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bpf: Add size arg to build_id_parse function 

It's possible to have other build id types (other than default SHA1).
Currently there's also ld support for MD5 build id.

Adding size argument to build_id_parse function, that returns (if defined)
size of the parsed build id, so we can recognize the build id type.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210114134044.1418404-3-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2021-01-14 14:40:43 +01:00 committed by Alexei Starovoitov
parent bd7525dacd
commit 921f88fc89
3 changed files with 24 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/buildid.h
View File

@ -6,6 +6,7 @@
#define BUILD_ID_SIZE_MAX 20
int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id);
int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id,
__u32 *size);
#endif

2
kernel/bpf/stackmap.c
View File

@ -189,7 +189,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
for (i = 0; i < trace_nr; i++) {
vma = find_vma(current->mm, ips[i]);
if (!vma || build_id_parse(vma, id_offs[i].build_id)) {
if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) {
/* per entry fall back to ips */
id_offs[i].status = BPF_STACK_BUILD_ID_IP;
id_offs[i].ip = ips[i];

29
lib/buildid.c
View File

@ -12,6 +12,7 @@
*/
static inline int parse_build_id(void *page_addr,
unsigned char *build_id,
__u32 *size,
void *note_start,
Elf32_Word note_size)
{
@ -38,6 +39,8 @@ static inline int parse_build_id(void *page_addr,
nhdr->n_descsz);
memset(build_id + nhdr->n_descsz, 0,
BUILD_ID_SIZE_MAX - nhdr->n_descsz);
if (size)
*size = nhdr->n_descsz;
return 0;
}
new_offs = note_offs + sizeof(Elf32_Nhdr) +
@ -50,7 +53,8 @@ static inline int parse_build_id(void *page_addr,
}
/* Parse build ID from 32-bit ELF */
static int get_build_id_32(void *page_addr, unsigned char *build_id)
static int get_build_id_32(void *page_addr, unsigned char *build_id,
__u32 *size)
{
Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr;
Elf32_Phdr *phdr;
@ -65,7 +69,7 @@ static int get_build_id_32(void *page_addr, unsigned char *build_id)
for (i = 0; i < ehdr->e_phnum; ++i) {
if (phdr[i].p_type == PT_NOTE &&
!parse_build_id(page_addr, build_id,
!parse_build_id(page_addr, build_id, size,
page_addr + phdr[i].p_offset,
phdr[i].p_filesz))
return 0;
@ -74,7 +78,8 @@ static int get_build_id_32(void *page_addr, unsigned char *build_id)
}
/* Parse build ID from 64-bit ELF */
static int get_build_id_64(void *page_addr, unsigned char *build_id)
static int get_build_id_64(void *page_addr, unsigned char *build_id,
__u32 *size)
{
Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr;
Elf64_Phdr *phdr;
@ -89,7 +94,7 @@ static int get_build_id_64(void *page_addr, unsigned char *build_id)
for (i = 0; i < ehdr->e_phnum; ++i) {
if (phdr[i].p_type == PT_NOTE &&
!parse_build_id(page_addr, build_id,
!parse_build_id(page_addr, build_id, size,
page_addr + phdr[i].p_offset,
phdr[i].p_filesz))
return 0;
@ -97,8 +102,16 @@ static int get_build_id_64(void *page_addr, unsigned char *build_id)
return -EINVAL;
}
/* Parse build ID of ELF file mapped to vma */
int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id)
/*
* Parse build ID of ELF file mapped to vma
* @vma: vma object
* @build_id: buffer to store build id, at least BUILD_ID_SIZE long
* @size: returns actual build id size in case of success
*
* Returns 0 on success, otherwise error (< 0).
*/
int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id,
__u32 *size)
{
Elf32_Ehdr *ehdr;
struct page *page;
@ -126,9 +139,9 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id)
goto out;
if (ehdr->e_ident[EI_CLASS] == ELFCLASS32)
ret = get_build_id_32(page_addr, build_id);
ret = get_build_id_32(page_addr, build_id, size);
else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64)
ret = get_build_id_64(page_addr, build_id);
ret = get_build_id_64(page_addr, build_id, size);
out:
kunmap_atomic(page_addr);
put_page(page);