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>

3 files changed, 17 insertions, 1 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();
diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index e3ad5802868a..1b13fa470977 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/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 */