From b6518e6a0086fc152f9a35ac5062930788f8b4bc Mon Sep 17 00:00:00 2001 From: David Daney Date: Tue, 11 Apr 2017 14:30:52 -0700 Subject: [PATCH] tools: bpf_jit_disasm: Add option to dump JIT image to a file. When debugging the JIT on an embedded platform or cross build environment, libbfd may not be available, making it impossible to run bpf_jit_disasm natively. Add an option to emit a binary image of the JIT code to a file. This file can then be disassembled off line. Typical usage in this case might be (pasting mips64 dmesg output to cat command): $ cat > jit.raw $ bpf_jit_disasm -f jit.raw -O jit.bin $ mips64-linux-gnu-objdump -D -b binary -m mips:isa64r2 -EB jit.bin Signed-off-by: David Daney Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- tools/net/bpf_jit_disasm.c | 40 ++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4 deletions(-) diff --git a/tools/net/bpf_jit_disasm.c b/tools/net/bpf_jit_disasm.c index 544b05a53b70..ad572e6cdbd0 100644 --- a/tools/net/bpf_jit_disasm.c +++ b/tools/net/bpf_jit_disasm.c @@ -229,6 +229,7 @@ static void usage(void) { printf("Usage: bpf_jit_disasm [...]\n"); printf(" -o Also display related opcodes (default: off).\n"); + printf(" -O Write binary image of code to file, don't disassemble to stdout.\n"); printf(" -f Read last image dump from file or stdin (default: klog).\n"); printf(" -h Display this help.\n"); } @@ -238,12 +239,19 @@ int main(int argc, char **argv) unsigned int len, klen, opt, opcodes = 0; static uint8_t image[32768]; char *kbuff, *file = NULL; + char *ofile = NULL; + int ofd; + ssize_t nr; + uint8_t *pos; - while ((opt = getopt(argc, argv, "of:")) != -1) { + while ((opt = getopt(argc, argv, "of:O:")) != -1) { switch (opt) { case 'o': opcodes = 1; break; + case 'O': + ofile = optarg; + break; case 'f': file = optarg; break; @@ -263,11 +271,35 @@ int main(int argc, char **argv) } len = get_last_jit_image(kbuff, klen, image, sizeof(image)); - if (len > 0) - get_asm_insns(image, len, opcodes); - else + if (len <= 0) { fprintf(stderr, "No JIT image found!\n"); + goto done; + } + if (!ofile) { + get_asm_insns(image, len, opcodes); + goto done; + } + + ofd = open(ofile, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE); + if (ofd < 0) { + fprintf(stderr, "Could not open file %s for writing: ", ofile); + perror(NULL); + goto done; + } + pos = image; + do { + nr = write(ofd, pos, len); + if (nr < 0) { + fprintf(stderr, "Could not write data to %s: ", ofile); + perror(NULL); + goto done; + } + len -= nr; + pos += nr; + } while (len); + close(ofd); +done: put_log_buff(kbuff); return 0; } -- 2.30.2