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Subject[PATCH] perf annotate: Numeric assembly labels cause incorrect annotation

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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