On 1/14/21 5:40 AM, Jiri Olsa wrote:
It's possible to have other build id types (other than default SHA1).
Currently there's also ld support for MD5 build id.
Currently, bpf build_id based stackmap does not returns the size of
the build_id. Did you see an issue here? I guess user space can check
the length of non-zero bits of the build id to decide what kind of
type it is, right?
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.
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Song Liu <songliubrav...@fb.com>
Signed-off-by: Jiri Olsa <jo...@kernel.org>
---
include/linux/buildid.h | 3 ++-
kernel/bpf/stackmap.c | 2 +-
lib/buildid.c | 29 +++++++++++++++++++++--------
3 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/include/linux/buildid.h b/include/linux/buildid.h
index 08028a212589..40232f90db6e 100644
--- a/include/linux/buildid.h
+++ b/include/linux/buildid.h
@@ -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
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index 55d254a59f07..cabaf7db8efc 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -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];
diff --git a/lib/buildid.c b/lib/buildid.c
index 4a4f520c0e29..6156997c3895 100644
--- a/lib/buildid.c
+++ b/lib/buildid.c
@@ -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,
}
[...]
