2023-04-12 17:36:39

by Josh Poimboeuf

[permalink] [raw]
Subject: [PATCH 1/3] context_tracking: Fix KCSAN noinstr violation

With KCSAN enabled, even empty inline stubs can be out-of-lined.

Force the context_tracking_guest_exit() stub inline.

Fixes the following warnings:

vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1be: call to context_tracking_guest_exit() leaves .noinstr.text section
vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0x85: call to context_tracking_guest_exit() leaves .noinstr.text section

Signed-off-by: Josh Poimboeuf <[email protected]>
---
include/linux/context_tracking.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index d4afa8508a80..5ae3abd767b4 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -97,7 +97,7 @@ static inline int exception_enter(void) { return 0; }
static inline void exception_exit(enum ctx_state prev_ctx) { }
static inline int ct_state(void) { return -1; }
static __always_inline bool context_tracking_guest_enter(void) { return false; }
-static inline void context_tracking_guest_exit(void) { }
+static __always_inline void context_tracking_guest_exit(void) { }
#define CT_WARN_ON(cond) do { } while (0)
#endif /* !CONFIG_CONTEXT_TRACKING_USER */

--
2.39.2


2023-04-13 13:59:08

by Frederic Weisbecker

[permalink] [raw]
Subject: Re: [PATCH 1/3] context_tracking: Fix KCSAN noinstr violation

Le Wed, Apr 12, 2023 at 10:24:06AM -0700, Josh Poimboeuf a ?crit :
> With KCSAN enabled, even empty inline stubs can be out-of-lined.
>
> Force the context_tracking_guest_exit() stub inline.
>
> Fixes the following warnings:
>
> vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1be: call to context_tracking_guest_exit() leaves .noinstr.text section
> vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0x85: call to context_tracking_guest_exit() leaves .noinstr.text section
>
> Signed-off-by: Josh Poimboeuf <[email protected]>

Acked-by: Frederic Weisbecker <[email protected]>

Thanks!

Subject: [tip: objtool/core] context_tracking: Fix KCSAN noinstr violation

The following commit has been merged into the objtool/core branch of tip:

Commit-ID: e8deb00c0c4808654d1bf96a8f79cf1deb59b631
Gitweb: https://git.kernel.org/tip/e8deb00c0c4808654d1bf96a8f79cf1deb59b631
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Wed, 12 Apr 2023 10:24:06 -07:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Fri, 14 Apr 2023 16:08:27 +02:00

context_tracking: Fix KCSAN noinstr violation

With KCSAN enabled, even empty inline stubs can be out-of-lined.

Force the context_tracking_guest_exit() stub inline.

Fixes the following warnings:

vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1be: call to context_tracking_guest_exit() leaves .noinstr.text section
vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0x85: call to context_tracking_guest_exit() leaves .noinstr.text section

Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/dc93f45abdec90c171108b4b590b7fff5790963c.1681320026.git.jpoimboe@kernel.org
---
include/linux/context_tracking.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index d4afa85..5ae3abd 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -97,7 +97,7 @@ static inline int exception_enter(void) { return 0; }
static inline void exception_exit(enum ctx_state prev_ctx) { }
static inline int ct_state(void) { return -1; }
static __always_inline bool context_tracking_guest_enter(void) { return false; }
-static inline void context_tracking_guest_exit(void) { }
+static __always_inline void context_tracking_guest_exit(void) { }
#define CT_WARN_ON(cond) do { } while (0)
#endif /* !CONFIG_CONTEXT_TRACKING_USER */