Commit 623b476f authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
Browse files

arm64: move sp_el0 and tpidr_el1 into cpu_suspend_ctx 



When returning from idle, we rely on the fact that thread_info lives at
the end of the kernel stack, and restore this by masking the saved stack
pointer. Subsequent patches will sever the relationship between the
stack and thread_info, and to cater for this we must save/restore sp_el0
explicitly, storing it in cpu_suspend_ctx.

As cpu_suspend_ctx must be doubleword aligned, this leaves us with an
extra slot in cpu_suspend_ctx. We can use this to save/restore tpidr_el1
in the same way, which simplifies the code, avoiding pointer chasing on
the restore path (as we no longer need to load thread_info::cpu followed
by the relevant slot in __per_cpu_offset based on this).

This patch stashes both registers in cpu_suspend_ctx.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by: default avatarLaura Abbott <labbott@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 9bbd4c56

arch/arm64/include/asm/suspend.h

+1 −1
Original line number Diff line number Diff line 
#ifndef __ASM_SUSPEND_H

#define __ASM_SUSPEND_H



#define NR_CTX_REGS 10

#define NR_CTX_REGS 12

#define NR_CALLEE_SAVED_REGS 12



/*

arch/arm64/kernel/sleep.S

+0 −3
Original line number Diff line number Diff line
@@ -125,9 +125,6 @@ ENTRY(_cpu_resume) 
	/* load sp from context */

	ldr	x2, [x0, #CPU_CTX_SP]

	mov	sp, x2

	/* save thread_info */

	and	x2, x2, #~(THREAD_SIZE - 1)

	msr	sp_el0, x2

	/*

	 * cpu_do_resume expects x0 to contain context address pointer

	 */

arch/arm64/kernel/suspend.c

+0 −6
Original line number Diff line number Diff line
@@ -46,12 +46,6 @@ void notrace __cpu_suspend_exit(void) 
	 */

	cpu_uninstall_idmap();



	/*

	 * Restore per-cpu offset before any kernel

	 * subsystem relying on it has a chance to run.

	 */

	set_my_cpu_offset(per_cpu_offset(cpu));



	/*

	 * PSTATE was not saved over suspend/resume, re-enable any detected

	 * features that might not have been set correctly.

arch/arm64/mm/proc.S

+6 −0
Original line number Diff line number Diff line
@@ -70,11 +70,14 @@ ENTRY(cpu_do_suspend) 
	mrs	x8, mdscr_el1

	mrs	x9, oslsr_el1

	mrs	x10, sctlr_el1

	mrs	x11, tpidr_el1

	mrs	x12, sp_el0

	stp	x2, x3, [x0]

	stp	x4, xzr, [x0, #16]

	stp	x5, x6, [x0, #32]

	stp	x7, x8, [x0, #48]

	stp	x9, x10, [x0, #64]

	stp	x11, x12, [x0, #80]

	ret

ENDPROC(cpu_do_suspend)
@@ -90,6 +93,7 @@ ENTRY(cpu_do_resume) 
	ldp	x6, x8, [x0, #32]

	ldp	x9, x10, [x0, #48]

	ldp	x11, x12, [x0, #64]

	ldp	x13, x14, [x0, #80]

	msr	tpidr_el0, x2

	msr	tpidrro_el0, x3

	msr	contextidr_el1, x4
@@ -112,6 +116,8 @@ ENTRY(cpu_do_resume) 
	msr	mdscr_el1, x10



	msr	sctlr_el1, x12

	msr	tpidr_el1, x13

	msr	sp_el0, x14

	/*

	 * Restore oslsr_el1 by writing oslar_el1

	 */

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