Messages in this thread |  | | Date | Thu, 3 Dec 2020 20:24:38 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH 02/25] bpf: Add size arg to build_id_parse function |
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On Thu, Nov 26, 2020 at 06:00:03PM +0100, 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. > > 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 <ast@kernel.org> > Cc: Song Liu <songliubraving@fb.com>
Alexei, Song, could you guys please check on this one?
thanks, jirka
> Signed-off-by: Jiri Olsa <jolsa@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 3be5b49719f1..72639d433873 100644 > --- a/include/linux/buildid.h > +++ b/include/linux/buildid.h > @@ -6,6 +6,7 @@ > > #define BUILD_ID_SIZE 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 7df08f8af5a1..a05fac2cbb05 100644 > --- a/kernel/bpf/stackmap.c > +++ b/kernel/bpf/stackmap.c > @@ -199,7 +199,7 @@ 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 e8d5feb7ef20..dbe1b7e247f3 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 - 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); > -- > 2.26.2 >
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