Messages in this thread | | | Date | Thu, 17 Mar 2022 12:37:00 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf symbols: Fix symbol size calculation condition |
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Em Thu, Mar 17, 2022 at 02:55:36PM +0100, Michael Petlan escreveu: > Before this patch, the symbol end address fixup to be called, needed two > conditions being met: > > if (prev->end == prev->start && prev->end != curr->start) > > Where > "prev->end == prev->start" means that prev is zero-long > (and thus needs a fixup) > and > "prev->end != curr->start" means that fixup hasn't been applied yet > > However, this logic is incorrect in the following situation: > > *curr = {rb_node = {__rb_parent_color = 278218928, > rb_right = 0x0, rb_left = 0x0}, > start = 0xc000000000062354, > end = 0xc000000000062354, namelen = 40, type = 2 '\002', > binding = 0 '\000', idle = 0 '\000', ignore = 0 '\000', > inlined = 0 '\000', arch_sym = 0 '\000', annotate2 = false, > name = 0x1159739e "kprobe_optinsn_page\t[__builtin__kprobes]"} > > *prev = {rb_node = {__rb_parent_color = 278219041, > rb_right = 0x109548b0, rb_left = 0x109547c0}, > start = 0xc000000000062354, > end = 0xc000000000062354, namelen = 12, type = 2 '\002', > binding = 1 '\001', idle = 0 '\000', ignore = 0 '\000', > inlined = 0 '\000', arch_sym = 0 '\000', annotate2 = false, > name = 0x1095486e "optinsn_slot"} > > In this case, prev->start == prev->end == curr->start == curr->end, > thus the condition above thinks that "we need a fixup due to zero > length of prev symbol, but it has been probably done, since the > prev->end == curr->start", which is wrong. > > After the patch, the execution path proceeds to arch__symbols__fixup_end > function which fixes up the size of prev symbol by adding page_size to > its end offset.
You missed this:
Fixes: 3b01a413c196c910 ("perf symbols: Improve kallsyms symbol end addr calculation")
I'll add it to the patch, ok?
- Arnaldo
> Signed-off-by: Michael Petlan <mpetlan@redhat.com> > --- > tools/perf/util/symbol.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > index fb075aa8f8f2..dea0fc495185 100644 > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c > @@ -231,7 +231,7 @@ void symbols__fixup_end(struct rb_root_cached *symbols) > prev = curr; > curr = rb_entry(nd, struct symbol, rb_node); > > - if (prev->end == prev->start && prev->end != curr->start) > + if (prev->end == prev->start || prev->end != curr->start) > arch__symbols__fixup_end(prev, curr); > } > > -- > 2.18.4
--
- Arnaldo
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