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authorDavid Daney <david.daney@cavium.com>2017-06-13 16:49:38 -0700
committerDavid S. Miller <davem@davemloft.net>2017-06-14 15:03:23 -0400
commit4b7190e8416d9238e995da993a7fb851996654e2 (patch)
treecd9223768849c8dc218787198acdc37d4ba2dc17 /samples
parentc1932cdb275e65cbef2f230f0df0c490fdd03c62 (diff)
download96b-common-4b7190e8416d9238e995da993a7fb851996654e2.tar.gz
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>
Diffstat (limited to 'samples')
-rw-r--r--samples/bpf/Makefile13
-rw-r--r--samples/bpf/syscall_nrs.c12
-rw-r--r--samples/bpf/tracex5_kern.c11
3 files changed, 33 insertions, 3 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 6c7468eb3684..a0561dc762fe 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -160,6 +160,17 @@ clean:
$(MAKE) -C ../../ M=$(CURDIR) clean
@rm -f *~
+$(obj)/syscall_nrs.s: $(src)/syscall_nrs.c
+ $(call if_changed_dep,cc_s_c)
+
+$(obj)/syscall_nrs.h: $(obj)/syscall_nrs.s FORCE
+ $(call filechk,offsets,__SYSCALL_NRS_H__)
+
+clean-files += syscall_nrs.h
+
+FORCE:
+
+
# Verify LLVM compiler tools are available and bpf target is supported by llc
.PHONY: verify_cmds verify_target_bpf $(CLANG) $(LLC)
@@ -180,6 +191,8 @@ verify_target_bpf: verify_cmds
$(src)/*.c: verify_target_bpf
+$(obj)/tracex5_kern.o: $(obj)/syscall_nrs.h
+
# asm/sysreg.h - inline assembly used by it is incompatible with llvm.
# But, there is no easy way to fix it, so just exclude it since it is
# useless for BPF samples.
diff --git a/samples/bpf/syscall_nrs.c b/samples/bpf/syscall_nrs.c
new file mode 100644
index 000000000000..ce2a30b11248
--- /dev/null
+++ b/samples/bpf/syscall_nrs.c
@@ -0,0 +1,12 @@
+#include <uapi/linux/unistd.h>
+#include <linux/kbuild.h>
+
+#define SYSNR(_NR) DEFINE(SYS ## _NR, _NR)
+
+void syscall_defines(void)
+{
+ COMMENT("Linux system call numbers.");
+ SYSNR(__NR_write);
+ SYSNR(__NR_read);
+ SYSNR(__NR_mmap);
+}
diff --git a/samples/bpf/tracex5_kern.c b/samples/bpf/tracex5_kern.c
index 7e4cf74553ff..f57f4e1ea1ec 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));