From a60b1a5bf88a250f1a77977c0224e502c901c77b Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Fri, 16 Jun 2017 00:14:12 +0100 Subject: [PATCH] MIPS: Send SIGILL for R6 branches in `__compute_return_epc_for_insn' 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. 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 Cc: James Hogan Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # 3.19+ Patchwork: https://patchwork.linux-mips.org/patch/16399/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/branch.c | 35 +++++++++++++++-------------------- 1 file changed, 15 insertions(+), 20 deletions(-) diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c index 64c8360e3d62e..6d536e5581e10 100644 --- a/arch/mips/kernel/branch.c +++ b/arch/mips/kernel/branch.c @@ -771,35 +771,27 @@ int __compute_return_epc_for_insn(struct pt_regs *regs, #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 pt_regs *regs, 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); -- 2.39.5