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Thu, 20 Feb 2025 16:09:31 -0800 (PST) Received: from aus-ird.tenstorrent.com ([38.104.49.66]) by smtp.gmail.com with ESMTPSA id 5614622812f47-3f40b027906sm1573401b6e.42.2025.02.20.16.09.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Feb 2025 16:09:30 -0800 (PST) From: Cyril Bur To: palmer@dabbelt.com, aou@eecs.berkeley.edu, paul.walmsley@sifive.com, charlie@rivosinc.com, jrtc27@jrtc27.com, ben.dooks@codethink.co.uk Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, jszhang@kernel.org Subject: [PATCH v3 4/4] riscv: uaccess: use 'asm_goto_output' for get_user() Date: Fri, 21 Feb 2025 00:09:24 +0000 Message-Id: <20250221000924.734006-5-cyrilbur@tenstorrent.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250221000924.734006-1-cyrilbur@tenstorrent.com> References: <20250221000924.734006-1-cyrilbur@tenstorrent.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250220_160932_537443_96E30C75 X-CRM114-Status: GOOD ( 13.30 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Jisheng Zhang With 'asm goto' we don't need to test the error etc, the exception just jumps to the error handling directly. Unlike put_user(), get_user() must work around GCC bugs [1] when using output clobbers in an asm goto statement. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 # 1 Signed-off-by: Jisheng Zhang [Cyril Bur: Rewritten commit message] Signed-off-by: Cyril Bur --- arch/riscv/include/asm/uaccess.h | 90 +++++++++++++++++++++++--------- 1 file changed, 65 insertions(+), 25 deletions(-) diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h index 1b926b61af66..ab48ef57565e 100644 --- a/arch/riscv/include/asm/uaccess.h +++ b/arch/riscv/include/asm/uaccess.h @@ -96,27 +96,56 @@ static inline unsigned long __untagged_addr_remote(struct mm_struct *mm, unsigne * call. */ -#define __get_user_asm(insn, x, ptr, err) \ +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define __get_user_asm(insn, x, ptr, label) \ + asm_goto_output( \ + "1:\n" \ + " " insn " %0, %1\n" \ + _ASM_EXTABLE_UACCESS_ERR(1b, %l2, %0) \ + : "=&r" (x) \ + : "m" (*(ptr)) : : label) +#else /* !CONFIG_CC_HAS_ASM_GOTO_OUTPUT */ +#define __get_user_asm(insn, x, ptr, label) \ do { \ - __typeof__(x) __x; \ + long __gua_err = 0; \ __asm__ __volatile__ ( \ "1:\n" \ " " insn " %1, %2\n" \ "2:\n" \ _ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %0, %1) \ - : "+r" (err), "=&r" (__x) \ + : "+r" (__gua_err), "=&r" (x) \ : "m" (*(ptr))); \ - (x) = __x; \ + if (__gua_err) \ + goto label; \ } while (0) +#endif /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */ #ifdef CONFIG_64BIT -#define __get_user_8(x, ptr, err) \ - __get_user_asm("ld", x, ptr, err) +#define __get_user_8(x, ptr, label) \ + __get_user_asm("ld", x, ptr, label) #else /* !CONFIG_64BIT */ -#define __get_user_8(x, ptr, err) \ + +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define __get_user_8(x, ptr, label) \ + u32 __user *__ptr = (u32 __user *)(ptr); \ + u32 __lo, __hi; \ + asm_goto_output( \ + "1:\n" \ + " lw %0, %2\n" \ + "2:\n" \ + " lw %1, %3\n" \ + _ASM_EXTABLE_UACCESS_ERR(1b, %l4, %0) \ + _ASM_EXTABLE_UACCESS_ERR(2b, %l4, %0) \ + : "=&r" (__lo), "=r" (__hi) \ + : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]) \ + : : label) + +#else /* !CONFIG_CC_HAS_ASM_GOTO_OUTPUT */ +#define __get_user_8(x, ptr, label) \ do { \ u32 __user *__ptr = (u32 __user *)(ptr); \ u32 __lo, __hi; \ + long __gu8_err = 0; \ __asm__ __volatile__ ( \ "1:\n" \ " lw %1, %3\n" \ @@ -125,35 +154,51 @@ do { \ "3:\n" \ _ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 3b, %0, %1) \ _ASM_EXTABLE_UACCESS_ERR_ZERO(2b, 3b, %0, %1) \ - : "+r" (err), "=&r" (__lo), "=r" (__hi) \ + : "+r" (__gu8_err), "=&r" (__lo), "=r" (__hi) \ : "m" (__ptr[__LSW]), "m" (__ptr[__MSW])); \ - if (err) \ + if (__gu8_err) { \ __hi = 0; \ + goto label; \ + } \ (x) = (__typeof__(x))((__typeof__((x)-(x)))( \ (((u64)__hi << 32) | __lo))); \ } while (0) +#endif /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */ + #endif /* CONFIG_64BIT */ -#define __get_user_nocheck(x, __gu_ptr, __gu_err) \ +#define __get_user_nocheck(x, __gu_ptr, label) \ do { \ switch (sizeof(*__gu_ptr)) { \ case 1: \ - __get_user_asm("lb", (x), __gu_ptr, __gu_err); \ + __get_user_asm("lb", (x), __gu_ptr, label); \ break; \ case 2: \ - __get_user_asm("lh", (x), __gu_ptr, __gu_err); \ + __get_user_asm("lh", (x), __gu_ptr, label); \ break; \ case 4: \ - __get_user_asm("lw", (x), __gu_ptr, __gu_err); \ + __get_user_asm("lw", (x), __gu_ptr, label); \ break; \ case 8: \ - __get_user_8((x), __gu_ptr, __gu_err); \ + __get_user_8((x), __gu_ptr, label); \ break; \ default: \ BUILD_BUG(); \ } \ } while (0) +#define __get_user_error(x, ptr, err) \ +do { \ + __label__ __gu_failed; \ + \ + __get_user_nocheck(x, ptr, __gu_failed); \ + err = 0; \ + break; \ +__gu_failed: \ + x = 0; \ + err = -EFAULT; \ +} while (0) + /** * __get_user: - Get a simple variable from user space, with less checking. * @x: Variable to store result. @@ -178,13 +223,16 @@ do { \ ({ \ const __typeof__(*(ptr)) __user *__gu_ptr = untagged_addr(ptr); \ long __gu_err = 0; \ + __typeof__(x) __gu_val; \ \ __chk_user_ptr(__gu_ptr); \ \ __enable_user_access(); \ - __get_user_nocheck(x, __gu_ptr, __gu_err); \ + __get_user_error(__gu_val, __gu_ptr, __gu_err); \ __disable_user_access(); \ \ + (x) = __gu_val; \ + \ __gu_err; \ }) @@ -369,13 +417,7 @@ unsigned long __must_check clear_user(void __user *to, unsigned long n) } #define __get_kernel_nofault(dst, src, type, err_label) \ -do { \ - long __kr_err = 0; \ - \ - __get_user_nocheck(*((type *)(dst)), (type *)(src), __kr_err); \ - if (unlikely(__kr_err)) \ - goto err_label; \ -} while (0) + __get_user_nocheck(*((type *)(dst)), (type *)(src), err_label) #define __put_kernel_nofault(dst, src, type, err_label) \ __put_user_nocheck(*((type *)(src)), (type *)(dst), err_label) @@ -401,11 +443,9 @@ static inline void user_access_restore(unsigned long enabled) { } __put_user_nocheck(x, (ptr), label) #define unsafe_get_user(x, ptr, label) do { \ - long __err = 0; \ __inttype(*(ptr)) __gu_val; \ - __get_user_nocheck(__gu_val, (ptr), __err); \ + __get_user_nocheck(__gu_val, (ptr), label); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ - if (__err) goto label; \ } while (0) #define unsafe_copy_loop(dst, src, len, type, label) \