Messages in this thread Patch in this message | | | Date | Wed, 28 Jul 2010 15:44:15 +0200 | From | Karol Lewandowski <> | Subject | Re: GCOV doesn't seem to work on ARM with kernel 2.6.35-rc6 |
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On 07/28/2010 03:12 PM, Peter Oberparleiter wrote: > On 27.07.2010 09:35, Karol Lewandowski wrote: >> On 07/26/2010 06:57 PM, Peter Oberparleiter wrote: >>> Karol Lewandowski wrote: >>>> On 07/26/2010 12:32 PM, Karol Lewandowski wrote: >>>>> I'm trying to use code coverage measurements with mainline Linux kernel >>>>> 2.6.35-rc6 on ARM platform (specifically on Samsung's S5PC110 board). >> ... >>> I just tested gcov support for 2.6.35-rc6 on s390 and it works without >>> a problem. My assumption would be that you are using an EABI-GCC to >>> compile your kernel. Those compilers name their constructor symbols >> >> Exactly. >> >>> differently than the vanilla GCC so that the whole constructor calling >>> mechanism on which the gcov support relies, will fail. If that is >>> indeed the case, the following testing patch should solve your >>> problem: >> >> Yes, that was the case and your patch indeed solved my problem. > > Excellent. I could imagine that other ARM users might also benefit from > this patch. Before I submit it for integration though, I need to make > sure that it also works for kernel modules. Could you enable profiling > for a kernel module and verify that you are seeing files in > /sys/kernel/debug/gcov belonging to that module??
That does work too.
However, having seen this[x] patch I would ask if constructor name might be dynamically selected via user-(in)visible Kconfig option (like in that patch?) I've tested it and it does seem to work too.
[x] http://groups.google.com/group/linux.kernel/browse_thread/thread/84439151c5386e0f/d7dbec62b9d7989f?show_docid=d7dbec62b9d7989f
I've copy pasted interesting parts from that patch below - I'm sure you get the idea.
Thanks.
--- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -442,7 +442,7 @@ #ifdef CONFIG_CONSTRUCTORS #define KERNEL_CTORS() . = ALIGN(8); \ VMLINUX_SYMBOL(__ctors_start) = .; \ - *(.ctors) \ + *(CONFIG_GCOV_CTORS) \
--- a/kernel/gcov/Kconfig +++ b/kernel/gcov/Kconfig +config GCOV_CTORS + string + depends on GCOV_KERNEL + default ".init_array" if ARM && AEABI + default ".ctors"
--- a/kernel/module.c +++ b/kernel/module.c @@ -2296,7 +2296,7 @@ static noinline struct module *load_module(void __user *umod, "__kcrctab_unused_gpl"); #endif #ifdef CONFIG_CONSTRUCTORS - mod->ctors = section_objs(hdr, sechdrs, secstrings, ".ctors", + mod->ctors = section_objs(hdr, sechdrs, secstrings, CONFIG_GCOV_CTORS, sizeof(*mod->ctors), &mod->num_ctors);
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