/*
 * Minimal BPF JIT image disassembler
 *
 * Disassembles BPF JIT compiler emitted opcodes back to asm insn's for
 * debugging or verification purposes.
 *
 * There is no Makefile. Compile with
 *
 *   `gcc -Wall -O2 bpf_jit_disasm.c -o bpf_jit_disasm -lopcodes -lbfd -ldl`
 *
 * or similar.
 *
 * To get the disassembly of the JIT code, do the following:
 *
 *  1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
 *  2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
 *  3) Run e.g. `bpf_jit_disasm -o` to read out the last JIT code
 *
 * Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
 * Licensed under the GNU General Public License, version 2.0 (GPLv2)
 *
 * Note: this is part of the Linux kernel and can be found under tools/net/.
 */

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <unistd.h>
#include <string.h>
#include <bfd.h>
#include <dis-asm.h>
#include <sys/klog.h>
#include <sys/types.h>
#include <regex.h>

static void get_exec_path(char *tpath, size_t size)
{
	char *path;
	ssize_t len;

	snprintf(tpath, size, "/proc/%d/exe", (int) getpid());
	tpath[size - 1] = 0;

	path = strdup(tpath);
	assert(path);

	len = readlink(path, tpath, size);
	tpath[len] = 0;

	free(path);
}

static void get_asm_insns(uint8_t *image, size_t len, unsigned long base,
			  int opcodes)
{
	int count, i, pc = 0;
	char tpath[256];
	struct disassemble_info info;
	disassembler_ftype disassemble;
	bfd *bfdf;

	memset(tpath, 0, sizeof(tpath));
	get_exec_path(tpath, sizeof(tpath));

	bfdf = bfd_openr(tpath, NULL);
	assert(bfdf);
	assert(bfd_check_format(bfdf, bfd_object));

	init_disassemble_info(&info, stdout, (fprintf_ftype) fprintf);
	info.arch = bfd_get_arch(bfdf);
	info.mach = bfd_get_mach(bfdf);
	info.buffer = image;
	info.buffer_length = len;

	disassemble_init_for_target(&info);

	disassemble = disassembler(bfdf);
	assert(disassemble);

	do {
		printf("%4x:\t", pc);

		count = disassemble(pc, &info);

		if (opcodes) {
			printf("\n\t");
			for (i = 0; i < count; ++i)
				printf("%02x ", (uint8_t) image[pc + i]);
		}
		printf("\n");

		pc += count;
	} while(count > 0 && pc < len);

	bfd_close(bfdf);
}

static char *get_klog_buff(int *klen)
{
	int ret, len = klogctl(10, NULL, 0);
	char *buff = malloc(len);

	assert(buff && klen);
	ret = klogctl(3, buff, len);
	assert(ret >= 0);
	*klen = ret;

	return buff;
}

static void put_klog_buff(char *buff)
{
	free(buff);
}

static int get_last_jit_image(char *haystack, size_t hlen,
			      uint8_t *image, size_t ilen,
			      unsigned long *base)
{
	char *ptr, *pptr, *tmp;
	off_t off = 0;
	int ret, flen, proglen, pass, ulen = 0;
	regmatch_t pmatch[1];
	regex_t regex;

	if (hlen == 0)
		return 0;

	ret = regcomp(&regex, "flen=[[:alnum:]]+ proglen=[[:digit:]]+ "
		      "pass=[[:digit:]]+ image=[[:xdigit:]]+", REG_EXTENDED);
	assert(ret == 0);

	ptr = haystack;
	while (1) {
		ret = regexec(&regex, ptr, 1, pmatch, 0);
		if (ret == 0) {
			ptr += pmatch[0].rm_eo;
			off += pmatch[0].rm_eo;
			assert(off < hlen);
		} else
			break;
	}

	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)
		return 0;

	tmp = ptr = haystack + off;
	while ((ptr = strtok(tmp, "\n")) != NULL && ulen < ilen) {
		tmp = NULL;
		if (!strstr(ptr, "JIT code"))
			continue;
		pptr = ptr;
		while ((ptr = strstr(pptr, ":")))
			pptr = ptr + 1;
		ptr = pptr;
		do {
			image[ulen++] = (uint8_t) strtoul(pptr, &pptr, 16);
			if (ptr == pptr || ulen >= ilen) {
				ulen--;
				break;
			}
			ptr = pptr;
		} while (1);
	}

	assert(ulen == proglen);
	printf("%d bytes emitted from JIT compiler (pass:%d, flen:%d)\n",
	       proglen, pass, flen);
	printf("%lx + <x>:\n", *base);

	regfree(&regex);
	return ulen;
}

int main(int argc, char **argv)
{
	int len, klen, opcodes = 0;
	char *kbuff;
	unsigned long base;
	uint8_t image[4096];

	if (argc > 1) {
		if (!strncmp("-o", argv[argc - 1], 2)) {
			opcodes = 1;
		} else {
			printf("usage: bpf_jit_disasm [-o: show opcodes]\n");
			exit(0);
		}
	}

	bfd_init();
	memset(image, 0, sizeof(image));

	kbuff = get_klog_buff(&klen);

	len = get_last_jit_image(kbuff, klen, image, sizeof(image), &base);
	if (len > 0 && base > 0)
		get_asm_insns(image, len, base, opcodes);

	put_klog_buff(kbuff);

	return 0;
}
stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Max Filippov &lt;jcmvbkbc@gmail.com&gt;</td><td class='right'>2016-08-04 15:45:32 +0300</td></tr>
<tr><th>committer</th><td>Max Filippov &lt;jcmvbkbc@gmail.com&gt;</td><td class='right'>2016-09-09 18:38:35 -0700</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/Documentation?h=nds-private-remove&amp;id=73a3eed0a4800cbe9d99cc6447fed8309d7fcb97'>73a3eed0a4800cbe9d99cc6447fed8309d7fcb97</a> (<a href='/cgit.cgi/linux/net-next.git/patch/Documentation?id=73a3eed0a4800cbe9d99cc6447fed8309d7fcb97'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=73a3eed0a4800cbe9d99cc6447fed8309d7fcb97'>16bc65b6e01480d678f8306a8dbe27c01c25e2cc</a> /<a href='/cgit.cgi/linux/net-next.git/tree/Documentation?h=nds-private-remove&amp;id=73a3eed0a4800cbe9d99cc6447fed8309d7fcb97'>Documentation</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/Documentation?h=nds-private-remove&amp;id=9e8511ff7e3f18df7d202da06c9704d940fa68f9'>9e8511ff7e3f18df7d202da06c9704d940fa68f9</a> (<a href='/cgit.cgi/linux/net-next.git/diff/Documentation?h=nds-private-remove&amp;id=73a3eed0a4800cbe9d99cc6447fed8309d7fcb97&amp;id2=9e8511ff7e3f18df7d202da06c9704d940fa68f9'>diff</a>)</td></tr></table>
<div class='commit-subject'>xtensa: fix default kernel load address</div><div class='commit-msg'>Make default kernel load address 0xd0003000 for MMUv2 cores and
0x60003000 for noMMU cores. Don't initialize MMU inside vmlinux for
predefined MMUv2 cores (it's noop anyway).

This fixes the following defconfig build error:
  arch/xtensa/kernel/built-in.o: In function `fast_alloca':
  (.text+0x99a): dangerous relocation: j: cannot encode: _WindowUnderflow12
  arch/xtensa/kernel/built-in.o: In function `fast_alloca':
  (.text+0x99d): dangerous relocation: j: cannot encode: _WindowUnderflow8
  arch/xtensa/kernel/built-in.o: In function `fast_alloca':
  (.text+0x9a0): dangerous relocation: j: cannot encode: _WindowUnderflow4
  arch/xtensa/kernel/built-in.o: In function `window_overflow_restore_a0_fixup':
  (.text+0x23a3): dangerous relocation: j: cannot encode: (.DoubleExceptionVector.text+0x104)
  arch/xtensa/kernel/built-in.o: In function `window_overflow_restore_a0_fixup':
  (.text+0x23c1): dangerous relocation: j: cannot encode: (.DoubleExceptionVector.text+0x104)
  arch/xtensa/kernel/built-in.o: In function `window_overflow_restore_a0_fixup':
  (.text+0x23dd): dangerous relocation: j: cannot encode: (.DoubleExceptionVector.text+0x104)

With this change all xtensa defconfigs build correctly.

Reported-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=73a3eed0a4800cbe9d99cc6447fed8309d7fcb97'>Diffstat</a> (limited to 'Documentation')</div><table summary='diffstat' class='diffstat'>