From ab4c15feb2ebcf9f4abe31457d7cbc8f3de9c2ab Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Mon, 13 Mar 2023 14:56:28 -0600 Subject: selftests/bpf: use canonical ftrace path The canonical location for the tracefs filesystem is at /sys/kernel/tracing. But, from Documentation/trace/ftrace.rst: Before 4.1, all ftrace tracing control files were within the debugfs file system, which is typically located at /sys/kernel/debug/tracing. For backward compatibility, when mounting the debugfs file system, the tracefs file system will be automatically mounted at: /sys/kernel/debug/tracing Many tests in the bpf selftest code still refer to this older debugfs path, so let's update them to avoid confusion. Signed-off-by: Ross Zwisler Acked-by: Michael S. Tsirkin Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/r/20230313205628.1058720-3-zwisler@kernel.org Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/trace_helpers.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'tools/testing/selftests/bpf/trace_helpers.c') diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index 09a16a77bae4..934bf28fc888 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -12,7 +12,8 @@ #include #include "trace_helpers.h" -#define DEBUGFS "/sys/kernel/debug/tracing/" +#define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe" +#define DEBUGFS_PIPE "/sys/kernel/debug/tracing/trace_pipe" #define MAX_SYMS 300000 static struct ksym syms[MAX_SYMS]; @@ -136,7 +137,10 @@ void read_trace_pipe(void) { int trace_fd; - trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0); + if (access(TRACEFS_PIPE, F_OK) == 0) + trace_fd = open(TRACEFS_PIPE, O_RDONLY, 0); + else + trace_fd = open(DEBUGFS_PIPE, O_RDONLY, 0); if (trace_fd < 0) return; -- cgit From 88dc8b3605b38a440fba45edcc53a6c7a98eee3b Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Fri, 31 Mar 2023 11:31:56 +0200 Subject: selftests/bpf: Add read_build_id function 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 Link: https://lore.kernel.org/r/20230331093157.1749137-3-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/trace_helpers.c | 82 +++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) (limited to 'tools/testing/selftests/bpf/trace_helpers.c') diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index 934bf28fc888..9b070cdf44ac 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -11,6 +11,9 @@ #include #include #include "trace_helpers.h" +#include +#include +#include #define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe" #define DEBUGFS_PIPE "/sys/kernel/debug/tracing/trace_pipe" @@ -234,3 +237,82 @@ 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; + + 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; + } + + note_offs = note_offs + sizeof(Elf32_Nhdr) + + ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); + } + + return -ENOENT; +} + +/* Reads binary from *path* file and returns it in the *build_id* buffer + * with *size* 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, size_t size) +{ + int fd, err = -EINVAL; + Elf *elf = NULL; + GElf_Ehdr ehdr; + size_t max, i; + + if (size < BPF_BUILD_ID_SIZE) + return -EINVAL; + + fd = open(path, O_RDONLY | O_CLOEXEC); + if (fd < 0) + return -errno; + + (void)elf_version(EV_CURRENT); + + elf = elf_begin(fd, ELF_C_READ_MMAP, NULL); + if (!elf) + goto out; + if (elf_kind(elf) != ELF_K_ELF) + goto out; + if (!gelf_getehdr(elf, &ehdr)) + 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 + phdr->p_memsz > max) + goto out; + err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id); + if (err > 0) + break; + } + +out: + if (elf) + elf_end(elf); + close(fd); + return err; +} -- cgit