 1;
return 0;
}
int kexec_crash_loaded(void)
{
return !!kexec_crash_image;
}
EXPORT_SYMBOL_GPL(kexec_crash_loaded);
/*
* When kexec transitions to the new kernel there is a one-to-one
* mapping between physical and virtual addresses. On processors
@ -209,6 +185,7 @@ int sanity_check_segment_list(struct kimage *image)
if (total_pages > nr_pages / 2)
return -EINVAL;
#ifdef CONFIG_CRASH_DUMP
/*
* Verify we have good destination addresses. Normally
* the caller is responsible for making certain we don't
@ -231,6 +208,7 @@ int sanity_check_segment_list(struct kimage *image)
return -EADDRNOTAVAIL;
}
}
#endif
return 0;
}
@ -403,6 +381,7 @@ static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
return pages;
}
#ifdef CONFIG_CRASH_DUMP
static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
unsigned int order)
{
@ -468,6 +447,7 @@ static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
return pages;
}
#endif
struct page *kimage_alloc_control_pages(struct kimage *image,
@ -479,48 +459,16 @@ struct page *kimage_alloc_control_pages(struct kimage *image,
case KEXEC_TYPE_DEFAULT:
pages = kimage_alloc_normal_control_pages(image, order);
break;
#ifdef CONFIG_CRASH_DUMP
case KEXEC_TYPE_CRASH:
pages = kimage_alloc_crash_control_pages(image, order);
break;
#endif
}
return pages;
}
int kimage_crash_copy_vmcoreinfo(struct kimage *image)
{
struct page *vmcoreinfo_page;
void *safecopy;
if (image->type != KEXEC_TYPE_CRASH)
return 0;
/*
* For kdump, allocate one vmcoreinfo safe copy from the
* crash memory. as we have arch_kexec_protect_crashkres()
* after kexec syscall, we naturally protect it from write
* (even read) access under kernel direct mapping. But on
* the other hand, we still need to operate it when crash
* happens to generate vmcoreinfo note, hereby we rely on
* vmap for this purpose.
*/
vmcoreinfo_page = kimage_alloc_control_pages(image, 0);
if (!vmcoreinfo_page) {
pr_warn("Could not allocate vmcoreinfo buffer\n");
return -ENOMEM;
}
safecopy = vmap(&vmcoreinfo_page, 1, VM_MAP, PAGE_KERNEL);
if (!safecopy) {
pr_warn("Could not vmap vmcoreinfo buffer\n");
return -ENOMEM;
}
image->vmcoreinfo_data_copy = safecopy;
crash_update_vmcoreinfo_safecopy(safecopy);
return 0;
}
static int kimage_add_entry(struct kimage *image, kimage_entry_t entry)
{
if (*image->entry != 0)
@ -603,10 +551,12 @@ void kimage_free(struct kimage *image)
if (!image)
return;
#ifdef CONFIG_CRASH_DUMP
if (image->vmcoreinfo_data_copy) {
crash_update_vmcoreinfo_safecopy(NULL);
vunmap(image->vmcoreinfo_data_copy);
}
#endif
kimage_free_extra_pages(image);
for_each_kimage_entry(image, ptr, entry) {
@ -824,6 +774,7 @@ out:
return result;
}
#ifdef CONFIG_CRASH_DUMP
static int kimage_load_crash_segment(struct kimage *image,
struct kexec_segment *segment)
{
@ -891,6 +842,7 @@ static int kimage_load_crash_segment(struct kimage *image,
out:
return result;
}
#endif
int kimage_load_segment(struct kimage *image,
struct kexec_segment *segment)
@ -901,9 +853,11 @@ int kimage_load_segment(struct kimage *image,
case KEXEC_TYPE_DEFAULT:
result = kimage_load_normal_segment(image, segment);
break;
#ifdef CONFIG_CRASH_DUMP
case KEXEC_TYPE_CRASH:
result = kimage_load_crash_segment(image, segment);
break;
#endif
}
return result;
@ -1027,186 +981,6 @@ bool kexec_load_permitted(int kexec_image_type)
return true;
}
/*
* No panic_cpu check version of crash_kexec(). This function is called
* only when panic_cpu holds the current CPU number; this is the only CPU
* which processes crash_kexec routines.
*/
void __noclone __crash_kexec(struct pt_regs *regs)
{
/* Take the kexec_lock here to prevent sys_kexec_load
* running on one cpu from replacing the crash kernel
* we are using after a panic on a different cpu.
*
* If the crash kernel was not located in a fixed area
* of memory the xchg(&kexec_crash_image) would be
* sufficient. But since I reuse the memory...
*/
if (kexec_trylock()) {
if (kexec_crash_image) {
struct pt_regs fixed_regs;
crash_setup_regs(&fixed_regs, regs);
crash_save_vmcoreinfo();
machine_crash_shutdown(&fixed_regs);
machine_kexec(kexec_crash_image);
}
kexec_unlock();
}
}
STACK_FRAME_NON_STANDARD(__crash_kexec);
__bpf_kfunc void crash_kexec(struct pt_regs *regs)
{
int old_cpu, this_cpu;
/*
* Only one CPU is allowed to execute the crash_kexec() code as with
* panic(). Otherwise parallel calls of panic() and crash_kexec()
* may stop each other. To exclude them, we use panic_cpu here too.
*/
old_cpu = PANIC_CPU_INVALID;
this_cpu = raw_smp_processor_id();
if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
/* This is the 1st CPU which comes here, so go ahead. */
__crash_kexec(regs);
/*
* Reset panic_cpu to allow another panic()/crash_kexec()
* call.
*/
atomic_set(&panic_cpu, PANIC_CPU_INVALID);
}
}
static inline resource_size_t crash_resource_size(const struct resource *res)
{
return !res->end ? 0 : resource_size(res);
}
ssize_t crash_get_memory_size(void)
{
ssize_t size = 0;
if (!kexec_trylock())
return -EBUSY;
size += crash_resource_size(&crashk_res);
size += crash_resource_size(&crashk_low_res);
kexec_unlock();
return size;
}
static int __crash_shrink_memory(struct resource *old_res,
unsigned long new_size)
{
struct resource *ram_res;
ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
if (!ram_res)
return -ENOMEM;
ram_res->start = old_res->start + new_size;
ram_res->end = old_res->end;
ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
ram_res->name = "System RAM";
if (!new_size) {
release_resource(old_res);
old_res->start = 0;
old_res->end = 0;
} else {
crashk_res.end = ram_res->start - 1;
}
crash_free_reserved_phys_range(ram_res->start, ram_res->end);
insert_resource(&iomem_resource, ram_res);
return 0;
}
int crash_shrink_memory(unsigned long new_size)
{
int ret = 0;
unsigned long old_size, low_size;
if (!kexec_trylock())
return -EBUSY;
if (kexec_crash_image) {
ret = -ENOENT;
goto unlock;
}
low_size = crash_resource_size(&crashk_low_res);
old_size = crash_resource_size(&crashk_res) + low_size;
new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN);
if (new_size >= old_size) {
ret = (new_size == old_size) ? 0 : -EINVAL;
goto unlock;
}
/*
* (low_size > new_size) implies that low_size is greater than zero.
* This also means that if low_size is zero, the else branch is taken.
*
* If low_size is greater than 0, (low_size > new_size) indicates that
* crashk_low_res also needs to be shrunken. Otherwise, only crashk_res
* needs to be shrunken.
*/
if (low_size > new_size) {
ret = __crash_shrink_memory(&crashk_res, 0);
if (ret)
goto unlock;
ret = __crash_shrink_memory(&crashk_low_res, new_size);
} else {
ret = __crash_shrink_memory(&crashk_res, new_size - low_size);
}
/* Swap crashk_res and crashk_low_res if needed */
if (!crashk_res.end && crashk_low_res.end) {
crashk_res.start = crashk_low_res.start;
crashk_res.end = crashk_low_res.end;
release_resource(&crashk_low_res);
crashk_low_res.start = 0;
crashk_low_res.end = 0;
insert_resource(&iomem_resource, &crashk_res);
}
unlock:
kexec_unlock();
return ret;
}
void crash_save_cpu(struct pt_regs *regs, int cpu)
{
struct elf_prstatus prstatus;
u32 *buf;
if ((cpu < 0) || (cpu >= nr_cpu_ids))
return;
/* Using ELF notes here is opportunistic.
* I need a well defined structure format
* for the data I pass, and I need tags
* on the data to indicate what information I have
* squirrelled away. ELF notes happen to provide
* all of that, so there is no need to invent something new.
*/
buf = (u32 *)per_cpu_ptr(crash_notes, cpu);
if (!buf)
return;
memset(&prstatus, 0, sizeof(prstatus));
prstatus.common.pr_pid = current->pid;
elf_core_copy_regs(&prstatus.pr_reg, regs);
buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
&prstatus, sizeof(prstatus));
final_note(buf);
}
/*
* Move into place and start executing a preloaded standalone
* executable. If nothing was preloaded return an error.

13
kernel/kexec_file.c
View File

@ -285,11 +285,13 @@ kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
kexec_file_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
image->file_mode = 1;
#ifdef CONFIG_CRASH_DUMP
if (kexec_on_panic) {
/* Enable special crash kernel control page alloc policy. */
image->control_page = crashk_res.start;
image->type = KEXEC_TYPE_CRASH;
}
#endif
ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
cmdline_ptr, cmdline_len, flags);
@ -349,13 +351,14 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
if (!kexec_trylock())
return -EBUSY;
#ifdef CONFIG_CRASH_DUMP
if (image_type == KEXEC_TYPE_CRASH) {
dest_image = &kexec_crash_image;
if (kexec_crash_image)
arch_kexec_unprotect_crashkres();
} else {
} else
#endif
dest_image = &kexec_image;
}
if (flags & KEXEC_FILE_UNLOAD)
goto exchange;
@ -419,8 +422,10 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
exchange:
image = xchg(dest_image, image);
out:
#ifdef CONFIG_CRASH_DUMP
if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
arch_kexec_protect_crashkres();
#endif
kexec_unlock();
kimage_free(image);
@ -595,12 +600,14 @@ static int kexec_walk_memblock(struct kexec_buf *kbuf,
static int kexec_walk_resources(struct kexec_buf *kbuf,
int (*func)(struct resource *, void *))
{
#ifdef CONFIG_CRASH_DUMP
if (kbuf->image->type == KEXEC_TYPE_CRASH)
return walk_iomem_res_desc(crashk_res.desc,
IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
crashk_res.start, crashk_res.end,
kbuf, func);
else if (kbuf->top_down)
#endif
if (kbuf->top_down)
return walk_system_ram_res_rev(0, ULONG_MAX, kbuf, func);
else
return walk_system_ram_res(0, ULONG_MAX, kbuf, func);

4
kernel/ksysfs.c
View File

@ -120,6 +120,7 @@ static ssize_t kexec_loaded_show(struct kobject *kobj,
}
KERNEL_ATTR_RO(kexec_loaded);
#ifdef CONFIG_CRASH_DUMP
static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@ -152,6 +153,7 @@ static ssize_t kexec_crash_size_store(struct kobject *kobj,
}
KERNEL_ATTR_RW(kexec_crash_size);
#endif /* CONFIG_CRASH_DUMP*/
#endif /* CONFIG_KEXEC_CORE */
#ifdef CONFIG_VMCORE_INFO
@ -262,9 +264,11 @@ static struct attribute * kernel_attrs[] = {
#endif
#ifdef CONFIG_KEXEC_CORE
&kexec_loaded_attr.attr,
#ifdef CONFIG_CRASH_DUMP
&kexec_crash_loaded_attr.attr,
&kexec_crash_size_attr.attr,
#endif
#endif
#ifdef CONFIG_VMCORE_INFO
&vmcoreinfo_attr.attr,
#ifdef CONFIG_CRASH_HOTPLUG