arm64: add macros for common adrp usages

The adrp instruction is mostly used in combination with either
an add, a ldr or a str instruction with the low bits of the
referenced symbol in the 12-bit immediate of the followup
instruction.

Introduce the macros adr_l, ldr_l and str_l that encapsulate
these common patterns.
Tested-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/include/asm/assembler.h

@@ -159,4 +159,52 @@ lr	.req	x30		// link register
 	orr	\rd, \lbits, \hbits, lsl #32
 	.endm
 
+/*
+ * Pseudo-ops for PC-relative adr/ldr/str <reg>, <symbol> where
+ * <symbol> is within the range +/- 4 GB of the PC.
+ */
+	/*
+	 * @dst: destination register (64 bit wide)
+	 * @sym: name of the symbol
+	 * @tmp: optional scratch register to be used if <dst> == sp, which
+	 *       is not allowed in an adrp instruction
+	 */
+	.macro	adr_l, dst, sym, tmp=
+	.ifb	\tmp
+	adrp	\dst, \sym
+	add	\dst, \dst, :lo12:\sym
+	.else
+	adrp	\tmp, \sym
+	add	\dst, \tmp, :lo12:\sym
+	.endif
+	.endm
+
+	/*
+	 * @dst: destination register (32 or 64 bit wide)
+	 * @sym: name of the symbol
+	 * @tmp: optional 64-bit scratch register to be used if <dst> is a
+	 *       32-bit wide register, in which case it cannot be used to hold
+	 *       the address
+	 */
+	.macro	ldr_l, dst, sym, tmp=
+	.ifb	\tmp
+	adrp	\dst, \sym
+	ldr	\dst, [\dst, :lo12:\sym]
+	.else
+	adrp	\tmp, \sym
+	ldr	\dst, [\tmp, :lo12:\sym]
+	.endif
+	.endm
+
+	/*
+	 * @src: source register (32 or 64 bit wide)
+	 * @sym: name of the symbol
+	 * @tmp: mandatory 64-bit scratch register to calculate the address
+	 *       while <src> needs to be preserved.
+	 */
+	.macro	str_l, src, sym, tmp
+	adrp	\tmp, \sym
+	str	\src, [\tmp, :lo12:\sym]
+	.endm
+
 #endif	/* __ASM_ASSEMBLER_H */