MIPS Kprobes: Refactor branch emulation

This patch refactors MIPS branch emulation code so as to allow skipping
delay slot instruction in case of branch likely instructions when branch is
not taken. This is useful for keeping the code common for use cases like
kprobes where one would like to handle the branch instructions keeping the
delay slot instuction also in picture for branch likely instructions. Also
allow emulation when instruction to be decoded is not at pt_regs->cp0_epc
as in case of kprobes where pt_regs->cp0_epc points to the breakpoint
instruction.

The patch also exports the function for modules.

Signed-off-by: Maneesh Soni <manesoni@cisco.com>
Signed-off-by: Victor Kamensky <kamensky@cisco.com>
Cc: David Daney <david.daney@cavium.com>
Cc: ananth@in.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2913/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index dbf2f93a5091..a03bf00a1a9c 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -245,7 +245,7 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
                  */
                 emulpc = xcp->cp0_epc + 4;      /* Snapshot emulation target */
 
-                if (__compute_return_epc(xcp)) {
+                if (__compute_return_epc(xcp) < 0) {
 #ifdef CP1DBG
                         printk("failed to emulate branch at %p\n",
                                 (void *) (xcp->cp0_epc));