commit 4b7190e8416d9238e995da993a7fb851996654e2
author David Daney <david.daney@cavium.com> Tue Jun 13 16:49:38 2017 -0700
committer David S. Miller <davem@davemloft.net> Wed Jun 14 15:03:23 2017 -0400
tree cd9223768849c8dc218787198acdc37d4ba2dc17
parent c1932cdb275e65cbef2f230f0df0c490fdd03c62

samples/bpf: Fix tracex5 to work with MIPS syscalls.

There are two problems:

1) In MIPS the __NR_* macros expand to an expression, this causes the
   sections of the object file to be named like:

  .
  .
  .
  [ 5] kprobe/(5000 + 1) PROGBITS        0000000000000000 000160 ...
  [ 6] kprobe/(5000 + 0) PROGBITS        0000000000000000 000258 ...
  [ 7] kprobe/(5000 + 9) PROGBITS        0000000000000000 000348 ...
  .
  .
  .

The fix here is to use the "asm_offsets" trick to evaluate the macros
in the C compiler and generate a header file with a usable form of the
macros.

2) MIPS syscall numbers start at 5000, so we need a bigger map to hold
the sub-programs.

Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf/tracex5_kern.c

diff --git a/samples/bpf/tracex5_kern.c b/samples/bpf/tracex5_kern.c
index 7e4cf74..f57f4e1 100644
--- a/samples/bpf/tracex5_kern.c
+++ b/samples/bpf/tracex5_kern.c
@@ -9,6 +9,7 @@
 #include <uapi/linux/bpf.h>
 #include <uapi/linux/seccomp.h>
 #include <uapi/linux/unistd.h>
+#include "syscall_nrs.h"
 #include "bpf_helpers.h"
 
 #define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
@@ -17,7 +18,11 @@ struct bpf_map_def SEC("maps") progs = {
 	.type = BPF_MAP_TYPE_PROG_ARRAY,
 	.key_size = sizeof(u32),
 	.value_size = sizeof(u32),
+#ifdef __mips__
+	.max_entries = 6000, /* MIPS n64 syscalls start at 5000 */
+#else
 	.max_entries = 1024,
+#endif
 };
 
 SEC("kprobe/__seccomp_filter")
@@ -37,7 +42,7 @@ int bpf_prog1(struct pt_regs *ctx)
 }
 
 /* we jump here when syscall number == __NR_write */
-PROG(__NR_write)(struct pt_regs *ctx)
+PROG(SYS__NR_write)(struct pt_regs *ctx)
 {
 	struct seccomp_data sd;
 
@@ -50,7 +55,7 @@ PROG(__NR_write)(struct pt_regs *ctx)
 	return 0;
 }
 
-PROG(__NR_read)(struct pt_regs *ctx)
+PROG(SYS__NR_read)(struct pt_regs *ctx)
 {
 	struct seccomp_data sd;
 
@@ -63,7 +68,7 @@ PROG(__NR_read)(struct pt_regs *ctx)
 	return 0;
 }
 
-PROG(__NR_mmap)(struct pt_regs *ctx)
+PROG(SYS__NR_mmap)(struct pt_regs *ctx)
 {
 	char fmt[] = "mmap\n";
 	bpf_trace_printk(fmt, sizeof(fmt));