From: Stephen Boyd <swboyd@xxxxxxxxxxxx> Subject: buildid: add API to parse build ID out of buffer Add an API that can parse the build ID out of a buffer, instead of a vma, to support printing a kernel module's build ID for stack traces. Link: https://lkml.kernel.org/r/20210511003845.2429846-3-swboyd@xxxxxxxxxxxx Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Jessica Yu <jeyu@xxxxxxxxxx> Cc: Evan Green <evgreen@xxxxxxxxxxxx> Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/buildid.h | 1 lib/buildid.c | 50 ++++++++++++++++++++++++++++---------- 2 files changed, 38 insertions(+), 13 deletions(-) --- a/include/linux/buildid.h~buildid-add-api-to-parse-build-id-out-of-buffer +++ a/include/linux/buildid.h @@ -8,5 +8,6 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size); +int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size); #endif --- a/lib/buildid.c~buildid-add-api-to-parse-build-id-out-of-buffer +++ a/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); @@ -50,9 +43,27 @@ static inline int parse_build_id(void *p 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) @@ -148,3 +159,16 @@ out: put_page(page); return ret; } + +/** + * build_id_parse_buf - Get build ID from a buffer + * @buf: Elf note section(s) to parse + * @buf_size: Size of @buf in bytes + * @build_id: Build ID parsed from @buf, at least BUILD_ID_SIZE_MAX long + * + * Return: 0 on success, -EINVAL otherwise + */ +int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size) +{ + return parse_build_id_buf(build_id, NULL, buf, buf_size); +} _
