arch/arm64/kernel/relocate_kernel.S

Source file repositories/reference/linux-study-clean/arch/arm64/kernel/relocate_kernel.S

File Facts

System
Linux kernel
Corpus path
arch/arm64/kernel/relocate_kernel.S
Extension
.S
Size
3105 bytes
Lines
102
Domain
Architecture Layer
Bucket
arch/arm64
Inferred role
Architecture Layer: arch/arm64
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/kexec.h>
#include <linux/linkage.h>

#include <asm/assembler.h>
#include <asm/kexec.h>
#include <asm/page.h>
#include <asm/sysreg.h>
#include <asm/virt.h>

.macro turn_off_mmu tmp1, tmp2
	mov_q   \tmp1, INIT_SCTLR_EL1_MMU_OFF
	pre_disable_mmu_workaround
	msr	sctlr_el1, \tmp1
	isb
.endm

.section    ".kexec_relocate.text", "ax"
/*
 * arm64_relocate_new_kernel - Put a 2nd stage image in place and boot it.
 *
 * The memory that the old kernel occupies may be overwritten when copying the
 * new image to its final location.  To assure that the
 * arm64_relocate_new_kernel routine which does that copy is not overwritten,
 * all code and data needed by arm64_relocate_new_kernel must be between the
 * symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end.  The
 * machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec
 * safe memory that has been set up to be preserved during the copy operation.
 */
SYM_CODE_START(arm64_relocate_new_kernel)
	/*
	 * The kimage structure isn't allocated specially and may be clobbered
	 * during relocation. We must load any values we need from it prior to
	 * any relocation occurring.
	 */
	ldr	x28, [x0, #KIMAGE_START]
	ldr	x27, [x0, #KIMAGE_ARCH_EL2_VECTORS]
	ldr	x26, [x0, #KIMAGE_ARCH_DTB_MEM]

	/* Setup the list loop variables. */
	ldr	x18, [x0, #KIMAGE_ARCH_ZERO_PAGE] /* x18 = zero page for BBM */
	ldr	x17, [x0, #KIMAGE_ARCH_TTBR1]	/* x17 = linear map copy */
	ldr	x16, [x0, #KIMAGE_HEAD]		/* x16 = kimage_head */
	ldr	x22, [x0, #KIMAGE_ARCH_PHYS_OFFSET]	/* x22 phys_offset */
	raw_dcache_line_size x15, x1		/* x15 = dcache line size */
	break_before_make_ttbr_switch	x18, x17, x1, x2 /* set linear map */
.Lloop:
	and	x12, x16, PAGE_MASK		/* x12 = addr */
	sub	x12, x12, x22			/* Convert x12 to virt */
	/* Test the entry flags. */
.Ltest_source:
	tbz	x16, IND_SOURCE_BIT, .Ltest_indirection

	/* Invalidate dest page to PoC. */
	mov	x19, x13
	copy_page x13, x12, x1, x2, x3, x4, x5, x6, x7, x8
	add	x1, x19, #PAGE_SIZE
	dcache_by_myline_op_nosync civac, x19, x1, x15, x20
	dsb	sy
	b	.Lnext
.Ltest_indirection:
	tbz	x16, IND_INDIRECTION_BIT, .Ltest_destination
	mov	x14, x12			/* ptr = addr */
	b	.Lnext
.Ltest_destination:
	tbz	x16, IND_DESTINATION_BIT, .Lnext
	mov	x13, x12			/* dest = addr */
.Lnext:
	ldr	x16, [x14], #8			/* entry = *ptr++ */
	tbz	x16, IND_DONE_BIT, .Lloop	/* while (!(entry & DONE)) */
	/* wait for writes from copy_page to finish */

Annotation

Implementation Notes