From a6ed38361b1e0f08d630bd491051c254d1fc71b9 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 30 Jul 2015 16:04:22 +0200 Subject: [PATCH] bpf_jit_disasm: also support reading jit dump from file This patch adds support to read the dmesg BPF JIT dump also from a file instead of the klog buffer. I found this quite useful when going through some 'before/after patch' logs. It also fixes a regex leak found by valgrind when no image dump was found. Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller --- tools/net/bpf_jit_disasm.c | 109 ++++++++++++++++++++++++++++++------- 1 file changed, 90 insertions(+), 19 deletions(-) diff --git a/tools/net/bpf_jit_disasm.c b/tools/net/bpf_jit_disasm.c index 618c2bcd4eab..2cd3d4c99738 100644 --- a/tools/net/bpf_jit_disasm.c +++ b/tools/net/bpf_jit_disasm.c @@ -22,9 +22,14 @@ #include #include #include +#include +#include #include #include -#include +#include + +#define CMD_ACTION_SIZE_BUFFER 10 +#define CMD_ACTION_READ_ALL 3 static void get_exec_path(char *tpath, size_t size) { @@ -87,20 +92,66 @@ static void get_asm_insns(uint8_t *image, size_t len, int opcodes) bfd_close(bfdf); } -static char *get_klog_buff(int *klen) +static char *get_klog_buff(unsigned int *klen) { - int ret, len = klogctl(10, NULL, 0); - char *buff = malloc(len); + int ret, len; + char *buff; + + len = klogctl(CMD_ACTION_SIZE_BUFFER, NULL, 0); + buff = malloc(len); + if (!buff) + return NULL; + + ret = klogctl(CMD_ACTION_READ_ALL, buff, len); + if (ret < 0) { + free(buff); + return NULL; + } - assert(buff && klen); - ret = klogctl(3, buff, len); - assert(ret >= 0); *klen = ret; + return buff; +} +static char *get_flog_buff(const char *file, unsigned int *klen) +{ + int fd, ret, len; + struct stat fi; + char *buff; + + fd = open(file, O_RDONLY); + if (fd < 0) + return NULL; + + ret = fstat(fd, &fi); + if (ret < 0 || !S_ISREG(fi.st_mode)) + goto out; + + len = fi.st_size + 1; + buff = malloc(len); + if (!buff) + goto out; + + memset(buff, 0, len); + ret = read(fd, buff, len - 1); + if (ret <= 0) + goto out_free; + + close(fd); + *klen = ret; return buff; +out_free: + free(buff); +out: + close(fd); + return NULL; +} + +static char *get_log_buff(const char *file, unsigned int *klen) +{ + return file ? get_flog_buff(file, klen) : get_klog_buff(klen); } -static void put_klog_buff(char *buff) +static void put_log_buff(char *buff) { free(buff); } @@ -138,8 +189,10 @@ static int get_last_jit_image(char *haystack, size_t hlen, ptr = haystack + off - (pmatch[0].rm_eo - pmatch[0].rm_so); ret = sscanf(ptr, "flen=%d proglen=%d pass=%d image=%lx", &flen, &proglen, &pass, &base); - if (ret != 4) + if (ret != 4) { + regfree(®ex); return 0; + } tmp = ptr = haystack + off; while ((ptr = strtok(tmp, "\n")) != NULL && ulen < ilen) { @@ -169,31 +222,49 @@ static int get_last_jit_image(char *haystack, size_t hlen, return ulen; } +static void usage(void) +{ + printf("Usage: bpf_jit_disasm [...]\n"); + printf(" -o Also display related opcodes (default: off).\n"); + printf(" -f Read last image dump from file or stdin (default: klog).\n"); + printf(" -h Display this help.\n"); +} + int main(int argc, char **argv) { - int len, klen, opcodes = 0; - char *kbuff; + unsigned int len, klen, opt, opcodes = 0; static uint8_t image[32768]; + char *kbuff, *file = NULL; - if (argc > 1) { - if (!strncmp("-o", argv[argc - 1], 2)) { + while ((opt = getopt(argc, argv, "of:")) != -1) { + switch (opt) { + case 'o': opcodes = 1; - } else { - printf("usage: bpf_jit_disasm [-o: show opcodes]\n"); - exit(0); + break; + case 'f': + file = optarg; + break; + default: + usage(); + return -1; } } bfd_init(); memset(image, 0, sizeof(image)); - kbuff = get_klog_buff(&klen); + kbuff = get_log_buff(file, &klen); + if (!kbuff) { + fprintf(stderr, "Could not retrieve log buffer!\n"); + return -1; + } len = get_last_jit_image(kbuff, klen, image, sizeof(image)); if (len > 0) get_asm_insns(image, len, opcodes); + else + fprintf(stderr, "No JIT image found!\n"); - put_klog_buff(kbuff); - + put_log_buff(kbuff); return 0; } -- 2.20.1