Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
On 09/14/2014 12:41 PM, Peter Zijlstra wrote: On Sat, Sep 13, 2014 at 06:34:37AM +0300, Avi Kivity wrote: It's not a simple matter of updating the test: the demangler interprets name beginning with __vt as C++ mangles names, which of course they aren't. Oh, that'll give cute 'problems' in a mixed C/C++ project that just happens to have __vt names in. Now of course I'm aware that C/C++ 'reserve' the __ prefix, which I suppose that makes it less likely in practise. If you have clashes there, perf demangling is the least of your worries. The only way I see to proceed is to make the demangling optional, default off. Seems like a good way out, we could think about adding a language heuristic that tries and guess the target language and auto enables when it guesses C++, but that needs to have overrides as well. It should be easy to look for common C++ mangled name prefixes and use that as a guess, but I expect that users who profile C++ guest kernels (or kernel modules) are capable of adding the switch themselves. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
On Sat, Sep 13, 2014 at 06:34:37AM +0300, Avi Kivity wrote: > It's not a simple matter of updating the test: the demangler interprets name > beginning with __vt as C++ mangles names, which of course they aren't. Oh, that'll give cute 'problems' in a mixed C/C++ project that just happens to have __vt names in. Now of course I'm aware that C/C++ 'reserve' the __ prefix, which I suppose that makes it less likely in practise. > The only way I see to proceed is to make the demangling optional, default > off. Seems like a good way out, we could think about adding a language heuristic that tries and guess the target language and auto enables when it guesses C++, but that needs to have overrides as well. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
On Sat, Sep 13, 2014 at 06:34:37AM +0300, Avi Kivity wrote: It's not a simple matter of updating the test: the demangler interprets name beginning with __vt as C++ mangles names, which of course they aren't. Oh, that'll give cute 'problems' in a mixed C/C++ project that just happens to have __vt names in. Now of course I'm aware that C/C++ 'reserve' the __ prefix, which I suppose that makes it less likely in practise. The only way I see to proceed is to make the demangling optional, default off. Seems like a good way out, we could think about adding a language heuristic that tries and guess the target language and auto enables when it guesses C++, but that needs to have overrides as well. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
On 09/14/2014 12:41 PM, Peter Zijlstra wrote: On Sat, Sep 13, 2014 at 06:34:37AM +0300, Avi Kivity wrote: It's not a simple matter of updating the test: the demangler interprets name beginning with __vt as C++ mangles names, which of course they aren't. Oh, that'll give cute 'problems' in a mixed C/C++ project that just happens to have __vt names in. Now of course I'm aware that C/C++ 'reserve' the __ prefix, which I suppose that makes it less likely in practise. If you have clashes there, perf demangling is the least of your worries. The only way I see to proceed is to make the demangling optional, default off. Seems like a good way out, we could think about adding a language heuristic that tries and guess the target language and auto enables when it guesses C++, but that needs to have overrides as well. It should be easy to look for common C++ mangled name prefixes and use that as a guess, but I expect that users who profile C++ guest kernels (or kernel modules) are capable of adding the switch themselves. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
On 09/06/2014 09:46 PM, Jiri Olsa wrote: hi, Jan Stancek found test 1 breakage, probably caused by following patch: 950b8354716e perf tools: Demangle kernel and kernel module symbols too it seems to break test 1: --- [jolsa@krava perf]$ ./perf test -v 1 1: vmlinux symtab matches kallsyms: --- start --- test child forked, pid 6288 Looking at the vmlinux_path (6 entries long) SNIP 0x8142dba0: diff name v: event_queue virtual table k: __vt_event_queue 0x8142dc00: diff name v: event_dequeue virtual table k: __vt_event_dequeue 0x8142dd90: diff name v: event_wait::israpart:: virtual table k: __vt_event_wait.isra.0.part.1 --- Avi, could you please update the tests/vmlinux-kallsyms.c to reflect the demangle change? It's not a simple matter of updating the test: the demangler interprets name beginning with __vt as C++ mangles names, which of course they aren't. The only way I see to proceed is to make the demangling optional, default off. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
ping On Sat, Sep 06, 2014 at 08:46:31PM +0200, Jiri Olsa wrote: > hi, > Jan Stancek found test 1 breakage, probably caused by following patch: > 950b8354716e perf tools: Demangle kernel and kernel module symbols too > > it seems to break test 1: > --- > [jolsa@krava perf]$ ./perf test -v 1 > 1: vmlinux symtab matches kallsyms: > --- start --- > test child forked, pid 6288 > Looking at the vmlinux_path (6 entries long) > > SNIP > > 0x8142dba0: diff name v: event_queue virtual table k: __vt_event_queue > 0x8142dc00: diff name v: event_dequeue virtual table k: > __vt_event_dequeue > 0x8142dd90: diff name v: event_wait::israpart:: virtual table k: > __vt_event_wait.isra.0.part.1 > --- > > Avi, > could you please update the tests/vmlinux-kallsyms.c to reflect > the demangle change? > > thanks, > jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
ping On Sat, Sep 06, 2014 at 08:46:31PM +0200, Jiri Olsa wrote: hi, Jan Stancek found test 1 breakage, probably caused by following patch: 950b8354716e perf tools: Demangle kernel and kernel module symbols too it seems to break test 1: --- [jolsa@krava perf]$ ./perf test -v 1 1: vmlinux symtab matches kallsyms: --- start --- test child forked, pid 6288 Looking at the vmlinux_path (6 entries long) SNIP 0x8142dba0: diff name v: event_queue virtual table k: __vt_event_queue 0x8142dc00: diff name v: event_dequeue virtual table k: __vt_event_dequeue 0x8142dd90: diff name v: event_wait::israpart:: virtual table k: __vt_event_wait.isra.0.part.1 --- Avi, could you please update the tests/vmlinux-kallsyms.c to reflect the demangle change? thanks, jirka -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG] perf tools: Demangle kernel and kernel module symbols too
On 09/06/2014 09:46 PM, Jiri Olsa wrote: hi, Jan Stancek found test 1 breakage, probably caused by following patch: 950b8354716e perf tools: Demangle kernel and kernel module symbols too it seems to break test 1: --- [jolsa@krava perf]$ ./perf test -v 1 1: vmlinux symtab matches kallsyms: --- start --- test child forked, pid 6288 Looking at the vmlinux_path (6 entries long) SNIP 0x8142dba0: diff name v: event_queue virtual table k: __vt_event_queue 0x8142dc00: diff name v: event_dequeue virtual table k: __vt_event_dequeue 0x8142dd90: diff name v: event_wait::israpart:: virtual table k: __vt_event_wait.isra.0.part.1 --- Avi, could you please update the tests/vmlinux-kallsyms.c to reflect the demangle change? It's not a simple matter of updating the test: the demangler interprets name beginning with __vt as C++ mangles names, which of course they aren't. The only way I see to proceed is to make the demangling optional, default off. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
