| Message ID | 20190509064455.1173-1-yamada.masahiro@socionext.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kbuild: add most of Clang-specific flags unconditionally | expand |
On Thu, May 9, 2019 at 8:45 AM Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > We do not support old Clang versions. Upgrade your clang version > if any of these flags is unsupported. > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > except -fcatch-undefined-behavior. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Looks good to me. Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> Just as sidenote: I experimented with a snapshot version of clang-9 and lld-9 and could build, link and boot on bare-metal with '-mglobal-merge' on Debian/buster AMD64. But forgot to document in [1]. [1] https://github.com/ClangBuiltLinux/linux/issues/431 > --- > > Makefile | 10 +++++----- > scripts/Makefile.extrawarn | 12 ++++++------ > 2 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/Makefile b/Makefile > index bd7ae11947cb..c71ffb6f55b5 100644 > --- a/Makefile > +++ b/Makefile > @@ -731,15 +731,15 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > KBUILD_CFLAGS += $(stackp-flags-y) > > ifdef CONFIG_CC_IS_CLANG > -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) > +KBUILD_CPPFLAGS += -Qunused-arguments > +KBUILD_CFLAGS += -Wno-format-invalid-specifier > +KBUILD_CFLAGS += -Wno-gnu > # Quiet clang warning: comparison of unsigned expression < 0 is always false > -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) > +KBUILD_CFLAGS += -Wno-tautological-compare > # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > # source of a reference will be _MergedGlobals and not on of the whitelisted names. > # See modpost pattern 2 > -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) > +KBUILD_CFLAGS += -mno-global-merge > KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior) > else > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > index 768306add591..523c4cafe2dc 100644 > --- a/scripts/Makefile.extrawarn > +++ b/scripts/Makefile.extrawarn > @@ -66,11 +66,11 @@ KBUILD_CFLAGS += $(warning) > else > > ifdef CONFIG_CC_IS_CLANG > -KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides) > -KBUILD_CFLAGS += $(call cc-disable-warning, unused-value) > -KBUILD_CFLAGS += $(call cc-disable-warning, format) > -KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare) > -KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length) > -KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized) > +KBUILD_CFLAGS += -Wno-initializer-overrides > +KBUILD_CFLAGS += -Wno-unused-value > +KBUILD_CFLAGS += -Wno-format > +KBUILD_CFLAGS += -Wno-sign-compare > +KBUILD_CFLAGS += -Wno-format-zero-length > +KBUILD_CFLAGS += -Wno-uninitialized > endif > endif > -- > 2.17.1 > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To post to this group, send email to clang-built-linux@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20190509064455.1173-1-yamada.masahiro%40socionext.com. > For more options, visit https://groups.google.com/d/optout.
On Thu, May 09, 2019 at 03:44:55PM +0900, Masahiro Yamada wrote: > We do not support old Clang versions. Upgrade your clang version > if any of these flags is unsupported. > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > except -fcatch-undefined-behavior. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > --- > > Makefile | 10 +++++----- > scripts/Makefile.extrawarn | 12 ++++++------ > 2 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/Makefile b/Makefile > index bd7ae11947cb..c71ffb6f55b5 100644 > --- a/Makefile > +++ b/Makefile > @@ -731,15 +731,15 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > KBUILD_CFLAGS += $(stackp-flags-y) > > ifdef CONFIG_CC_IS_CLANG > -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) > +KBUILD_CPPFLAGS += -Qunused-arguments > +KBUILD_CFLAGS += -Wno-format-invalid-specifier > +KBUILD_CFLAGS += -Wno-gnu > # Quiet clang warning: comparison of unsigned expression < 0 is always false > -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) > +KBUILD_CFLAGS += -Wno-tautological-compare > # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > # source of a reference will be _MergedGlobals and not on of the whitelisted names. > # See modpost pattern 2 > -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) > +KBUILD_CFLAGS += -mno-global-merge > KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior) I think we should just remove this, I'm fairly confident the kernel can't be reliably compiled with anything earlier than Clang 4 (Pixel 2 was shipped with it but had some hacks, this commit is from Clang 3.5): https://github.com/llvm/llvm-project/commit/cb3f812b6b9fab8f3b41414f24e90222170417b4 Otherwise: Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > else > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > index 768306add591..523c4cafe2dc 100644 > --- a/scripts/Makefile.extrawarn > +++ b/scripts/Makefile.extrawarn > @@ -66,11 +66,11 @@ KBUILD_CFLAGS += $(warning) > else > > ifdef CONFIG_CC_IS_CLANG > -KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides) > -KBUILD_CFLAGS += $(call cc-disable-warning, unused-value) > -KBUILD_CFLAGS += $(call cc-disable-warning, format) > -KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare) > -KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length) > -KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized) > +KBUILD_CFLAGS += -Wno-initializer-overrides > +KBUILD_CFLAGS += -Wno-unused-value > +KBUILD_CFLAGS += -Wno-format > +KBUILD_CFLAGS += -Wno-sign-compare > +KBUILD_CFLAGS += -Wno-format-zero-length > +KBUILD_CFLAGS += -Wno-uninitialized > endif > endif > -- > 2.17.1 >
Hi. On Thu, May 9, 2019 at 8:15 PM Nathan Chancellor <natechancellor@gmail.com> wrote: > > On Thu, May 09, 2019 at 03:44:55PM +0900, Masahiro Yamada wrote: > > We do not support old Clang versions. Upgrade your clang version > > if any of these flags is unsupported. > > > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > > except -fcatch-undefined-behavior. > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > --- > > > > Makefile | 10 +++++----- > > scripts/Makefile.extrawarn | 12 ++++++------ > > 2 files changed, 11 insertions(+), 11 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index bd7ae11947cb..c71ffb6f55b5 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -731,15 +731,15 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > > KBUILD_CFLAGS += $(stackp-flags-y) > > > > ifdef CONFIG_CC_IS_CLANG > > -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > > -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > > -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) > > +KBUILD_CPPFLAGS += -Qunused-arguments > > +KBUILD_CFLAGS += -Wno-format-invalid-specifier > > +KBUILD_CFLAGS += -Wno-gnu > > # Quiet clang warning: comparison of unsigned expression < 0 is always false > > -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) > > +KBUILD_CFLAGS += -Wno-tautological-compare > > # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > > # source of a reference will be _MergedGlobals and not on of the whitelisted names. > > # See modpost pattern 2 > > -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) > > +KBUILD_CFLAGS += -mno-global-merge > > KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior) > > I think we should just remove this, I'm fairly confident the kernel > can't be reliably compiled with anything earlier than Clang 4 (Pixel 2 > was shipped with it but had some hacks, this commit is from Clang 3.5): > > https://github.com/llvm/llvm-project/commit/cb3f812b6b9fab8f3b41414f24e90222170417b4 Oh, I did not know this was deprecated. Could you send a patch to remove it with filling the commit log ? Thanks.
On Thu, May 09, 2019 at 08:35:05PM +0900, Masahiro Yamada wrote: > Hi. > > On Thu, May 9, 2019 at 8:15 PM Nathan Chancellor > <natechancellor@gmail.com> wrote: > > > > On Thu, May 09, 2019 at 03:44:55PM +0900, Masahiro Yamada wrote: > > > We do not support old Clang versions. Upgrade your clang version > > > if any of these flags is unsupported. > > > > > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > > > except -fcatch-undefined-behavior. > > > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > > --- > > > > > > Makefile | 10 +++++----- > > > scripts/Makefile.extrawarn | 12 ++++++------ > > > 2 files changed, 11 insertions(+), 11 deletions(-) > > > > > > diff --git a/Makefile b/Makefile > > > index bd7ae11947cb..c71ffb6f55b5 100644 > > > --- a/Makefile > > > +++ b/Makefile > > > @@ -731,15 +731,15 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > > > KBUILD_CFLAGS += $(stackp-flags-y) > > > > > > ifdef CONFIG_CC_IS_CLANG > > > -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > > > -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > > > -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) > > > +KBUILD_CPPFLAGS += -Qunused-arguments > > > +KBUILD_CFLAGS += -Wno-format-invalid-specifier > > > +KBUILD_CFLAGS += -Wno-gnu > > > # Quiet clang warning: comparison of unsigned expression < 0 is always false > > > -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) > > > +KBUILD_CFLAGS += -Wno-tautological-compare > > > # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > > > # source of a reference will be _MergedGlobals and not on of the whitelisted names. > > > # See modpost pattern 2 > > > -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) > > > +KBUILD_CFLAGS += -mno-global-merge > > > KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior) > > > > I think we should just remove this, I'm fairly confident the kernel > > can't be reliably compiled with anything earlier than Clang 4 (Pixel 2 > > was shipped with it but had some hacks, this commit is from Clang 3.5): > > > > https://github.com/llvm/llvm-project/commit/cb3f812b6b9fab8f3b41414f24e90222170417b4 > > > Oh, I did not know this was deprecated. > > Could you send a patch to remove it > with filling the commit log ? Sure! > > > Thanks. > > > > -- > Best Regards > Masahiro Yamada > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To post to this group, send email to clang-built-linux@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/CAK7LNASpsid7_sh4rdRNSTwZ1YtW_%2BuH2eoarJNNUttntQZ-kg%40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout.
> On Thu, May 09, 2019 at 03:44:55PM +0900, Masahiro Yamada wrote: > > We do not support old Clang versions. Upgrade your clang version > > if any of these flags is unsupported. > > > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > > except -fcatch-undefined-behavior. > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > --- > > > > Makefile | 10 +++++----- > > scripts/Makefile.extrawarn | 12 ++++++------ > > 2 files changed, 11 insertions(+), 11 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index bd7ae11947cb..c71ffb6f55b5 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -731,15 +731,15 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > > KBUILD_CFLAGS += $(stackp-flags-y) > > > > ifdef CONFIG_CC_IS_CLANG > > -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > > -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > > -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) > > +KBUILD_CPPFLAGS += -Qunused-arguments > > +KBUILD_CFLAGS += -Wno-format-invalid-specifier > > +KBUILD_CFLAGS += -Wno-gnu > > # Quiet clang warning: comparison of unsigned expression < 0 is always false > > -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) > > +KBUILD_CFLAGS += -Wno-tautological-compare > > # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > > # source of a reference will be _MergedGlobals and not on of the whitelisted names. > > # See modpost pattern 2 > > -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) > > +KBUILD_CFLAGS += -mno-global-merge > > KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior) > > I think we should just remove this, I'm fairly confident the kernel > can't be reliably compiled with anything earlier than Clang 4 (Pixel 2 > was shipped with it but had some hacks, this commit is from Clang 3.5): Yeah, clang-4 is usually what I test these with, as that's the earliest known version of Clang that I ever had success with. Hopefully a lot of things will stabilize for the clang-9 release. Anyways, I checked these all w/ godbolt w/ clang-4. Tested-by: Nick Desaulniers <ndesaulniers@google.com> > > https://github.com/llvm/llvm-project/commit/cb3f812b6b9fab8f3b41414f24e90222170417b4 > > Otherwise: > > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > > > else > > > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > > index 768306add591..523c4cafe2dc 100644 > > --- a/scripts/Makefile.extrawarn > > +++ b/scripts/Makefile.extrawarn > > @@ -66,11 +66,11 @@ KBUILD_CFLAGS += $(warning) > > else > > > > ifdef CONFIG_CC_IS_CLANG > > -KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides) > > -KBUILD_CFLAGS += $(call cc-disable-warning, unused-value) > > -KBUILD_CFLAGS += $(call cc-disable-warning, format) > > -KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare) > > -KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length) > > -KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized) > > +KBUILD_CFLAGS += -Wno-initializer-overrides > > +KBUILD_CFLAGS += -Wno-unused-value > > +KBUILD_CFLAGS += -Wno-format > > +KBUILD_CFLAGS += -Wno-sign-compare > > +KBUILD_CFLAGS += -Wno-format-zero-length > > +KBUILD_CFLAGS += -Wno-uninitialized > > endif > > endif > > -- > > 2.17.1 > >
On Thu, May 9, 2019 at 4:06 PM Sedat Dilek <sedat.dilek@gmail.com> wrote: > > On Thu, May 9, 2019 at 8:45 AM Masahiro Yamada > <yamada.masahiro@socionext.com> wrote: > > > > We do not support old Clang versions. Upgrade your clang version > > if any of these flags is unsupported. > > > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > > except -fcatch-undefined-behavior. > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > Looks good to me. > > Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> > > Just as sidenote: > I experimented with a snapshot version of clang-9 and lld-9 and could > build, link and boot on bare-metal with '-mglobal-merge' on > Debian/buster AMD64. The comment says # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the # source of a reference will be _MergedGlobals and not on of the whitelisted names. # See modpost pattern 2 So, it seems it is just a matter of modpost, but I am not sure enough. This flag has been here since the initial support. (61163efae02040f66a95c8ed17f4407951ba58fa) Perhaps, we should review clang flags one by one again? > But forgot to document in [1]. > > [1] https://github.com/ClangBuiltLinux/linux/issues/431
On Fri, May 10, 2019 at 6:54 AM Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > On Thu, May 9, 2019 at 4:06 PM Sedat Dilek <sedat.dilek@gmail.com> wrote: > > > > On Thu, May 9, 2019 at 8:45 AM Masahiro Yamada > > <yamada.masahiro@socionext.com> wrote: > > > > > > We do not support old Clang versions. Upgrade your clang version > > > if any of these flags is unsupported. > > > > > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > > > except -fcatch-undefined-behavior. > > > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > > > Looks good to me. > > > > Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com> > > > > Just as sidenote: > > I experimented with a snapshot version of clang-9 and lld-9 and could > > build, link and boot on bare-metal with '-mglobal-merge' on > > Debian/buster AMD64. > > > The comment says > # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > # source of a reference will be _MergedGlobals and not on of the > whitelisted names. > # See modpost pattern 2 > > So, it seems it is just a matter of modpost, > but I am not sure enough. > > This flag has been here since the initial support. > (61163efae02040f66a95c8ed17f4407951ba58fa) > > > Perhaps, we should review clang flags one by one again? Yes, it's always good to re-evaluate if something is just cruft and can be removed. +Behan I don't quite understand the comment about _MergedGlobals, Behan, do happen to have more context?
diff --git a/Makefile b/Makefile index bd7ae11947cb..c71ffb6f55b5 100644 --- a/Makefile +++ b/Makefile @@ -731,15 +731,15 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong KBUILD_CFLAGS += $(stackp-flags-y) ifdef CONFIG_CC_IS_CLANG -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) +KBUILD_CPPFLAGS += -Qunused-arguments +KBUILD_CFLAGS += -Wno-format-invalid-specifier +KBUILD_CFLAGS += -Wno-gnu # Quiet clang warning: comparison of unsigned expression < 0 is always false -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) +KBUILD_CFLAGS += -Wno-tautological-compare # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the # source of a reference will be _MergedGlobals and not on of the whitelisted names. # See modpost pattern 2 -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) +KBUILD_CFLAGS += -mno-global-merge KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior) else diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 768306add591..523c4cafe2dc 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -66,11 +66,11 @@ KBUILD_CFLAGS += $(warning) else ifdef CONFIG_CC_IS_CLANG -KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides) -KBUILD_CFLAGS += $(call cc-disable-warning, unused-value) -KBUILD_CFLAGS += $(call cc-disable-warning, format) -KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare) -KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length) -KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized) +KBUILD_CFLAGS += -Wno-initializer-overrides +KBUILD_CFLAGS += -Wno-unused-value +KBUILD_CFLAGS += -Wno-format +KBUILD_CFLAGS += -Wno-sign-compare +KBUILD_CFLAGS += -Wno-format-zero-length +KBUILD_CFLAGS += -Wno-uninitialized endif endif
We do not support old Clang versions. Upgrade your clang version if any of these flags is unsupported. Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, except -fcatch-undefined-behavior. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- Makefile | 10 +++++----- scripts/Makefile.extrawarn | 12 ++++++------ 2 files changed, 11 insertions(+), 11 deletions(-)