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| author | Omar Sandoval <osandov@fb.com> | 2018-08-21 21:55:20 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-22 10:52:46 -0700 |
| commit | 23c85094fe1895caefdd19ef624ee687ec5f4507 (patch) | |
| tree | 13a0d0b93980e585384310a021b3772dc37b9e54 /fs/proc | |
| parent | eff4345e7fba0aac8665f00e8599b36946d9aaec (diff) | |
| download | linux-23c85094fe1895caefdd19ef624ee687ec5f4507.tar.gz | |
proc/kcore: add vmcoreinfo note to /proc/kcore
The vmcoreinfo information is useful for runtime debugging tools, not just for crash dumps. A lot of this information can be determined by other means, but this is much more convenient, and it only adds a page at most to the file. Link: http://lkml.kernel.org/r/fddbcd08eed76344863303878b12de1c1e2a04b6.1531953780.git.osandov@fb.com Signed-off-by: Omar Sandoval <osandov@fb.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Bhupesh Sharma <bhsharma@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: James Morse <james.morse@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/Kconfig | 1 | ||||
| -rw-r--r-- | fs/proc/kcore.c | 18 |
2 files changed, 17 insertions, 2 deletions
diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig index 0eaeb41453f5..817c02b13b1d 100644 --- a/fs/proc/Kconfig +++ b/fs/proc/Kconfig @@ -31,6 +31,7 @@ config PROC_FS config PROC_KCORE bool "/proc/kcore support" if !ARM depends on PROC_FS && MMU + select CRASH_CORE help Provides a virtual ELF core file of the live kernel. This can be read with gdb and other ELF tools. No modifications can be diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 758c14e46a44..80464432dfe6 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -10,6 +10,7 @@ * Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com> */ +#include <linux/crash_core.h> #include <linux/mm.h> #include <linux/proc_fs.h> #include <linux/kcore.h> @@ -81,10 +82,13 @@ static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len, } *phdrs_len = *nphdr * sizeof(struct elf_phdr); - *notes_len = (3 * (sizeof(struct elf_note) + ALIGN(sizeof(CORE_STR), 4)) + + *notes_len = (4 * sizeof(struct elf_note) + + 3 * ALIGN(sizeof(CORE_STR), 4) + + VMCOREINFO_NOTE_NAME_BYTES + ALIGN(sizeof(struct elf_prstatus), 4) + ALIGN(sizeof(struct elf_prpsinfo), 4) + - ALIGN(arch_task_struct_size, 4)); + ALIGN(arch_task_struct_size, 4) + + ALIGN(vmcoreinfo_size, 4)); *data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len + *notes_len); return *data_offset + size; @@ -406,6 +410,16 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) sizeof(prpsinfo)); append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current, arch_task_struct_size); + /* + * vmcoreinfo_size is mostly constant after init time, but it + * can be changed by crash_save_vmcoreinfo(). Racing here with a + * panic on another CPU before the machine goes down is insanely + * unlikely, but it's better to not leave potential buffer + * overflows lying around, regardless. + */ + append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0, + vmcoreinfo_data, + min(vmcoreinfo_size, notes_len - i)); tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { |