| Message ID | 20170411213052.7337-1-david.daney@cavium.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On 04/11/2017 11:30 PM, David Daney wrote: > 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 <david.daney@cavium.com> Seems good, we could at some point also add an -I jit.bin option if needed for offline analysis/comparison instead of using -f plain text. Thanks! Acked-by: Daniel Borkmann <daniel@iogearbox.net>
On 04/11/2017 02:54 PM, Daniel Borkmann wrote: > On 04/11/2017 11:30 PM, David Daney wrote: >> 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 <david.daney@cavium.com> > > Seems good, we could at some point also add an -I jit.bin option > if needed for offline analysis/comparison instead of using -f > plain text. > FWIW: The objdump incantation in the changelog does just about the same disassembly as the bpf_jit_disasm internal implementation. > Thanks! > > Acked-by: Daniel Borkmann <daniel@iogearbox.net>
From: David Daney <david.daney@cavium.com> Date: Tue, 11 Apr 2017 14:30:52 -0700 > 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 <david.daney@cavium.com> Applied, thanks.
diff --git a/tools/net/bpf_jit_disasm.c b/tools/net/bpf_jit_disasm.c index 544b05a..ad572e6 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 <file> Write binary image of code to file, don't disassemble to stdout.\n"); printf(" -f <file> 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; }
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 <david.daney@cavium.com> --- tools/net/bpf_jit_disasm.c | 40 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4 deletions(-)