linux-kernel - [PATCH 4.4 22/92] arm64: introduce mov_q macro to move a constant into a 64-bit register

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Message-Id: <20180524093201.122741037@linuxfoundation.org>
Date:   Thu, 24 May 2018 11:37:59 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Will Deacon <will.deacon@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH 4.4 22/92] arm64: introduce mov_q macro to move a constant into a 64-bit register

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@...aro.org>

commit 30b5ba5cf333cc650e474eaf2cc1ae91bc7cf89f upstream.

Implement a macro mov_q that can be used to move an immediate constant
into a 64-bit register, using between 2 and 4 movz/movk instructions
(depending on the operand)

Acked-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/include/asm/assembler.h |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -204,4 +204,24 @@ lr	.req	x30		// link register
 	.size	__pi_##x, . - x;	\
 	ENDPROC(x)
 
+	/*
+	 * mov_q - move an immediate constant into a 64-bit register using
+	 *         between 2 and 4 movz/movk instructions (depending on the
+	 *         magnitude and sign of the operand)
+	 */
+	.macro	mov_q, reg, val
+	.if (((\val) >> 31) == 0 || ((\val) >> 31) == 0x1ffffffff)
+	movz	\reg, :abs_g1_s:\val
+	.else
+	.if (((\val) >> 47) == 0 || ((\val) >> 47) == 0x1ffff)
+	movz	\reg, :abs_g2_s:\val
+	.else
+	movz	\reg, :abs_g3:\val
+	movk	\reg, :abs_g2_nc:\val
+	.endif
+	movk	\reg, :abs_g1_nc:\val
+	.endif
+	movk	\reg, :abs_g0_nc:\val
+	.endm
+
 #endif	/* __ASM_ASSEMBLER_H */