Messages in this thread | | | Subject | Re: [PATCH] gcov: support GCC 7.1 | From | Peter Oberparleiter <> | Date | Thu, 8 Dec 2016 13:52:45 +0100 |
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On 24.11.2016 13:46, Martin Liška wrote: > On 11/09/2016 10:21 AM, Peter Oberparleiter wrote: >> On 31.10.2016 10:35, Martin Liška wrote: >>> Starting from GCC 7.1, __gcov_exit is a new symbol expected >>> to be implemented in a profiling runtime. >> >> I tested your patch with kernel 4.9-rc4 compiled with GCC 7.0.0 20161107 >> (experimental) and validated that it fixes the build error due to a >> missing __gcov_exit symbol. >> >> An attempt to read from one of the .gcda files generated by a kernel >> compiled this way resulted in a crash though. It appears that the number >> of GCOV_COUNTERS has changed again for GCC 7.x and must be adjusted in >> the kernel as well. Could you add that to your patch as well? > > Hello. > > Sorry, this is fixed in second version of the patch. > >> Given that GCC 7.1 has not yet been released, I'm wondering if it is >> safe to program against interfaces that have not yet been fully >> finalized. Can you provide an indication on whether these gcov-related >> aspects of GCC might still be changed until release? > > Well, we just flipped to stage3 which means that any new features should > be added to current master. If you prefer we can commit the patch after > a release of 7.1 will be done?
I've given this some more thought: if your patch is not applied, GCOV kernel profiling will definitely not work with GCC 7.x. If it is applied, there is a high probability that it will work, and a small chance that additional patches will be required. Overall I would say this justifies applying the patch now.
>> As a side note, please post your patches inline instead of as attachment >> as that helps quoting them in replies. See also >> linux/Documentation/SubmittingPatches. > > Sure, thanks for info. I'm attaching new version: > > Starting from GCC 7.1, __gcov_exit is a new symbol expected > to be implemented in a profiling runtime. Update number of profile > counters. > > Signed-off-by: Martin Liska <mliska@suse.cz>
Looks good, thanks! Tested successfully with GCC 7.0.0 20161208 (experimental) on Linux kernel 4.9-rc8 (compiles successfully and produces valid kernel .gcda files).
Andrew, could you pick this change up via your tree?
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Tested-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
> --- > kernel/gcov/base.c | 6 ++++++ > kernel/gcov/gcc_4_7.c | 4 +++- > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/kernel/gcov/base.c b/kernel/gcov/base.c > index 2f9df37..85dca5d 100644 > --- a/kernel/gcov/base.c > +++ b/kernel/gcov/base.c > @@ -98,6 +98,12 @@ void __gcov_merge_icall_topn(gcov_type *counters, unsigned int n_counters) > } > EXPORT_SYMBOL(__gcov_merge_icall_topn); > > +void __gcov_exit (void) > +{ > + /* Unused. */ > +} > +EXPORT_SYMBOL(__gcov_exit); > + > /** > * gcov_enable_events - enable event reporting through gcov_event() > * > diff --git a/kernel/gcov/gcc_4_7.c b/kernel/gcov/gcc_4_7.c > index 6a5c239..46a18e7 100644 > --- a/kernel/gcov/gcc_4_7.c > +++ b/kernel/gcov/gcc_4_7.c > @@ -18,7 +18,9 @@ > #include <linux/vmalloc.h> > #include "gcov.h" > > -#if (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1) > +#if (__GNUC__ >= 7) > +#define GCOV_COUNTERS 9 > +#elif (__GNUC__ > 5) || (__GNUC__ == 5 && __GNUC_MINOR__ >= 1) > #define GCOV_COUNTERS 10 > #elif __GNUC__ == 4 && __GNUC_MINOR__ >= 9 > #define GCOV_COUNTERS 9 >
-- Peter Oberparleiter Linux on z Systems Development - IBM Germany
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