[PATCH RFC v2 bpf-next 2/9] bpf: Use file's inode object build id in stackmap

Jiri Olsa
2023-02-28T09:32:49Z

Use build id from file's inode object in stackmap if it's available.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
kernel/bpf/stackmap.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index aecea7451b61..9b9578e0cada 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -124,6 +124,28 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
return ERR_PTR(err);
}

+#ifdef CONFIG_INODE_BUILD_ID
+static int vma_get_build_id(struct vm_area_struct *vma, unsigned char *build_id)
+{
+ struct build_id *bid;
+
+ if (!vma->vm_file)
+ return -EINVAL;
+ bid = file_inode(vma->vm_file)->i_build_id;
+ if (IS_ERR_OR_NULL(bid))
+ return bid ? PTR_ERR(bid) : -ENOENT;
+ if (bid->sz > BUILD_ID_SIZE_MAX)
+ return -EINVAL;
+ memcpy(build_id, bid->data, bid->sz);
+ return 0;
+}
+#else
+static int vma_get_build_id(struct vm_area_struct *vma, unsigned char *build_id)
+{
+ return build_id_parse(vma, build_id, NULL);
+}
+#endif
+
static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
u64 *ips, u32 trace_nr, bool user)
{
@@ -156,7 +178,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
goto build_id_valid;
}
vma = find_vma(current->mm, ips[i]);
- if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) {
+ if (!vma || vma_get_build_id(vma, id_offs[i].build_id)) {
/* per entry fall back to ips */
id_offs[i].status = BPF_STACK_BUILD_ID_IP;
id_offs[i].ip = ips[i];
--
2.39.2