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 <[email protected]> Reviewed-by: Alexandre Chartre <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
berg · Jun 11, 2020 · 5916d5f · 5916d5f
1 parent 126f21f
commit 5916d5f
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Showing 3 changed files with 13 additions and 3 deletions.
diff --git 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
@@ -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
@@ -680,10 +680,12 @@ 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);