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Commit a6ed3836 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1df33a11

tools/net/bpf_jit_disasm.c

+90 −19
Original line number Diff line number Diff line
@@ -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 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 void put_klog_buff(char *buff)

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;

}