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Commit f7da281b authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Alistair Delva
Browse files

FROMLIST: arm64: mm: avoid x18 in idmap_kpti_install_ng_mappings 

idmap_kpti_install_ng_mappings uses x18 as a temporary register, which
will result in a conflict when x18 is reserved. Use x16 and x17 instead
where needed.

Bug: 145210207
Change-Id: I57cc0a9f242bd66e9ed6cb4f251ad951b63aaae8
(am from https://lore.kernel.org/patchwork/patch/1149052/

)
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
parent 9f8f79ab

arch/arm64/mm/proc.S

+31 −30
Original line number Diff line number Diff line
@@ -264,15 +264,15 @@ ENTRY(idmap_kpti_install_ng_mappings) 
	/* We're the boot CPU. Wait for the others to catch up */

	sevl

1:	wfe

	ldaxr	w18, [flag_ptr]

	eor	w18, w18, num_cpus

	cbnz	w18, 1b

	ldaxr	w17, [flag_ptr]

	eor	w17, w17, num_cpus

	cbnz	w17, 1b



	/* We need to walk swapper, so turn off the MMU. */

	pre_disable_mmu_workaround

	mrs	x18, sctlr_el1

	bic	x18, x18, #SCTLR_ELx_M

	msr	sctlr_el1, x18

	mrs	x17, sctlr_el1

	bic	x17, x17, #SCTLR_ELx_M

	msr	sctlr_el1, x17

	isb



	/* Everybody is enjoying the idmap, so we can rewrite swapper. */
@@ -295,9 +295,9 @@ skip_pgd: 
	isb



	/* We're done: fire up the MMU again */

	mrs	x18, sctlr_el1

	orr	x18, x18, #SCTLR_ELx_M

	msr	sctlr_el1, x18

	mrs	x17, sctlr_el1

	orr	x17, x17, #SCTLR_ELx_M

	msr	sctlr_el1, x17

	isb



	/*
@@ -367,45 +367,46 @@ skip_pte: 
	b.ne	do_pte

	b	next_pmd



	.unreq	cpu

	.unreq	num_cpus

	.unreq	swapper_pa

	.unreq	cur_pgdp

	.unreq	end_pgdp

	.unreq	pgd

	.unreq	cur_pudp

	.unreq	end_pudp

	.unreq	pud

	.unreq	cur_pmdp

	.unreq	end_pmdp

	.unreq	pmd

	.unreq	cur_ptep

	.unreq	end_ptep

	.unreq	pte



	/* Secondary CPUs end up here */

__idmap_kpti_secondary:

	/* Uninstall swapper before surgery begins */

	__idmap_cpu_set_reserved_ttbr1 x18, x17

	__idmap_cpu_set_reserved_ttbr1 x16, x17



	/* Increment the flag to let the boot CPU we're ready */

1:	ldxr	w18, [flag_ptr]

	add	w18, w18, #1

	stxr	w17, w18, [flag_ptr]

1:	ldxr	w16, [flag_ptr]

	add	w16, w16, #1

	stxr	w17, w16, [flag_ptr]

	cbnz	w17, 1b



	/* Wait for the boot CPU to finish messing around with swapper */

	sevl

1:	wfe

	ldxr	w18, [flag_ptr]

	cbnz	w18, 1b

	ldxr	w16, [flag_ptr]

	cbnz	w16, 1b



	/* All done, act like nothing happened */

	msr	ttbr1_el1, swapper_ttb

	isb

	ret



	.unreq	cpu

	.unreq	num_cpus

	.unreq	swapper_pa

	.unreq	swapper_ttb

	.unreq	flag_ptr

	.unreq	cur_pgdp

	.unreq	end_pgdp

	.unreq	pgd

	.unreq	cur_pudp

	.unreq	end_pudp

	.unreq	pud

	.unreq	cur_pmdp

	.unreq	end_pmdp

	.unreq	pmd

	.unreq	cur_ptep

	.unreq	end_ptep

	.unreq	pte

ENDPROC(idmap_kpti_install_ng_mappings)

	.popsection

#endif