diff options
author | Will Deacon <will.deacon@arm.com> | 2018-02-05 15:34:22 +0000 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-02-06 22:53:39 +0000 |
commit | 84624087dd7e3b482b7b11c170ebc1f329b3a218 (patch) | |
tree | 0f50e8eab78b53f0953ba57488777d66222214f5 | |
parent | c2f0ad4fc089cff81cef6a13d04b399980ecbfcc (diff) | |
download | linux-84624087dd7e3b482b7b11c170ebc1f329b3a218.tar.bz2 |
arm64: uaccess: Don't bother eliding access_ok checks in __{get, put}_user
access_ok isn't an expensive operation once the addr_limit for the current
thread has been loaded into the cache. Given that the initial access_ok
check preceding a sequence of __{get,put}_user operations will take
the brunt of the miss, we can make the __* variants identical to the
full-fat versions, which brings with it the benefits of address masking.
The likely cost in these sequences will be from toggling PAN/UAO, which
we can address later by implementing the *_unsafe versions.
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r-- | arch/arm64/include/asm/uaccess.h | 54 |
1 files changed, 32 insertions, 22 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 2057deed7697..e5002bc7130d 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -306,28 +306,33 @@ do { \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ } while (0) -#define __get_user(x, ptr) \ +#define __get_user_check(x, ptr, err) \ ({ \ - int __gu_err = 0; \ - __get_user_err((x), (ptr), __gu_err); \ - __gu_err; \ + __typeof__(*(ptr)) __user *__p = (ptr); \ + might_fault(); \ + if (access_ok(VERIFY_READ, __p, sizeof(*__p))) { \ + __p = uaccess_mask_ptr(__p); \ + __get_user_err((x), __p, (err)); \ + } else { \ + (x) = 0; (err) = -EFAULT; \ + } \ }) #define __get_user_error(x, ptr, err) \ ({ \ - __get_user_err((x), (ptr), (err)); \ + __get_user_check((x), (ptr), (err)); \ (void)0; \ }) -#define get_user(x, ptr) \ +#define __get_user(x, ptr) \ ({ \ - __typeof__(*(ptr)) __user *__p = (ptr); \ - might_fault(); \ - access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ - __p = uaccess_mask_ptr(__p), __get_user((x), __p) : \ - ((x) = 0, -EFAULT); \ + int __gu_err = 0; \ + __get_user_check((x), (ptr), __gu_err); \ + __gu_err; \ }) +#define get_user __get_user + #define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ asm volatile( \ "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ @@ -370,28 +375,33 @@ do { \ uaccess_disable_not_uao(); \ } while (0) -#define __put_user(x, ptr) \ +#define __put_user_check(x, ptr, err) \ ({ \ - int __pu_err = 0; \ - __put_user_err((x), (ptr), __pu_err); \ - __pu_err; \ + __typeof__(*(ptr)) __user *__p = (ptr); \ + might_fault(); \ + if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) { \ + __p = uaccess_mask_ptr(__p); \ + __put_user_err((x), __p, (err)); \ + } else { \ + (err) = -EFAULT; \ + } \ }) #define __put_user_error(x, ptr, err) \ ({ \ - __put_user_err((x), (ptr), (err)); \ + __put_user_check((x), (ptr), (err)); \ (void)0; \ }) -#define put_user(x, ptr) \ +#define __put_user(x, ptr) \ ({ \ - __typeof__(*(ptr)) __user *__p = (ptr); \ - might_fault(); \ - access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ - __p = uaccess_mask_ptr(__p), __put_user((x), __p) : \ - -EFAULT; \ + int __pu_err = 0; \ + __put_user_check((x), (ptr), __pu_err); \ + __pu_err; \ }) +#define put_user __put_user + extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); #define raw_copy_from_user __arch_copy_from_user extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); |