linux-kernel - [PATCH 09/11] perf/imx_ddr: Fix undefined behavior due to shift overflowing the constant

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Message-Id: <20220405151517.29753-10-bp@alien8.de>
Date:   Tue,  5 Apr 2022 17:15:15 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frank Li <Frank.li@....com>, Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 09/11] perf/imx_ddr: Fix undefined behavior due to shift overflowing the constant

From: Borislav Petkov <bp@...e.de>

Fix:

  In file included from <command-line>:0:0:
  In function ‘ddr_perf_counter_enable’,
      inlined from ‘ddr_perf_irq_handler’ at drivers/perf/fsl_imx8_ddr_perf.c:651:2:
  ././include/linux/compiler_types.h:352:38: error: call to ‘__compiletime_assert_729’ \
	declared with attribute error: FIELD_PREP: mask is not constant
    _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
...

See https://lore.kernel.org/r/YkwQ6%2BtIH8GQpuct@zn.tnic for the gory
details as to why it triggers with older gccs only.

Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Frank Li <Frank.li@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Shawn Guo <shawnguo@...nel.org>
Cc: Sascha Hauer <s.hauer@...gutronix.de>
Cc: Pengutronix Kernel Team <kernel@...gutronix.de>
Cc: Fabio Estevam <festevam@...il.com>
Cc: NXP Linux Team <linux-imx@....com>
Cc: linux-arm-kernel@...ts.infradead.org
---
 drivers/perf/fsl_imx8_ddr_perf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/perf/fsl_imx8_ddr_perf.c b/drivers/perf/fsl_imx8_ddr_perf.c
index 94ebc1ecace7..b1b2a55de77f 100644
--- a/drivers/perf/fsl_imx8_ddr_perf.c
+++ b/drivers/perf/fsl_imx8_ddr_perf.c
@@ -29,7 +29,7 @@
 #define CNTL_OVER_MASK		0xFFFFFFFE
 
 #define CNTL_CSV_SHIFT		24
-#define CNTL_CSV_MASK		(0xFF << CNTL_CSV_SHIFT)
+#define CNTL_CSV_MASK		(0xFFU << CNTL_CSV_SHIFT)
 
 #define EVENT_CYCLES_ID		0
 #define EVENT_CYCLES_COUNTER	0
-- 
2.35.1