On Tue, Jun 25, 2013 at 11:24:56AM +0530, Prabhat Kumar Ravi wrote:
> On 3.4-rc49, I got following failure running `perf test`:
>
> / # perf test -v 1
> 1: vmlinux symtab matches kallsyms:
> --- start ---
> dso__find_symbol_by_name ---- end ----
> vmlinux symtab matches kallsyms: FAILED!
>
> Perf test is failing at dsofind_symbol_by_name
>
> where
>
> kallsyms_map = machine__kernel_map(&kallsyms, type);
>
> sym = map__find_symbol_by_name(kallsyms_map, ref_reloc_sym.name, NULL);
> if (sym == NULL) {
> pr_debug("dso__find_symbol_by_name ");
> goto out;
> }
>
> Here sym is search for "_stext" which is NULL here so perf test fails
> here only.
>
> On investigation found that _stext having same address as asm_do_IRQ
> and exception_text_start,
>
> c00081c0 T asm_do_IRQ
> c00081c0 T _stext
> c00081c0 T __exception_text_start
>
> so being deleted by symbolsfixup_duplicate in
>
> if (choose_best_symbol(curr, next) == SYMBOL_A) {
>
> rb_erase(&next->rb_node, symbols); --> symbole
> getting erase here.
> goto again;
> } else {
>
>
I recently fixed this test for another kind of error rising from
the /proc/kallsyms being not as precise as vmlinux file. This one
looks like another one.
acme's tree:
b8bae2c perf tests: Omit end of the symbol check failure for test 1
> My doubt is, Is we really need this commit??:
>
> commit 3f5a42722b9e78a434d5a4ee5e607dc33c69ac80
> Author: Anton Blanchard <an...@samba.org>
> Date: Wed Aug 24 16:40:15 2011 +1000
>
> perf symbols: /proc/kallsyms does not sort module symbols
>
> kallsyms__parse assumes that /proc/kallsyms is sorted and sets the end
> of the previous symbol to the start of the current one.
>
> Unfortunately module symbols are not sorted, eg:
>
> ffffffffa0081f30 t e1000_clean_rx_irq [e1000e]
> ffffffffa00817a0 t e1000_alloc_rx_buffers [e1000e]
>
> Some symbols end up with a negative length and others have a length
> larger than they should. This results in confusing perf output.
>
> We already have a function to fixup the end of zero length symbols so
> use that instead.
>
> Or we can search for other string.??
This one looks important, I think we should fix the test again.
Maybe bisable duplicates removal for test? Keep removed symbols
list? ;-)
jirka
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