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Subject[PATCH V4 05/13] perf tools: avoid SyS kernel syscall aliases
Date
When removing duplicate symbols, prefer to remove
syscall aliases starting with SyS or compat_SyS.

A side-effect of that is that it results in slightly
improved results for the "vmlinux symtab matches kallsyms"
test.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/util/symbol.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b407c53..04300dd 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -87,6 +87,7 @@ static int choose_best_symbol(struct symbol *syma, struct symbol *symb)
{
s64 a;
s64 b;
+ size_t na, nb;

/* Prefer a symbol with non zero length */
a = syma->end - syma->start;
@@ -120,11 +121,21 @@ static int choose_best_symbol(struct symbol *syma, struct symbol *symb)
else if (a > b)
return SYMBOL_B;

- /* If all else fails, choose the symbol with the longest name */
- if (strlen(syma->name) >= strlen(symb->name))
+ /* Choose the symbol with the longest name */
+ na = strlen(syma->name);
+ nb = strlen(symb->name);
+ if (na > nb)
return SYMBOL_A;
- else
+ else if (na < nb)
+ return SYMBOL_B;
+
+ /* Avoid "SyS" kernel syscall aliases */
+ if (na >= 3 && !strncmp(syma->name, "SyS", 3))
return SYMBOL_B;
+ if (na >= 10 && !strncmp(syma->name, "compat_SyS", 10))
+ return SYMBOL_B;
+
+ return SYMBOL_A;
}

void symbols__fixup_duplicate(struct rb_root *symbols)
--
1.7.11.7


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