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arm-trusted-firmware/bl32/tsp/aarch64/tsp_entrypoint.S
Achin Gupta 754a2b7a09 Remove coherent stack usage from the cold boot path 
This patch reworks the cold boot path across the BL1, BL2, BL3-1 and BL3-2 boot
loader stages to not use stacks allocated in coherent memory for early platform
setup and enabling the MMU. Stacks allocated in normal memory are used instead.

Attributes for stack memory change from nGnRnE when the MMU is disabled to
Normal WBWA Inner-shareable when the MMU and data cache are enabled. It is
possible for the CPU to read stale stack memory after the MMU is enabled from
another CPUs cache. Hence, it is unsafe to turn on the MMU and data cache while
using normal stacks when multiple CPUs are a part of the same coherency
domain. It is safe to do so in the cold boot path as only the primary cpu
executes it. The secondary cpus are in a quiescent state.

This patch does not remove the allocation of coherent stack memory. That is done
in a subsequent patch.

Change-Id: I12c80b7c7ab23506d425c5b3a8a7de693498f830
2014-07-19 23:31:50 +01:00

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/*
* Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of ARM nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <arch.h>
#include <asm_macros.S>
#include <tsp.h>
.globl tsp_entrypoint
.globl tsp_vector_table
/* ---------------------------------------------
* Populate the params in x0-x7 from the pointer
* to the smc args structure in x0.
* ---------------------------------------------
*/
.macro restore_args_call_smc
ldp x6, x7, [x0, #TSP_ARG6]
ldp x4, x5, [x0, #TSP_ARG4]
ldp x2, x3, [x0, #TSP_ARG2]
ldp x0, x1, [x0, #TSP_ARG0]
smc #0
.endm
.macro save_eret_context reg1 reg2
mrs \reg1, elr_el1
mrs \reg2, spsr_el1
stp \reg1, \reg2, [sp, #-0x10]!
stp x30, x18, [sp, #-0x10]!
.endm
.macro restore_eret_context reg1 reg2
ldp x30, x18, [sp], #0x10
ldp \reg1, \reg2, [sp], #0x10
msr elr_el1, \reg1
msr spsr_el1, \reg2
.endm
.section .text, "ax"
.align 3
func tsp_entrypoint
/* ---------------------------------------------
* The entrypoint is expected to be executed
* only by the primary cpu (at least for now).
* So, make sure no secondary has lost its way.
* ---------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_is_primary_cpu
cbz x0, tsp_entrypoint_panic
/* ---------------------------------------------
* Set the exception vector to something sane.
* ---------------------------------------------
*/
adr x0, tsp_exceptions
msr vbar_el1, x0
/* ---------------------------------------------
* Enable the instruction cache.
* ---------------------------------------------
*/
mrs x0, sctlr_el1
orr x0, x0, #SCTLR_I_BIT
msr sctlr_el1, x0
isb
/* ---------------------------------------------
* Zero out NOBITS sections. There are 2 of them:
* - the .bss section;
* - the coherent memory section.
* ---------------------------------------------
*/
ldr x0, =__BSS_START__
ldr x1, =__BSS_SIZE__
bl zeromem16
ldr x0, =__COHERENT_RAM_START__
ldr x1, =__COHERENT_RAM_UNALIGNED_SIZE__
bl zeromem16
/* --------------------------------------------
* Allocate a stack whose memory will be marked
* as Normal-IS-WBWA when the MMU is enabled.
* There is no risk of reading stale stack
* memory after enabling the MMU as only the
* primary cpu is running at the moment.
* --------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_stack
/* ---------------------------------------------
* Perform early platform setup & platform
* specific early arch. setup e.g. mmu setup
* ---------------------------------------------
*/
bl bl32_early_platform_setup
bl bl32_plat_arch_setup
/* ---------------------------------------------
* Jump to main function.
* ---------------------------------------------
*/
bl tsp_main
/* ---------------------------------------------
* Tell TSPD that we are done initialising
* ---------------------------------------------
*/
mov x1, x0
mov x0, #TSP_ENTRY_DONE
smc #0
tsp_entrypoint_panic:
b tsp_entrypoint_panic
/* -------------------------------------------
* Table of entrypoint vectors provided to the
* TSPD for the various entrypoints
* -------------------------------------------
*/
func tsp_vector_table
b tsp_std_smc_entry
b tsp_fast_smc_entry
b tsp_cpu_on_entry
b tsp_cpu_off_entry
b tsp_cpu_resume_entry
b tsp_cpu_suspend_entry
b tsp_fiq_entry
/*---------------------------------------------
* This entrypoint is used by the TSPD when this
* cpu is to be turned off through a CPU_OFF
* psci call to ask the TSP to perform any
* bookeeping necessary. In the current
* implementation, the TSPD expects the TSP to
* re-initialise its state so nothing is done
* here except for acknowledging the request.
* ---------------------------------------------
*/
func tsp_cpu_off_entry
bl tsp_cpu_off_main
restore_args_call_smc
/*---------------------------------------------
* This entrypoint is used by the TSPD when this
* cpu is turned on using a CPU_ON psci call to
* ask the TSP to initialise itself i.e. setup
* the mmu, stacks etc. Minimal architectural
* state will be initialised by the TSPD when
* this function is entered i.e. Caches and MMU
* will be turned off, the execution state
* will be aarch64 and exceptions masked.
* ---------------------------------------------
*/
func tsp_cpu_on_entry
/* ---------------------------------------------
* Set the exception vector to something sane.
* ---------------------------------------------
*/
adr x0, tsp_exceptions
msr vbar_el1, x0
/* ---------------------------------------------
* Enable the instruction cache.
* ---------------------------------------------
*/
mrs x0, sctlr_el1
orr x0, x0, #SCTLR_I_BIT
msr sctlr_el1, x0
isb
/* --------------------------------------------
* Give ourselves a small coherent stack to
* ease the pain of initializing the MMU
* --------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_coherent_stack
/* ---------------------------------------------
* Initialise the MMU
* ---------------------------------------------
*/
bl bl32_plat_enable_mmu
/* ---------------------------------------------
* Give ourselves a stack allocated in Normal
* -IS-WBWA memory
* ---------------------------------------------
*/
mrs x0, mpidr_el1
bl platform_set_stack
/* ---------------------------------------------
* Enter C runtime to perform any remaining
* book keeping
* ---------------------------------------------
*/
bl tsp_cpu_on_main
restore_args_call_smc
/* Should never reach here */
tsp_cpu_on_entry_panic:
b tsp_cpu_on_entry_panic
/*---------------------------------------------
* This entrypoint is used by the TSPD when this
* cpu is to be suspended through a CPU_SUSPEND
* psci call to ask the TSP to perform any
* bookeeping necessary. In the current
* implementation, the TSPD saves and restores
* the EL1 state.
* ---------------------------------------------
*/
func tsp_cpu_suspend_entry
bl tsp_cpu_suspend_main
restore_args_call_smc
/*---------------------------------------------
* This entrypoint is used by the TSPD to pass
* control for handling a pending S-EL1 FIQ.
* 'x0' contains a magic number which indicates
* this. TSPD expects control to be handed back
* at the end of FIQ processing. This is done
* through an SMC. The handover agreement is:
*
* 1. PSTATE.DAIF are set upon entry. 'x1' has
* the ELR_EL3 from the non-secure state.
* 2. TSP has to preserve the callee saved
* general purpose registers, SP_EL1/EL0 and
* LR.
* 3. TSP has to preserve the system and vfp
* registers (if applicable).
* 4. TSP can use 'x0-x18' to enable its C
* runtime.
* 5. TSP returns to TSPD using an SMC with
* 'x0' = TSP_HANDLED_S_EL1_FIQ
* ---------------------------------------------
*/
func tsp_fiq_entry
#if DEBUG
mov x2, #(TSP_HANDLE_FIQ_AND_RETURN & ~0xffff)
movk x2, #(TSP_HANDLE_FIQ_AND_RETURN & 0xffff)
cmp x0, x2
b.ne tsp_fiq_entry_panic
#endif
/*---------------------------------------------
* Save any previous context needed to perform
* an exception return from S-EL1 e.g. context
* from a previous IRQ. Update statistics and
* handle the FIQ before returning to the TSPD.
* IRQ/FIQs are not enabled since that will
* complicate the implementation. Execution
* will be transferred back to the normal world
* in any case. A non-zero return value from the
* fiq handler is an error.
* ---------------------------------------------
*/
save_eret_context x2 x3
bl tsp_update_sync_fiq_stats
bl tsp_fiq_handler
cbnz x0, tsp_fiq_entry_panic
restore_eret_context x2 x3
mov x0, #(TSP_HANDLED_S_EL1_FIQ & ~0xffff)
movk x0, #(TSP_HANDLED_S_EL1_FIQ & 0xffff)
smc #0
tsp_fiq_entry_panic:
b tsp_fiq_entry_panic
/*---------------------------------------------
* This entrypoint is used by the TSPD when this
* cpu resumes execution after an earlier
* CPU_SUSPEND psci call to ask the TSP to
* restore its saved context. In the current
* implementation, the TSPD saves and restores
* EL1 state so nothing is done here apart from
* acknowledging the request.
* ---------------------------------------------
*/
func tsp_cpu_resume_entry
bl tsp_cpu_resume_main
restore_args_call_smc
tsp_cpu_resume_panic:
b tsp_cpu_resume_panic
/*---------------------------------------------
* This entrypoint is used by the TSPD to ask
* the TSP to service a fast smc request.
* ---------------------------------------------
*/
func tsp_fast_smc_entry
bl tsp_smc_handler
restore_args_call_smc
tsp_fast_smc_entry_panic:
b tsp_fast_smc_entry_panic
/*---------------------------------------------
* This entrypoint is used by the TSPD to ask
* the TSP to service a std smc request.
* We will enable preemption during execution
* of tsp_smc_handler.
* ---------------------------------------------
*/
func tsp_std_smc_entry
msr daifclr, #DAIF_FIQ_BIT | DAIF_IRQ_BIT
bl tsp_smc_handler
msr daifset, #DAIF_FIQ_BIT | DAIF_IRQ_BIT
restore_args_call_smc
tsp_std_smc_entry_panic:
b tsp_std_smc_entry_panic
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