Clang warns:
arch/x86/kernel/cpu/bugs.c:58:21: error: section attribute is specified on redeclared variable [-Werror,-Wsection] DEFINE_PER_CPU(u64, x86_spec_ctrl_current); ^ arch/x86/include/asm/nospec-branch.h:283:12: note: previous declaration is here extern u64 x86_spec_ctrl_current; ^ 1 error generated.
The declaration should be using DECLARE_PER_CPU instead so all attributes stay in sync.
Cc: stable@vger.kernel.org Fixes: fc02735b14ff ("KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Nathan Chancellor nathan@kernel.org ---
v1 -> v2: https://lore.kernel.org/20220713152222.1697913-1-nathan@kernel.org/
* Use asm/percpu.h instead of linux/percpu.h to avoid static call include errors.
arch/x86/include/asm/nospec-branch.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index bb05ed4f46bd..10a3bfc1eb23 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -11,6 +11,7 @@ #include <asm/cpufeatures.h> #include <asm/msr-index.h> #include <asm/unwind_hints.h> +#include <asm/percpu.h>
#define RETPOLINE_THUNK_SIZE 32
@@ -280,7 +281,7 @@ static inline void indirect_branch_prediction_barrier(void)
/* The Intel SPEC CTRL MSR base value cache */ extern u64 x86_spec_ctrl_base; -extern u64 x86_spec_ctrl_current; +DECLARE_PER_CPU(u64, x86_spec_ctrl_current); extern void write_spec_ctrl_current(u64 val, bool force); extern u64 spec_ctrl_current(void);
base-commit: 72a8e05d4f66b5af7854df4490e3135168694b6b
On Wed, Jul 13, 2022 at 8:25 AM Nathan Chancellor nathan@kernel.org wrote:
Clang warns:
arch/x86/kernel/cpu/bugs.c:58:21: error: section attribute is specified on redeclared variable [-Werror,-Wsection] DEFINE_PER_CPU(u64, x86_spec_ctrl_current); ^ arch/x86/include/asm/nospec-branch.h:283:12: note: previous declaration is here extern u64 x86_spec_ctrl_current; ^ 1 error generated.
The declaration should be using DECLARE_PER_CPU instead so all attributes stay in sync.
Cc: stable@vger.kernel.org Fixes: fc02735b14ff ("KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Nathan Chancellor nathan@kernel.org
Thanks for the patch! Reviewed-by: Nick Desaulniers ndesaulniers@google.com Tested-by: Nick Desaulniers ndesaulniers@google.com
v1 -> v2: https://lore.kernel.org/20220713152222.1697913-1-nathan@kernel.org/
- Use asm/percpu.h instead of linux/percpu.h to avoid static call include errors.
arch/x86/include/asm/nospec-branch.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index bb05ed4f46bd..10a3bfc1eb23 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -11,6 +11,7 @@ #include <asm/cpufeatures.h> #include <asm/msr-index.h> #include <asm/unwind_hints.h> +#include <asm/percpu.h>
#define RETPOLINE_THUNK_SIZE 32
@@ -280,7 +281,7 @@ static inline void indirect_branch_prediction_barrier(void)
/* The Intel SPEC CTRL MSR base value cache */ extern u64 x86_spec_ctrl_base; -extern u64 x86_spec_ctrl_current; +DECLARE_PER_CPU(u64, x86_spec_ctrl_current); extern void write_spec_ctrl_current(u64 val, bool force); extern u64 spec_ctrl_current(void);
base-commit: 72a8e05d4f66b5af7854df4490e3135168694b6b
2.37.1
On Wed, Jul 13, 2022 at 08:24:37AM -0700, Nathan Chancellor wrote:
Clang warns:
arch/x86/kernel/cpu/bugs.c:58:21: error: section attribute is specified on redeclared variable [-Werror,-Wsection] DEFINE_PER_CPU(u64, x86_spec_ctrl_current); ^ arch/x86/include/asm/nospec-branch.h:283:12: note: previous declaration is here extern u64 x86_spec_ctrl_current; ^ 1 error generated.
The declaration should be using DECLARE_PER_CPU instead so all attributes stay in sync.
Cc: stable@vger.kernel.org Fixes: fc02735b14ff ("KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Nathan Chancellor nathan@kernel.org
v1 -> v2: https://lore.kernel.org/20220713152222.1697913-1-nathan@kernel.org/
- Use asm/percpu.h instead of linux/percpu.h to avoid static call include errors.
arch/x86/include/asm/nospec-branch.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index bb05ed4f46bd..10a3bfc1eb23 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -11,6 +11,7 @@ #include <asm/cpufeatures.h> #include <asm/msr-index.h> #include <asm/unwind_hints.h> +#include <asm/percpu.h> #define RETPOLINE_THUNK_SIZE 32
When I tried this earlier today I ran into cyclic headers, you sure this works?
On Wed, Jul 13, 2022 at 06:22:41PM +0200, Peter Zijlstra wrote:
On Wed, Jul 13, 2022 at 08:24:37AM -0700, Nathan Chancellor wrote:
Clang warns:
arch/x86/kernel/cpu/bugs.c:58:21: error: section attribute is specified on redeclared variable [-Werror,-Wsection] DEFINE_PER_CPU(u64, x86_spec_ctrl_current); ^ arch/x86/include/asm/nospec-branch.h:283:12: note: previous declaration is here extern u64 x86_spec_ctrl_current; ^ 1 error generated.
The declaration should be using DECLARE_PER_CPU instead so all attributes stay in sync.
Cc: stable@vger.kernel.org Fixes: fc02735b14ff ("KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Nathan Chancellor nathan@kernel.org
v1 -> v2: https://lore.kernel.org/20220713152222.1697913-1-nathan@kernel.org/
- Use asm/percpu.h instead of linux/percpu.h to avoid static call include errors.
arch/x86/include/asm/nospec-branch.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index bb05ed4f46bd..10a3bfc1eb23 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -11,6 +11,7 @@ #include <asm/cpufeatures.h> #include <asm/msr-index.h> #include <asm/unwind_hints.h> +#include <asm/percpu.h> #define RETPOLINE_THUNK_SIZE 32
When I tried this earlier today I ran into cyclic headers, you sure this works?
Yes, I did my regular set of x86 builds with clang and they all passed.
Cheers, Nathan
On Wed, 13 Jul 2022 08:24:37 -0700 Nathan Chancellor wrote:
Clang warns:
arch/x86/kernel/cpu/bugs.c:58:21: error: section attribute is specified on redeclared variable [-Werror,-Wsection] DEFINE_PER_CPU(u64, x86_spec_ctrl_current); ^ arch/x86/include/asm/nospec-branch.h:283:12: note: previous declaration is here extern u64 x86_spec_ctrl_current; ^ 1 error generated.
The declaration should be using DECLARE_PER_CPU instead so all attributes stay in sync.
Cc: stable@vger.kernel.org Fixes: fc02735b14ff ("KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Nathan Chancellor nathan@kernel.org
Hi, sorry to bother, any idea on the ETA for this fix getting into Linus's tree? I'm trying to figure out if we should wait with forwarding the networking trees or this will take a while.
On Thu, Jul 14, 2022 at 2:30 PM Jakub Kicinski kuba@kernel.org wrote:
Hi, sorry to bother, any idea on the ETA for this fix getting into Linus's tree? I'm trying to figure out if we should wait with forwarding the networking trees or this will take a while.
Well, I have that patch by now in my own clang tree, but was holding it off just because I was expecting a few other fixes for the fallout.
But if this particular one causes problems for maintainers, I can easily just take it right away just cherry-pick it from my own test-tree to my "main" tree.
Linus
On Thu, Jul 14, 2022 at 2:51 PM Linus Torvalds torvalds@linux-foundation.org wrote:
But if this particular one causes problems for maintainers, I can easily just take it right away just cherry-pick it from my own test-tree to my "main" tree.
Oh, and as I did that cherry-pick, I suddenly remembered that I think PeterZ had a slightly different version of it - the one I picked up is Nathan's "v2".
PeterZ, do you have preferences? I've waited this long, I might as well wait a bit more before I push out whatever version people prefer.
Linus
On Thu, Jul 14, 2022 at 02:56:12PM -0700, Linus Torvalds wrote:
On Thu, Jul 14, 2022 at 2:51 PM Linus Torvalds torvalds@linux-foundation.org wrote:
But if this particular one causes problems for maintainers, I can easily just take it right away just cherry-pick it from my own test-tree to my "main" tree.
Oh, and as I did that cherry-pick, I suddenly remembered that I think PeterZ had a slightly different version of it - the one I picked up is Nathan's "v2".
PeterZ, do you have preferences? I've waited this long, I might as well wait a bit more before I push out whatever version people prefer.
Nathan's is much nicer; I got bit by header hell and punted.
On Thu, 14 Jul 2022 14:51:52 -0700 Linus Torvalds wrote:
On Thu, Jul 14, 2022 at 2:30 PM Jakub Kicinski kuba@kernel.org wrote:
Hi, sorry to bother, any idea on the ETA for this fix getting into Linus's tree? I'm trying to figure out if we should wait with forwarding the networking trees or this will take a while.
Well, I have that patch by now in my own clang tree, but was holding it off just because I was expecting a few other fixes for the fallout.
But if this particular one causes problems for maintainers, I can easily just take it right away just cherry-pick it from my own test-tree to my "main" tree.
I have clang 13, let me double check this fix is enough for the build to complete without disabling WERROR. If it's not a hassle it'd certainly make my life easier if the fix gotten applied now...
On Thu, Jul 14, 2022 at 2:56 PM Jakub Kicinski kuba@kernel.org wrote:
I have clang 13, let me double check this fix is enough for the build to complete without disabling WERROR.
I have clang 14 locally, and it builds fine with that (and doesn't build without it).
I actually normally build the kernel with both gcc and clang. My "upstream" kernel I build with gcc, and then I have my "private random collection of patches" kernel that I build with clang and that are just rebased on top of the kernel-of-the-day.
This is all entirely for historical reasons - part of my "private random collection of patches" used to be the "asm goto with outputs", which had clang support first.
But then the reason I never even noticed the build breakage with the retbleed patches until much too late was that those I just had as a third fork off my upstream kernel, so despite me usually building with clang too, that only got attention from gcc.
So it's really just a microcosm version of the exact same bigger issue we always have with those embargoed hw security patches: they end up missing out on all the usual test environments.
Anyway, I cherry-picked Nathan's patch from my clang tree and pushed it out as commit db886979683a ("x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current").
Linus
On Thu, 14 Jul 2022 15:14:53 -0700 Linus Torvalds wrote:
On Thu, Jul 14, 2022 at 2:56 PM Jakub Kicinski kuba@kernel.org wrote:
I have clang 13, let me double check this fix is enough for the build to complete without disabling WERROR.
I have clang 14 locally, and it builds fine with that (and doesn't build without it).
FWIW I can confirm - builds with clang 13 as well.
I actually normally build the kernel with both gcc and clang. My "upstream" kernel I build with gcc, and then I have my "private random collection of patches" kernel that I build with clang and that are just rebased on top of the kernel-of-the-day.
This is all entirely for historical reasons - part of my "private random collection of patches" used to be the "asm goto with outputs", which had clang support first.
But then the reason I never even noticed the build breakage with the retbleed patches until much too late was that those I just had as a third fork off my upstream kernel, so despite me usually building with clang too, that only got attention from gcc.
So it's really just a microcosm version of the exact same bigger issue we always have with those embargoed hw security patches: they end up missing out on all the usual test environments.
Anyway, I cherry-picked Nathan's patch from my clang tree and pushed it out as commit db886979683a ("x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current").
Awesome, thanks!
On Thu, Jul 14, 2022 at 03:14:53PM -0700, Linus Torvalds wrote:
Anyway, I cherry-picked Nathan's patch from my clang tree and pushed it out as commit db886979683a ("x86/speculation: Use DECLARE_PER_CPU for x86_spec_ctrl_current").
... and I've zapped it from my lineup.
Thx.
linux-stable-mirror@lists.linaro.org
-
Borislav Petkov -
Jakub Kicinski -
Linus Torvalds -
Nathan Chancellor -
Nick Desaulniers -
Peter Zijlstra