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crash: Add crash_prepare_headers() to exclude crash kernel memory

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The crash memory alloc, and the exclude of crashk_res, crashk_low_res
and crashk_cma memory are almost identical across different architectures,
handling them in the crash core would eliminate a lot of duplication, so
add crash_prepare_headers() helper to handle them in the common code.

To achieve the above goal, three architecture-specific functions are
introduced:

- arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.

- arch_crash_populate_cmem(). Collects the memory ranges and fills them
  into cmem.

- arch_crash_exclude_ranges(). Architecture's additional crash memory
  ranges exclusion, defaulting to empty.

Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260629094746.191843-4-ruanjinjie@huawei.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
This commit is contained in:
Jinjie Ruan 2026-06-29 17:47:39 +08:00 committed by Mike Rapoport (Microsoft)
parent 202b5de3ec
commit 5beabef0cf
2 changed files with 84 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/crash_core.h
View File

@ -59,6 +59,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
unsigned long long mend);
extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
void **addr, unsigned long *sz);
extern int crash_prepare_headers(int need_kernel_map, void **addr,
unsigned long *sz, unsigned long *nr_mem_ranges);
struct kimage;
struct kexec_segment;
@ -76,6 +78,9 @@ 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);
extern unsigned int arch_get_system_nr_ranges(void);
extern int arch_crash_populate_cmem(struct crash_mem *cmem);
extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
#else /* !CONFIG_CRASH_DUMP*/
struct pt_regs;

82
kernel/crash_core.c
View File

@ -168,9 +168,6 @@ 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)
{
@ -272,6 +269,85 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
return 0;
}
static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
{
struct crash_mem *cmem;
cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
if (!cmem)
return NULL;
cmem->max_nr_ranges = nr_ranges;
return cmem;
}
unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
static int crash_exclude_core_ranges(struct crash_mem *cmem)
{
int ret, i;
/* Exclude crashkernel region */
ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
if (ret)
return ret;
if (crashk_low_res.end) {
ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
if (ret)
return ret;
}
for (i = 0; i < crashk_cma_cnt; ++i) {
ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
crashk_cma_ranges[i].end);
if (ret)
return ret;
}
return 0;
}
int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
unsigned long *nr_mem_ranges)
{
unsigned int max_nr_ranges;
struct crash_mem *cmem;
int ret;
max_nr_ranges = arch_get_system_nr_ranges();
if (!max_nr_ranges)
return -ENOMEM;
cmem = alloc_cmem(max_nr_ranges);
if (!cmem)
return -ENOMEM;
ret = arch_crash_populate_cmem(cmem);
if (ret)
goto out;
ret = crash_exclude_core_ranges(cmem);
if (ret)
goto out;
ret = arch_crash_exclude_ranges(cmem);
if (ret)
goto out;
/* Return the computed number of memory ranges, for hotplug usage */
if (nr_mem_ranges)
*nr_mem_ranges = cmem->nr_ranges;
ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
out:
kvfree(cmem);
return ret;
}
/**
* crash_exclude_mem_range - exclude a mem range for existing ranges
* @mem: mem->range contains an array of ranges sorted in ascending order