Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / tools / net / bpf_jit_disasm.c

diff --git a/kernel/tools/net/bpf_jit_disasm.c b/kernel/tools/net/bpf_jit_disasm.c
new file mode 100644 (file)
index 0000000..618c2bc
--- /dev/null
+++ b/kernel/tools/net/bpf_jit_disasm.c
@@ -0,0 +1,199 @@
+/*
+ * Minimal BPF JIT image disassembler
+ *
+ * Disassembles BPF JIT compiler emitted opcodes back to asm insn's for
+ * debugging or verification purposes.
+ *
+ * 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)
+ */
+
+#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, 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)
+{
+       char *ptr, *pptr, *tmp;
+       off_t off = 0;
+       int ret, flen, proglen, pass, ulen = 0;
+       regmatch_t pmatch[1];
+       unsigned long base;
+       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;
+       memset(pmatch, 0, sizeof(pmatch));
+
+       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;
+       static uint8_t image[32768];
+
+       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));
+       if (len > 0)
+               get_asm_insns(image, len, opcodes);
+
+       put_klog_buff(kbuff);
+
+       return 0;
+}