/*
 * 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;
}
<option value='2'>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>Valentin Rothberg &lt;valentinrothberg@gmail.com&gt;</td><td class='right'>2016-10-05 07:57:26 +0200</td></tr>
<tr><th>committer</th><td>Michael Ellerman &lt;mpe@ellerman.id.au&gt;</td><td class='right'>2016-10-27 21:52:59 +1100</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=39715bf972ed4fee18fe5409609a971fb16b1771'>39715bf972ed4fee18fe5409609a971fb16b1771</a> (<a href='/cgit.cgi/linux/net-next.git/patch/Documentation?id=39715bf972ed4fee18fe5409609a971fb16b1771'>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=39715bf972ed4fee18fe5409609a971fb16b1771'>1d423c94bc8d3199a42f16b6296c9d96e929982b</a> /<a href='/cgit.cgi/linux/net-next.git/tree/Documentation?h=nds-private-remove&amp;id=39715bf972ed4fee18fe5409609a971fb16b1771'>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=09b7e37b18eecc1e347f4b1a3bc863f32801f634'>09b7e37b18eecc1e347f4b1a3bc863f32801f634</a> (<a href='/cgit.cgi/linux/net-next.git/diff/Documentation?h=nds-private-remove&amp;id=39715bf972ed4fee18fe5409609a971fb16b1771&amp;id2=09b7e37b18eecc1e347f4b1a3bc863f32801f634'>diff</a>)</td></tr></table>
<div class='commit-subject'>powerpc/process: Fix CONFIG_ALIVEC typo in restore_tm_state()</div><div class='commit-msg'>It should be ALTIVEC, not ALIVEC.

Cyril explains: If a thread performs a transaction with altivec and then
gets preempted for whatever reason, this bug may cause the kernel to not
re-enable altivec when that thread runs again. This will result in an
altivec unavailable fault, when that fault happens inside a user
transaction the kernel has no choice but to enable altivec and doom the
transaction.

The result is that transactions using altivec may get aborted more often
than they should.

The difficulty in catching this with a selftest is my deliberate use of
the word may above. Optimisations to avoid FPU/altivec/VSX faults mean
that the kernel will always leave them on for 255 switches. This code
prevents the kernel turning it off if it got to the 256th switch (and
userspace was transactional).

Fixes: dc16b553c949 ("powerpc: Always restore FPU/VEC/VSX if hardware transactional memory in use")
Reviewed-by: Cyril Bur &lt;cyrilbur@gmail.com&gt;
Signed-off-by: Valentin Rothberg &lt;valentinrothberg@gmail.com&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=39715bf972ed4fee18fe5409609a971fb16b1771'>Diffstat</a> (limited to 'Documentation')</div><table summary='diffstat' class='diffstat'>