Hi Jirka,
On Tue, Jun 25, 2013 at 5:37 PM, Prabhat Kumar Ravi
<prabhatrav...@gmail.com> wrote:
> Hi Jirka,
>
> As _stext getting removed in
>
> dso__load_kallsyms
> --> symbols__fixup_duplicate (here _stext removed)
>
> as we have same address in /proc/kallsyms for _stext, asm_do_IRQ and
> __exception_text_start
>
> So, we need to disable symbols__fixup_duplicate in dso__load_kallsyms,
>
> Prabhat
>
> On Tue, Jun 25, 2013 at 2:37 PM, Jiri Olsa <jo...@redhat.com> wrote:
>> 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
Thanks for your input otherwise I am thinking to change _stext to some
other symbol.
- Prabhat
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