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@chromium.org Signed-off-by: Stephen Boyd <swboyd@chromium.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Jessica Yu <jeyu@kernel.org> Cc: Evan Green <evgreen@chromium.org> Cc: Hsin-Yi Wang <hsinyi@chromium.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Young <dyoung@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Sasha Levin <sashal@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -8,5 +8,6 @@
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int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id,
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__u32 *size);
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int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size);
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#endif
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@ -2,30 +2,23 @@
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#include <linux/buildid.h>
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#include <linux/elf.h>
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#include <linux/kernel.h>
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#include <linux/pagemap.h>
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#define BUILD_ID 3
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/*
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* Parse build id from the note segment. This logic can be shared between
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* 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are
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* identical.
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*/
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static inline int parse_build_id(void *page_addr,
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unsigned char *build_id,
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__u32 *size,
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void *note_start,
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Elf32_Word note_size)
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static int parse_build_id_buf(unsigned char *build_id,
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__u32 *size,
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const void *note_start,
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Elf32_Word note_size)
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{
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Elf32_Word note_offs = 0, new_offs;
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/* check for overflow */
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if (note_start < page_addr || note_start + note_size < note_start)
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return -EINVAL;
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/* only supports note that fits in the first page */
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if (note_start + note_size > page_addr + PAGE_SIZE)
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return -EINVAL;
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while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
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Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
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@ -50,9 +43,27 @@ static inline int parse_build_id(void *page_addr,
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break;
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note_offs = new_offs;
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}
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return -EINVAL;
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}
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static inline int parse_build_id(void *page_addr,
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unsigned char *build_id,
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__u32 *size,
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void *note_start,
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Elf32_Word note_size)
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{
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/* check for overflow */
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if (note_start < page_addr || note_start + note_size < note_start)
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return -EINVAL;
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/* only supports note that fits in the first page */
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if (note_start + note_size > page_addr + PAGE_SIZE)
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return -EINVAL;
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return parse_build_id_buf(build_id, size, note_start, note_size);
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}
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/* Parse build ID from 32-bit ELF */
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static int get_build_id_32(void *page_addr, unsigned char *build_id,
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__u32 *size)
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@ -148,3 +159,16 @@ out:
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put_page(page);
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return ret;
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}
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/**
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* build_id_parse_buf - Get build ID from a buffer
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* @buf: Elf note section(s) to parse
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* @buf_size: Size of @buf in bytes
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* @build_id: Build ID parsed from @buf, at least BUILD_ID_SIZE_MAX long
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*
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* Return: 0 on success, -EINVAL otherwise
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*/
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int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size)
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{
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return parse_build_id_buf(build_id, NULL, buf, buf_size);
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}
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