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authorAndrii Nakryiko <andrii@kernel.org>2024-08-29 19:42:27 +0200
committerAlexei Starovoitov <ast@kernel.org>2024-09-11 18:58:30 +0200
commit45b8fc3096542a53bfd245a9ad8ef870384b4897 (patch)
treeaa3e8ebc9186ed39d591841f629451762240801c /lib/buildid.c
parentlib/buildid: remove single-page limit for PHDR search (diff)
downloadlinux-45b8fc3096542a53bfd245a9ad8ef870384b4897.tar.xz
linux-45b8fc3096542a53bfd245a9ad8ef870384b4897.zip
lib/buildid: rename build_id_parse() into build_id_parse_nofault()
Make it clear that build_id_parse() assumes that it can take no page fault by renaming it and current few users to build_id_parse_nofault(). Also add build_id_parse() stub which for now falls back to non-sleepable implementation, but will be changed in subsequent patches to take advantage of sleepable context. PROCMAP_QUERY ioctl() on /proc/<pid>/maps file is using build_id_parse() and will automatically take advantage of more reliable sleepable context implementation. Reviewed-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20240829174232.3133883-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'lib/buildid.c')
-rw-r--r--lib/buildid.c25
1 files changed, 22 insertions, 3 deletions
diff --git a/lib/buildid.c b/lib/buildid.c
index e8fc4aeb01f2..c1cbd34f3685 100644
--- a/lib/buildid.c
+++ b/lib/buildid.c
@@ -293,10 +293,12 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si
* @build_id: buffer to store build id, at least BUILD_ID_SIZE long
* @size: returns actual build id size in case of success
*
- * Return: 0 on success, -EINVAL otherwise
+ * Assumes no page fault can be taken, so if relevant portions of ELF file are
+ * not already paged in, fetching of build ID fails.
+ *
+ * Return: 0 on success; negative error, otherwise
*/
-int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id,
- __u32 *size)
+int build_id_parse_nofault(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size)
{
const Elf32_Ehdr *ehdr;
struct freader r;
@@ -335,6 +337,23 @@ out:
return ret;
}
+/*
+ * 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
+ *
+ * Assumes faultable context and can cause page faults to bring in file data
+ * into page cache.
+ *
+ * Return: 0 on success; negative error, otherwise
+ */
+int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size)
+{
+ /* fallback to non-faultable version for now */
+ return build_id_parse_nofault(vma, build_id, size);
+}
+
/**
* build_id_parse_buf - Get build ID from a buffer
* @buf: ELF note section(s) to parse