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>

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)

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();

arch/blackfin/mach-common/entry.S

@@ -917,7 +917,7 @@ ENTRY(_ex_table)
 	.long _ex_soft_bp       /* 0x01 - User Defined - Software breakpoint */
 	.long _ex_replaceable   /* 0x02 - User Defined */
 	.long _ex_trap_c        /* 0x03 - User Defined - userspace stack overflow */
-	.long _ex_replaceable   /* 0x04 - User Defined */
+	.long _ex_trap_c        /* 0x04 - User Defined - dump trace buffer */
 	.long _ex_replaceable   /* 0x05 - User Defined */
 	.long _ex_replaceable   /* 0x06 - User Defined */
 	.long _ex_replaceable   /* 0x07 - User Defined */

include/asm-blackfin/bfin-global.h

@@ -80,6 +80,7 @@ extern int atomic_sub32(void);
 extern int atomic_ior32(void);
 extern int atomic_and32(void);
 extern int atomic_xor32(void);
+extern void safe_user_instruction(void);
 extern void sigreturn_stub(void);
 
 extern void *l1_data_A_sram_alloc(size_t);

include/asm-blackfin/fixed_code.h

@@ -17,4 +17,6 @@
 
 #define ATOMIC_SEQS_END		0x480
 
-#define FIXED_CODE_END		0x480
+#define SAFE_USER_INSTRUCTION   0x480
+
+#define FIXED_CODE_END		0x490