Add vmlinux_build_id() so that callers can get a hex format string representation of the running kernel's build ID. This will be used in the kdump and dump_stack code so that developers can easily locate the vmlinux for a stacktrace.
Cc: Jiri Olsa <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Jessica Yu <[email protected]> Cc: Evan Green <[email protected]> Cc: Hsin-Yi Wang <[email protected]> Signed-off-by: Stephen Boyd <[email protected]> --- include/linux/buildid.h | 3 ++ lib/buildid.c | 65 ++++++++++++++++++++++++++++++++--------- 2 files changed, 55 insertions(+), 13 deletions(-) diff --git a/include/linux/buildid.h b/include/linux/buildid.h index 40232f90db6e..dd134a96a87c 100644 --- a/include/linux/buildid.h +++ b/include/linux/buildid.h @@ -5,8 +5,11 @@ #include <linux/mm_types.h> #define BUILD_ID_SIZE_MAX 20 +#define BUILD_ID_STR_SIZE_MAX (BUILD_ID_SIZE_MAX * 2 + 1) int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size); +const char *vmlinux_build_id(void); + #endif diff --git a/lib/buildid.c b/lib/buildid.c index 6156997c3895..57daf928b133 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -2,30 +2,23 @@ #include <linux/buildid.h> #include <linux/elf.h> +#include <linux/kernel.h> #include <linux/pagemap.h> #define BUILD_ID 3 + /* * Parse build id from the note segment. This logic can be shared between * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are * identical. */ -static inline int parse_build_id(void *page_addr, - unsigned char *build_id, - __u32 *size, - void *note_start, - Elf32_Word note_size) +static int parse_build_id_buf(unsigned char *build_id, + __u32 *size, + const void *note_start, + Elf32_Word note_size) { Elf32_Word note_offs = 0, new_offs; - /* check for overflow */ - if (note_start < page_addr || note_start + note_size < note_start) - return -EINVAL; - - /* only supports note that fits in the first page */ - if (note_start + note_size > page_addr + PAGE_SIZE) - return -EINVAL; - while (note_offs + sizeof(Elf32_Nhdr) < note_size) { Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); @@ -49,9 +42,27 @@ static inline int parse_build_id(void *page_addr, break; note_offs = new_offs; } + return -EINVAL; } +static inline int parse_build_id(void *page_addr, + unsigned char *build_id, + __u32 *size, + void *note_start, + Elf32_Word note_size) +{ + /* check for overflow */ + if (note_start < page_addr || note_start + note_size < note_start) + return -EINVAL; + + /* only supports note that fits in the first page */ + if (note_start + note_size > page_addr + PAGE_SIZE) + return -EINVAL; + + return parse_build_id_buf(build_id, size, note_start, note_size); +} + /* Parse build ID from 32-bit ELF */ static int get_build_id_32(void *page_addr, unsigned char *build_id, __u32 *size) @@ -147,3 +158,31 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, put_page(page); return ret; } + +static void build_id2hex(char *dst, const unsigned char *src, __u32 size) +{ + bin2hex(dst, src, size); + dst[2 * size] = '\0'; +} + +/** + * vmlinux_build_id - Get the running kernel's build-id in hex string format + * + * Return: Running kernel's build-id in hex string format + */ +const char *vmlinux_build_id(void) +{ + extern const void __start_notes __weak; + extern const void __stop_notes __weak; + unsigned int notes_size = &__stop_notes - &__start_notes; + unsigned char build_id[BUILD_ID_SIZE_MAX]; + __u32 size; + static char vmlinux_build_id_buf[BUILD_ID_STR_SIZE_MAX]; + + if (vmlinux_build_id_buf[0] == '\0') { + if (!parse_build_id_buf(build_id, &size, &__start_notes, notes_size)) + build_id2hex(vmlinux_build_id_buf, build_id, size); + } + + return vmlinux_build_id_buf; +} -- https://chromeos.dev
