diff options
| -rw-r--r-- | arch/arm64/include/asm/uaccess.h | 34 |
1 files changed, 10 insertions, 24 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 2e20879fe3cf..199c553b740a 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -26,6 +26,14 @@ #include <asm/memory.h> #include <asm/extable.h> +static inline int __access_ok(const void __user *ptr, unsigned long size) +{ + unsigned long limit = TASK_SIZE_MAX; + unsigned long addr = (unsigned long)ptr; + + return (size <= limit) && (addr <= (limit - size)); +} + /* * Test whether a block of memory is a valid user space address. * Returns 1 if the range is valid, 0 otherwise. @@ -33,10 +41,8 @@ * This is equivalent to the following test: * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX */ -static inline unsigned long __range_ok(const void __user *addr, unsigned long size) +static inline int access_ok(const void __user *addr, unsigned long size) { - unsigned long ret, limit = TASK_SIZE_MAX - 1; - /* * Asynchronous I/O running in a kernel thread does not have the * TIF_TAGGED_ADDR flag of the process owning the mm, so always untag @@ -46,29 +52,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR))) addr = untagged_addr(addr); - __chk_user_ptr(addr); - asm volatile( - // A + B <= C + 1 for all A,B,C, in four easy steps: - // 1: X = A + B; X' = X % 2^64 - " adds %0, %3, %2\n" - // 2: Set C = 0 if X > 2^64, to guarantee X' > C in step 4 - " csel %1, xzr, %1, hi\n" - // 3: Set X' = ~0 if X >= 2^64. For X == 2^64, this decrements X' - // to compensate for the carry flag being set in step 4. For - // X > 2^64, X' merely has to remain nonzero, which it does. - " csinv %0, %0, xzr, cc\n" - // 4: For X < 2^64, this gives us X' - C - 1 <= 0, where the -1 - // comes from the carry in being clear. Otherwise, we are - // testing X' - C == 0, subject to the previous adjustments. - " sbcs xzr, %0, %1\n" - " cset %0, ls\n" - : "=&r" (ret), "+r" (limit) : "Ir" (size), "0" (addr) : "cc"); - - return ret; + return likely(__access_ok(addr, size)); } -#define access_ok(addr, size) __range_ok(addr, size) - /* * User access enabling/disabling. */ |