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Date: Thu, 26 Nov 2020 18:00:03 +0100 From: Jiri Olsa <jolsa@...nel.org> To: Arnaldo Carvalho de Melo <acme@...nel.org> Cc: Alexei Starovoitov <ast@...nel.org>, Song Liu <songliubraving@...com>, lkml <linux-kernel@...r.kernel.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Ingo Molnar <mingo@...nel.org>, Mark Rutland <mark.rutland@....com>, Namhyung Kim <namhyung@...nel.org>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Michael Petlan <mpetlan@...hat.com>, Ian Rogers <irogers@...gle.com>, Stephane Eranian <eranian@...gle.com>, Alexey Budankov <alexey.budankov@...ux.intel.com>, Andi Kleen <ak@...ux.intel.com>, Adrian Hunter <adrian.hunter@...el.com> Subject: [PATCH 02/25] 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. Cc: Alexei Starovoitov <ast@...nel.org> Cc: Song Liu <songliubraving@...com> Signed-off-by: Jiri Olsa <jolsa@...nel.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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