Commit 921f88fc authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

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: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210114134044.1418404-3-jolsa@kernel.org
parent bd7525da

include/linux/buildid.h

+2 −1
Original line number Diff line number Diff line
@@ -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

kernel/bpf/stackmap.c

+1 −1
Original line number Diff line number Diff line
@@ -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];

lib/buildid.c

+21 −8
Original line number Diff line number Diff line
@@ -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);