mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-05 10:29:37 +00:00
9b57fb7e35
The 'if' keyword is a define that expands to complex code when
CONFIG_PROFILE_ALL_BRANCHES is selected, which causes a 'perf test LLVM'
failure like:
$ ./perf test LLVM
35: LLVM search and compile :
35.1: Basic BPF llvm compile : Ok
35.2: kbuild searching : Ok
35.3: Compile source for BPF prologue generation: FAILED!
35.4: Compile source for BPF relocation : Skip
The only affected test case is bpf-script-test-prologue.c
because it uses kernel headers and has 'if' inside.
This patch undefines 'if' to make it passes perf test.
More detailed analysis from a message in this thread, also by Wang:
The problem is caused by following relocation information:
$ readelf -a ./llvmsubtest3
...
[ 5] _ftrace_branch PROGBITS 0000000000000000 00000260
00000000000000a0 0000000000000000 WA 0 0 4
...
Relocation section '.relfunc=null_lseek file->f_mode offset orig' at
offset 0x490 contains 4 entries:
Offset Info Type Sym. Value Sym. Name
000000000038 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch
0000000000b0 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch
000000000128 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch
0000000001c0 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch
Relocation section '.rel_ftrace_branch' at offset 0x4d0 contains 8 entries:
Offset Info Type Sym. Value Sym. Name
000000000000 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n
000000000008 000100000001 unrecognized: 1 0000000000000015 .L.str
000000000028 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n
000000000030 000100000001 unrecognized: 1 0000000000000015 .L.str
000000000050 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n
000000000058 000100000001 unrecognized: 1 0000000000000015 .L.str
000000000078 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n
000000000080 000100000001 unrecognized: 1 0000000000000015 .L.str
...
So I think the failure is because you enabled CONFIG_PROFILE_ALL_BRANCHES.
I can reproduce your buggy result by selecting
CONFIG_PROFILE_ALL_BRANCHES in my kbuild:
$ ./perf test LLVM
35: LLVM search and compile :
35.1: Basic BPF llvm compile : Ok
35.2: kbuild searching : Ok
35.3: Compile source for BPF prologue generation: FAILED!
35.4: Compile source for BPF relocation : Skip
Simply undef CONFIG_PROFILE_ALL_BRANCHES in clang opts not working
because it is introduced by "#include <uapi/linux/fs.h>", which override
cmdline options. So I think the best way is to undefine 'if' inside BPF
script.
Reported-and-Tested-by: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/20170620183203.2517-1-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
44 lines
1,019 B
C
44 lines
1,019 B
C
/*
|
|
* bpf-script-test-prologue.c
|
|
* Test BPF prologue
|
|
*/
|
|
#ifndef LINUX_VERSION_CODE
|
|
# error Need LINUX_VERSION_CODE
|
|
# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
|
|
#endif
|
|
#define SEC(NAME) __attribute__((section(NAME), used))
|
|
|
|
#include <uapi/linux/fs.h>
|
|
|
|
/*
|
|
* If CONFIG_PROFILE_ALL_BRANCHES is selected,
|
|
* 'if' is redefined after include kernel header.
|
|
* Recover 'if' for BPF object code.
|
|
*/
|
|
#ifdef if
|
|
# undef if
|
|
#endif
|
|
|
|
#define FMODE_READ 0x1
|
|
#define FMODE_WRITE 0x2
|
|
|
|
static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
|
|
(void *) 6;
|
|
|
|
SEC("func=null_lseek file->f_mode offset orig")
|
|
int bpf_func__null_lseek(void *ctx, int err, unsigned long f_mode,
|
|
unsigned long offset, unsigned long orig)
|
|
{
|
|
if (err)
|
|
return 0;
|
|
if (f_mode & FMODE_WRITE)
|
|
return 0;
|
|
if (offset & 1)
|
|
return 0;
|
|
if (orig == SEEK_CUR)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
int _version SEC("version") = LINUX_VERSION_CODE;
|