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arm-trusted-firmware/bl32/tsp/aarch64/tsp_entrypoint.S
Achin Gupta 54dc71e7ec Make generic code work in presence of system caches 
On the ARMv8 architecture, cache maintenance operations by set/way on the last
level of integrated cache do not affect the system cache. This means that such a
flush or clean operation could result in the data being pushed out to the system
cache rather than main memory. Another CPU could access this data before it
enables its data cache or MMU. Such accesses could be serviced from the main
memory instead of the system cache. If the data in the sysem cache has not yet
been flushed or evicted to main memory then there could be a loss of
coherency. The only mechanism to guarantee that the main memory will be updated
is to use cache maintenance operations to the PoC by MVA(See section D3.4.11
(System level caches) of ARMv8-A Reference Manual (Issue A.g/ARM DDI0487A.G).

This patch removes the reliance of Trusted Firmware on the flush by set/way
operation to ensure visibility of data in the main memory. Cache maintenance
operations by MVA are now used instead. The following are the broad category of
changes:

1. The RW areas of BL2/BL31/BL32 are invalidated by MVA before the C runtime is
   initialised. This ensures that any stale cache lines at any level of cache
   are removed.

2. Updates to global data in runtime firmware (BL31) by the primary CPU are made
   visible to secondary CPUs using a cache clean operation by MVA.

3. Cache maintenance by set/way operations are only used prior to power down.

NOTE: NON-UPSTREAM TRUSTED FIRMWARE CODE SHOULD MAKE EQUIVALENT CHANGES IN
ORDER TO FUNCTION CORRECTLY ON PLATFORMS WITH SUPPORT FOR SYSTEM CACHES.

Fixes ARM-software/tf-issues#205

Change-Id: I64f1b398de0432813a0e0881d70f8337681f6e9a
2015-09-14 22:09:40 +01:00

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/*
* Copyright (c) 2013-2015, 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>
#include <xlat_tables.h>
#include "../tsp_private.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
/* ---------------------------------------------
* Set the exception vector to something sane.
* ---------------------------------------------
*/
adr x0, tsp_exceptions
msr vbar_el1, x0
isb
/* ---------------------------------------------
* Enable the SError interrupt now that the
* exception vectors have been setup.
* ---------------------------------------------
*/
msr daifclr, #DAIF_ABT_BIT
/* ---------------------------------------------
* Enable the instruction cache, stack pointer
* and data access alignment checks
* ---------------------------------------------
*/
mov x1, #(SCTLR_I_BIT | SCTLR_A_BIT | SCTLR_SA_BIT)
mrs x0, sctlr_el1
orr x0, x0, x1
msr sctlr_el1, x0
isb
/* ---------------------------------------------
* Invalidate the RW memory used by the BL32
* image. This includes the data and NOBITS
* sections. This is done to safeguard against
* possible corruption of this memory by dirty
* cache lines in a system cache as a result of
* use by an earlier boot loader stage.
* ---------------------------------------------
*/
adr x0, __RW_START__
adr x1, __RW_END__
sub x1, x1, x0
bl inv_dcache_range
/* ---------------------------------------------
* 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
#if USE_COHERENT_MEM
ldr x0, =__COHERENT_RAM_START__
ldr x1, =__COHERENT_RAM_UNALIGNED_SIZE__
bl zeromem16
#endif
/* --------------------------------------------
* 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.
* --------------------------------------------
*/
bl plat_set_my_stack
/* ---------------------------------------------
* Perform early platform setup & platform
* specific early arch. setup e.g. mmu setup
* ---------------------------------------------
*/
bl tsp_early_platform_setup
bl tsp_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
endfunc tsp_entrypoint
/* -------------------------------------------
* 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
b tsp_system_off_entry
b tsp_system_reset_entry
endfunc tsp_vector_table
/*---------------------------------------------
* 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
endfunc tsp_cpu_off_entry
/*---------------------------------------------
* This entrypoint is used by the TSPD when the
* system is about to be switched off (through
* a SYSTEM_OFF psci call) to ask the TSP to
* perform any necessary bookkeeping.
* ---------------------------------------------
*/
func tsp_system_off_entry
bl tsp_system_off_main
restore_args_call_smc
endfunc tsp_system_off_entry
/*---------------------------------------------
* This entrypoint is used by the TSPD when the
* system is about to be reset (through a
* SYSTEM_RESET psci call) to ask the TSP to
* perform any necessary bookkeeping.
* ---------------------------------------------
*/
func tsp_system_reset_entry
bl tsp_system_reset_main
restore_args_call_smc
endfunc tsp_system_reset_entry
/*---------------------------------------------
* 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
isb
/* Enable the SError interrupt */
msr daifclr, #DAIF_ABT_BIT
/* ---------------------------------------------
* Enable the instruction cache, stack pointer
* and data access alignment checks
* ---------------------------------------------
*/
mov x1, #(SCTLR_I_BIT | SCTLR_A_BIT | SCTLR_SA_BIT)
mrs x0, sctlr_el1
orr x0, x0, x1
msr sctlr_el1, x0
isb
/* --------------------------------------------
* Give ourselves a stack whose memory will be
* marked as Normal-IS-WBWA when the MMU is
* enabled.
* --------------------------------------------
*/
bl plat_set_my_stack
/* --------------------------------------------
* Enable the MMU with the DCache disabled. It
* is safe to use stacks allocated in normal
* memory as a result. All memory accesses are
* marked nGnRnE when the MMU is disabled. So
* all the stack writes will make it to memory.
* All memory accesses are marked Non-cacheable
* when the MMU is enabled but D$ is disabled.
* So used stack memory is guaranteed to be
* visible immediately after the MMU is enabled
* Enabling the DCache at the same time as the
* MMU can lead to speculatively fetched and
* possibly stale stack memory being read from
* other caches. This can lead to coherency
* issues.
* --------------------------------------------
*/
mov x0, #DISABLE_DCACHE
bl bl32_plat_enable_mmu
/* ---------------------------------------------
* Enable the Data cache now that the MMU has
* been enabled. The stack has been unwound. It
* will be written first before being read. This
* will invalidate any stale cache lines resi-
* -dent in other caches. We assume that
* interconnect coherency has been enabled for
* this cluster by EL3 firmware.
* ---------------------------------------------
*/
mrs x0, sctlr_el1
orr x0, x0, #SCTLR_C_BIT
msr sctlr_el1, x0
isb
/* ---------------------------------------------
* 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
endfunc tsp_cpu_on_entry
/*---------------------------------------------
* 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
endfunc tsp_cpu_suspend_entry
/*---------------------------------------------
* 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
endfunc tsp_fiq_entry
/*---------------------------------------------
* 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
endfunc tsp_cpu_resume_entry
/*---------------------------------------------
* 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
endfunc tsp_fast_smc_entry
/*---------------------------------------------
* 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
endfunc tsp_std_smc_entry
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