| Message ID | 20230228093206.821563-6-jolsa@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/bpf/perf: Store build id in inode object | expand |
On Tue, Feb 28, 2023 at 1:33 AM Jiri Olsa <jolsa@kernel.org> wrote: > > Adding read_build_id function that parses out build id from > specified binary. > > It will replace extract_build_id and also be used in following > changes. > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > tools/testing/selftests/bpf/trace_helpers.c | 98 +++++++++++++++++++++ > tools/testing/selftests/bpf/trace_helpers.h | 5 ++ > 2 files changed, 103 insertions(+) > > diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c > index 09a16a77bae4..c10e16626cd3 100644 > --- a/tools/testing/selftests/bpf/trace_helpers.c > +++ b/tools/testing/selftests/bpf/trace_helpers.c > @@ -11,6 +11,9 @@ > #include <linux/perf_event.h> > #include <sys/mman.h> > #include "trace_helpers.h" > +#include <linux/limits.h> > +#include <libelf.h> > +#include <gelf.h> > > #define DEBUGFS "/sys/kernel/debug/tracing/" > > @@ -230,3 +233,98 @@ ssize_t get_rel_offset(uintptr_t addr) > fclose(f); > return -EINVAL; > } > + > +static int > +parse_build_id_buf(const void *note_start, Elf32_Word note_size, > + char *build_id) > +{ > + Elf32_Word note_offs = 0, new_offs; > + > + while (note_offs + sizeof(Elf32_Nhdr) < note_size) { > + Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); > + > + if (nhdr->n_type == 3 && > + nhdr->n_namesz == sizeof("GNU") && > + !strcmp((char *)(nhdr + 1), "GNU") && > + nhdr->n_descsz > 0 && > + nhdr->n_descsz <= BPF_BUILD_ID_SIZE) { > + memcpy(build_id, note_start + note_offs + > + ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), > + nhdr->n_descsz); > + memset(build_id + nhdr->n_descsz, 0, > + BPF_BUILD_ID_SIZE - nhdr->n_descsz); I won't count :) but if something fits within 100 characters, please keep it on single line > + return (int) nhdr->n_descsz; > + } > + > + new_offs = note_offs + sizeof(Elf32_Nhdr) + > + ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); > + > + if (new_offs >= note_size) > + break; > + note_offs = new_offs; > + } > + > + return -EINVAL; > +} > + > +/* Reads binary from *path* file and returns it in the *build_id* > + * which is expected to be at least BPF_BUILD_ID_SIZE bytes. > + * Returns size of build id on success. On error the error value > + * is returned. > + */ > +int read_build_id(const char *path, char *build_id) > +{ > + int fd, err = -EINVAL; > + Elf *elf = NULL; > + GElf_Ehdr ehdr; > + size_t max, i; > + > + fd = open(path, O_RDONLY | O_CLOEXEC); > + if (fd < 0) > + return -errno; > + > + (void)elf_version(EV_CURRENT); > + > + elf = elf_begin(fd, ELF_C_READ, NULL); > + if (!elf) > + goto out; > + > + if (elf_kind(elf) != ELF_K_ELF) > + goto out; > + > + if (gelf_getehdr(elf, &ehdr) == NULL) > + goto out; > + > + if (ehdr.e_ident[EI_CLASS] != ELFCLASS64) > + goto out; > + > + for (i = 0; i < ehdr.e_phnum; i++) { > + GElf_Phdr mem, *phdr; > + char *data; > + > + phdr = gelf_getphdr(elf, i, &mem); > + if (!phdr) > + goto out; > + > + if (phdr->p_type != PT_NOTE) > + continue; > + > + data = elf_rawfile(elf, &max); > + if (!data) > + goto out; > + > + if (phdr->p_offset >= max || > + (phdr->p_offset + phdr->p_memsz >= max)) > + goto out; > + > + err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id); > + if (err > 0) > + goto out; > + } > + > +out: > + if (elf) > + elf_end(elf); > + close(fd); > + return err; > +} > diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h > index 53efde0e2998..50b2cc498ba7 100644 > --- a/tools/testing/selftests/bpf/trace_helpers.h > +++ b/tools/testing/selftests/bpf/trace_helpers.h > @@ -4,6 +4,9 @@ > > #include <bpf/libbpf.h> > > +#define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a)-1) > +#define __ALIGN_MASK(x, mask) (((x)+(mask))&~(mask)) nit: I know these are macros, but why would you first use __ALIGN_MASK and then #define it? swap them? > + > struct ksym { > long addr; > char *name; > @@ -23,4 +26,6 @@ void read_trace_pipe(void); > ssize_t get_uprobe_offset(const void *addr); > ssize_t get_rel_offset(uintptr_t addr); > > +int read_build_id(const char *path, char *build_id); > + > #endif > -- > 2.39.2 >
On Tue, Mar 07, 2023 at 05:22:51PM -0800, Andrii Nakryiko wrote: > On Tue, Feb 28, 2023 at 1:33 AM Jiri Olsa <jolsa@kernel.org> wrote: > > > > Adding read_build_id function that parses out build id from > > specified binary. > > > > It will replace extract_build_id and also be used in following > > changes. > > > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > tools/testing/selftests/bpf/trace_helpers.c | 98 +++++++++++++++++++++ > > tools/testing/selftests/bpf/trace_helpers.h | 5 ++ > > 2 files changed, 103 insertions(+) > > > > diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c > > index 09a16a77bae4..c10e16626cd3 100644 > > --- a/tools/testing/selftests/bpf/trace_helpers.c > > +++ b/tools/testing/selftests/bpf/trace_helpers.c > > @@ -11,6 +11,9 @@ > > #include <linux/perf_event.h> > > #include <sys/mman.h> > > #include "trace_helpers.h" > > +#include <linux/limits.h> > > +#include <libelf.h> > > +#include <gelf.h> > > > > #define DEBUGFS "/sys/kernel/debug/tracing/" > > > > @@ -230,3 +233,98 @@ ssize_t get_rel_offset(uintptr_t addr) > > fclose(f); > > return -EINVAL; > > } > > + > > +static int > > +parse_build_id_buf(const void *note_start, Elf32_Word note_size, > > + char *build_id) > > +{ > > + Elf32_Word note_offs = 0, new_offs; > > + > > + while (note_offs + sizeof(Elf32_Nhdr) < note_size) { > > + Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); > > + > > + if (nhdr->n_type == 3 && > > + nhdr->n_namesz == sizeof("GNU") && > > + !strcmp((char *)(nhdr + 1), "GNU") && > > + nhdr->n_descsz > 0 && > > + nhdr->n_descsz <= BPF_BUILD_ID_SIZE) { > > + memcpy(build_id, note_start + note_offs + > > + ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), > > + nhdr->n_descsz); > > + memset(build_id + nhdr->n_descsz, 0, > > + BPF_BUILD_ID_SIZE - nhdr->n_descsz); > > I won't count :) but if something fits within 100 characters, please > keep it on single line copy&paste from kernel code ;-) I'll reformat that SNIP > > diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h > > index 53efde0e2998..50b2cc498ba7 100644 > > --- a/tools/testing/selftests/bpf/trace_helpers.h > > +++ b/tools/testing/selftests/bpf/trace_helpers.h > > @@ -4,6 +4,9 @@ > > > > #include <bpf/libbpf.h> > > > > +#define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a)-1) > > +#define __ALIGN_MASK(x, mask) (((x)+(mask))&~(mask)) > > nit: I know these are macros, but why would you first use __ALIGN_MASK > and then #define it? swap them? same reason as above, I'll swap that thanks, jirka
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index 09a16a77bae4..c10e16626cd3 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -11,6 +11,9 @@ #include <linux/perf_event.h> #include <sys/mman.h> #include "trace_helpers.h" +#include <linux/limits.h> +#include <libelf.h> +#include <gelf.h> #define DEBUGFS "/sys/kernel/debug/tracing/" @@ -230,3 +233,98 @@ ssize_t get_rel_offset(uintptr_t addr) fclose(f); return -EINVAL; } + +static int +parse_build_id_buf(const void *note_start, Elf32_Word note_size, + char *build_id) +{ + Elf32_Word note_offs = 0, new_offs; + + while (note_offs + sizeof(Elf32_Nhdr) < note_size) { + Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); + + if (nhdr->n_type == 3 && + nhdr->n_namesz == sizeof("GNU") && + !strcmp((char *)(nhdr + 1), "GNU") && + nhdr->n_descsz > 0 && + nhdr->n_descsz <= BPF_BUILD_ID_SIZE) { + memcpy(build_id, note_start + note_offs + + ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), + nhdr->n_descsz); + memset(build_id + nhdr->n_descsz, 0, + BPF_BUILD_ID_SIZE - nhdr->n_descsz); + return (int) nhdr->n_descsz; + } + + new_offs = note_offs + sizeof(Elf32_Nhdr) + + ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); + + if (new_offs >= note_size) + break; + note_offs = new_offs; + } + + return -EINVAL; +} + +/* Reads binary from *path* file and returns it in the *build_id* + * which is expected to be at least BPF_BUILD_ID_SIZE bytes. + * Returns size of build id on success. On error the error value + * is returned. + */ +int read_build_id(const char *path, char *build_id) +{ + int fd, err = -EINVAL; + Elf *elf = NULL; + GElf_Ehdr ehdr; + size_t max, i; + + fd = open(path, O_RDONLY | O_CLOEXEC); + if (fd < 0) + return -errno; + + (void)elf_version(EV_CURRENT); + + elf = elf_begin(fd, ELF_C_READ, NULL); + if (!elf) + goto out; + + if (elf_kind(elf) != ELF_K_ELF) + goto out; + + if (gelf_getehdr(elf, &ehdr) == NULL) + goto out; + + if (ehdr.e_ident[EI_CLASS] != ELFCLASS64) + goto out; + + for (i = 0; i < ehdr.e_phnum; i++) { + GElf_Phdr mem, *phdr; + char *data; + + phdr = gelf_getphdr(elf, i, &mem); + if (!phdr) + goto out; + + if (phdr->p_type != PT_NOTE) + continue; + + data = elf_rawfile(elf, &max); + if (!data) + goto out; + + if (phdr->p_offset >= max || + (phdr->p_offset + phdr->p_memsz >= max)) + goto out; + + err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id); + if (err > 0) + goto out; + } + +out: + if (elf) + elf_end(elf); + close(fd); + return err; +} diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h index 53efde0e2998..50b2cc498ba7 100644 --- a/tools/testing/selftests/bpf/trace_helpers.h +++ b/tools/testing/selftests/bpf/trace_helpers.h @@ -4,6 +4,9 @@ #include <bpf/libbpf.h> +#define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a)-1) +#define __ALIGN_MASK(x, mask) (((x)+(mask))&~(mask)) + struct ksym { long addr; char *name; @@ -23,4 +26,6 @@ void read_trace_pipe(void); ssize_t get_uprobe_offset(const void *addr); ssize_t get_rel_offset(uintptr_t addr); +int read_build_id(const char *path, char *build_id); + #endif
Adding read_build_id function that parses out build id from specified binary. It will replace extract_build_id and also be used in following changes. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- tools/testing/selftests/bpf/trace_helpers.c | 98 +++++++++++++++++++++ tools/testing/selftests/bpf/trace_helpers.h | 5 ++ 2 files changed, 103 insertions(+)