x86/asm: Carve out a generic movdir64b() helper for general usage (0888e103) · Commits · 戴 / test

arch/x86/include/asm/io.h

+3 −14

Original line number	Diff line number	Diff line
		@@ -401,7 +401,7 @@ extern bool phys_mem_access_encrypted(unsigned long phys_addr,

		/**
		* iosubmit_cmds512 - copy data to single MMIO location, in 512-bit units
		* @__dst: destination, in MMIO space (must be 512-bit aligned)
		* @dst: destination, in MMIO space (must be 512-bit aligned)
		* @src: source
		* @count: number of 512 bits quantities to submit
		*
		@@ -412,25 +412,14 @@ extern bool phys_mem_access_encrypted(unsigned long phys_addr,
		* Warning: Do not use this helper unless your driver has checked that the CPU
		* instruction is supported on the platform.
		*/
		static inline void iosubmit_cmds512(void __iomem __dst, const void src,
		static inline void iosubmit_cmds512(void __iomem dst, const void src,
		size_t count)
		{
		/*
		* Note that this isn't an "on-stack copy", just definition of "dst"
		* as a pointer to 64-bytes of stuff that is going to be overwritten.
		* In the MOVDIR64B case that may be needed as you can use the
		* MOVDIR64B instruction to copy arbitrary memory around. This trick
		* lets the compiler know how much gets clobbered.
		*/
		volatile struct { char _[64]; } *dst = __dst;
		const u8 *from = src;
		const u8 end = from + count 64;

		while (from < end) {
		/* MOVDIR64B [rdx], rax */
		asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
		: "=m" (dst)
		: "d" (from), "a" (dst));
		movdir64b(dst, from);
		from += 64;
		}
		}

+22 −0

Original line number	Diff line number	Diff line
		@@ -234,6 +234,28 @@ static inline void clwb(volatile void *__p)

		#define nop() asm volatile ("nop")

		/* The dst parameter must be 64-bytes aligned */
		static inline void movdir64b(void dst, const void src)
		{
		const struct { char _[64]; } *__src = src;
		struct { char _[64]; } *__dst = dst;

		/*
		* MOVDIR64B %(rdx), rax.
		*
		* Both __src and __dst must be memory constraints in order to tell the
		* compiler that no other memory accesses should be reordered around
		* this one.
		*
		* Also, both must be supplied as lvalues because this tells
		* the compiler what the object is (its size) the instruction accesses.
		* I.e., not the pointers but what they point to, thus the deref'ing '*'.
		*/
		asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
		: "+m" (*__dst)
		: "m" (*__src), "a" (__dst), "d" (__src));
		}

		#endif /* __KERNEL__ */

		#endif /* _ASM_X86_SPECIAL_INSNS_H */