Fix:
* commit 8467ca0122e2 ("MIPS: Emulate the new MIPS R6 branch compact
(BC) instruction"),
* commit 84fef630127a ("MIPS: Emulate the new MIPS R6 BALC
instruction"),
* commit 69b9a2fd05a3 ("MIPS: Emulate the new MIPS R6 BEQZC and JIC
instructions"),
* commit 28d6f93d201d ("MIPS: Emulate the new MIPS R6 BNEZC and JIALC
instructions"),
* commit c893ce38b265 ("MIPS: Emulate the new MIPS R6 BOVC, BEQC and
BEQZALC instructions")
and send SIGILL rather than returning -SIGILL for R6 branch and jump
instructions. 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: 8467ca0122e2 ("MIPS: Emulate the new MIPS R6 branch compact (BC) instruction")
Fixes: 84fef630127a ("MIPS: Emulate the new MIPS R6 BALC instruction")
Fixes: 69b9a2fd05a3 ("MIPS: Emulate the new MIPS R6 BEQZC and JIC instructions")
Fixes: 28d6f93d201d ("MIPS: Emulate the new MIPS R6 BNEZC and JIALC instructions")
Fixes: c893ce38b265 ("MIPS: Emulate the new MIPS R6 BOVC, BEQC and BEQZALC instructions")
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxx>
---
Unchanged from v1.
linux-mips-epc-for-insn-sigill-r6.diff
Index: linux-sfr-test/arch/mips/kernel/branch.c
===================================================================
--- linux-sfr-test.orig/arch/mips/kernel/branch.c 2017-06-01 06:33:32.663567000 +0100
+++ linux-sfr-test/arch/mips/kernel/branch.c 2017-06-01 06:35:33.359652000 +0100
@@ -771,35 +771,27 @@ int __compute_return_epc_for_insn(struct
#else
case bc6_op:
/* Only valid for MIPS R6 */
- if (!cpu_has_mips_r6) {
- ret = -SIGILL;
- break;
- }
+ if (!cpu_has_mips_r6)
+ goto sigill_r6;
regs->cp0_epc += 8;
break;
case balc6_op:
- if (!cpu_has_mips_r6) {
- ret = -SIGILL;
- break;
- }
+ if (!cpu_has_mips_r6)
+ goto sigill_r6;
/* Compact branch: BALC */
regs->regs[31] = epc + 4;
epc += 4 + (insn.i_format.simmediate << 2);
regs->cp0_epc = epc;
break;
case pop66_op:
- if (!cpu_has_mips_r6) {
- ret = -SIGILL;
- break;
- }
+ if (!cpu_has_mips_r6)
+ goto sigill_r6;
/* Compact branch: BEQZC || JIC */
regs->cp0_epc += 8;
break;
case pop76_op:
- if (!cpu_has_mips_r6) {
- ret = -SIGILL;
- break;
- }
+ if (!cpu_has_mips_r6)
+ goto sigill_r6;
/* Compact branch: BNEZC || JIALC */
if (insn.i_format.rs)
regs->regs[31] = epc + 4;
@@ -809,10 +801,8 @@ int __compute_return_epc_for_insn(struct
case pop10_op:
case pop30_op:
/* Only valid for MIPS R6 */
- if (!cpu_has_mips_r6) {
- ret = -SIGILL;
- break;
- }
+ if (!cpu_has_mips_r6)
+ goto sigill_r6;
/*
* Compact branches:
* bovc, beqc, beqzalc, bnvc, bnec, bnezlac
@@ -835,6 +825,11 @@ int __compute_return_epc_for_insn(struct
current->comm);
force_sig(SIGILL, current);
return -EFAULT;
+sigill_r6:
+ pr_info("%s: R6 branch but no MIPSr6 ISA support - sending SIGILL.\n",
+ current->comm);
+ force_sig(SIGILL, current);
+ return -EFAULT;
}
EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);