Fix commit 319824eabc3f ("MIPS: kernel: branch: Do not emulate the
branch likelies on MIPS R6") and also send SIGILL rather than returning
-SIGILL for BLTZAL, BLTZALL, BGEZAL and BGEZALL instruction encodings no
longer supported in R6, except where emulated. Returning -SIGILL is
never correct as the API defines this function's result upon error to be
-EFAULT and a signal actually issued.
Cc: stable@xxxxxxxxxxxxxxx # 3.19+
Fixes: 319824eabc3f ("MIPS: kernel: branch: Do not emulate the branch likelies on MIPS R6")
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxx>
---
linux-mips-epc-for-insn-sigill-r2r6.diff
Index: linux-sfr-test/arch/mips/kernel/branch.c
===================================================================
--- linux-sfr-test.orig/arch/mips/kernel/branch.c 2017-06-01 06:33:27.149519000 +0100
+++ linux-sfr-test/arch/mips/kernel/branch.c 2017-06-01 06:33:32.663567000 +0100
@@ -473,10 +473,8 @@ int __compute_return_epc_for_insn(struct
case bltzal_op:
case bltzall_op:
if (NO_R6EMU && (insn.i_format.rs ||
- insn.i_format.rt == bltzall_op)) {
- ret = -SIGILL;
- break;
- }
+ insn.i_format.rt == bltzall_op))
+ goto sigill_r2r6;
regs->regs[31] = epc + 8;
/*
* OK we are here either because we hit a NAL
@@ -507,10 +505,8 @@ int __compute_return_epc_for_insn(struct
case bgezal_op:
case bgezall_op:
if (NO_R6EMU && (insn.i_format.rs ||
- insn.i_format.rt == bgezall_op)) {
- ret = -SIGILL;
- break;
- }
+ insn.i_format.rt == bgezall_op))
+ goto sigill_r2r6;
regs->regs[31] = epc + 8;
/*
* OK we are here either because we hit a BAL