| Message ID | 20180914040649.1794-6-joel@jms.id.au (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc: Clang build fixes | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
| snowpatch_ozlabs/checkpatch | fail | Test checkpatch on branch next |
| snowpatch_ozlabs/build-ppc64le | success | Test build-ppc64le on branch next |
| snowpatch_ozlabs/build-ppc64be | success | Test build-ppc64be on branch next |
| snowpatch_ozlabs/build-ppc64e | success | Test build-ppc64e on branch next |
| snowpatch_ozlabs/build-ppc32 | success | Test build-ppc32 on branch next |
On Fri, 14 Sep 2018 13:36:49 +0930 Joel Stanley <joel@jms.id.au> wrote: > This effectively reverts 7563dc645853 ("powerpc: Work around gcc's > -fno-omit-frame-pointer bug"), a workaround for a bug in GCC 4.1.3 when > building 2.6.26 kernel. > > The flag is not supported by clang, but reading the history of the > bug[1] suggests it is no longer required by supported GCC versions, with > GCC 4.6 now being the minimum. > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=11414 > Signed-off-by: Joel Stanley <joel@jms.id.au> > --- > Last time this was proposed there was an issue reported: > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-September/121214.html > > If some machines still have an issue, we could instead wrap this in a > flag check. I don't think we can remove it completely because up to at least 4.6 maybe 4.8 has problems. I have a few patches lying around I started looking at this... I'll send them. Thanks, Nick
On Thu, Sep 13, 2018 at 9:07 PM Joel Stanley <joel@jms.id.au> wrote: > Last time this was proposed there was an issue reported: > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-September/121214.html Heh, did PASemi sell boxes? Interesting, I'll have to read up on my history. On Thu, Sep 13, 2018 at 10:06 PM Nicholas Piggin <npiggin@gmail.com> wrote: > I don't think we can remove it completely because up to at least 4.6 > maybe 4.8 has problems. > > I have a few patches lying around I started looking at this... I'll > send them. Yeah, it's too bad the link above doesn't mention gcc version. The gcc bugreport mentions fixing the bug in 7563dc64585324f443f5ac107eb6d89ee813a2d2, not sure how to check what release version of gcc that is? (Do they tag releases?) Nick, do you have a test case or more context about this still being an issue in gcc 4.8? (maybe I should wait for your patch series?)
On Fri, 14 Sep 2018 11:03:38 -0700 Nick Desaulniers <ndesaulniers@google.com> wrote: > On Thu, Sep 13, 2018 at 9:07 PM Joel Stanley <joel@jms.id.au> wrote: > > Last time this was proposed there was an issue reported: > > > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-September/121214.html > > Heh, did PASemi sell boxes? Interesting, I'll have to read up on my history. > > On Thu, Sep 13, 2018 at 10:06 PM Nicholas Piggin <npiggin@gmail.com> wrote: > > I don't think we can remove it completely because up to at least 4.6 > > maybe 4.8 has problems. > > > > I have a few patches lying around I started looking at this... I'll > > send them. > > Yeah, it's too bad the link above doesn't mention gcc version. > > The gcc bugreport mentions fixing the bug in > 7563dc64585324f443f5ac107eb6d89ee813a2d2, not sure how to check what > release version of gcc that is? (Do they tag releases?) I'm not sure, that's not in my gcc tree AFAIKS. > > Nick, do you have a test case or more context about this still being > an issue in gcc 4.8? (maybe I should wait for your patch series?) Sorry I forgot to cc you. This has links to some of the sched epilog bugs. https://marc.info/?l=linuxppc-embedded&m=153690223909654&w=2 Thanks, Nick
On Sat, Sep 15, 2018 at 06:43:05AM +1000, Nicholas Piggin wrote: > On Fri, 14 Sep 2018 11:03:38 -0700 > Nick Desaulniers <ndesaulniers@google.com> wrote: > > > On Thu, Sep 13, 2018 at 9:07 PM Joel Stanley <joel@jms.id.au> wrote: > > > Last time this was proposed there was an issue reported: > > > > > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-September/121214.html > > > > Heh, did PASemi sell boxes? Interesting, I'll have to read up on my history. > > > > On Thu, Sep 13, 2018 at 10:06 PM Nicholas Piggin <npiggin@gmail.com> wrote: > > > I don't think we can remove it completely because up to at least 4.6 > > > maybe 4.8 has problems. > > > > > > I have a few patches lying around I started looking at this... I'll > > > send them. > > > > Yeah, it's too bad the link above doesn't mention gcc version. > > > > The gcc bugreport mentions fixing the bug in > > 7563dc64585324f443f5ac107eb6d89ee813a2d2, not sure how to check what > > release version of gcc that is? (Do they tag releases?) > > I'm not sure, that's not in my gcc tree AFAIKS. This is a git hash in the kernel tree. > > Nick, do you have a test case or more context about this still being > > an issue in gcc 4.8? (maybe I should wait for your patch series?) > > Sorry I forgot to cc you. This has links to some of the sched > epilog bugs. > > https://marc.info/?l=linuxppc-embedded&m=153690223909654&w=2 PR44199 was backported to 4.4 and PR52828 is fixed in 4.8. Segher
On Fri, Sep 14, 2018 at 2:56 PM Segher Boessenkool <segher@kernel.crashing.org> wrote: > > On Sat, Sep 15, 2018 at 06:43:05AM +1000, Nicholas Piggin wrote: > > On Fri, 14 Sep 2018 11:03:38 -0700 > > Nick Desaulniers <ndesaulniers@google.com> wrote: > > > > > On Thu, Sep 13, 2018 at 9:07 PM Joel Stanley <joel@jms.id.au> wrote: > > > > Last time this was proposed there was an issue reported: > > > > > > > > https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-September/121214.html > > > > > > Heh, did PASemi sell boxes? Interesting, I'll have to read up on my history. > > > > > > On Thu, Sep 13, 2018 at 10:06 PM Nicholas Piggin <npiggin@gmail.com> wrote: > > > > I don't think we can remove it completely because up to at least 4.6 > > > > maybe 4.8 has problems. > > > > > > > > I have a few patches lying around I started looking at this... I'll > > > > send them. > > > > > > Yeah, it's too bad the link above doesn't mention gcc version. > > > > > > The gcc bugreport mentions fixing the bug in > > > 7563dc64585324f443f5ac107eb6d89ee813a2d2, not sure how to check what > > > release version of gcc that is? (Do they tag releases?) > > > > I'm not sure, that's not in my gcc tree AFAIKS. > > This is a git hash in the kernel tree. > > > > Nick, do you have a test case or more context about this still being > > > an issue in gcc 4.8? (maybe I should wait for your patch series?) > > > > Sorry I forgot to cc you. This has links to some of the sched > > epilog bugs. > > > > https://marc.info/?l=linuxppc-embedded&m=153690223909654&w=2 Cool, cc me on the thread if you'd like me to add my reviewed-by tag visibly on the thread. > > PR44199 was backported to 4.4 and PR52828 is fixed in 4.8. Are those GCC versions? If so, what does that mean for the users of the many GCC releases between 4.4 and 4.8?
On Fri, Sep 14, 2018 at 03:20:18PM -0700, Nick Desaulniers wrote: > On Fri, Sep 14, 2018 at 2:56 PM Segher Boessenkool > <segher@kernel.crashing.org> wrote: > > On Sat, Sep 15, 2018 at 06:43:05AM +1000, Nicholas Piggin wrote: > > > On Fri, 14 Sep 2018 11:03:38 -0700 > > > Nick Desaulniers <ndesaulniers@google.com> wrote: > > > > > > Sorry I forgot to cc you. This has links to some of the sched > > > epilog bugs. > > > > > > https://marc.info/?l=linuxppc-embedded&m=153690223909654&w=2 > > Cool, cc me on the thread if you'd like me to add my reviewed-by tag > visibly on the thread. > > > PR44199 was backported to 4.4 and PR52828 is fixed in 4.8. > > Are those GCC versions? If so, what does that mean for the users of > the many GCC releases between 4.4 and 4.8? Yes, GCC bug 44199 was fixed in GCC version 4.4, etc. It of course also is fixed in all later versions; so GCC releases between 4.4 and 4.8 have the fix for PR44199 but not that for PR52828. I didn't check exactly what 4.4.x versions have the fix, etc. I always assume anyone using x.y.z uses the highest z available. I don't know if those are the only fixes you need; those are the two bugs mentioned in Nicholas' patch (that MARC link above). Segher
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index a70639482053..ef8eca40ffef 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -229,11 +229,6 @@ ifdef CONFIG_6xx KBUILD_CFLAGS += -mcpu=powerpc endif -# Work around a gcc code-gen bug with -fno-omit-frame-pointer. -ifdef CONFIG_FUNCTION_TRACER -KBUILD_CFLAGS += -mno-sched-epilog -endif - cpu-as-$(CONFIG_4xx) += -Wa,-m405 cpu-as-$(CONFIG_ALTIVEC) += $(call as-option,-Wa$(comma)-maltivec) cpu-as-$(CONFIG_E200) += -Wa,-me200 diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 3b66f2c19c84..1e64cfe22a83 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -22,10 +22,10 @@ CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) ifdef CONFIG_FUNCTION_TRACER # Do not trace early boot code -CFLAGS_REMOVE_cputable.o = -mno-sched-epilog $(CC_FLAGS_FTRACE) -CFLAGS_REMOVE_prom_init.o = -mno-sched-epilog $(CC_FLAGS_FTRACE) -CFLAGS_REMOVE_btext.o = -mno-sched-epilog $(CC_FLAGS_FTRACE) -CFLAGS_REMOVE_prom.o = -mno-sched-epilog $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_cputable.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_prom_init.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_btext.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_prom.o = $(CC_FLAGS_FTRACE) endif obj-y := cputable.o ptrace.o syscalls.o \ diff --git a/arch/powerpc/kernel/trace/Makefile b/arch/powerpc/kernel/trace/Makefile index d22d8bafb643..d868ba42032f 100644 --- a/arch/powerpc/kernel/trace/Makefile +++ b/arch/powerpc/kernel/trace/Makefile @@ -7,7 +7,7 @@ subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror ifdef CONFIG_FUNCTION_TRACER # do not trace tracer code -CFLAGS_REMOVE_ftrace.o = -mno-sched-epilog $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE) endif obj32-$(CONFIG_FUNCTION_TRACER) += ftrace_32.o diff --git a/arch/powerpc/platforms/powermac/Makefile b/arch/powerpc/platforms/powermac/Makefile index f2839eed0f89..561a67d65e4d 100644 --- a/arch/powerpc/platforms/powermac/Makefile +++ b/arch/powerpc/platforms/powermac/Makefile @@ -3,7 +3,7 @@ CFLAGS_bootx_init.o += -fPIC ifdef CONFIG_FUNCTION_TRACER # Do not trace early boot code -CFLAGS_REMOVE_bootx_init.o = -mno-sched-epilog $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_bootx_init.o = $(CC_FLAGS_FTRACE) endif obj-y += pic.o setup.o time.o feature.o pci.o \ diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile index 1bc3abb237cd..93cc1f1b8b61 100644 --- a/arch/powerpc/xmon/Makefile +++ b/arch/powerpc/xmon/Makefile @@ -8,7 +8,7 @@ UBSAN_SANITIZE := n # Disable ftrace for the entire directory ORIG_CFLAGS := $(KBUILD_CFLAGS) -KBUILD_CFLAGS = $(subst -mno-sched-epilog,,$(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))) +KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS)) ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
This effectively reverts 7563dc645853 ("powerpc: Work around gcc's -fno-omit-frame-pointer bug"), a workaround for a bug in GCC 4.1.3 when building 2.6.26 kernel. The flag is not supported by clang, but reading the history of the bug[1] suggests it is no longer required by supported GCC versions, with GCC 4.6 now being the minimum. [1] https://bugzilla.kernel.org/show_bug.cgi?id=11414 Signed-off-by: Joel Stanley <joel@jms.id.au> --- Last time this was proposed there was an issue reported: https://lists.ozlabs.org/pipermail/linuxppc-dev/2014-September/121214.html If some machines still have an issue, we could instead wrap this in a flag check. --- arch/powerpc/Makefile | 5 ----- arch/powerpc/kernel/Makefile | 8 ++++---- arch/powerpc/kernel/trace/Makefile | 2 +- arch/powerpc/platforms/powermac/Makefile | 2 +- arch/powerpc/xmon/Makefile | 2 +- 5 files changed, 7 insertions(+), 12 deletions(-)