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Commit b929fe32 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Will Deacon
Browse files

arm64: kernel: drop use of x24 from primary boot path 



Keeping __PHYS_OFFSET in x24 is actually less clear than simply taking
the value of __PHYS_OFFSET using an adrp instruction in the three places
that we need it. So change that.

Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 9dcf7914

arch/arm64/kernel/head.S

+12 −8
Original line number Diff line number Diff line
@@ -211,8 +211,8 @@ efi_header_end: 
ENTRY(stext)

	bl	preserve_boot_args

	bl	el2_setup			// Drop to EL1, w0=cpu_boot_mode

	adrp	x24, __PHYS_OFFSET

	and	x23, x24, MIN_KIMG_ALIGN - 1	// KASLR offset, defaults to 0

	adrp	x23, __PHYS_OFFSET

	and	x23, x23, MIN_KIMG_ALIGN - 1	// KASLR offset, defaults to 0

	bl	set_cpu_boot_mode_flag

	bl	__create_page_tables

	/*
@@ -412,6 +412,8 @@ ENDPROC(__create_page_tables) 


/*

 * The following fragment of code is executed with the MMU enabled.

 *

 *   x0 = __PHYS_OFFSET

 */

	.set	initial_sp, init_thread_union + THREAD_START_SP

__primary_switched:
@@ -420,6 +422,12 @@ __primary_switched: 
	msr	vbar_el1, x8			// vector table address

	isb



	str_l	x21, __fdt_pointer, x5		// Save FDT pointer



	ldr_l	x4, kimage_vaddr		// Save the offset between

	sub	x4, x4, x0			// the kernel virtual and

	str_l	x4, kimage_voffset, x5		// physical mappings



	// Clear BSS

	adr_l	x0, __bss_start

	mov	x1, xzr
@@ -432,12 +440,6 @@ __primary_switched: 
	mov	x4, sp

	and	x4, x4, #~(THREAD_SIZE - 1)

	msr	sp_el0, x4			// Save thread_info

	str_l	x21, __fdt_pointer, x5		// Save FDT pointer



	ldr_l	x4, kimage_vaddr		// Save the offset between

	sub	x4, x4, x24			// the kernel virtual and

	str_l	x4, kimage_voffset, x5		// physical mappings



	mov	x29, #0

#ifdef CONFIG_KASAN

	bl	kasan_early_init
@@ -794,6 +796,7 @@ __primary_switch: 
	bl	__relocate_kernel

#ifdef CONFIG_RANDOMIZE_BASE

	ldr	x8, =__primary_switched

	adrp	x0, __PHYS_OFFSET

	blr	x8



	/*
@@ -818,5 +821,6 @@ __primary_switch: 
#endif

#endif

	ldr	x8, =__primary_switched

	adrp	x0, __PHYS_OFFSET

	br	x8

ENDPROC(__primary_switch)