Messages in this thread Patch in this message | | | Date | Tue, 7 Feb 2012 14:55:35 +1100 | From | Anton Blanchard <> | Subject | [PATCH] perf annotate: Numeric assembly labels cause incorrect annotation |
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A perf annotate of a kernel function written in assembly shows very strange percentages:
: _GLOBAL(__copy_tofrom_user_base)
...
: addi r3,r3,1 99.67 : c00000000004d78c: addi r3,r3,1 : 0.00 : 1: bf cr7*4+2,2f 0.07 : c00000000004d790: bne- cr7,c00000000004d7a4 : err1; lhz r0,0(r4) 0.00 : c00000000004d794: lhz r0,0(r4) : addi r4,r4,2 0.00 : c00000000004d798: addi r4,r4,2 : err1; sth r0,0(r3) 0.00 : c00000000004d79c: sth r0,0(r3) : addi r3,r3,2 99.60 : c00000000004d7a0: addi r3,r3,2 : 0.00 : 2: bf cr7*4+1,3f 0.12 : c00000000004d7a4: ble- cr7,c00000000004d7b8 : err1; lwz r0,0(r4) 0.00 : c00000000004d7a8: lwz r0,0(r4) : addi r4,r4,4 0.00 : c00000000004d7ac: addi r4,r4,4 : err1; stw r0,0(r3) 0.00 : c00000000004d7b0: stw r0,0(r3) : addi r3,r3,4 99.48 : c00000000004d7b4: addi r3,r3,4
~300% in one function. Urgh.
This is caused by the way we parse objdump -S output, eg:
addi r3,r3,1 c00000000004d78c: addi r3,r3,1
1: bf cr7*4+2,2f c00000000004d790: bne- cr7,c00000000004d7a4
We assume the asm label (1:) is an address, compute a bogus offset into the function and then screw up the matching of samples to lines. I notice this also fails with c inline assembly in a similar manner.
We already have a sanity check that the address is not beyond the end of the function, so add a check against the start too.
Signed-off-by: Anton Blanchard <anton@samba.org> --- Cc: <stable@kernel.org>
Index: linux-tip/tools/perf/util/annotate.c =================================================================== --- linux-tip.orig/tools/perf/util/annotate.c 2012-01-09 17:45:09.056373433 +1100 +++ linux-tip/tools/perf/util/annotate.c 2012-02-07 13:53:01.610970209 +1100 @@ -244,7 +244,7 @@ static int symbol__parse_objdump_line(st end = map__rip_2objdump(map, sym->end); offset = line_ip - start; - if (offset < 0 || (u64)line_ip > end) + if (offset < 0 || (u64)line_ip < start || (u64)line_ip > end) offset = -1; }
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