On Mon, Mar 25, 2024 at 11:40:33AM +0800, Su Hui wrote:
Clang static checker(scan-build): sound/soc/sti/uniperif_player.c:1115:12: warning: The result of the left shift is undefined because the right operand is negative [core.UndefinedBinaryOperatorResult]
When UNIPERIF_CONFIG_BACK_STALL_REQ_SHIFT(ip) equals to -1, the result of SET_UNIPERIF_CONFIG_BACK_STALL_REQ_DISABLE(ip) is undefined.
Here are some results of using different compilers. 1UL >> -1 1UL << -1 gcc 10.2.1 0x2 0 gcc 11.4.0 0 0x8000000000000000 clang 14.0.0 0x64b8a45d72a0 0x64b8a45d72a0 clang 17.0.0 0x556c43b0f2a0 0x556c43b0f2a0
Add some macros to ensure that when right opreand is negative or other invalid values, the results of bitwise shift is zero.
Fixes: e1ecace6a685 ("ASoC: sti: Add uniperipheral header file") Signed-off-by: Su Hui suhui@nfschina.com
sound/soc/sti/uniperif.h | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/sound/soc/sti/uniperif.h b/sound/soc/sti/uniperif.h index 2a5de328501c..1cbff01fbff0 100644 --- a/sound/soc/sti/uniperif.h +++ b/sound/soc/sti/uniperif.h @@ -12,17 +12,28 @@
#include <sound/dmaengine_pcm.h>
+#define SR_SHIFT(a, b) ({unsigned long __a = (a); \
unsigned int __b = (b); \__b < BITS_PER_LONG ? \__a >> __b : 0; })
The code definitely looks buggy, but how do you know your solution is correct without testing it?
I don't like this solution at all. This is basically a really complicated way of writing "if (b != -1)". Instead of checking for -1, the better solution is to just stop passing -1. If you review that file, every time it uses "-1" that's either dead code or a bug...
sound/soc/sti/uniperif.h 132 #define UNIPERIF_ITS_UNDERFLOW_REC_DONE_SHIFT(ip) \ 133 ((ip)->ver < SND_ST_UNIPERIF_VERSION_UNI_PLR_TOP_1_0 ? -1 : 12) ^^^^ This is dead code
134 #define UNIPERIF_ITS_UNDERFLOW_REC_DONE_MASK(ip) \ 135 ((ip)->ver < SND_ST_UNIPERIF_VERSION_UNI_PLR_TOP_1_0 ? \ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ because the version is checked here.
136 0 : (BIT(UNIPERIF_ITS_UNDERFLOW_REC_DONE_SHIFT(ip))))
Just delete UNIPERIF_ITS_UNDERFLOW_REC_DONE_SHIFT() and use 12 directly.
[ snip ]
988 #define UNIPERIF_BIT_CONTROL_OFFSET(ip) \ 989 ((ip)->ver < SND_ST_UNIPERIF_VERSION_UNI_PLR_TOP_1_0 ? -1 : 0x004c) ^^^ Negative offsets seem like a bug.
990 #define GET_UNIPERIF_BIT_CONTROL(ip) \ 991 readl_relaxed(ip->base + UNIPERIF_BIT_CONTROL_OFFSET(ip))
regards, dan carpenter