linux-kernel - [PATCH v2 2/9] x86/asm: move the raw asm in iosubmit_cmds512() to special

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Message-ID: <158982801306.37989.17977882738076524234.stgit@djiang5-desk3.ch.intel.com>
Date:   Mon, 18 May 2020 11:53:33 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     vkoul@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, bhelgaas@...gle.com,
        gregkh@...uxfoundation.org, arnd@...db.de
Cc:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        x86@...nel.org, dan.j.williams@...el.com, ashok.raj@...el.com,
        fenghua.yu@...el.com, tony.luck@...el.com, jing.lin@...el.com,
        sanjay.k.kumar@...el.com, dave.hansen@...el.com
Subject: [PATCH v2 2/9] x86/asm: move the raw asm in iosubmit_cmds512() to
 special_insns.h

The MOVDIR64B instruction can be used by other wrapper instructions. Move
the core asm code to special_insns.h and have iosubmit_cmds512() call the
core asm function.

Signed-off-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/include/asm/io.h            |   15 ++-------------
 arch/x86/include/asm/special_insns.h |   17 +++++++++++++++++
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index e1aa17a468a8..56421666115e 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -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;
 	}
 }
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 1b9b2e79c353..9ad28d82de70 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -256,6 +256,23 @@ static inline int write_user_shstk_64(unsigned long addr, unsigned long val)
 
 #define nop() asm volatile ("nop")
 
+static inline void movdir64b(void *__dst, const void *src)
+{
+	/*
+	 * 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;
+
+	/* MOVDIR64B [rdx], rax */
+	asm volatile(".byte 0x66, 0x0f, 0x38, 0xf8, 0x02"
+		     : "=m" (dst)
+		     : "d" (src), "a" (dst));
+}
+
 
 #endif /* __KERNEL__ */