linux-kernel - [PATCH 1/3] arm64: perf: Mark expected switch fall-through

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Message-Id: <20190726112716.19104-1-anders.roxell@linaro.org>
Date:   Fri, 26 Jul 2019 13:27:16 +0200
From:   Anders Roxell <anders.roxell@...aro.org>
To:     will@...nel.org, mark.rutland@....com, catalin.marinas@....com
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anders Roxell <anders.roxell@...aro.org>,
        stable@...r.kernel.org
Subject: [PATCH 1/3] arm64: perf: Mark expected switch fall-through

When fall-through warnings was enabled by default, commit d93512ef0f0e
("Makefile: Globally enable fall-through warning"), the following
warnings was starting to show up:

../arch/arm64/kernel/hw_breakpoint.c: In function ‘hw_breakpoint_arch_parse’:
../arch/arm64/kernel/hw_breakpoint.c:540:7: warning: this statement may fall
 through [-Wimplicit-fallthrough=]
    if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
       ^
../arch/arm64/kernel/hw_breakpoint.c:542:3: note: here
   case 2:
   ^~~~
../arch/arm64/kernel/hw_breakpoint.c:544:7: warning: this statement may fall
 through [-Wimplicit-fallthrough=]
    if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
       ^
../arch/arm64/kernel/hw_breakpoint.c:546:3: note: here
   default:
   ^~~~~~~

Rework so that the compiler doesn't warn about fall-through. Rework so
the code looks like the arm code. Since the comment in the function
indicates taht this is supposed to behave the same way as arm32 because
it handles 32-bit tasks also.

Cc: stable@...r.kernel.org # v3.16+
Fixes: 6ee33c2712fc ("ARM: hw_breakpoint: correct and simplify alignment fixup code")
Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
---
 arch/arm64/kernel/hw_breakpoint.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
index dceb84520948..ea616adf1cf1 100644
--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -535,14 +535,17 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
 		case 0:
 			/* Aligned */
 			break;
-		case 1:
-			/* Allow single byte watchpoint. */
-			if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
-				break;
 		case 2:
 			/* Allow halfword watchpoints and breakpoints. */
 			if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
 				break;
+			/* Fall through */
+		case 1:
+		case 3:
+			/* Allow single byte watchpoint. */
+			if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
+				break;
+			/* Fall through */
 		default:
 			return -EINVAL;
 		}
-- 
2.20.1