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bpf_jit_disasm: also support reading jit dump from file

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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 <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2015-07-30 16:04:22 +02:00 committed by David S. Miller
parent 1df33a1145
commit a6ed38361b
1 changed files with 91 additions and 20 deletions
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111
tools/net/bpf_jit_disasm.c
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@ -22,9 +22,14 @@
#include <string.h>
#include <bfd.h>
#include <dis-asm.h>
#include <regex.h>
#include <fcntl.h>
#include <sys/klog.h>
#include <sys/types.h>
#include <regex.h>
#include <sys/stat.h>
#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 void put_klog_buff(char *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_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(&regex);
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 <file> 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;
}