x86: start using named parameters for low-level uaccess asms (890f0b0d) · Commits · 戴 / test

This is partly for readability - using named arguments instead of numbered ones makes it muchmore obvious just what is going on. Using "%[efault]" instead of "%4" for the special -EFAULT constant just means that you don't have to count the arguments to see what's up. But the motivation for all this cleanup is that when we'll start to conditionally use "asm goto" even for the __get_user_asm() case, the argument numbers will depend on whether we have an error output, or an error label we can just directly jump to. So this moves us towards named arguments for the same reason that we have to use named arguments for the asms that use SET_CC(): numbering will eventually become similarly unreliable and depends on whether we can use particular compiler features or not. Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/include/asm/uaccess.h

+15 −11

Original line number	Diff line number	Diff line
		@@ -289,20 +289,22 @@ do { \
		({ \
		__typeof__(ptr) __ptr = (ptr); \
		asm volatile("\n" \
		"1: movl %2,%%eax\n" \
		"2: movl %3,%%edx\n" \
		"1: movl %[lowbits],%%eax\n" \
		"2: movl %[highbits],%%edx\n" \
		"3:\n" \
		".section .fixup,\"ax\"\n" \
		"4: mov %4,%0\n" \
		"4: mov %[efault],%[errout]\n" \
		" xorl %%eax,%%eax\n" \
		" xorl %%edx,%%edx\n" \
		" jmp 3b\n" \
		".previous\n" \
		_ASM_EXTABLE_UA(1b, 4b) \
		_ASM_EXTABLE_UA(2b, 4b) \
		: "=r" (retval), "=&A"(x) \
		: "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1), \
		"i" (-EFAULT), "0" (retval)); \
		: [errout] "=r" (retval), \
		[output] "=&A"(x) \
		: [lowbits] "m" (__m(__ptr)), \
		[highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \
		[efault] "i" (-EFAULT), "0" (retval)); \
		})

		#else
		@@ -334,16 +336,18 @@ do { \

		#define __get_user_asm(x, addr, err, itype, ltype) \
		asm volatile("\n" \
		"1: mov"itype" %2,%1\n" \
		"1: mov"itype" %[umem],%[output]\n" \
		"2:\n" \
		".section .fixup,\"ax\"\n" \
		"3: mov %3,%0\n" \
		" xor"itype" %1,%1\n" \
		"3: mov %[efault],%[errout]\n" \
		" xor"itype" %[output],%[output]\n" \
		" jmp 2b\n" \
		".previous\n" \
		_ASM_EXTABLE_UA(1b, 3b) \
		: "=r" (err), ltype(x) \
		: "m" (__m(addr)), "i" (-EFAULT), "0" (err))
		: [errout] "=r" (err), \
		[output] ltype(x) \
		: [umem] "m" (__m(addr)), \
		[efault] "i" (-EFAULT), "0" (err))

		#define __put_user_nocheck(x, ptr, size) \
		({ \

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