tools: bpf_jit_disasm: ignore image address for disasm

seccomp filters use kernel JIT image addresses, so bpf_jit_enable=2 prints
[ 20.146438] flen=3 proglen=82 pass=0 image=0000000000000000
[ 20.146442] JIT code: 00000000: 55 48 89 e5 48 81 ec 28 02 00 00 ...

ignore image address, so that seccomp filters can be disassembled

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 10 deletions

diff --git a/tools/net/bpf_jit_disasm.c b/tools/net/bpf_jit_disasm.c
index cfe0cdcda3de..d9730c3319b9 100644
--- a/tools/net/bpf_jit_disasm.c
+++ b/tools/net/bpf_jit_disasm.c
@@ -43,8 +43,7 @@ static void get_exec_path(char *tpath, size_t size)
         free(path);
 }
 
-static void get_asm_insns(uint8_t *image, size_t len, unsigned long base,
-                          int opcodes)
+static void get_asm_insns(uint8_t *image, size_t len, int opcodes)
 {
         int count, i, pc = 0;
         char tpath[256];
@@ -107,13 +106,13 @@ static void put_klog_buff(char *buff)
 }
 
 static int get_last_jit_image(char *haystack, size_t hlen,
-                              uint8_t *image, size_t ilen,
-                              unsigned long *base)
+                              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)
@@ -136,7 +135,7 @@ static int get_last_jit_image(char *haystack, size_t hlen,
 
         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);
+                     &flen, &proglen, &pass, &base);
         if (ret != 4)
                 return 0;
 
@@ -162,7 +161,7 @@ static int get_last_jit_image(char *haystack, size_t hlen,
         assert(ulen == proglen);
         printf("%d bytes emitted from JIT compiler (pass:%d, flen:%d)\n",
                proglen, pass, flen);
-        printf("%lx + <x>:\n", *base);
+        printf("%lx + <x>:\n", base);
 
         regfree(&regex);
         return ulen;
@@ -172,7 +171,6 @@ int main(int argc, char **argv)
 {
         int len, klen, opcodes = 0;
         char *kbuff;
-        unsigned long base;
         uint8_t image[4096];
 
         if (argc > 1) {
@@ -189,9 +187,9 @@ int main(int argc, char **argv)
 
         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);
+        len = get_last_jit_image(kbuff, klen, image, sizeof(image));
+        if (len > 0)
+                get_asm_insns(image, len, opcodes);
 
         put_klog_buff(kbuff);