5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christophe Leroy <christophe.leroy@xxxxxxxxxx> [ Upstream commit 5cd29b1fd3e8f2b45fe6d011588d832417defe31 ] clang 11 and future GCC are supporting asm goto with outputs. Use it to implement get_user in order to get better generated code. Note that clang requires to set x in the default branch of __get_user_size_goto() otherwise is compliant about x not being initialised :puzzled: Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/403745b5aaa1b315bb4e8e46c1ba949e77eecec0.1615398265.git.christophe.leroy@xxxxxxxxxx Stable-dep-of: 50934945d542 ("powerpc/uaccess: Use YZ asm constraint for ld") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/powerpc/include/asm/uaccess.h | 55 ++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index 6b808bcdecd52..d4d59f57c42d9 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -243,6 +243,59 @@ extern long __get_user_bad(void); : "=r" (err) \ : "b" (uaddr), "b" (kaddr), "i" (-EFAULT), "0" (err)) +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT + +#define __get_user_asm_goto(x, addr, label, op) \ + asm_volatile_goto( \ + "1: "op"%U1%X1 %0, %1 # get_user\n" \ + EX_TABLE(1b, %l2) \ + : "=r" (x) \ + : "m"UPD_CONSTR (*addr) \ + : \ + : label) + +#ifdef __powerpc64__ +#define __get_user_asm2_goto(x, addr, label) \ + __get_user_asm_goto(x, addr, label, "ld") +#else /* __powerpc64__ */ +#define __get_user_asm2_goto(x, addr, label) \ + asm_volatile_goto( \ + "1: lwz%X1 %0, %1\n" \ + "2: lwz%X1 %L0, %L1\n" \ + EX_TABLE(1b, %l2) \ + EX_TABLE(2b, %l2) \ + : "=r" (x) \ + : "m" (*addr) \ + : \ + : label) +#endif /* __powerpc64__ */ + +#define __get_user_size_goto(x, ptr, size, label) \ +do { \ + BUILD_BUG_ON(size > sizeof(x)); \ + switch (size) { \ + case 1: __get_user_asm_goto(x, (u8 __user *)ptr, label, "lbz"); break; \ + case 2: __get_user_asm_goto(x, (u16 __user *)ptr, label, "lhz"); break; \ + case 4: __get_user_asm_goto(x, (u32 __user *)ptr, label, "lwz"); break; \ + case 8: __get_user_asm2_goto(x, (u64 __user *)ptr, label); break; \ + default: x = 0; BUILD_BUG(); \ + } \ +} while (0) + +#define __get_user_size_allowed(x, ptr, size, retval) \ +do { \ + __label__ __gus_failed; \ + \ + __get_user_size_goto(x, ptr, size, __gus_failed); \ + retval = 0; \ + break; \ +__gus_failed: \ + x = 0; \ + retval = -EFAULT; \ +} while (0) + +#else /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */ + #define __get_user_asm(x, addr, err, op) \ __asm__ __volatile__( \ "1: "op"%U2%X2 %1, %2 # get_user\n" \ @@ -299,6 +352,8 @@ do { \ prevent_read_from_user(ptr, size); \ } while (0) +#endif /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */ + /* * This is a type: either unsigned long, if the argument fits into * that type, or otherwise unsigned long long. -- 2.43.0
