linux-kernel - [PATCH 3.10 021/139] MIPS: Send SIGILL for BPOSGE32 in `__compute_return_epc_for

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Message-Id: <1509571159-4405-22-git-send-email-w@1wt.eu>
Date:   Wed,  1 Nov 2017 22:17:21 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     "Maciej W. Rozycki" <macro@...tec.com>,
        James Hogan <james.hogan@...tec.com>,
        linux-mips@...ux-mips.org, Ralf Baechle <ralf@...ux-mips.org>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 021/139] MIPS: Send SIGILL for BPOSGE32 in `__compute_return_epc_for_insn'

From: "Maciej W. Rozycki" <macro@...tec.com>

commit 7b82c1058ac1f8f8b9f2b8786b1f710a57a870a8 upstream.

Fix commit e50c0a8fa60d ("Support the MIPS32 / MIPS64 DSP ASE.") and
send SIGILL rather than SIGBUS whenever an unimplemented BPOSGE32 DSP
ASE instruction has been encountered in `__compute_return_epc_for_insn'
as our Reserved Instruction exception handler would in response to an
attempt to actually execute the instruction.  Sending SIGBUS only makes
sense for the unaligned PC case, since moved to `__compute_return_epc'.
Adjust function documentation accordingly, correct formatting and use
`pr_info' rather than `printk' as the other exit path already does.

Fixes: e50c0a8fa60d ("Support the MIPS32 / MIPS64 DSP ASE.")
Signed-off-by: Maciej W. Rozycki <macro@...tec.com>
Cc: James Hogan <james.hogan@...tec.com>
Cc: linux-mips@...ux-mips.org
Cc: stable@...r.kernel.org 
Patchwork: https://patchwork.linux-mips.org/patch/16396/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Willy Tarreau <w@....eu>
---
 arch/mips/kernel/branch.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index 46c2ad0..9250996 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -200,7 +200,7 @@ int __MIPS16e_compute_return_epc(struct pt_regs *regs)
  *
  * @regs:	Pointer to pt_regs
  * @insn:	branch instruction to decode
- * @returns:	-EFAULT on error and forces SIGBUS, and on success
+ * @returns:	-EFAULT on error and forces SIGILL, and on success
  *		returns 0 or BRANCH_LIKELY_TAKEN as appropriate after
  *		evaluating the branch.
  */
@@ -436,8 +436,9 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
 	return ret;
 
 sigill:
-	printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
-	force_sig(SIGBUS, current);
+	pr_info("%s: DSP branch but not DSP ASE - sending SIGILL.\n",
+		current->comm);
+	force_sig(SIGILL, current);
 	return -EFAULT;
 }
 EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);
-- 
2.8.0.rc2.1.gbe9624a