linux-kernel - [PATCH 04/11] drm/r128: Fix undefined behavior due to shift overflowing the constant

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Message-Id: <20220405151517.29753-5-bp@alien8.de>
Date:   Tue,  5 Apr 2022 17:15:10 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Alex Deucher <alexander.deucher@....com>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH 04/11] drm/r128: Fix undefined behavior due to shift overflowing the constant

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

Fix:

  drivers/gpu/drm/r128/r128_cce.c: In function ‘r128_do_init_cce’:
  drivers/gpu/drm/r128/r128_cce.c:417:2: error: case label does not reduce to an integer constant
    case R128_PM4_64BM_64VCBM_64INDBM:
    ^~~~
  drivers/gpu/drm/r128/r128_cce.c:418:2: error: case label does not reduce to an integer constant
    case R128_PM4_64PIO_64VCPIO_64INDPIO:
    ^~~~

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: David Airlie <airlied@...ux.ie>
Cc: Daniel Vetter <daniel@...ll.ch>
Cc: Alex Deucher <alexander.deucher@....com>
Cc: dri-devel@...ts.freedesktop.org
---
 drivers/gpu/drm/r128/r128_drv.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/r128/r128_drv.h b/drivers/gpu/drm/r128/r128_drv.h
index 2e1bc01aa5c9..970e192b0d51 100644
--- a/drivers/gpu/drm/r128/r128_drv.h
+++ b/drivers/gpu/drm/r128/r128_drv.h
@@ -300,8 +300,8 @@ extern long r128_compat_ioctl(struct file *filp, unsigned int cmd,
 #	define R128_PM4_64PIO_128INDBM		(5  << 28)
 #	define R128_PM4_64BM_128INDBM		(6  << 28)
 #	define R128_PM4_64PIO_64VCBM_64INDBM	(7  << 28)
-#	define R128_PM4_64BM_64VCBM_64INDBM	(8  << 28)
-#	define R128_PM4_64PIO_64VCPIO_64INDPIO	(15 << 28)
+#	define R128_PM4_64BM_64VCBM_64INDBM	(8U  << 28)
+#	define R128_PM4_64PIO_64VCPIO_64INDPIO	(15U << 28)
 #	define R128_PM4_BUFFER_CNTL_NOUPDATE	(1  << 27)
 
 #define R128_PM4_BUFFER_WM_CNTL		0x0708
-- 
2.35.1