[ARM] 4183/1: do_undefinstr: read svc undefined instructions with svc privileges

do_undefinstr currently does not expect undefined instructions in kernel
code, since it always uses get_user() to read the instruction.

Dereference the 'pc' pointer directly in the SVC case.

Per Nicolas Pitre's note, kernel code is never in thumb mode.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 329609b84d3b..24095601359b 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -282,7 +282,10 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
         regs->ARM_pc -= correction;
 
         pc = (void __user *)instruction_pointer(regs);
-        if (thumb_mode(regs)) {
+
+        if (processor_mode(regs) == SVC_MODE) {
+                instr = *(u32 *) pc;
+        } else if (thumb_mode(regs)) {
                 get_user(instr, (u16 __user *)pc);
         } else {
                 get_user(instr, (u32 __user *)pc);