qemu/bitops.h: Limit rotate amounts

Rotates have been fixed up to only allow for reasonable rotate amounts
(ie, no rotates >7 on an 8b value etc.)  This fixes a problem with riscv
vector rotate instructions.

Signed-off-by: Dickon Hood <dickon.hood@codethink.co.uk>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230428144757.57530-9-lawrence.hunter@codethink.co.uk>
[rth: Mask shifts in both directions.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
index 03213ce952c6d4142814cfb62ee8080da125ccc5..cb3526d1f44dae3a041abc73019ea172faeeadc0 100644 (file)
--- a/include/qemu/bitops.h
+++ b/include/qemu/bitops.h
@@ -218,7 +218,7 @@ static inline unsigned long find_first_zero_bit(const unsigned long *addr,
  */
 static inline uint8_t rol8(uint8_t word, unsigned int shift)
 {
-    return (word << shift) | (word >> ((8 - shift) & 7));
+    return (word << (shift & 7)) | (word >> (-shift & 7));
 }
 
 /**
@@ -228,7 +228,7 @@ static inline uint8_t rol8(uint8_t word, unsigned int shift)
  */
 static inline uint8_t ror8(uint8_t word, unsigned int shift)
 {
-    return (word >> shift) | (word << ((8 - shift) & 7));
+    return (word >> (shift & 7)) | (word << (-shift & 7));
 }
 
 /**
@@ -238,7 +238,7 @@ static inline uint8_t ror8(uint8_t word, unsigned int shift)
  */
 static inline uint16_t rol16(uint16_t word, unsigned int shift)
 {
-    return (word << shift) | (word >> ((16 - shift) & 15));
+    return (word << (shift & 15)) | (word >> (-shift & 15));
 }
 
 /**
@@ -248,7 +248,7 @@ static inline uint16_t rol16(uint16_t word, unsigned int shift)
  */
 static inline uint16_t ror16(uint16_t word, unsigned int shift)
 {
-    return (word >> shift) | (word << ((16 - shift) & 15));
+    return (word >> (shift & 15)) | (word << (-shift & 15));
 }
 
 /**
@@ -258,7 +258,7 @@ static inline uint16_t ror16(uint16_t word, unsigned int shift)
  */
 static inline uint32_t rol32(uint32_t word, unsigned int shift)
 {
-    return (word << shift) | (word >> ((32 - shift) & 31));
+    return (word << (shift & 31)) | (word >> (-shift & 31));
 }
 
 /**
@@ -268,7 +268,7 @@ static inline uint32_t rol32(uint32_t word, unsigned int shift)
  */
 static inline uint32_t ror32(uint32_t word, unsigned int shift)
 {
-    return (word >> shift) | (word << ((32 - shift) & 31));
+    return (word >> (shift & 31)) | (word << (-shift & 31));
 }
 
 /**
@@ -278,7 +278,7 @@ static inline uint32_t ror32(uint32_t word, unsigned int shift)
  */
 static inline uint64_t rol64(uint64_t word, unsigned int shift)
 {
-    return (word << shift) | (word >> ((64 - shift) & 63));
+    return (word << (shift & 63)) | (word >> (-shift & 63));
 }
 
 /**
@@ -288,7 +288,7 @@ static inline uint64_t rol64(uint64_t word, unsigned int shift)
  */
 static inline uint64_t ror64(uint64_t word, unsigned int shift)
 {
-    return (word >> shift) | (word << ((64 - shift) & 63));
+    return (word >> (shift & 63)) | (word << (-shift & 63));
 }
 
 /**