Patch "MIPS: Send SIGILL for R6 branches in `__compute_return_epc_for_insn'" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

MIPS: Send SIGILL for R6 branches in `__compute_return_epc_for_insn'

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mips-send-sigill-for-r6-branches-in-__compute_return_epc_for_insn.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Maciej W. Rozycki" <[email protected]>
Date: Fri, 16 Jun 2017 00:14:12 +0100
Subject: MIPS: Send SIGILL for R6 branches in `__compute_return_epc_for_insn'

From: Maciej W. Rozycki <[email protected]>

commit a60b1a5bf88a250f1a77977c0224e502c901c77b upstream.

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.

Patchwork: https://patchwork.linux-mips.org/patch/16399/

---
 arch/mips/kernel/branch.c |   35 +++++++++++++++--------------------
 1 file changed, 15 insertions(+), 20 deletions(-)

@@ -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) {
 			/* JIALC: set $31/ra */

@@ -811,10 +803,8 @@ 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

@@ -837,6 +827,11 @@ sigill_r2r6:
 		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);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/mips-send-sigill-for-bposge32-in-__compute_return_epc_for_insn.patch queue-4.9/mips-actually-decode-jalx-in-__compute_return_epc_for_insn.patch queue-4.9/mips-fix-a-typo-s-preset-present-in-r2-to-r6-emulation-error-message.patch queue-4.9/mips-fix-unaligned-pc-interpretation-in-compute_return_epc.patch queue-4.9/mips-rename-sigill_r6-to-sigill_r2r6-in-__compute_return_epc_for_insn.patch queue-4.9/mips-send-sigill-for-r6-branches-in-__compute_return_epc_for_insn.patch queue-4.9/mips-send-sigill-for-linked-branches-in-__compute_return_epc_for_insn.patch queue-4.9/mips-math-emu-prevent-wrong-isa-mode-instruction-emulation.patch