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Commit f9076ecf authored by Geoff Levand's avatar Geoff Levand Committed by Catalin Marinas
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arm64: Add back cpu reset routines 



Commit 68234df4 ("arm64: kill flush_cache_all()") removed the global
arm64 routines cpu_reset() and cpu_soft_restart() needed by the arm64
kexec and kdump support.  Add back a simplified version of
cpu_soft_restart() with some changes needed for kexec in the new files
cpu_reset.S, and cpu_reset.h.

When a CPU is reset it needs to be put into the exception level it had when
it entered the kernel. Update cpu_soft_restart() to accept an argument
which signals if the reset address should be entered at EL1 or EL2, and
add a new hypercall HVC_SOFT_RESTART which is used for the EL2 switch.

Signed-off-by: default avatarGeoff Levand <geoff@infradead.org>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent b69e0dc1

arch/arm64/include/asm/virt.h

+5 −0
Original line number Diff line number Diff line
@@ -34,6 +34,11 @@ 
 */

#define HVC_SET_VECTORS 1



/*

 * HVC_SOFT_RESTART - CPU soft reset, used by the cpu_soft_restart routine.

 */

#define HVC_SOFT_RESTART 2



#define BOOT_CPU_MODE_EL1	(0xe11)

#define BOOT_CPU_MODE_EL2	(0xe12)

arch/arm64/kernel/cpu-reset.S

0 → 100644
+54 −0
Original line number Diff line number Diff line 
/*

 * CPU reset routines

 *

 * Copyright (C) 2001 Deep Blue Solutions Ltd.

 * Copyright (C) 2012 ARM Ltd.

 * Copyright (C) 2015 Huawei Futurewei Technologies.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



#include <linux/linkage.h>

#include <asm/assembler.h>

#include <asm/sysreg.h>

#include <asm/virt.h>



.text

.pushsection    .idmap.text, "ax"



/*

 * __cpu_soft_restart(el2_switch, entry, arg0, arg1, arg2) - Helper for

 * cpu_soft_restart.

 *

 * @el2_switch: Flag to indicate a swich to EL2 is needed.

 * @entry: Location to jump to for soft reset.

 * arg0: First argument passed to @entry.

 * arg1: Second argument passed to @entry.

 * arg2: Third argument passed to @entry.

 *

 * Put the CPU into the same state as it would be if it had been reset, and

 * branch to what would be the reset vector. It must be executed with the

 * flat identity mapping.

 */

ENTRY(__cpu_soft_restart)

	/* Clear sctlr_el1 flags. */

	mrs	x12, sctlr_el1

	ldr	x13, =SCTLR_ELx_FLAGS

	bic	x12, x12, x13

	msr	sctlr_el1, x12

	isb



	cbz	x0, 1f				// el2_switch?

	mov	x0, #HVC_SOFT_RESTART

	hvc	#0				// no return



1:	mov	x18, x1				// entry

	mov	x0, x2				// arg0

	mov	x1, x3				// arg1

	mov	x2, x4				// arg2

	br	x18

ENDPROC(__cpu_soft_restart)



.popsection

arch/arm64/kernel/cpu-reset.h

0 → 100644
+34 −0
Original line number Diff line number Diff line 
/*

 * CPU reset routines

 *

 * Copyright (C) 2015 Huawei Futurewei Technologies.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



#ifndef _ARM64_CPU_RESET_H

#define _ARM64_CPU_RESET_H



#include <asm/virt.h>



void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry,

	unsigned long arg0, unsigned long arg1, unsigned long arg2);



static inline void __noreturn cpu_soft_restart(unsigned long el2_switch,

	unsigned long entry, unsigned long arg0, unsigned long arg1,

	unsigned long arg2)

{

	typeof(__cpu_soft_restart) *restart;



	el2_switch = el2_switch && !is_kernel_in_hyp_mode() &&

		is_hyp_mode_available();

	restart = (void *)virt_to_phys(__cpu_soft_restart);



	cpu_install_idmap();

	restart(el2_switch, entry, arg0, arg1, arg2);

	unreachable();

}



#endif

arch/arm64/kernel/hyp-stub.S

+9 −1
Original line number Diff line number Diff line
@@ -71,8 +71,16 @@ el1_sync: 
	msr	vbar_el2, x1

	b	9f



2:	cmp	x0, #HVC_SOFT_RESTART

	b.ne	3f

	mov	x0, x2

	mov	x2, x4

	mov	x4, x1

	mov	x1, x3

	br	x4				// no return



	/* Someone called kvm_call_hyp() against the hyp-stub... */

2:	mov     x0, #ARM_EXCEPTION_HYP_GONE

3:	mov	x0, #ARM_EXCEPTION_HYP_GONE



9:	eret

ENDPROC(el1_sync)