linux-kernel - [PATCH 3.16 13/83] arm64: compat: Allow single-byte watchpoints on all addresses

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Date:   Wed, 20 Nov 2019 15:37:23 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Will Deacon" <will@...nel.org>
Subject: [PATCH 3.16 13/83] arm64: compat: Allow single-byte watchpoints
 on all addresses

3.16.78-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Will Deacon <will@...nel.org>

commit 849adec41203ac5837c40c2d7e08490ffdef3c2c upstream.

Commit d968d2b801d8 ("ARM: 7497/1: hw_breakpoint: allow single-byte
watchpoints on all addresses") changed the validation requirements for
hardware watchpoints on arch/arm/. Update our compat layer to implement
the same relaxation.

Signed-off-by: Will Deacon <will@...nel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/arm64/kernel/hw_breakpoint.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -501,13 +501,14 @@ int arch_validate_hwbkpt_settings(struct
 			/* Aligned */
 			break;
 		case 1:
-			/* Allow single byte watchpoint. */
-			if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
-				break;
 		case 2:
 			/* Allow halfword watchpoints and breakpoints. */
 			if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
 				break;
+		case 3:
+			/* Allow single byte watchpoint. */
+			if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
+				break;
 		default:
 			return -EINVAL;
 		}