Re: [PATCH] x86/retpoline: Fix forcing me to update my compiler
On Sat, Dec 08, 2018 at 02:14:47PM +0100, Kirill Marinushkin wrote: > >> First problem: I cannot compile the kernel with my version of compiler > > >> Second problem: when I disable the feature - it cannot take effect, > >> because the parse-time error happens before `syncconfig` > > On 12/08/18 13:42, Borislav Petkov wrote: > > Does this help? > > > > https://git.kernel.org/tip/25896d073d8a0403b07e6dec56f58e6c33678207 > > > > The patch which you mentioned fixes the second problem: now I can disable > CONFIG_RETPOLINE. > But, the first problem is still here: with defconfig and gcc v6.4.0, kernel > doesn't build, with this message: > > > $ make > scripts/kconfig/conf --syncconfig Kconfig > You are building kernel with non-retpoline compiler. > Please update your compiler. > make: *** [arch/x86/Makefile:311: checkbin] Error 1 > > > I don't think that this is a proper behavior. I suggest to allow compilation No, you asked for retpoline, and your compiler can not provide that, so erroring out is the correct behavior. It is worse for you to have an option enabled and it not being enabled just because your compiler does not support it. That way you do not have the false sense of security. thanks, greg k-h
Re: [PATCH] x86/retpoline: Fix forcing me to update my compiler
On Sat, Dec 08, 2018 at 02:14:47PM +0100, Kirill Marinushkin wrote: > >> First problem: I cannot compile the kernel with my version of compiler > > >> Second problem: when I disable the feature - it cannot take effect, > >> because the parse-time error happens before `syncconfig` > > On 12/08/18 13:42, Borislav Petkov wrote: > > Does this help? > > > > https://git.kernel.org/tip/25896d073d8a0403b07e6dec56f58e6c33678207 > > > > The patch which you mentioned fixes the second problem: now I can disable > CONFIG_RETPOLINE. > But, the first problem is still here: with defconfig and gcc v6.4.0, kernel > doesn't build, with this message: > > > $ make > scripts/kconfig/conf --syncconfig Kconfig > You are building kernel with non-retpoline compiler. > Please update your compiler. > make: *** [arch/x86/Makefile:311: checkbin] Error 1 > > > I don't think that this is a proper behavior. I suggest to allow compilation No, you asked for retpoline, and your compiler can not provide that, so erroring out is the correct behavior. It is worse for you to have an option enabled and it not being enabled just because your compiler does not support it. That way you do not have the false sense of security. thanks, greg k-h
Re: [PATCH] x86/retpoline: Fix forcing me to update my compiler
>> First problem: I cannot compile the kernel with my version of compiler >> Second problem: when I disable the feature - it cannot take effect, >> because the parse-time error happens before `syncconfig` On 12/08/18 13:42, Borislav Petkov wrote: > Does this help? > > https://git.kernel.org/tip/25896d073d8a0403b07e6dec56f58e6c33678207 > The patch which you mentioned fixes the second problem: now I can disable CONFIG_RETPOLINE. But, the first problem is still here: with defconfig and gcc v6.4.0, kernel doesn't build, with this message: $ make scripts/kconfig/conf --syncconfig Kconfig You are building kernel with non-retpoline compiler. Please update your compiler. make: *** [arch/x86/Makefile:311: checkbin] Error 1 I don't think that this is a proper behavior. I suggest to allow compilation Best Regards, Kirill
Re: [PATCH] x86/retpoline: Fix forcing me to update my compiler
>> First problem: I cannot compile the kernel with my version of compiler >> Second problem: when I disable the feature - it cannot take effect, >> because the parse-time error happens before `syncconfig` On 12/08/18 13:42, Borislav Petkov wrote: > Does this help? > > https://git.kernel.org/tip/25896d073d8a0403b07e6dec56f58e6c33678207 > The patch which you mentioned fixes the second problem: now I can disable CONFIG_RETPOLINE. But, the first problem is still here: with defconfig and gcc v6.4.0, kernel doesn't build, with this message: $ make scripts/kconfig/conf --syncconfig Kconfig You are building kernel with non-retpoline compiler. Please update your compiler. make: *** [arch/x86/Makefile:311: checkbin] Error 1 I don't think that this is a proper behavior. I suggest to allow compilation Best Regards, Kirill
Re: [PATCH] x86/retpoline: Fix forcing me to update my compiler
On Sat, Dec 08, 2018 at 01:38:16PM +0100, Kirill Marinushkin wrote: > First problem: I cannot compile the kernel with my version of compiler > > > $ make defconfig > *** Default configuration is based on 'i386_defconfig' > \# > \# configuration written to .config > \# > $ grep CONFIG_RETPOLINE .config > CONFIG_RETPOLINE=y > $ make > arch/x86/Makefile:224: *** You are building kernel with non-retpoline > compiler, please update your compiler.. Stop. > Does this help? https://git.kernel.org/tip/25896d073d8a0403b07e6dec56f58e6c33678207 -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
Re: [PATCH] x86/retpoline: Fix forcing me to update my compiler
On Sat, Dec 08, 2018 at 01:38:16PM +0100, Kirill Marinushkin wrote: > First problem: I cannot compile the kernel with my version of compiler > > > $ make defconfig > *** Default configuration is based on 'i386_defconfig' > \# > \# configuration written to .config > \# > $ grep CONFIG_RETPOLINE .config > CONFIG_RETPOLINE=y > $ make > arch/x86/Makefile:224: *** You are building kernel with non-retpoline > compiler, please update your compiler.. Stop. > Does this help? https://git.kernel.org/tip/25896d073d8a0403b07e6dec56f58e6c33678207 -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
[PATCH] x86/retpoline: Fix forcing me to update my compiler
First problem: I cannot compile the kernel with my version of compiler
$ make defconfig
*** Default configuration is based on 'i386_defconfig'
\#
\# configuration written to .config
\#
$ grep CONFIG_RETPOLINE .config
CONFIG_RETPOLINE=y
$ make
arch/x86/Makefile:224: *** You are building kernel with non-retpoline
compiler, please update your compiler.. Stop.
Second problem: when I disable the feature - it cannot take effect,
because the parse-time error happens before `syncconfig`
$ scripts/config -d RETPOLINE
$ grep CONFIG_RETPOLINE .config
\# CONFIG_RETPOLINE is not set
$ make
arch/x86/Makefile:224: *** You are building kernel with non-retpoline
compiler, please update your compiler.. Stop.
Fixes: 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler
support")
Signed-off-by: Kirill Marinushkin
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Borislav Petkov
Cc: Zhenzhong Duan
Cc: H. Peter Anvin
Cc: x...@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: sta...@vger.kernel.org
---
arch/x86/Makefile | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f5d7f4134524..26a2198c59b3 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -220,9 +220,6 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
# Avoid indirect branches in kernel to deal with Spectre
ifdef CONFIG_RETPOLINE
-ifeq ($(RETPOLINE_CFLAGS),)
- $(error You are building kernel with non-retpoline compiler, please update
your compiler.)
-endif
KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
endif
--
2.13.6
[PATCH] x86/retpoline: Fix forcing me to update my compiler
First problem: I cannot compile the kernel with my version of compiler
$ make defconfig
*** Default configuration is based on 'i386_defconfig'
\#
\# configuration written to .config
\#
$ grep CONFIG_RETPOLINE .config
CONFIG_RETPOLINE=y
$ make
arch/x86/Makefile:224: *** You are building kernel with non-retpoline
compiler, please update your compiler.. Stop.
Second problem: when I disable the feature - it cannot take effect,
because the parse-time error happens before `syncconfig`
$ scripts/config -d RETPOLINE
$ grep CONFIG_RETPOLINE .config
\# CONFIG_RETPOLINE is not set
$ make
arch/x86/Makefile:224: *** You are building kernel with non-retpoline
compiler, please update your compiler.. Stop.
Fixes: 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler
support")
Signed-off-by: Kirill Marinushkin
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Borislav Petkov
Cc: Zhenzhong Duan
Cc: H. Peter Anvin
Cc: x...@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: sta...@vger.kernel.org
---
arch/x86/Makefile | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f5d7f4134524..26a2198c59b3 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -220,9 +220,6 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
# Avoid indirect branches in kernel to deal with Spectre
ifdef CONFIG_RETPOLINE
-ifeq ($(RETPOLINE_CFLAGS),)
- $(error You are building kernel with non-retpoline compiler, please update
your compiler.)
-endif
KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
endif
--
2.13.6
