diff options
Diffstat (limited to 'arch/x86/include/asm/uaccess_64.h')
| -rw-r--r-- | arch/x86/include/asm/uaccess_64.h | 31 |
1 files changed, 20 insertions, 11 deletions
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index 81b826d3b753..afce8ee5d7b7 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -11,6 +11,7 @@ #include <asm/alternative.h> #include <asm/cpufeatures.h> #include <asm/page.h> +#include <asm/percpu.h> #ifdef CONFIG_ADDRESS_MASKING /* @@ -18,14 +19,10 @@ */ static inline unsigned long __untagged_addr(unsigned long addr) { - /* - * Refer tlbstate_untag_mask directly to avoid RIP-relative relocation - * in alternative instructions. The relocation gets wrong when gets - * copied to the target place. - */ asm (ALTERNATIVE("", - "and %%gs:tlbstate_untag_mask, %[addr]\n\t", X86_FEATURE_LAM) - : [addr] "+r" (addr) : "m" (tlbstate_untag_mask)); + "and " __percpu_arg([mask]) ", %[addr]", X86_FEATURE_LAM) + : [addr] "+r" (addr) + : [mask] "m" (__my_cpu_var(tlbstate_untag_mask))); return addr; } @@ -54,7 +51,18 @@ static inline unsigned long __untagged_addr_remote(struct mm_struct *mm, * half and a user half. When cast to a signed type, user pointers * are positive and kernel pointers are negative. */ -#define valid_user_address(x) ((long)(x) >= 0) +#define valid_user_address(x) ((__force long)(x) >= 0) + +/* + * Masking the user address is an alternative to a conditional + * user_access_begin that can avoid the fencing. This only works + * for dense accesses starting at the address. + */ +#define mask_user_address(x) ((typeof(x))((long)(x)|((long)(x)>>63))) +#define masked_user_access_begin(x) ({ \ + __auto_type __masked_ptr = (x); \ + __masked_ptr = mask_user_address(__masked_ptr); \ + __uaccess_begin(); __masked_ptr; }) /* * User pointers can have tag bits on x86-64. This scheme tolerates @@ -87,8 +95,9 @@ static inline bool __access_ok(const void __user *ptr, unsigned long size) if (__builtin_constant_p(size <= PAGE_SIZE) && size <= PAGE_SIZE) { return valid_user_address(ptr); } else { - unsigned long sum = size + (unsigned long)ptr; - return valid_user_address(sum) && sum >= (unsigned long)ptr; + unsigned long sum = size + (__force unsigned long)ptr; + + return valid_user_address(sum) && sum >= (__force unsigned long)ptr; } } #define __access_ok __access_ok @@ -116,7 +125,7 @@ copy_user_generic(void *to, const void *from, unsigned long len) "2:\n" _ASM_EXTABLE_UA(1b, 2b) :"+c" (len), "+D" (to), "+S" (from), ASM_CALL_CONSTRAINT - : : "memory", "rax", "r8", "r9", "r10", "r11"); + : : "memory", "rax"); clac(); return len; } |