Commit 7eaf3cf3 authored by Stephen Boyd's avatar Stephen Boyd Committed by Linus Torvalds
Browse files

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: default avatarStephen 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a010d79b

include/linux/buildid.h

+1 −0
Original line number Diff line number Diff line
@@ -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

lib/buildid.c

+37 −13
Original line number Diff line number Diff line
@@ -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,

static int parse_build_id_buf(unsigned char *build_id,

			      __u32 *size,

				 void *note_start,

			      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);
@@ -50,7 +43,25 @@ 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 */
@@ -148,3 +159,16 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, 
	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);

}