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authorMax Filippov <jcmvbkbc@gmail.com>2019-10-11 06:55:35 +0300
committerMax Filippov <jcmvbkbc@gmail.com>2019-10-15 00:14:21 +0300
commitc9c63f3c7a9081e4768291514991d3208ae8a697 (patch)
treebfd6f2c748194fe121d0d638a35954ded1e56b63 /arch
parentc0437642966fd32b827034af6f00eecd80b89325 (diff)
downloadlinux-c9c63f3c7a9081e4768291514991d3208ae8a697.tar.xz
xtensa: fix type conversion in __get_user_[no]check
__get_user_[no]check uses temporary buffer of type long to store result of __get_user_size and do sign extension on it when necessary. This doesn't work correctly for 64-bit data. Fix it by moving temporary buffer/sign extension logic to __get_user_asm. Don't do assignment of __get_user_bad result to (x) as it may not always be integer-compatible now and issue warning even when it's going to be optimized. Instead do (x) = 0; and call __get_user_bad separately. Zero initialize __x in __get_user_asm and use '+' constraint for its assembly argument, so that its value is preserved in error cases. This may add at most 1 cycle to the fast path, but saves an instruction and two padding bytes in the fixup section for each use of this macro and works for both misaligned store and store exception. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/xtensa/include/asm/uaccess.h55
1 files changed, 29 insertions, 26 deletions
diff --git a/arch/xtensa/include/asm/uaccess.h b/arch/xtensa/include/asm/uaccess.h
index da4d35445063..3f80386f1883 100644
--- a/arch/xtensa/include/asm/uaccess.h
+++ b/arch/xtensa/include/asm/uaccess.h
@@ -172,19 +172,19 @@ __asm__ __volatile__( \
#define __get_user_nocheck(x, ptr, size) \
({ \
- long __gu_err, __gu_val; \
- __get_user_size(__gu_val, (ptr), (size), __gu_err); \
- (x) = (__force __typeof__(*(ptr)))__gu_val; \
+ long __gu_err; \
+ __get_user_size((x), (ptr), (size), __gu_err); \
__gu_err; \
})
#define __get_user_check(x, ptr, size) \
({ \
- long __gu_err = -EFAULT, __gu_val = 0; \
+ long __gu_err = -EFAULT; \
const __typeof__(*(ptr)) *__gu_addr = (ptr); \
- if (access_ok(__gu_addr, size)) \
- __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
- (x) = (__force __typeof__(*(ptr)))__gu_val; \
+ if (access_ok(__gu_addr, size)) \
+ __get_user_size((x), __gu_addr, (size), __gu_err); \
+ else \
+ (x) = 0; \
__gu_err; \
})
@@ -208,7 +208,7 @@ do { \
} \
break; \
} \
- default: (x) = __get_user_bad(); \
+ default: (x) = 0; __get_user_bad(); \
} \
} while (0)
@@ -218,24 +218,27 @@ do { \
* __check_align_* macros still work.
*/
#define __get_user_asm(x_, addr_, err_, align, insn, cb) \
-__asm__ __volatile__( \
- __check_align_##align \
- "1: "insn" %[x], %[addr], 0 \n" \
- "2: \n" \
- " .section .fixup,\"ax\" \n" \
- " .align 4 \n" \
- " .literal_position \n" \
- "5: \n" \
- " movi %[tmp], 2b \n" \
- " movi %[x], 0 \n" \
- " movi %[err], %[efault] \n" \
- " jx %[tmp] \n" \
- " .previous \n" \
- " .section __ex_table,\"a\" \n" \
- " .long 1b, 5b \n" \
- " .previous" \
- :[err] "+r"(err_), [tmp] "=r"(cb), [x] "=r"(x_)\
- :[addr] "r"(addr_), [efault] "i"(-EFAULT))
+do { \
+ u32 __x = 0; \
+ __asm__ __volatile__( \
+ __check_align_##align \
+ "1: "insn" %[x], %[addr], 0 \n" \
+ "2: \n" \
+ " .section .fixup,\"ax\" \n" \
+ " .align 4 \n" \
+ " .literal_position \n" \
+ "5: \n" \
+ " movi %[tmp], 2b \n" \
+ " movi %[err], %[efault] \n" \
+ " jx %[tmp] \n" \
+ " .previous \n" \
+ " .section __ex_table,\"a\" \n" \
+ " .long 1b, 5b \n" \
+ " .previous" \
+ :[err] "+r"(err_), [tmp] "=r"(cb), [x] "+r"(__x) \
+ :[addr] "r"(addr_), [efault] "i"(-EFAULT)); \
+ (x_) = (__force __typeof__(*(addr_)))__x; \
+} while (0)
/*