Re: perf test 'instruction decoder' failing

[Adrian Hunter <adrian.hunter@intel.com>]

On 24/02/17 22:27, Arnaldo Carvalho de Melo wrote:
> Hi Adrian,
> 
> 	This test is failing, I'll try to recheck this and bisect it,
> but since I haven't had the time so far and I saw it since yesterday (at
> least), lemme document it here:
> 
> 
> [root@jouet ~]# perf test -v 57
> 57: x86 instruction decoder - new instructions :
> --- start ---
> test child forked, pid 18975
> Decoded ok: 0f 31                	rdtsc  
> Decoded ok: 0f 1b 80 78 56 34 12 	bndstx %bnd0,0x12345678(%eax)
> <SNIP tons of OKays>
> Decoded ok: 0f 1b 85 78 56 34 12 	bndstx %bnd0,0x12345678(%ebp)
> Decoded ok: 0f 1b 84 01 78 56 34 12 	bndstx %bnd0,0x12345678(%ecx,%eax,1)
> Decoded ok: 0f 1b 84 05 78 56 34 12 	bndstx %bnd0,0x12345678(%ebp,%eax,1)
> Decoded ok: 0f 1b 84 08 78 56 34 12 	bndstx %bnd0,0x12345678(%eax,%ecx,1)
> Decoded ok: f2 e8 fc ff ff ff    	bnd call fce <main+0xfce>
> Failed to decode 'rel' value (0xfffffffc vs expected 0): f2 ff 10             	bnd call *(%eax)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): f2 c3                	bnd ret 
> Decoded ok: f2 e9 fc ff ff ff    	bnd jmp fd9 <main+0xfd9>
> Decoded ok: f2 e9 fc ff ff ff    	bnd jmp fdf <main+0xfdf>
> Failed to decode 'rel' value (0xfffffffc vs expected 0): f2 ff 21             	bnd jmp *(%ecx)
> Decoded ok: f2 0f 85 fc ff ff ff 	bnd jne fe9 <main+0xfe9>
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc c1 00       	sha1rnds4 $0x0,%xmm1,%xmm0
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc d7 91       	sha1rnds4 $0x91,%xmm7,%xmm2
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc 00 91       	sha1rnds4 $0x91,(%eax),%xmm0
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc 05 78 56 34 12 91 	sha1rnds4 $0x91,0x12345678,%xmm0
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc 18 91       	sha1rnds4 $0x91,(%eax),%xmm3
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc 04 01 91    	sha1rnds4 $0x91,(%ecx,%eax,1),%xmm0
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc 04 05 78 56 34 12 91 	sha1rnds4 $0x91,0x12345678(,%eax,1),%xmm0
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc 04 08 91    	sha1rnds4 $0x91,(%eax,%ecx,1),%xmm0
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 3a cc 04 c8 91    	sha1rnds4 $0x91,(%eax,%ecx,8),%xmm0
> <SNIP lots of fails>
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 45 12          	bndstx %bnd0,0x12(%rbp)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 44 01 12       	bndstx %bnd0,0x12(%rcx,%rax,1)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 44 05 12       	bndstx %bnd0,0x12(%rbp,%rax,1)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 44 08 12       	bndstx %bnd0,0x12(%rax,%rcx,1)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 80 78 56 34 12 	bndstx %bnd0,0x12345678(%rax)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 85 78 56 34 12 	bndstx %bnd0,0x12345678(%rbp)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 84 01 78 56 34 12 	bndstx %bnd0,0x12345678(%rcx,%rax,1)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 84 05 78 56 34 12 	bndstx %bnd0,0x12345678(%rbp,%rax,1)
> Failed to decode 'rel' value (0xfffffffc vs expected 0): 0f 1b 84 08 78 56 34 12 	bndstx %bnd0,0x12345678(%rax,%rcx,1)
> Decoded ok: f2 e8 00 00 00 00    	bnd callq f22 <main+0xf22>
> Decoded ok: 67 f2 ff 10          	bnd callq *(%eax)
> <SNIP lots of OKays>
> Decoded ok: 41 0f c7 9c c8 78 56 34 12 	xrstors 0x12345678(%r8,%rcx,8)
> Decoded ok: 0f 01 ee             	rdpkru
> Decoded ok: 0f 01 ef             	wrpkru
> test child finished with -1
> ---- end ----
> x86 instruction decoder - new instructions: FAILED!
> 
> Fedora 25,
> 
> [acme@jouet linux]$ uname -a
> Linux jouet 4.10.0-rc8 #2 SMP Wed Feb 15 15:26:36 BRT 2017 x86_64 x86_64 x86_64 GNU/Linux
> 
> [acme@jouet linux]$ rpm -q binutils elfutils gcc glibc
> binutils-2.26.1-1.fc25.x86_64
> elfutils-0.168-1.fc25.x86_64
> gcc-6.3.1-1.fc25.x86_64
> glibc-2.24-4.fc25.x86_64
> glibc-2.24-4.fc25.i686
> [acme@jouet linux]$
> 
> [acme@jouet linux]$ perf -v
> perf version 4.10.g264b77
> 
> perf as in tip/perf/core and soon as in acme/perf/core

There is missing initialization.  It only affects the test because it is checking 'rel' even in cases where there is no value.

Here is the fix.


diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-insn-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-insn-decoder.c
index 7913363bde5c..55b6250350d7 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-insn-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-insn-decoder.c
@@ -39,6 +39,8 @@ static void intel_pt_insn_decoder(struct insn *insn,
 	enum intel_pt_insn_branch branch = INTEL_PT_BR_NO_BRANCH;
 	int ext;
 
+	intel_pt_insn->rel = 0;
+
 	if (insn_is_avx(insn)) {
 		intel_pt_insn->op = INTEL_PT_OP_OTHER;
 		intel_pt_insn->branch = INTEL_PT_BR_NO_BRANCH;