ARM: BUG if jumping to usermode address in kernel mode
Detect if we are returning to usermode via the normal kernel exit paths
but the saved PSR value indicates that we are in kernel mode. This
could occur due to corrupted stack state, which has been observed with
"ftracetest".
This ensures that we catch the problem case before we get to user code.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index ad301f1..bc8d4bb 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -518,4 +518,22 @@ THUMB( orr \reg , \reg , #PSR_T_BIT )
#endif
.endm
+ .macro bug, msg, line
+#ifdef CONFIG_THUMB2_KERNEL
+1: .inst 0xde02
+#else
+1: .inst 0xe7f001f2
+#endif
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+ .pushsection .rodata.str, "aMS", %progbits, 1
+2: .asciz "\msg"
+ .popsection
+ .pushsection __bug_table, "aw"
+ .align 2
+ .word 1b, 2b
+ .hword \line
+ .popsection
+#endif
+ .endm
+
#endif /* __ASM_ASSEMBLER_H__ */