perf symbols: Add some heuristics for choosing the best duplicate symbol
Try and pick the best symbol based on a few heuristics: - Prefer a non weak symbol over a weak one - Prefer a global symbol over a non global one - Prefer a symbol with less underscores (idea taken from kallsyms.c) - If all else fails, choose the symbol with the longest name Cc: Eric B Munson <emunson@mgebm.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110824065243.161953371@samba.org Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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@ -86,6 +86,92 @@ bool symbol_type__is_a(char symbol_type, enum map_type map_type)
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}
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}
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static int prefix_underscores_count(const char *str)
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{
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const char *tail = str;
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while (*tail == '_')
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tail++;
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return tail - str;
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}
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#define SYMBOL_A 0
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#define SYMBOL_B 1
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static int choose_best_symbol(struct symbol *syma, struct symbol *symb)
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{
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s64 a;
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s64 b;
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/* Prefer a symbol with non zero length */
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a = syma->end - syma->start;
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b = symb->end - symb->start;
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if ((b == 0) && (a > 0))
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return SYMBOL_A;
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else if ((a == 0) && (b > 0))
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return SYMBOL_B;
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/* Prefer a non weak symbol over a weak one */
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a = syma->binding == STB_WEAK;
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b = symb->binding == STB_WEAK;
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if (b && !a)
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return SYMBOL_A;
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if (a && !b)
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return SYMBOL_B;
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/* Prefer a global symbol over a non global one */
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a = syma->binding == STB_GLOBAL;
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b = symb->binding == STB_GLOBAL;
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if (a && !b)
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return SYMBOL_A;
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if (b && !a)
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return SYMBOL_B;
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/* Prefer a symbol with less underscores */
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a = prefix_underscores_count(syma->name);
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b = prefix_underscores_count(symb->name);
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if (b > a)
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return SYMBOL_A;
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else if (a > b)
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return SYMBOL_B;
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/* If all else fails, choose the symbol with the longest name */
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if (strlen(syma->name) >= strlen(symb->name))
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return SYMBOL_A;
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else
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return SYMBOL_B;
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}
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static void symbols__fixup_duplicate(struct rb_root *symbols)
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{
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struct rb_node *nd;
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struct symbol *curr, *next;
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nd = rb_first(symbols);
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while (nd) {
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curr = rb_entry(nd, struct symbol, rb_node);
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again:
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nd = rb_next(&curr->rb_node);
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next = rb_entry(nd, struct symbol, rb_node);
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if (!nd)
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break;
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if (curr->start != next->start)
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continue;
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if (choose_best_symbol(curr, next) == SYMBOL_A) {
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rb_erase(&next->rb_node, symbols);
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goto again;
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} else {
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nd = rb_next(&curr->rb_node);
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rb_erase(&curr->rb_node, symbols);
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}
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}
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}
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static void symbols__fixup_end(struct rb_root *symbols)
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{
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struct rb_node *nd, *prevnd = rb_first(symbols);
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@ -692,6 +778,7 @@ int dso__load_kallsyms(struct dso *dso, const char *filename,
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if (dso__load_all_kallsyms(dso, filename, map) < 0)
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return -1;
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symbols__fixup_duplicate(&dso->symbols[map->type]);
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symbols__fixup_end(&dso->symbols[map->type]);
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if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
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@ -1269,6 +1356,7 @@ new_symbol:
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* For misannotated, zeroed, ASM function sizes.
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*/
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if (nr > 0) {
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symbols__fixup_duplicate(&dso->symbols[map->type]);
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symbols__fixup_end(&dso->symbols[map->type]);
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if (kmap) {
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/*
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