4.15-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Richter tmricht@linux.vnet.ibm.com
[ Upstream commit 36c263607d36c6a3788c09301d9f5fe35404048a ]
This patch fixes a bug introduced with commit d9f8dfa9baf9 ("perf annotate s390: Implement jump types for perf annotate").
'perf annotate' displays annotated assembler output by reading output of command objdump and parsing the disassembled lines. For each shown mnemonic this function sequence is executed:
disasm_line__new() | +--> disasm_line__init_ins() | +--> ins__find() | +--> arch->associate_instruction_ops()
The s390x specific function assigned to function pointer associate_instruction_ops refers to function s390__associate_ins_ops().
This function checks for supported mnemonics and assigns a NULL pointer to unsupported mnemonics. However even the NULL pointer is added to the architecture dependend instruction array.
This leads to an extremely large architecture instruction array (due to array resize logic in function arch__grow_instructions()).
Depending on the objdump output being parsed the array can end up with several ten-thousand elements.
This patch checks if a mnemonic is supported and only adds supported ones into the architecture instruction array. The array does not contain elements with NULL pointers anymore.
Before the patch (With some debug printf output):
[root@s35lp76 perf]# time ./perf annotate --stdio > /tmp/xxxbb
real 8m49.679s user 7m13.008s sys 0m1.649s [root@s35lp76 perf]# fgrep '__ins__find sorted:1 nr_instructions:' /tmp/xxxbb | tail -1 __ins__find sorted:1 nr_instructions:87433 ins:0x341583c0 [root@s35lp76 perf]#
The number of different s390x branch/jump/call/return instructions entered into the array is 87433.
After the patch (With some printf debug output:)
[root@s35lp76 perf]# time ./perf annotate --stdio > /tmp/xxxaa
real 1m24.553s user 0m0.587s sys 0m1.530s [root@s35lp76 perf]# fgrep '__ins__find sorted:1 nr_instructions:' /tmp/xxxaa | tail -1 __ins__find sorted:1 nr_instructions:56 ins:0x3f406570 [root@s35lp76 perf]#
The number of different s390x branch/jump/call/return instructions entered into the array is 56 which is sensible.
Signed-off-by: Thomas Richter tmricht@linux.vnet.ibm.com Reviewed-by: Hendrik Brueckner brueckner@linux.vnet.ibm.com Acked-by: Ravi Bangoria ravi.bangoria@linux.vnet.ibm.com Cc: Heiko Carstens heiko.carstens@de.ibm.com Cc: Martin Schwidefsky schwidefsky@de.ibm.com Link: http://lkml.kernel.org/r/20171124094637.55558-1-tmricht@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/perf/arch/s390/annotate/instructions.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/tools/perf/arch/s390/annotate/instructions.c +++ b/tools/perf/arch/s390/annotate/instructions.c @@ -18,7 +18,8 @@ static struct ins_ops *s390__associate_i if (!strcmp(name, "br")) ops = &ret_ops;
- arch__associate_ins_ops(arch, name, ops); + if (ops) + arch__associate_ins_ops(arch, name, ops); return ops; }