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linux/arch/arm64/kernel/cpu-reset.S

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arm64: Add back cpu reset routines Commit 68234df4ea79 ("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: Geoff Levand <geoff@infradead.org> Reviewed-by: James Morse <james.morse@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-06-24 01:54:48 +08:00
/*
* 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
arm64: Add software workaround for Falkor erratum 1041 The ARM architecture defines the memory locations that are permitted to be accessed as the result of a speculative instruction fetch from an exception level for which all stages of translation are disabled. Specifically, the core is permitted to speculatively fetch from the 4KB region containing the current program counter 4K and next 4K. When translation is changed from enabled to disabled for the running exception level (SCTLR_ELn[M] changed from a value of 1 to 0), the Falkor core may errantly speculatively access memory locations outside of the 4KB region permitted by the architecture. The errant memory access may lead to one of the following unexpected behaviors. 1) A System Error Interrupt (SEI) being raised by the Falkor core due to the errant memory access attempting to access a region of memory that is protected by a slave-side memory protection unit. 2) Unpredictable device behavior due to a speculative read from device memory. This behavior may only occur if the instruction cache is disabled prior to or coincident with translation being changed from enabled to disabled. The conditions leading to this erratum will not occur when either of the following occur: 1) A higher exception level disables translation of a lower exception level (e.g. EL2 changing SCTLR_EL1[M] from a value of 1 to 0). 2) An exception level disabling its stage-1 translation if its stage-2 translation is enabled (e.g. EL1 changing SCTLR_EL1[M] from a value of 1 to 0 when HCR_EL2[VM] has a value of 1). To avoid the errant behavior, software must execute an ISB immediately prior to executing the MSR that will change SCTLR_ELn[M] from 1 to 0. Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-01-29 19:59:52 +08:00
pre_disable_mmu_workaround
arm64: Add back cpu reset routines Commit 68234df4ea79 ("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: Geoff Levand <geoff@infradead.org> Reviewed-by: James Morse <james.morse@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-06-24 01:54:48 +08:00
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