linux-kernel - [tip: x86/entry] bug: Annotate WARN/BUG/stackfail as noinstr safe

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Date:   Tue, 19 May 2020 19:58:46 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Peter Zijlstra <peterz@...radead.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/entry] bug: Annotate WARN/BUG/stackfail as noinstr safe

The following commit has been merged into the x86/entry branch of tip:

Commit-ID:     4b162e41d8bb552516cd8fa5efaca5cd8160d5c8
Gitweb:        https://git.kernel.org/tip/4b162e41d8bb552516cd8fa5efaca5cd8160d5c8
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Fri, 13 Mar 2020 13:49:51 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Tue, 19 May 2020 15:47:23 +02:00

bug: Annotate WARN/BUG/stackfail as noinstr safe

Warnings, bugs and stack protection fails from noinstr sections, e.g. low
level and early entry code, are likely to be fatal.

Mark them as "safe" to be invoked from noinstr protected code to avoid
annotating all usage sites. Getting the information out is important.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20200505134100.376598577@linutronix.de


---
 arch/x86/include/asm/bug.h |  3 +++
 include/asm-generic/bug.h  |  9 +++++++--
 kernel/panic.c             |  4 +++-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index facba9b..fb34ff6 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -70,14 +70,17 @@ do {									\
 #define HAVE_ARCH_BUG
 #define BUG()							\
 do {								\
+	instrumentation_begin();				\
 	_BUG_FLAGS(ASM_UD2, 0);					\
 	unreachable();						\
 } while (0)
 
 #define __WARN_FLAGS(flags)					\
 do {								\
+	instrumentation_begin();				\
 	_BUG_FLAGS(ASM_UD2, BUGFLAG_WARNING|(flags));		\
 	annotate_reachable();					\
+	instrumentation_end();					\
 } while (0)
 
 #include <asm-generic/bug.h>
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 384b5c8..c94e33a 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -83,14 +83,19 @@ extern __printf(4, 5)
 void warn_slowpath_fmt(const char *file, const int line, unsigned taint,
 		       const char *fmt, ...);
 #define __WARN()		__WARN_printf(TAINT_WARN, NULL)
-#define __WARN_printf(taint, arg...)					\
-	warn_slowpath_fmt(__FILE__, __LINE__, taint, arg)
+#define __WARN_printf(taint, arg...) do {				\
+		instrumentation_begin();				\
+		warn_slowpath_fmt(__FILE__, __LINE__, taint, arg);	\
+		instrumentation_end();					\
+	} while (0)
 #else
 extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
 #define __WARN()		__WARN_FLAGS(BUGFLAG_TAINT(TAINT_WARN))
 #define __WARN_printf(taint, arg...) do {				\
+		instrumentation_begin();				\
 		__warn_printk(arg);					\
 		__WARN_FLAGS(BUGFLAG_NO_CUT_HERE | BUGFLAG_TAINT(taint));\
+		instrumentation_end();					\
 	} while (0)
 #define WARN_ON_ONCE(condition) ({				\
 	int __ret_warn_on = !!(condition);			\
diff --git a/kernel/panic.c b/kernel/panic.c
index b69ee9e..1cfb47d 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -662,10 +662,12 @@ device_initcall(register_warn_debugfs);
  * Called when gcc's -fstack-protector feature is used, and
  * gcc detects corruption of the on-stack canary value
  */
-__visible void __stack_chk_fail(void)
+__visible noinstr void __stack_chk_fail(void)
 {
+	instrumentation_begin();
 	panic("stack-protector: Kernel stack is corrupted in: %pB",
 		__builtin_return_address(0));
+	instrumentation_end();
 }
 EXPORT_SYMBOL(__stack_chk_fail);