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OVMS3-idf/components/freertos/xtensa/xtensa_loadstore_handler.S
Sachin Parekh 301dacfb33 Exception handlers for LoadStoreError and LoadStoreAlignmentError 
Configurable option to use IRAM as byte accessible memory (in single core mode) using
load-store (non-word aligned and non-word size IRAM access specific) exception handlers.
This allows to use IRAM for use-cases where certain performance penalty
(upto 170 cpu cycles per load or store operation) is acceptable. Additional configuration
option has been provided to redirect mbedTLS specific in-out content length buffers to
IRAM (in single core mode), allows to save 20KB per TLS connection.
2020-02-26 20:21:59 +08:00

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ArmAsm
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/*
Copyright 2019 Espressif Systems (Shanghai) PTE LTD
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
/*
* LoadStoreErrorCause: Occurs when trying to access 32 bit addressable memory region as 8 bit or 16 bit
* LoadStoreAlignmentCause: Occurs when trying to access in an unaligned manner
*
* xxxx xxxx = imm8 field
* yyyy = imm4 field
* ssss = s field
* tttt = t field
*
* 16 0
* -------------------
* L32I.N yyyy ssss tttt 1000
* S32I.N yyyy ssss tttt 1001
*
* 23 0
* -----------------------------
* L8UI xxxx xxxx 0000 ssss tttt 0010 <- LoadStoreError
* L16UI xxxx xxxx 0001 ssss tttt 0010 <- LoadStoreError, LoadStoreAlignment
* L16SI xxxx xxxx 1001 ssss tttt 0010 <- LoadStoreError, LoadStoreAlignment
* L32I xxxx xxxx 0010 ssss tttt 0010 <- LoadStoreAlignment
*
* S8I xxxx xxxx 0100 ssss tttt 0010 <- LoadStoreError
* S16I xxxx xxxx 0101 ssss tttt 0010 <- LoadStoreError, LoadStoreAlignment
* S32I xxxx xxxx 0110 ssss tttt 0010 <- LoadStoreAlignment
*
* ******* UNSUPPORTED *******
*
* L32E 0000 1001 rrrr ssss tttt 0000
* S32E 0100 1001 rrrr ssss tttt 0000
* -----------------------------
*/
#include "xtensa_rtos.h"
#include "sdkconfig.h"
#include "soc/soc.h"
#define LOADSTORE_HANDLER_STACK_SZ 8
.section .bss, "aw"
.balign 16
LoadStoreHandlerStack:
.rept LOADSTORE_HANDLER_STACK_SZ
.word 0
.endr
/* LoadStoreErrorCause handler:
*
* Completes 8-bit or 16-bit load/store instructions from 32-bit aligned memory region
* Called from UserExceptionVector if EXCCAUSE is LoadStoreErrorCause
*/
.global LoadStoreErrorHandler
.section .iram1, "ax"
.literal_position
.balign 4
LoadStoreErrorHandler:
.type LoadStoreErrorHandler, @function
wsr a0, depc // Save return address in depc
mov a0, sp
movi sp, LoadStoreHandlerStack
s32i a0, sp, 0x04 // Since a0 contains value of a1
s32i a2, sp, 0x08
s32i a3, sp, 0x0c
s32i a4, sp, 0x10
rsr a0, sar // Save SAR in a0 to restore later
/* Check whether the address lies in the valid range */
rsr a3, excvaddr
movi a4, _iram_text_end // End of code section of IRAM
bge a3, a4, 1f
movi a4, SOC_CACHE_APP_LOW // Check if in APP cache region
blt a3, a4, .LS_wrong_opcode
movi a4, SOC_CACHE_APP_HIGH
bge a3, a4, .LS_wrong_opcode
j 2f
1:
movi a4, SOC_IRAM_HIGH // End of IRAM address range
bge a3, a4, .LS_wrong_opcode
2:
/* Examine the opcode which generated the exception */
/* Note: Instructions are in this order to avoid pipeline stalls. */
rsr a2, epc1
movi a4, ~3
ssa8l a2 // sar is now correct shift for aligned read
and a2, a2, a4 // a2 now 4-byte aligned address of instruction
l32i a4, a2, 0
l32i a2, a2, 4
src a2, a2, a4 // a2 now instruction that failed
bbci a2, 1, .LS_wrong_opcode
bbsi a2, 14, .LSE_store_op // Store instruction
/* l8/l16ui/l16si */
movi a4, ~3
and a4, a3, a4 // a4 now word aligned read address
ssa8l a3 // sar is now shift to extract a3's byte
l32i a4, a4, 0 // perform the actual read
srl a4, a4 // shift right correct distance
extui a3, a2, 12, 4
bnez a3, 1f // l16ui/l16si
extui a4, a4, 0, 8 // mask off bits needed for an l8
j 2f
1:
extui a4, a4, 0, 16
bbci a2, 15, 2f // l16ui
/* Sign adjustment */
slli a4, a4, 16
srai a4, a4, 16 // a4 contains the value
2:
/* a4 contains the value */
rsr a3, epc1
addi a3, a3, 3
wsr a3, epc1
wsr a0, sar
rsr a0, excsave1
extui a2, a2, 3, 5
blti a2, 10, .LSE_stack_reg
movi a3, .LS_jumptable_base
addx8 a2, a2, a3 // a2 is now the address to jump to
l32i a3, sp, 0x0c
jx a2
.LSE_stack_reg:
addx2 a2, a2, sp
s32i a4, a2, 0
/* Restore all values */
l32i a4, sp, 0x10
l32i a3, sp, 0x0c
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.LSE_store_op:
s32i a5, a1, 0x14
s32i a6, a1, 0x18
/* a2 -> instruction that caused the error */
/* a3 -> unaligned address */
extui a4, a2, 4, 4
blti a4, 7, 1f
movi a5, .LSE_store_reg
addx8 a5, a4, a5
jx a5
1:
addx4 a4, a4, sp
l32i a4, a4, 0
.LSE_store_data:
/* a4 contains the value */
rsr a6, epc1
addi a6, a6, 3
wsr a6, epc1
ssa8b a3
movi a5, -1
bbsi a2, 12, 1f // s16
extui a4, a4, 0, 8
movi a6, 0xff
j 2f
1:
extui a4, a4, 0, 16
movi a6, 0xffff
2:
sll a4, a4 // shift the value to proper offset
sll a6, a6
xor a5, a5, a6 // a5 contains the mask
movi a6, ~3
and a3, a3, a6 // a3 has the aligned address
l32i a6, a3, 0 // a6 contains the data at the aligned address
and a6, a6, a5
or a4, a6, a4
s32i a4, a3, 0
/* Restore registers */
wsr a0, sar
l32i a6, sp, 0x18
l32i a5, sp, 0x14
l32i a4, sp, 0x10
l32i a3, sp, 0x0c
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rsr a0, excsave1
rfe
.LSE_store_reg:
.org .LSE_store_reg + (7 * 8)
mov a4, a7
j .LSE_store_data
.org .LSE_store_reg + (8 * 8)
mov a4, a8
j .LSE_store_data
.org .LSE_store_reg + (9 * 8)
mov a4, a9
j .LSE_store_data
.org .LSE_store_reg + (10 * 8)
mov a4, a10
j .LSE_store_data
.org .LSE_store_reg + (11 * 8)
mov a4, a11
j .LSE_store_data
.org .LSE_store_reg + (12 * 8)
mov a4, a12
j .LSE_store_data
.org .LSE_store_reg + (13 * 8)
mov a4, a13
j .LSE_store_data
.org .LSE_store_reg + (14 * 8)
mov a4, a14
j .LSE_store_data
.org .LSE_store_reg + (15 * 8)
mov a4, a15
j .LSE_store_data
/* LoadStoreAlignmentCause handler:
*
* Completes unaligned 16-bit and 32-bit load/store instructions from 32-bit aligned memory region
* Called from UserExceptionVector if EXCCAUSE is LoadStoreAlignmentCause
*/
.global AlignmentErrorHandler
.section .iram1, "ax"
.literal_position
.balign 4
AlignmentErrorHandler:
.type AlignmentErrorHandler, @function
wsr a0, depc // Save return address in depc
mov a0, sp
movi sp, LoadStoreHandlerStack
s32i a0, sp, 0x04 // Since a0 contains value of a1
s32i a2, sp, 0x08
s32i a3, sp, 0x0c
s32i a4, sp, 0x10
rsr a0, sar // Save SAR in a0 to restore later
/* Check whether the address lies in the valid range */
rsr a3, excvaddr
movi a4, _iram_text_end // End of code section of IRAM
bge a3, a4, 1f
movi a4, SOC_CACHE_APP_LOW // Check if in APP cache region
blt a3, a4, .LS_wrong_opcode
movi a4, SOC_CACHE_APP_HIGH
bge a3, a4, .LS_wrong_opcode
j 2f
1:
movi a4, SOC_IRAM_HIGH // End of IRAM address range
bge a3, a4, .LS_wrong_opcode
2:
/* Examine the opcode which generated the exception */
/* Note: Instructions are in this order to avoid pipeline stalls. */
rsr a2, epc1
movi a4, ~3
ssa8l a2 // sar is now correct shift for aligned read
and a2, a2, a4 // a2 now 4-byte aligned address of instruction
l32i a4, a2, 0
l32i a2, a2, 4
/* a2 has the instruction that caused the error */
src a2, a2, a4
extui a4, a2, 0, 4
addi a4, a4, -9
beqz a4, .LSA_store_op
bbsi a2, 14, .LSA_store_op
ssa8l a3 // a3 contains the unaligned address
movi a4, ~3
and a4, a3, a4 // a4 has the aligned address
l32i a3, a4, 0
l32i a4, a4, 4
src a4, a4, a3
rsr a3, epc1
addi a3, a3, 2
bbsi a2, 3, 1f // l32i.n
bbci a2, 1, .LS_wrong_opcode
addi a3, a3, 1
bbsi a2, 13, 1f // l32
extui a4, a4, 0, 16
bbci a2, 15, 1f // l16ui
/* Sign adjustment */
slli a4, a4, 16
srai a4, a4, 16 // a4 contains the value
1:
wsr a3, epc1
wsr a0, sar
rsr a0, excsave1
extui a2, a2, 4, 4
blti a2, 5, .LSA_stack_reg // a3 contains the target register
movi a3, .LS_jumptable_base
slli a2, a2, 4
add a2, a2, a3 // a2 is now the address to jump to
l32i a3, sp, 0x0c
jx a2
.LSA_stack_reg:
addx4 a2, a2, sp
s32i a4, a2, 0
/* Restore all values */
l32i a4, sp, 0x10
l32i a3, sp, 0x0c
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
/* Store instruction */
.LSA_store_op:
s32i a5, sp, 0x14
s32i a6, sp, 0x18
s32i a7, sp, 0x1c
/* a2 -> instruction that caused the error */
/* a3 -> unaligned address */
extui a4, a2, 4, 4
blti a4, 8, 1f
movi a5, .LSA_store_reg
addx8 a5, a4, a5
jx a5
1:
addx4 a4, a4, sp
l32i a4, a4, 0 // a4 contains the value
.LSA_store_data:
movi a6, 0
rsr a7, epc1
addi a7, a7 ,2
bbsi a2, 3, 1f // s32i.n
bbci a2, 1, .LS_wrong_opcode
addi a7, a7, 1
bbsi a2, 13, 1f // s32i
movi a5, -1
extui a4, a4, 0, 16
slli a6, a5, 16 // 0xffff0000
1:
wsr a7, epc1
movi a5, ~3
and a5, a3, a5 // a5 has the aligned address
ssa8b a3
movi a3, -1
src a7, a6, a3
src a3, a3, a6
/* Store data on lower address */
l32i a6, a5, 0
and a6, a6, a7
sll a7, a4
or a6, a6, a7
s32i a6, a5, 0
/* Store data on higher address */
l32i a7, a5, 4
srl a6, a4
and a3, a7, a3
or a3, a3, a6
s32i a3, a5, 4
/* Restore registers */
wsr a0, sar
rsr a0, excsave1
l32i a7, sp, 0x1c
l32i a6, sp, 0x18
l32i a5, sp, 0x14
l32i a4, sp, 0x10
l32i a3, sp, 0x0c
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.LSA_store_reg:
.org .LSA_store_reg + (8 * 8)
mov a4, a8
j .LSA_store_data
.org .LSA_store_reg + (9 * 8)
mov a4, a9
j .LSA_store_data
.org .LSA_store_reg + (10 * 8)
mov a4, a10
j .LSA_store_data
.org .LSA_store_reg + (11 * 8)
mov a4, a11
j .LSA_store_data
.org .LSA_store_reg + (12 * 8)
mov a4, a12
j .LSA_store_data
.org .LSA_store_reg + (13 * 8)
mov a4, a13
j .LSA_store_data
.org .LSA_store_reg + (14 * 8)
mov a4, a14
j .LSA_store_data
.org .LSA_store_reg + (15 * 8)
mov a4, a15
j .LSA_store_data
/*
* Common routines for both the exception handlers
*/
.balign 4
.LS_jumptable:
/* The first 5 entries (80 bytes) of this table are unused (registers
a0..a4 are handled separately above). Rather than have a whole bunch
of wasted space, just pretend that the table starts 80 bytes
earlier in memory. */
.set .LS_jumptable_base, .LS_jumptable - (16 * 5)
.org .LS_jumptable_base + (16 * 5)
mov a5, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 6)
mov a6, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 7)
mov a7, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 8)
mov a8, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 9)
mov a9, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 10)
mov a10, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 11)
mov a11, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 12)
mov a12, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 13)
mov a13, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 14)
mov a14, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.org .LS_jumptable_base + (16 * 15)
mov a15, a4
l32i a4, sp, 0x10
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rfe
.LS_wrong_opcode:
/* Reaches here if the address is in invalid range or the opcode isn't supported.
* Restore registers and jump back to _xt_user_exc
*/
wsr a0, sar
l32i a4, sp, 0x10
l32i a3, sp, 0x0c
l32i a2, sp, 0x08
l32i a1, sp, 0x04
rsr a0, depc
ret // Equivalent to jx a0
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