Commit 5bb6834f authored by Pasha Tatashin's avatar Pasha Tatashin Committed by Will Deacon
Browse files

arm64: kexec: skip relocation code for inplace kexec 



In case of kdump or when segments are already in place the relocation
is not needed, therefore the setup of relocation function and call to
it can be skipped.

Signed-off-by: default avatarPasha Tatashin <pasha.tatashin@soleen.com>
Suggested-by: default avatarJames Morse <james.morse@arm.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210930143113.1502553-6-pasha.tatashin@soleen.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 0d8732e4

arch/arm64/kernel/machine_kexec.c

+21 −13
Original line number Diff line number Diff line
@@ -144,16 +144,16 @@ int machine_kexec_post_load(struct kimage *kimage) 
{

	void *reloc_code = page_to_virt(kimage->control_code_page);



	/* If in place flush new kernel image, else flush lists and buffers */

	if (kimage->head & IND_DONE)

	/* If in place, relocation is not used, only flush next kernel */

	if (kimage->head & IND_DONE) {

		kexec_segment_flush(kimage);

	else

		kexec_list_flush(kimage);

		kexec_image_info(kimage);

		return 0;

	}



	memcpy(reloc_code, arm64_relocate_new_kernel,

	       arm64_relocate_new_kernel_size);

	kimage->arch.kern_reloc = __pa(reloc_code);

	kexec_image_info(kimage);



	/* Flush the reloc_code in preparation for its execution. */

	dcache_clean_inval_poc((unsigned long)reloc_code,
@@ -162,6 +162,8 @@ int machine_kexec_post_load(struct kimage *kimage) 
	icache_inval_pou((uintptr_t)reloc_code,

			 (uintptr_t)reloc_code +

			 arm64_relocate_new_kernel_size);

	kexec_list_flush(kimage);

	kexec_image_info(kimage);



	return 0;

}
@@ -188,19 +190,25 @@ void machine_kexec(struct kimage *kimage) 
	local_daif_mask();



	/*

	 * cpu_soft_restart will shutdown the MMU, disable data caches, then

	 * transfer control to the kern_reloc which contains a copy of

	 * the arm64_relocate_new_kernel routine.  arm64_relocate_new_kernel

	 * uses physical addressing to relocate the new image to its final

	 * position and transfers control to the image entry point when the

	 * relocation is complete.

	 * Both restart and cpu_soft_restart will shutdown the MMU, disable data

	 * caches. However, restart will start new kernel or purgatory directly,

	 * cpu_soft_restart will transfer control to arm64_relocate_new_kernel

	 * In kexec case, kimage->start points to purgatory assuming that

	 * kernel entry and dtb address are embedded in purgatory by

	 * userspace (kexec-tools).

	 * In kexec_file case, the kernel starts directly without purgatory.

	 */

	cpu_soft_restart(kimage->arch.kern_reloc, kimage->head, kimage->start,

			 kimage->arch.dtb_mem);

	if (kimage->head & IND_DONE) {

		typeof(__cpu_soft_restart) *restart;



		cpu_install_idmap();

		restart = (void *)__pa_symbol(function_nocfi(__cpu_soft_restart));

		restart(is_hyp_nvhe(), kimage->start, kimage->arch.dtb_mem,

			0, 0);

	} else {

		cpu_soft_restart(kimage->arch.kern_reloc, kimage->head,

				 kimage->start, kimage->arch.dtb_mem);

	}



	BUG(); /* Should never get here. */

}

arch/arm64/kernel/relocate_kernel.S

+0 −3
Original line number Diff line number Diff line
@@ -32,8 +32,6 @@ SYM_CODE_START(arm64_relocate_new_kernel) 
	mov	x16, x0				/* x16 = kimage_head */

	mov	x14, xzr			/* x14 = entry ptr */

	mov	x13, xzr			/* x13 = copy dest */

	/* Check if the new image needs relocation. */

	tbnz	x16, IND_DONE_BIT, .Ldone

	raw_dcache_line_size x15, x1		/* x15 = dcache line size */

.Lloop:

	and	x12, x16, PAGE_MASK		/* x12 = addr */
@@ -65,7 +63,6 @@ SYM_CODE_START(arm64_relocate_new_kernel) 
.Lnext:

	ldr	x16, [x14], #8			/* entry = *ptr++ */

	tbz	x16, IND_DONE_BIT, .Lloop	/* while (!(entry & DONE)) */

.Ldone:

	/* wait for writes from copy_page to finish */

	dsb	nsh

	ic	iallu