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| author | Nick Desaulniers <ndesaulniers@google.com> | 2020-08-07 13:59:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-12 18:43:08 -0700 |
| commit | 865c50e1d279671728c2936cb7680eb89355eeea (patch) | |
| tree | 45bc6cf5392974a642f9264cd0c1871b375131e7 | |
| parent | d55564cfc222326e944893eff0c4118353e349ec (diff) | |
| download | linux-865c50e1d279671728c2936cb7680eb89355eeea.tar.gz | |
x86/uaccess: utilize CONFIG_CC_HAS_ASM_GOTO_OUTPUT
Clang-11 shipped support for outputs to asm goto statments along the fallthrough path. Double up some of the get_user() and related macros to be able to take advantage of this extended GNU C extension. This should help improve the generated code's performance for these accesses. Cc: Bill Wendling <morbo@google.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 4c2f8bb32d78..aa60c239931b 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -310,6 +310,55 @@ do { \ } \ } while (0) +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT + +#ifdef CONFIG_X86_32 +#define __get_user_asm_u64(x, ptr, label) do { \ + unsigned int __gu_low, __gu_high; \ + const unsigned int __user *__gu_ptr; \ + __gu_ptr = (const void __user *)(ptr); \ + __get_user_asm(__gu_low, ptr, "l", "=r", label); \ + __get_user_asm(__gu_high, ptr+1, "l", "=r", label); \ + (x) = ((unsigned long long)__gu_high << 32) | __gu_low; \ +} while (0) +#else +#define __get_user_asm_u64(x, ptr, label) \ + __get_user_asm(x, ptr, "q", "=r", label) +#endif + +#define __get_user_size(x, ptr, size, label) \ +do { \ + __chk_user_ptr(ptr); \ + switch (size) { \ + unsigned char x_u8__; \ + case 1: \ + __get_user_asm(x_u8__, ptr, "b", "=q", label); \ + (x) = x_u8__; \ + break; \ + case 2: \ + __get_user_asm(x, ptr, "w", "=r", label); \ + break; \ + case 4: \ + __get_user_asm(x, ptr, "l", "=r", label); \ + break; \ + case 8: \ + __get_user_asm_u64(x, ptr, label); \ + break; \ + default: \ + (x) = __get_user_bad(); \ + } \ +} while (0) + +#define __get_user_asm(x, addr, itype, ltype, label) \ + asm_volatile_goto("\n" \ + "1: mov"itype" %[umem],%[output]\n" \ + _ASM_EXTABLE_UA(1b, %l2) \ + : [output] ltype(x) \ + : [umem] "m" (__m(addr)) \ + : : label) + +#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT + #ifdef CONFIG_X86_32 #define __get_user_asm_u64(x, ptr, retval) \ ({ \ @@ -378,6 +427,8 @@ do { \ : [umem] "m" (__m(addr)), \ [efault] "i" (-EFAULT), "0" (err)) +#endif // CONFIG_CC_ASM_GOTO_OUTPUT + /* FIXME: this hack is definitely wrong -AK */ struct __large_struct { unsigned long buf[100]; }; #define __m(x) (*(struct __large_struct __user *)(x)) @@ -452,6 +503,14 @@ static __must_check __always_inline bool user_access_begin(const void __user *pt #define unsafe_put_user(x, ptr, label) \ __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label) +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define unsafe_get_user(x, ptr, err_label) \ +do { \ + __inttype(*(ptr)) __gu_val; \ + __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label); \ + (x) = (__force __typeof__(*(ptr)))__gu_val; \ +} while (0) +#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT #define unsafe_get_user(x, ptr, err_label) \ do { \ int __gu_err; \ @@ -460,6 +519,7 @@ do { \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ if (unlikely(__gu_err)) goto err_label; \ } while (0) +#endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT /* * We want the unsafe accessors to always be inlined and use @@ -486,6 +546,11 @@ do { \ #define HAVE_GET_KERNEL_NOFAULT +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define __get_kernel_nofault(dst, src, type, err_label) \ + __get_user_size(*((type *)(dst)), (__force type __user *)(src), \ + sizeof(type), err_label) +#else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT #define __get_kernel_nofault(dst, src, type, err_label) \ do { \ int __kr_err; \ @@ -495,6 +560,7 @@ do { \ if (unlikely(__kr_err)) \ goto err_label; \ } while (0) +#endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT #define __put_kernel_nofault(dst, src, type, err_label) \ __put_user_size(*((type *)(src)), (__force type __user *)(dst), \ |