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https://github.com/ARM-software/arm-trusted-firmware.git
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b51da82182
This patch uses stacks allocated in normal memory to enable the MMU early in the warm boot path thus removing the dependency on stacks allocated in coherent memory. Necessary cache and stack maintenance is performed when a cpu is being powered down and up. This avoids any coherency issues that can arise from reading speculatively fetched stale stack memory from another CPUs cache. These changes affect the warm boot path in both BL3-1 and BL3-2. The EL3 system registers responsible for preserving the MMU state are not saved and restored any longer. Static values are used to program these system registers when a cpu is powered on or resumed from suspend. Change-Id: I8357e2eb5eb6c5f448492c5094b82b8927603784
143 lines
4.8 KiB
ArmAsm
143 lines
4.8 KiB
ArmAsm
/*
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* Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of ARM nor the names of its contributors may be used
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* to endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <arch.h>
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#include <asm_macros.S>
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#include <psci.h>
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#include <xlat_tables.h>
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.globl psci_aff_on_finish_entry
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.globl psci_aff_suspend_finish_entry
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.globl __psci_cpu_off
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.globl __psci_cpu_suspend
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.globl psci_power_down_wfi
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/* -----------------------------------------------------
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* This cpu has been physically powered up. Depending
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* upon whether it was resumed from suspend or simply
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* turned on, call the common power on finisher with
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* the handlers (chosen depending upon original state).
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* For ease, the finisher is called with coherent
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* stacks. This allows the cluster/cpu finishers to
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* enter coherency and enable the mmu without running
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* into issues. We switch back to normal stacks once
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* all this is done.
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* -----------------------------------------------------
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*/
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func psci_aff_on_finish_entry
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adr x23, psci_afflvl_on_finishers
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b psci_aff_common_finish_entry
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psci_aff_suspend_finish_entry:
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adr x23, psci_afflvl_suspend_finishers
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psci_aff_common_finish_entry:
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/* ---------------------------------------------
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* Initialise the pcpu cache pointer for the CPU
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* ---------------------------------------------
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*/
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bl init_cpu_data_ptr
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/* ---------------------------------------------
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* Set the exception vectors
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* ---------------------------------------------
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*/
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adr x0, runtime_exceptions
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msr vbar_el3, x0
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isb
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/* ---------------------------------------------
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* Use SP_EL0 for the C runtime stack.
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* ---------------------------------------------
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*/
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msr spsel, #0
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/* --------------------------------------------
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* Give ourselves a stack whose memory will be
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* marked as Normal-IS-WBWA when the MMU is
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* enabled.
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* --------------------------------------------
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*/
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mrs x0, mpidr_el1
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bl platform_set_stack
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/* --------------------------------------------
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* Enable the MMU with the DCache disabled. It
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* is safe to use stacks allocated in normal
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* memory as a result. All memory accesses are
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* marked nGnRnE when the MMU is disabled. So
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* all the stack writes will make it to memory.
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* All memory accesses are marked Non-cacheable
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* when the MMU is enabled but D$ is disabled.
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* So used stack memory is guaranteed to be
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* visible immediately after the MMU is enabled
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* Enabling the DCache at the same time as the
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* MMU can lead to speculatively fetched and
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* possibly stale stack memory being read from
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* other caches. This can lead to coherency
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* issues.
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* --------------------------------------------
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*/
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mov x0, #DISABLE_DCACHE
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bl bl31_plat_enable_mmu
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/* ---------------------------------------------
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* Call the finishers starting from affinity
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* level 0.
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* ---------------------------------------------
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*/
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mrs x0, mpidr_el1
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bl get_power_on_target_afflvl
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cmp x0, xzr
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b.lt _panic
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mov x2, x23
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mov x1, x0
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mov x0, #MPIDR_AFFLVL0
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bl psci_afflvl_power_on_finish
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b el3_exit
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_panic:
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b _panic
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/* --------------------------------------------
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* This function is called to indicate to the
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* power controller that it is safe to power
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* down this cpu. It should not exit the wfi
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* and will be released from reset upon power
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* up. 'wfi_spill' is used to catch erroneous
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* exits from wfi.
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* --------------------------------------------
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*/
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func psci_power_down_wfi
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dsb sy // ensure write buffer empty
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wfi
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wfi_spill:
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b wfi_spill
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