Blackfin arch: ensure that speculative loads of bad pointers don't cause us to do bad things.

Fix/change formatting of a few more things.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

2 files changed, 16 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/fixed_code.S b/arch/blackfin/kernel/fixed_code.S
index d8b1ebc70996..90262691b11a 100644
--- a/arch/blackfin/kernel/fixed_code.S
+++ b/arch/blackfin/kernel/fixed_code.S
@@ -129,4 +129,18 @@ ENTRY(_atomic_xor32)
 	rts;
 ENDPROC (_atomic_ior32)
 
+.align 16
+	/*
+	 * safe_user_instruction
+	 * Four NOPS are enough to allow the pipeline to speculativily load
+	 * execute anything it wants. After that, things have gone bad, and
+	 * we are stuck - so panic. Since we might be in user space, we can't
+	 * call panic, so just cause a unhandled exception, this should cause
+	 * a dump of the trace buffer so we can tell were we are, and a reboot
+	 */
+ENTRY(_safe_user_instruction)
+	NOP; NOP; NOP; NOP;
+	EXCPT 0x4;
+ENDPROC(_safe_user_instruction)
+
 ENTRY(_fixed_code_end)
diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index fc22ec8c2f47..934234f43839 100644
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -431,6 +431,8 @@ void __init setup_arch(char **cmdline_p)
 	       != ATOMIC_AND32 - FIXED_CODE_START);
 	BUG_ON((char *)&atomic_xor32 - (char *)&fixed_code_start
 	       != ATOMIC_XOR32 - FIXED_CODE_START);
+	BUG_ON((char *)&safe_user_instruction - (char *)&fixed_code_start
+		!= SAFE_USER_INSTRUCTION - FIXED_CODE_START);
 
 	init_exception_vectors();
 	bf53x_cache_init();