tree 29d3bb0f0ee5cc177475365bba82a9ceb30dbc36
parent 8994e97be3eb3c3a7b59d6223018ffab8c272e2d
author Chengdong Li <chengdongli@tencent.com> 1652752646 +0800
committer Arnaldo Carvalho de Melo <acme@redhat.com> 1653155784 -0300

perf session: Fix Intel LBR callstack entries and nr print message

When generating callstack information from branch_stack(Intel LBR), the
actual number of callstack entry should be bigger than the number of
branch_stack, for example:

	branch_stack records:
		B() -> C()
		A() -> B()
	converted callstack records should be:
		C()
		B()
		A()
though, the number of callstack equals
to the number of branch stack plus 1.

This patch fixes above issue in branch_stack__printf(). For example,

	# echo 'scale=2000; 4*a(1)' > cmd
	# perf record --call-graph lbr bc -l < cmd

Before applying this patch, `perf script -D` output:

	1220022677386876 0x2a40 [0xd8]: PERF_RECORD_SAMPLE(IP, 0x4002): 17990/17990: 0x40a6d6 period: 894172 addr: 0
	... LBR call chain: nr:8
	.....  0: fffffffffffffe00
	.....  1: 000000000040a410
	.....  2: 000000000040573c
	.....  3: 0000000000408650
	.....  4: 00000000004022f2
	.....  5: 00000000004015f5
	.....  6: 00007f5ed6dcb553
	.....  7: 0000000000401698
	... FP chain: nr:2
	.....  0: fffffffffffffe00
	.....  1: 000000000040a6d8
	... branch callstack: nr:6    # which is not consistent with LBR records.
	.....  0: 000000000040a410
	.....  1: 0000000000408650    # ditto
	.....  2: 00000000004022f2
	.....  3: 00000000004015f5
	.....  4: 00007f5ed6dcb553
	.....  5: 0000000000401698
	 ... thread: bc:17990
	 ...... dso: /usr/bin/bc
	bc 17990 1220022.677386:     894172 cycles:
			  40a410 [unknown] (/usr/bin/bc)
			  40573c [unknown] (/usr/bin/bc)
			  408650 [unknown] (/usr/bin/bc)
			  4022f2 [unknown] (/usr/bin/bc)
			  4015f5 [unknown] (/usr/bin/bc)
		    7f5ed6dcb553 __libc_start_main+0xf3 (/usr/lib64/libc-2.17.so)
			  401698 [unknown] (/usr/bin/bc)

After applied:

	1220022677386876 0x2a40 [0xd8]: PERF_RECORD_SAMPLE(IP, 0x4002): 17990/17990: 0x40a6d6 period: 894172 addr: 0
	... LBR call chain: nr:8
	.....  0: fffffffffffffe00
	.....  1: 000000000040a410
	.....  2: 000000000040573c
	.....  3: 0000000000408650
	.....  4: 00000000004022f2
	.....  5: 00000000004015f5
	.....  6: 00007f5ed6dcb553
	.....  7: 0000000000401698
	... FP chain: nr:2
	.....  0: fffffffffffffe00
	.....  1: 000000000040a6d8
	... branch callstack: nr:7
	.....  0: 000000000040a410
	.....  1: 000000000040573c
	.....  2: 0000000000408650
	.....  3: 00000000004022f2
	.....  4: 00000000004015f5
	.....  5: 00007f5ed6dcb553
	.....  6: 0000000000401698
	 ... thread: bc:17990
	 ...... dso: /usr/bin/bc
	bc 17990 1220022.677386:     894172 cycles:
			  40a410 [unknown] (/usr/bin/bc)
			  40573c [unknown] (/usr/bin/bc)
			  408650 [unknown] (/usr/bin/bc)
			  4022f2 [unknown] (/usr/bin/bc)
			  4015f5 [unknown] (/usr/bin/bc)
		    7f5ed6dcb553 __libc_start_main+0xf3 (/usr/lib64/libc-2.17.so)
			  401698 [unknown] (/usr/bin/bc)

Change from v1:
	- refined code style according to Jiri's review comments.

Signed-off-by: Chengdong Li <chengdongli@tencent.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: likexu@tencent.com
Link: https://lore.kernel.org/r/20220517015726.96131-1-chengdongli@tencent.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>