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Initial public version
2016-08-17 11:08:22 -04:00
/*******************************************************************************
Copyright (c) 2006-2015 Cadence Design Systems Inc.
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
--------------------------------------------------------------------------------
XTENSA VECTORS AND LOW LEVEL HANDLERS FOR AN RTOS
Xtensa low level exception and interrupt vectors and handlers for an RTOS.
Interrupt handlers and user exception handlers support interaction with
the RTOS by calling XT_RTOS_INT_ENTER and XT_RTOS_INT_EXIT before and
after user's specific interrupt handlers. These macros are defined in
xtensa_<rtos>.h to call suitable functions in a specific RTOS.
Users can install application-specific interrupt handlers for low and
medium level interrupts, by calling xt_set_interrupt_handler(). These
handlers can be written in C, and must obey C calling convention. The
handler table is indexed by the interrupt number. Each handler may be
provided with an argument.
Note that the system timer interrupt is handled specially, and is
dispatched to the RTOS-specific handler. This timer cannot be hooked
by application code.
Optional hooks are also provided to install a handler per level at
run-time, made available by compiling this source file with
'-DXT_INTEXC_HOOKS' (useful for automated testing).
!! This file is a template that usually needs to be modified to handle !!
!! application specific interrupts. Search USER_EDIT for helpful comments !!
!! on where to insert handlers and how to write them. !!
Users can also install application-specific exception handlers in the
same way, by calling xt_set_exception_handler(). One handler slot is
provided for each exception type. Note that some exceptions are handled
by the porting layer itself, and cannot be taken over by application
code in this manner. These are the alloca, syscall, and coprocessor
exceptions.
The exception handlers can be written in C, and must follow C calling
convention. Each handler is passed a pointer to an exception frame as
its single argument. The exception frame is created on the stack, and
holds the saved context of the thread that took the exception. If the
handler returns, the context will be restored and the instruction that
caused the exception will be retried. If the handler makes any changes
to the saved state in the exception frame, the changes will be applied
when restoring the context.
Because Xtensa is a configurable architecture, this port supports all user
generated configurations (except restrictions stated in the release notes).
This is accomplished by conditional compilation using macros and functions
defined in the Xtensa HAL (hardware adaptation layer) for your configuration.
Only the relevant parts of this file will be included in your RTOS build.
For example, this file provides interrupt vector templates for all types and
all priority levels, but only the ones in your configuration are built.
NOTES on the use of 'call0' for long jumps instead of 'j':
1. This file should be assembled with the -mlongcalls option to xt-xcc.
2. The -mlongcalls compiler option causes 'call0 dest' to be expanded to
a sequence 'l32r a0, dest' 'callx0 a0' which works regardless of the
distance from the call to the destination. The linker then relaxes
it back to 'call0 dest' if it determines that dest is within range.
This allows more flexibility in locating code without the performance
overhead of the 'l32r' literal data load in cases where the destination
is in range of 'call0'. There is an additional benefit in that 'call0'
has a longer range than 'j' due to the target being word-aligned, so
the 'l32r' sequence is less likely needed.
3. The use of 'call0' with -mlongcalls requires that register a0 not be
live at the time of the call, which is always the case for a function
call but needs to be ensured if 'call0' is used as a jump in lieu of 'j'.
4. This use of 'call0' is independent of the C function call ABI.
*******************************************************************************/
#include "xtensa_rtos.h"
/* Enable stack backtrace across exception/interrupt - see below */
#define XT_DEBUG_BACKTRACE 0
/*
--------------------------------------------------------------------------------
Defines used to access _xtos_interrupt_table.
--------------------------------------------------------------------------------
*/
#define XIE_HANDLER 0
#define XIE_ARG 4
#define XIE_SIZE 8
/*
--------------------------------------------------------------------------------
Macro extract_msb - return the input with only the highest bit set.
Input : "ain" - Input value, clobbered.
Output : "aout" - Output value, has only one bit set, MSB of "ain".
The two arguments must be different AR registers.
--------------------------------------------------------------------------------
*/
.macro extract_msb aout ain
1:
addi \aout, \ain, -1 /* aout = ain - 1 */
and \ain, \ain, \aout /* ain = ain & aout */
bnez \ain, 1b /* repeat until ain == 0 */
addi \aout, \aout, 1 /* return aout + 1 */
.endm
/*
--------------------------------------------------------------------------------
Macro dispatch_c_isr - dispatch interrupts to user ISRs.
This will dispatch to user handlers (if any) that are registered in the
XTOS dispatch table (_xtos_interrupt_table). These handlers would have
been registered by calling _xtos_set_interrupt_handler(). There is one
exception - the timer interrupt used by the OS will not be dispatched
to a user handler - this must be handled by the caller of this macro.
Level triggered and software interrupts are automatically deasserted by
this code.
ASSUMPTIONS:
-- PS.INTLEVEL is set to "level" at entry
-- PS.EXCM = 0, C calling enabled
NOTE: For CALL0 ABI, a12-a15 have not yet been saved.
NOTE: This macro will use registers a0 and a2-a6. The arguments are:
level -- interrupt level
mask -- interrupt bitmask for this level
--------------------------------------------------------------------------------
*/
.macro dispatch_c_isr level mask
/* Get mask of pending, enabled interrupts at this level into a2. */
.L_xt_user_int_&level&:
rsr a2, INTENABLE
rsr a3, INTERRUPT
movi a4, \mask
and a2, a2, a3
and a2, a2, a4
beqz a2, 9f /* nothing to do */
/* This bit of code provides a nice debug backtrace in the debugger.
It does take a few more instructions, so undef XT_DEBUG_BACKTRACE
if you want to save the cycles.
*/
#if XT_DEBUG_BACKTRACE
#ifndef __XTENSA_CALL0_ABI__
rsr a0, EPC_1 + \level - 1 /* return address */
movi a4, 0xC0000000 /* constant with top 2 bits set (call size) */
or a0, a0, a4 /* set top 2 bits */
addx2 a0, a4, a0 /* clear top bit -- simulating call4 size */
#endif
#endif
#ifdef XT_INTEXC_HOOKS
/* Call interrupt hook if present to (pre)handle interrupts. */
movi a4, _xt_intexc_hooks
l32i a4, a4, \level << 2
beqz a4, 2f
#ifdef __XTENSA_CALL0_ABI__
callx0 a4
beqz a2, 9f
#else
mov a6, a2
callx4 a4
beqz a6, 9f
mov a2, a6
#endif
2:
#endif
/* Now look up in the dispatch table and call user ISR if any. */
/* If multiple bits are set then MSB has highest priority. */
extract_msb a4, a2 /* a4 = MSB of a2, a2 trashed */
#ifdef XT_USE_SWPRI
/* Enable all interrupts at this level that are numerically higher
than the one we just selected, since they are treated as higher
priority.
*/
movi a3, \mask /* a3 = all interrupts at this level */
add a2, a4, a4 /* a2 = a4 << 1 */
addi a2, a2, -1 /* a2 = mask of 1's <= a4 bit */
and a2, a2, a3 /* a2 = mask of all bits <= a4 at this level */
movi a3, _xt_intdata
l32i a6, a3, 4 /* a6 = _xt_vpri_mask */
neg a2, a2
addi a2, a2, -1 /* a2 = mask to apply */
and a5, a6, a2 /* mask off all bits <= a4 bit */
s32i a5, a3, 4 /* update _xt_vpri_mask */
rsr a3, INTENABLE
and a3, a3, a2 /* mask off all bits <= a4 bit */
wsr a3, INTENABLE
rsil a3, \level - 1 /* lower interrupt level by 1 */
#endif
movi a3, XT_TIMER_INTEN /* a3 = timer interrupt bit */
wsr a4, INTCLEAR /* clear sw or edge-triggered interrupt */
beq a3, a4, 7f /* if timer interrupt then skip table */
find_ms_setbit a3, a4, a3, 0 /* a3 = interrupt number */
movi a4, _xt_interrupt_table
addx8 a3, a3, a4 /* a3 = address of interrupt table entry */
l32i a4, a3, XIE_HANDLER /* a4 = handler address */
#ifdef __XTENSA_CALL0_ABI__
mov a12, a6 /* save in callee-saved reg */
l32i a2, a3, XIE_ARG /* a2 = handler arg */
callx0 a4 /* call handler */
mov a2, a12
#else
mov a2, a6 /* save in windowed reg */
l32i a6, a3, XIE_ARG /* a6 = handler arg */
callx4 a4 /* call handler */
#endif
#ifdef XT_USE_SWPRI
j 8f
#else
j .L_xt_user_int_&level& /* check for more interrupts */
#endif
7:
.ifeq XT_TIMER_INTPRI - \level
.L_xt_user_int_timer_&level&:
/*
Interrupt handler for the RTOS tick timer if at this level.
We'll be reading the interrupt state again after this call
so no need to preserve any registers except a6 (vpri_mask).
*/
#ifdef __XTENSA_CALL0_ABI__
mov a12, a6
call0 XT_RTOS_TIMER_INT
mov a2, a12
#else
mov a2, a6
call4 XT_RTOS_TIMER_INT
#endif
.endif
#ifdef XT_USE_SWPRI
j 8f
#else
j .L_xt_user_int_&level& /* check for more interrupts */
#endif
#ifdef XT_USE_SWPRI
8:
/* Restore old value of _xt_vpri_mask from a2. Also update INTENABLE from
virtual _xt_intenable which _could_ have changed during interrupt
processing. */
movi a3, _xt_intdata
l32i a4, a3, 0 /* a4 = _xt_intenable */
s32i a2, a3, 4 /* update _xt_vpri_mask */
and a4, a4, a2 /* a4 = masked intenable */
wsr a4, INTENABLE /* update INTENABLE */
#endif
9:
/* done */
.endm
/*
--------------------------------------------------------------------------------
Panic handler.
Should be reached by call0 (preferable) or jump only. If call0, a0 says where
from. If on simulator, display panic message and abort, else loop indefinitely.
--------------------------------------------------------------------------------
*/
.text
.global panicHandlerRegs
.global panicHandler
.global panicStack
.global _xt_panic
.type _xt_panic,@function
.align 4
_xt_panic:
//ToDo: save registers
movi a2, panicHandlerRegs
s32i a0,a2,0
s32i a1,a2,4
s32i a2,a2,8
s32i a3,a2,12
s32i a4,a2,16
s32i a5,a2,20
s32i a6,a2,24
s32i a7,a2,28
s32i a8,a2,32
s32i a9,a2,36
s32i a10,a2,40
s32i a11,a2,44
s32i a12,a2,48
s32i a13,a2,52
s32i a14,a2,56
s32i a15,a2,60
rsr a3, EXCSAVE
s32i a3,a2,64
rsr a3, EXCSAVE+1
s32i a3,a2,68
rsr a3, EXCSAVE+2
s32i a3,a2,72
rsr a3, EXCSAVE+3
s32i a3,a2,76
rsr a3, EXCSAVE+4
s32i a3,a2,80
rsr a3, EXCSAVE+5
s32i a3,a2,84
rsr a3, EXCSAVE+6
s32i a3,a2,88
rsr a3, EXCSAVE+7
s32i a3,a2,92
rsr a3, EPC
s32i a3,a2,96
rsr a3, EPC+1
s32i a3,a2,100
rsr a3, EPC+2
s32i a3,a2,104
rsr a3, EPC+3
s32i a3,a2,108
rsr a3, EPC+4
s32i a3,a2,112
rsr a3, EPC+5
s32i a3,a2,116
rsr a3, EPC+6
s32i a3,a2,120
rsr a3, EPC+7
s32i a3,a2,124
rsr a3, DEPC
s32i a3,a2,128
rsr a3, EXCVADDR
s32i a3,a2,132
//Reset window start / base to 0
movi a2, 1
wsr a2, windowstart
movi a2, 0
wsr a2, windowbase
rsync
//Clear EXCM, set WOE flags
rsr a2, ps
movi a3, ~(PS_EXCM_MASK)
and a2, a2, a3
movi a3, PS_WOE_MASK
or a2, a2, a3
wsr a2, ps
rsync
//Switch to private stack
movi a1,panicStack+(255*4)
rsil a2, XCHAL_EXCM_LEVEL /* disable all low & med ints */
// Debug: output '!' on serport
movi a2,0x60000000
movi a3,'!'
s32i a3,a2,0
movi a3, panicHandlerRegs
l32i a2,a3,0
call0 panic_print_hex
rsr a2, EXCCAUSE
call0 panic_print_hex
rsr a2, EXCVADDR
call0 panic_print_hex
rsr a2,EPC+1
call0 panic_print_hex
rsr a2,EPC+2
call0 panic_print_hex
rsr a2,EPC+3
call0 panic_print_hex
rsr a2,EPC+6
call0 panic_print_hex
rsr a2,EXCSAVE_1
call0 panic_print_hex
rsr a2,DEPC
call0 panic_print_hex
//Call panic handler
// movi a4, panicHandler
// callx4 a4
call4 panicHandler
movi a2,0x60000000
movi a3,'d'
s32i a3,a2,0
1: j 1b /* loop infinitely */
.align 4
panicHandlerz:
entry a1,32
movi a2,0x60000000
movi a3,'h'
memw
s32i a3,a2,0
retw
.align 4
//Call using call0. Prints the hex char in a2. Kills a3, a4, a5
panic_print_hex:
movi a3,0x60000000
movi a4,8
panic_print_hex_loop:
l32i a5, a3, 0x1c
extui a5, a5, 16, 8
bgei a5,64,panic_print_hex_loop
srli a5,a2,28
bgei a5,10,panic_print_hex_a
addi a5,a5,'0'
j panic_print_hex_ok
panic_print_hex_a:
addi a5,a5,'A'-10
panic_print_hex_ok:
s32i a5,a3,0
slli a2,a2,4
addi a4,a4,-1
bnei a4,0,panic_print_hex_loop
movi a5,' '
s32i a5,a3,0
ret
.section .rodata, "a"
.align 4
/*
--------------------------------------------------------------------------------
Hooks to dynamically install handlers for exceptions and interrupts.
Allows automated regression frameworks to install handlers per test.
Consists of an array of function pointers indexed by interrupt level,
with index 0 containing the entry for user exceptions.
Initialized with all 0s, meaning no handler is installed at each level.
See comment in xtensa_rtos.h for more details.
--------------------------------------------------------------------------------
*/
#ifdef XT_INTEXC_HOOKS
.data
.global _xt_intexc_hooks
.type _xt_intexc_hooks,@object
.align 4
_xt_intexc_hooks:
.fill XT_INTEXC_HOOK_NUM, 4, 0
#endif
/*
--------------------------------------------------------------------------------
EXCEPTION AND LEVEL 1 INTERRUPT VECTORS AND LOW LEVEL HANDLERS
(except window exception vectors).
Each vector goes at a predetermined location according to the Xtensa
hardware configuration, which is ensured by its placement in a special
section known to the Xtensa linker support package (LSP). It performs
the minimum necessary before jumping to the handler in the .text section.
The corresponding handler goes in the normal .text section. It sets up
the appropriate stack frame, saves a few vector-specific registers and
calls XT_RTOS_INT_ENTER to save the rest of the interrupted context
and enter the RTOS, then sets up a C environment. It then calls the
user's interrupt handler code (which may be coded in C) and finally
calls XT_RTOS_INT_EXIT to transfer control to the RTOS for scheduling.
While XT_RTOS_INT_EXIT does not return directly to the interruptee,
eventually the RTOS scheduler will want to dispatch the interrupted
task or handler. The scheduler will return to the exit point that was
saved in the interrupt stack frame at XT_STK_EXIT.
--------------------------------------------------------------------------------
*/
/*
--------------------------------------------------------------------------------
Debug Exception.
--------------------------------------------------------------------------------
*/
#if XCHAL_HAVE_DEBUG
.begin literal_prefix .DebugExceptionVector
.section .DebugExceptionVector.text, "ax"
.global _DebugExceptionVector
.align 4
_DebugExceptionVector:
#ifdef XT_SIMULATOR
/*
In the simulator, let the debugger (if any) handle the debug exception,
or simply stop the simulation:
*/
wsr a2, EXCSAVE+XCHAL_DEBUGLEVEL /* save a2 where sim expects it */
movi a2, SYS_gdb_enter_sktloop
simcall /* have ISS handle debug exc. */
#elif 0 /* change condition to 1 to use the HAL minimal debug handler */
wsr a3, EXCSAVE+XCHAL_DEBUGLEVEL
movi a3, xthal_debugexc_defhndlr_nw /* use default debug handler */
jx a3
#else
wsr a0, EXCSAVE+XCHAL_DEBUGLEVEL /* save original a0 somewhere */
call0 _xt_panic /* does not return */
rfi XCHAL_DEBUGLEVEL /* make a0 point here not later */
#endif
.end literal_prefix
#endif
/*
--------------------------------------------------------------------------------
Double Exception.
Double exceptions are not a normal occurrence. They indicate a bug of some kind.
--------------------------------------------------------------------------------
*/
#ifdef XCHAL_DOUBLEEXC_VECTOR_VADDR
.begin literal_prefix .DoubleExceptionVector
.section .DoubleExceptionVector.text, "ax"
.global _DoubleExceptionVector
.align 4
_DoubleExceptionVector:
#if XCHAL_HAVE_DEBUG
break 1, 4 /* unhandled double exception */
#endif
call0 _xt_panic /* does not return */
rfde /* make a0 point here not later */
.end literal_prefix
#endif /* XCHAL_DOUBLEEXC_VECTOR_VADDR */
/*
--------------------------------------------------------------------------------
Kernel Exception (including Level 1 Interrupt from kernel mode).
--------------------------------------------------------------------------------
*/
.begin literal_prefix .KernelExceptionVector
.section .KernelExceptionVector.text, "ax"
.global _KernelExceptionVector
.align 4
_KernelExceptionVector:
wsr a0, EXCSAVE_1 /* preserve a0 */
call0 _xt_kernel_exc /* kernel exception handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.align 4
_xt_kernel_exc:
#if XCHAL_HAVE_DEBUG
break 1, 0 /* unhandled kernel exception */
#endif
call0 _xt_panic /* does not return */
rfe /* make a0 point here not there */
/*
--------------------------------------------------------------------------------
User Exception (including Level 1 Interrupt from user mode).
--------------------------------------------------------------------------------
*/
.begin literal_prefix .UserExceptionVector
.section .UserExceptionVector.text, "ax"
.global _UserExceptionVector
.type _UserExceptionVector,@function
.align 4
_UserExceptionVector:
wsr a0, EXCSAVE_1 /* preserve a0 */
call0 _xt_user_exc /* user exception handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
/*
--------------------------------------------------------------------------------
Insert some waypoints for jumping beyond the signed 8-bit range of
conditional branch instructions, so the conditional branchces to specific
exception handlers are not taken in the mainline. Saves some cycles in the
mainline.
--------------------------------------------------------------------------------
*/
.text
#if XCHAL_HAVE_WINDOWED
.align 4
_xt_to_alloca_exc:
call0 _xt_alloca_exc /* in window vectors section */
/* never returns here - call0 is used as a jump (see note at top) */
#endif
.align 4
_xt_to_syscall_exc:
call0 _xt_syscall_exc
/* never returns here - call0 is used as a jump (see note at top) */
#if XCHAL_CP_NUM > 0
.align 4
_xt_to_coproc_exc:
call0 _xt_coproc_exc
/* never returns here - call0 is used as a jump (see note at top) */
#endif
/*
--------------------------------------------------------------------------------
User exception handler.
--------------------------------------------------------------------------------
*/
.type _xt_user_exc,@function
.align 4
_xt_user_exc:
/* If level 1 interrupt then jump to the dispatcher */
rsr a0, EXCCAUSE
beqi a0, EXCCAUSE_LEVEL1INTERRUPT, _xt_lowint1
/* Handle any coprocessor exceptions. Rely on the fact that exception
numbers above EXCCAUSE_CP0_DISABLED all relate to the coprocessors.
*/
#if XCHAL_CP_NUM > 0
bgeui a0, EXCCAUSE_CP0_DISABLED, _xt_to_coproc_exc
#endif
/* Handle alloca and syscall exceptions */
#if XCHAL_HAVE_WINDOWED
beqi a0, EXCCAUSE_ALLOCA, _xt_to_alloca_exc
#endif
beqi a0, EXCCAUSE_SYSCALL, _xt_to_syscall_exc
//HACK! No custom vector stuff, just call panic handler directly. ToDo: remove this when possible. -JD
call0 _xt_panic
/* Handle all other exceptions. All can have user-defined handlers. */
/* NOTE: we'll stay on the user stack for exception handling. */
/* Allocate exception frame and save minimal context. */
mov a0, sp
addi sp, sp, -XT_STK_FRMSZ
s32i a0, sp, XT_STK_A1
#if XCHAL_HAVE_WINDOWED
s32e a0, sp, -12 /* for debug backtrace */
#endif
rsr a0, PS /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_1 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_1 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
#if XCHAL_HAVE_WINDOWED
s32e a0, sp, -16 /* for debug backtrace */
#endif
s32i a12, sp, XT_STK_A12 /* _xt_context_save requires A12- */
s32i a13, sp, XT_STK_A13 /* A13 to have already been saved */
call0 _xt_context_save
/* Save exc cause and vaddr into exception frame */
rsr a0, EXCCAUSE
s32i a0, sp, XT_STK_EXCCAUSE
rsr a0, EXCVADDR
s32i a0, sp, XT_STK_EXCVADDR
/* Set up PS for C, reenable hi-pri interrupts, and clear EXCM. */
#ifdef __XTENSA_CALL0_ABI__
movi a0, PS_INTLEVEL(XCHAL_EXCM_LEVEL) | PS_UM
#else
movi a0, PS_INTLEVEL(XCHAL_EXCM_LEVEL) | PS_UM | PS_WOE
#endif
wsr a0, PS
#ifdef XT_DEBUG_BACKTRACE
#ifndef __XTENSA_CALL0_ABI__
rsr a0, EPC_1 /* return address for debug backtrace */
movi a5, 0xC0000000 /* constant with top 2 bits set (call size) */
rsync /* wait for WSR.PS to complete */
or a0, a0, a5 /* set top 2 bits */
addx2 a0, a5, a0 /* clear top bit -- thus simulating call4 size */
#else
rsync /* wait for WSR.PS to complete */
#endif
#endif
rsr a2, EXCCAUSE /* recover exc cause */
#ifdef XT_INTEXC_HOOKS
/*
Call exception hook to pre-handle exceptions (if installed).
Pass EXCCAUSE in a2, and check result in a2 (if -1, skip default handling).
*/
movi a4, _xt_intexc_hooks
l32i a4, a4, 0 /* user exception hook index 0 */
beqz a4, 1f
.Ln_xt_user_exc_call_hook:
#ifdef __XTENSA_CALL0_ABI__
callx0 a4
beqi a2, -1, .L_xt_user_done
#else
mov a6, a2
callx4 a4
beqi a6, -1, .L_xt_user_done
mov a2, a6
#endif
1:
#endif
rsr a2, EXCCAUSE /* recover exc cause */
movi a3, _xt_exception_table
addx4 a4, a2, a3 /* a4 = address of exception table entry */
l32i a4, a4, 0 /* a4 = handler address */
#ifdef __XTENSA_CALL0_ABI__
mov a2, sp /* a2 = pointer to exc frame */
callx0 a4 /* call handler */
#else
mov a6, sp /* a6 = pointer to exc frame */
callx4 a4 /* call handler */
#endif
.L_xt_user_done:
/* Restore context and return */
call0 _xt_context_restore
l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */
wsr a0, PS
l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */
wsr a0, EPC_1
l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */
l32i sp, sp, XT_STK_A1 /* remove exception frame */
rsync /* ensure PS and EPC written */
rfe /* PS.EXCM is cleared */
/*
--------------------------------------------------------------------------------
Exit point for dispatch. Saved in interrupt stack frame at XT_STK_EXIT
on entry and used to return to a thread or interrupted interrupt handler.
--------------------------------------------------------------------------------
*/
.global _xt_user_exit
.type _xt_user_exit,@function
.align 4
_xt_user_exit:
l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */
wsr a0, PS
l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */
wsr a0, EPC_1
l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */
l32i sp, sp, XT_STK_A1 /* remove interrupt stack frame */
rsync /* ensure PS and EPC written */
rfe /* PS.EXCM is cleared */
/*
--------------------------------------------------------------------------------
Syscall Exception Handler (jumped to from User Exception Handler).
Syscall 0 is required to spill the register windows (no-op in Call 0 ABI).
Only syscall 0 is handled here. Other syscalls return -1 to caller in a2.
--------------------------------------------------------------------------------
*/
.text
.type _xt_syscall_exc,@function
.align 4
_xt_syscall_exc:
#ifdef __XTENSA_CALL0_ABI__
/*
Save minimal regs for scratch. Syscall 0 does nothing in Call0 ABI.
Use a minimal stack frame (16B) to save A2 & A3 for scratch.
PS.EXCM could be cleared here, but unlikely to improve worst-case latency.
rsr a0, PS
addi a0, a0, -PS_EXCM_MASK
wsr a0, PS
*/
addi sp, sp, -16
s32i a2, sp, 8
s32i a3, sp, 12
#else /* Windowed ABI */
/*
Save necessary context and spill the register windows.
PS.EXCM is still set and must remain set until after the spill.
Reuse context save function though it saves more than necessary.
For this reason, a full interrupt stack frame is allocated.
*/
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a12, sp, XT_STK_A12 /* _xt_context_save requires A12- */
s32i a13, sp, XT_STK_A13 /* A13 to have already been saved */
call0 _xt_context_save
#endif
/*
Grab the interruptee's PC and skip over the 'syscall' instruction.
If it's at the end of a zero-overhead loop and it's not on the last
iteration, decrement loop counter and skip to beginning of loop.
*/
rsr a2, EPC_1 /* a2 = PC of 'syscall' */
addi a3, a2, 3 /* ++PC */
#if XCHAL_HAVE_LOOPS
rsr a0, LEND /* if (PC == LEND */
bne a3, a0, 1f
rsr a0, LCOUNT /* && LCOUNT != 0) */
beqz a0, 1f /* { */
addi a0, a0, -1 /* --LCOUNT */
rsr a3, LBEG /* PC = LBEG */
wsr a0, LCOUNT /* } */
#endif
1: wsr a3, EPC_1 /* update PC */
/* Restore interruptee's context and return from exception. */
#ifdef __XTENSA_CALL0_ABI__
l32i a2, sp, 8
l32i a3, sp, 12
addi sp, sp, 16
#else
call0 _xt_context_restore
addi sp, sp, XT_STK_FRMSZ
#endif
movi a0, -1
movnez a2, a0, a2 /* return -1 if not syscall 0 */
rsr a0, EXCSAVE_1
rfe
/*
--------------------------------------------------------------------------------
Co-Processor Exception Handler (jumped to from User Exception Handler).
These exceptions are generated by co-processor instructions, which are only
allowed in thread code (not in interrupts or kernel code). This restriction is
deliberately imposed to reduce the burden of state-save/restore in interrupts.
--------------------------------------------------------------------------------
*/
#if XCHAL_CP_NUM > 0
.section .rodata, "a"
/* Offset to CP n save area in thread's CP save area. */
.global _xt_coproc_sa_offset
.type _xt_coproc_sa_offset,@object
.align 16 /* minimize crossing cache boundaries */
_xt_coproc_sa_offset:
.word XT_CP0_SA, XT_CP1_SA, XT_CP2_SA, XT_CP3_SA
.word XT_CP4_SA, XT_CP5_SA, XT_CP6_SA, XT_CP7_SA
/* Bitmask for CP n's CPENABLE bit. */
.type _xt_coproc_mask,@object
.align 16,,8 /* try to keep it all in one cache line */
.set i, 0
_xt_coproc_mask:
.rept XCHAL_CP_MAX
.long (i<<16) | (1<<i) // upper 16-bits = i, lower = bitmask
.set i, i+1
.endr
.data
/* Owner thread of CP n, identified by thread's CP save area (0 = unowned). */
.global _xt_coproc_owner_sa
.type _xt_coproc_owner_sa,@object
.align 16,,XCHAL_CP_MAX<<2 /* minimize crossing cache boundaries */
_xt_coproc_owner_sa:
.space XCHAL_CP_MAX << 2
.text
.align 4
.L_goto_invalid:
j .L_xt_coproc_invalid /* not in a thread (invalid) */
.align 4
.L_goto_done:
j .L_xt_coproc_done
/*
--------------------------------------------------------------------------------
Coprocessor exception handler.
At entry, only a0 has been saved (in EXCSAVE_1).
--------------------------------------------------------------------------------
*/
.type _xt_coproc_exc,@function
.align 4
_xt_coproc_exc:
/* Allocate interrupt stack frame and save minimal context. */
mov a0, sp /* sp == a1 */
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a0, sp, XT_STK_A1 /* save pre-interrupt SP */
#if XCHAL_HAVE_WINDOWED
s32e a0, sp, -12 /* for debug backtrace */
#endif
rsr a0, PS /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_1 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_1 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
#if XCHAL_HAVE_WINDOWED
s32e a0, sp, -16 /* for debug backtrace */
#endif
movi a0, _xt_user_exit /* save exit point for dispatch */
s32i a0, sp, XT_STK_EXIT
rsr a0, EXCCAUSE
s32i a5, sp, XT_STK_A5 /* save a5 */
addi a5, a0, -EXCCAUSE_CP0_DISABLED /* a5 = CP index */
/* Save a few more of interruptee's registers (a5 was already saved). */
s32i a2, sp, XT_STK_A2
s32i a3, sp, XT_STK_A3
s32i a4, sp, XT_STK_A4
s32i a15, sp, XT_STK_A15
/* Get co-processor state save area of new owner thread. */
call0 XT_RTOS_CP_STATE /* a15 = new owner's save area */
beqz a15, .L_goto_invalid /* not in a thread (invalid) */
/* Enable the co-processor's bit in CPENABLE. */
movi a0, _xt_coproc_mask
rsr a4, CPENABLE /* a4 = CPENABLE */
addx4 a0, a5, a0 /* a0 = &_xt_coproc_mask[n] */
l32i a0, a0, 0 /* a0 = (n << 16) | (1 << n) */
movi a3, _xt_coproc_owner_sa /* (placed here for load slot) */
extui a2, a0, 0, 16 /* coprocessor bitmask portion */
or a4, a4, a2 /* a4 = CPENABLE | (1 << n) */
wsr a4, CPENABLE
/* Get old coprocessor owner thread (save area ptr) and assign new one. */
addx4 a3, a5, a3 /* a3 = &_xt_coproc_owner_sa[n] */
l32i a2, a3, 0 /* a2 = old owner's save area */
s32i a15, a3, 0 /* _xt_coproc_owner_sa[n] = new */
rsync /* ensure wsr.CPENABLE is complete */
/* Only need to context switch if new owner != old owner. */
beq a15, a2, .L_goto_done /* new owner == old, we're done */
/* If no old owner then nothing to save. */
beqz a2, .L_check_new
/* If old owner not actively using CP then nothing to save. */
l16ui a4, a2, XT_CPENABLE /* a4 = old owner's CPENABLE */
bnone a4, a0, .L_check_new /* old owner not using CP */
.L_save_old:
/* Save old owner's coprocessor state. */
movi a5, _xt_coproc_sa_offset
/* Mark old owner state as no longer active (CPENABLE bit n clear). */
xor a4, a4, a0 /* clear CP bit in CPENABLE */
s16i a4, a2, XT_CPENABLE /* update old owner's CPENABLE */
extui a4, a0, 16, 5 /* a4 = CP index = n */
addx4 a5, a4, a5 /* a5 = &_xt_coproc_sa_offset[n] */
/* Mark old owner state as saved (CPSTORED bit n set). */
l16ui a4, a2, XT_CPSTORED /* a4 = old owner's CPSTORED */
l32i a5, a5, 0 /* a5 = XT_CP[n]_SA offset */
or a4, a4, a0 /* set CP in old owner's CPSTORED */
s16i a4, a2, XT_CPSTORED /* update old owner's CPSTORED */
l32i a2, a2, XT_CP_ASA /* ptr to actual (aligned) save area */
extui a3, a0, 16, 5 /* a3 = CP index = n */
add a2, a2, a5 /* a2 = old owner's area for CP n */
/*
The config-specific HAL macro invoked below destroys a2-5, preserves a0-1.
It is theoretically possible for Xtensa processor designers to write TIE
that causes more address registers to be affected, but it is generally
unlikely. If that ever happens, more registers needs to be saved/restored
around this macro invocation, and the value in a15 needs to be recomputed.
*/
xchal_cpi_store_funcbody
.L_check_new:
/* Check if any state has to be restored for new owner. */
/* NOTE: a15 = new owner's save area, cannot be zero when we get here. */
l16ui a3, a15, XT_CPSTORED /* a3 = new owner's CPSTORED */
movi a4, _xt_coproc_sa_offset
bnone a3, a0, .L_check_cs /* full CP not saved, check callee-saved */
xor a3, a3, a0 /* CPSTORED bit is set, clear it */
s16i a3, a15, XT_CPSTORED /* update new owner's CPSTORED */
/* Adjust new owner's save area pointers to area for CP n. */
extui a3, a0, 16, 5 /* a3 = CP index = n */
addx4 a4, a3, a4 /* a4 = &_xt_coproc_sa_offset[n] */
l32i a4, a4, 0 /* a4 = XT_CP[n]_SA */
l32i a5, a15, XT_CP_ASA /* ptr to actual (aligned) save area */
add a2, a4, a5 /* a2 = new owner's area for CP */
/*
The config-specific HAL macro invoked below destroys a2-5, preserves a0-1.
It is theoretically possible for Xtensa processor designers to write TIE
that causes more address registers to be affected, but it is generally
unlikely. If that ever happens, more registers needs to be saved/restored
around this macro invocation.
*/
xchal_cpi_load_funcbody
/* Restore interruptee's saved registers. */
/* Can omit rsync for wsr.CPENABLE here because _xt_user_exit does it. */
.L_xt_coproc_done:
l32i a15, sp, XT_STK_A15
l32i a5, sp, XT_STK_A5
l32i a4, sp, XT_STK_A4
l32i a3, sp, XT_STK_A3
l32i a2, sp, XT_STK_A2
call0 _xt_user_exit /* return via exit dispatcher */
/* Never returns here - call0 is used as a jump (see note at top) */
.L_check_cs:
/* a0 = CP mask in low bits, a15 = new owner's save area */
l16ui a2, a15, XT_CP_CS_ST /* a2 = mask of CPs saved */
bnone a2, a0, .L_xt_coproc_done /* if no match then done */
and a2, a2, a0 /* a2 = which CPs to restore */
extui a2, a2, 0, 8 /* extract low 8 bits */
s32i a6, sp, XT_STK_A6 /* save extra needed regs */
s32i a7, sp, XT_STK_A7
s32i a13, sp, XT_STK_A13
s32i a14, sp, XT_STK_A14
call0 _xt_coproc_restorecs /* restore CP registers */
l32i a6, sp, XT_STK_A6 /* restore saved registers */
l32i a7, sp, XT_STK_A7
l32i a13, sp, XT_STK_A13
l32i a14, sp, XT_STK_A14
j .L_xt_coproc_done
/* Co-processor exception occurred outside a thread (not supported). */
.L_xt_coproc_invalid:
#if XCHAL_HAVE_DEBUG
break 1, 1 /* unhandled user exception */
#endif
call0 _xt_panic /* not in a thread (invalid) */
/* never returns */
#endif /* XCHAL_CP_NUM */
/*
-------------------------------------------------------------------------------
Level 1 interrupt dispatch. Assumes stack frame has not been allocated yet.
-------------------------------------------------------------------------------
*/
.text
.type _xt_lowint1,@function
.align 4
_xt_lowint1:
mov a0, sp /* sp == a1 */
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a0, sp, XT_STK_A1 /* save pre-interrupt SP */
rsr a0, PS /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_1 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_1 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
movi a0, _xt_user_exit /* save exit point for dispatch */
s32i a0, sp, XT_STK_EXIT
/* Save rest of interrupt context and enter RTOS. */
call0 XT_RTOS_INT_ENTER /* common RTOS interrupt entry */
/* !! We are now on the RTOS system stack !! */
/* Set up PS for C, enable interrupts above this level and clear EXCM. */
#ifdef __XTENSA_CALL0_ABI__
movi a0, PS_INTLEVEL(1) | PS_UM
#else
movi a0, PS_INTLEVEL(1) | PS_UM | PS_WOE
#endif
wsr a0, PS
rsync
/* OK to call C code at this point, dispatch user ISRs */
dispatch_c_isr 1 XCHAL_INTLEVEL1_MASK
/* Done handling interrupts, transfer control to OS */
call0 XT_RTOS_INT_EXIT /* does not return directly here */
/*
-------------------------------------------------------------------------------
MEDIUM PRIORITY (LEVEL 2+) INTERRUPT VECTORS AND LOW LEVEL HANDLERS.
Medium priority interrupts are by definition those with priority greater
than 1 and not greater than XCHAL_EXCM_LEVEL. These are disabled by
setting PS.EXCM and therefore can easily support a C environment for
handlers in C, and interact safely with an RTOS.
Each vector goes at a predetermined location according to the Xtensa
hardware configuration, which is ensured by its placement in a special
section known to the Xtensa linker support package (LSP). It performs
the minimum necessary before jumping to the handler in the .text section.
The corresponding handler goes in the normal .text section. It sets up
the appropriate stack frame, saves a few vector-specific registers and
calls XT_RTOS_INT_ENTER to save the rest of the interrupted context
and enter the RTOS, then sets up a C environment. It then calls the
user's interrupt handler code (which may be coded in C) and finally
calls XT_RTOS_INT_EXIT to transfer control to the RTOS for scheduling.
While XT_RTOS_INT_EXIT does not return directly to the interruptee,
eventually the RTOS scheduler will want to dispatch the interrupted
task or handler. The scheduler will return to the exit point that was
saved in the interrupt stack frame at XT_STK_EXIT.
-------------------------------------------------------------------------------
*/
#if XCHAL_EXCM_LEVEL >= 2
.begin literal_prefix .Level2InterruptVector
.section .Level2InterruptVector.text, "ax"
.global _Level2Vector
.type _Level2Vector,@function
.align 4
_Level2Vector:
wsr a0, EXCSAVE_2 /* preserve a0 */
call0 _xt_medint2 /* load interrupt handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.type _xt_medint2,@function
.align 4
_xt_medint2:
mov a0, sp /* sp == a1 */
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a0, sp, XT_STK_A1 /* save pre-interrupt SP */
rsr a0, EPS_2 /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_2 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_2 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
movi a0, _xt_medint2_exit /* save exit point for dispatch */
s32i a0, sp, XT_STK_EXIT
/* Save rest of interrupt context and enter RTOS. */
call0 XT_RTOS_INT_ENTER /* common RTOS interrupt entry */
/* !! We are now on the RTOS system stack !! */
/* Set up PS for C, enable interrupts above this level and clear EXCM. */
#ifdef __XTENSA_CALL0_ABI__
movi a0, PS_INTLEVEL(2) | PS_UM
#else
movi a0, PS_INTLEVEL(2) | PS_UM | PS_WOE
#endif
wsr a0, PS
rsync
/* OK to call C code at this point, dispatch user ISRs */
dispatch_c_isr 2 XCHAL_INTLEVEL2_MASK
/* Done handling interrupts, transfer control to OS */
call0 XT_RTOS_INT_EXIT /* does not return directly here */
/*
Exit point for dispatch. Saved in interrupt stack frame at XT_STK_EXIT
on entry and used to return to a thread or interrupted interrupt handler.
*/
.global _xt_medint2_exit
.type _xt_medint2_exit,@function
.align 4
_xt_medint2_exit:
/* Restore only level-specific regs (the rest were already restored) */
l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */
wsr a0, EPS_2
l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */
wsr a0, EPC_2
l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */
l32i sp, sp, XT_STK_A1 /* remove interrupt stack frame */
rsync /* ensure EPS and EPC written */
rfi 2
#endif /* Level 2 */
#if XCHAL_EXCM_LEVEL >= 3
.begin literal_prefix .Level3InterruptVector
.section .Level3InterruptVector.text, "ax"
.global _Level3Vector
.type _Level3Vector,@function
.align 4
_Level3Vector:
wsr a0, EXCSAVE_3 /* preserve a0 */
call0 _xt_medint3 /* load interrupt handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.type _xt_medint3,@function
.align 4
_xt_medint3:
mov a0, sp /* sp == a1 */
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a0, sp, XT_STK_A1 /* save pre-interrupt SP */
rsr a0, EPS_3 /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_3 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_3 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
movi a0, _xt_medint3_exit /* save exit point for dispatch */
s32i a0, sp, XT_STK_EXIT
/* Save rest of interrupt context and enter RTOS. */
call0 XT_RTOS_INT_ENTER /* common RTOS interrupt entry */
/* !! We are now on the RTOS system stack !! */
/* Set up PS for C, enable interrupts above this level and clear EXCM. */
#ifdef __XTENSA_CALL0_ABI__
movi a0, PS_INTLEVEL(3) | PS_UM
#else
movi a0, PS_INTLEVEL(3) | PS_UM | PS_WOE
#endif
wsr a0, PS
rsync
/* OK to call C code at this point, dispatch user ISRs */
dispatch_c_isr 3 XCHAL_INTLEVEL3_MASK
/* Done handling interrupts, transfer control to OS */
call0 XT_RTOS_INT_EXIT /* does not return directly here */
/*
Exit point for dispatch. Saved in interrupt stack frame at XT_STK_EXIT
on entry and used to return to a thread or interrupted interrupt handler.
*/
.global _xt_medint3_exit
.type _xt_medint3_exit,@function
.align 4
_xt_medint3_exit:
/* Restore only level-specific regs (the rest were already restored) */
l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */
wsr a0, EPS_3
l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */
wsr a0, EPC_3
l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */
l32i sp, sp, XT_STK_A1 /* remove interrupt stack frame */
rsync /* ensure EPS and EPC written */
rfi 3
#endif /* Level 3 */
#if XCHAL_EXCM_LEVEL >= 4
.begin literal_prefix .Level4InterruptVector
.section .Level4InterruptVector.text, "ax"
.global _Level4Vector
.type _Level4Vector,@function
.align 4
_Level4Vector:
wsr a0, EXCSAVE_4 /* preserve a0 */
call0 _xt_medint4 /* load interrupt handler */
.end literal_prefix
.text
.type _xt_medint4,@function
.align 4
_xt_medint4:
mov a0, sp /* sp == a1 */
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a0, sp, XT_STK_A1 /* save pre-interrupt SP */
rsr a0, EPS_4 /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_4 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_4 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
movi a0, _xt_medint4_exit /* save exit point for dispatch */
s32i a0, sp, XT_STK_EXIT
/* Save rest of interrupt context and enter RTOS. */
call0 XT_RTOS_INT_ENTER /* common RTOS interrupt entry */
/* !! We are now on the RTOS system stack !! */
/* Set up PS for C, enable interrupts above this level and clear EXCM. */
#ifdef __XTENSA_CALL0_ABI__
movi a0, PS_INTLEVEL(4) | PS_UM
#else
movi a0, PS_INTLEVEL(4) | PS_UM | PS_WOE
#endif
wsr a0, PS
rsync
/* OK to call C code at this point, dispatch user ISRs */
dispatch_c_isr 4 XCHAL_INTLEVEL4_MASK
/* Done handling interrupts, transfer control to OS */
call0 XT_RTOS_INT_EXIT /* does not return directly here */
/*
Exit point for dispatch. Saved in interrupt stack frame at XT_STK_EXIT
on entry and used to return to a thread or interrupted interrupt handler.
*/
.global _xt_medint4_exit
.type _xt_medint4_exit,@function
.align 4
_xt_medint4_exit:
/* Restore only level-specific regs (the rest were already restored) */
l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */
wsr a0, EPS_4
l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */
wsr a0, EPC_4
l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */
l32i sp, sp, XT_STK_A1 /* remove interrupt stack frame */
rsync /* ensure EPS and EPC written */
rfi 4
#endif /* Level 4 */
#if XCHAL_EXCM_LEVEL >= 5
.begin literal_prefix .Level5InterruptVector
.section .Level5InterruptVector.text, "ax"
.global _Level5Vector
.type _Level5Vector,@function
.align 4
_Level5Vector:
wsr a0, EXCSAVE_5 /* preserve a0 */
call0 _xt_medint5 /* load interrupt handler */
.end literal_prefix
.text
.type _xt_medint5,@function
.align 4
_xt_medint5:
mov a0, sp /* sp == a1 */
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a0, sp, XT_STK_A1 /* save pre-interrupt SP */
rsr a0, EPS_5 /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_5 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_5 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
movi a0, _xt_medint5_exit /* save exit point for dispatch */
s32i a0, sp, XT_STK_EXIT
/* Save rest of interrupt context and enter RTOS. */
call0 XT_RTOS_INT_ENTER /* common RTOS interrupt entry */
/* !! We are now on the RTOS system stack !! */
/* Set up PS for C, enable interrupts above this level and clear EXCM. */
#ifdef __XTENSA_CALL0_ABI__
movi a0, PS_INTLEVEL(5) | PS_UM
#else
movi a0, PS_INTLEVEL(5) | PS_UM | PS_WOE
#endif
wsr a0, PS
rsync
/* OK to call C code at this point, dispatch user ISRs */
dispatch_c_isr 5 XCHAL_INTLEVEL5_MASK
/* Done handling interrupts, transfer control to OS */
call0 XT_RTOS_INT_EXIT /* does not return directly here */
/*
Exit point for dispatch. Saved in interrupt stack frame at XT_STK_EXIT
on entry and used to return to a thread or interrupted interrupt handler.
*/
.global _xt_medint5_exit
.type _xt_medint5_exit,@function
.align 4
_xt_medint5_exit:
/* Restore only level-specific regs (the rest were already restored) */
l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */
wsr a0, EPS_5
l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */
wsr a0, EPC_5
l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */
l32i sp, sp, XT_STK_A1 /* remove interrupt stack frame */
rsync /* ensure EPS and EPC written */
rfi 5
#endif /* Level 5 */
#if XCHAL_EXCM_LEVEL >= 6
.begin literal_prefix .Level6InterruptVector
.section .Level6InterruptVector.text, "ax"
.global _Level6Vector
.type _Level6Vector,@function
.align 4
_Level6Vector:
wsr a0, EXCSAVE_6 /* preserve a0 */
call0 _xt_medint6 /* load interrupt handler */
.end literal_prefix
.text
.type _xt_medint6,@function
.align 4
_xt_medint6:
mov a0, sp /* sp == a1 */
addi sp, sp, -XT_STK_FRMSZ /* allocate interrupt stack frame */
s32i a0, sp, XT_STK_A1 /* save pre-interrupt SP */
rsr a0, EPS_6 /* save interruptee's PS */
s32i a0, sp, XT_STK_PS
rsr a0, EPC_6 /* save interruptee's PC */
s32i a0, sp, XT_STK_PC
rsr a0, EXCSAVE_6 /* save interruptee's a0 */
s32i a0, sp, XT_STK_A0
movi a0, _xt_medint6_exit /* save exit point for dispatch */
s32i a0, sp, XT_STK_EXIT
/* Save rest of interrupt context and enter RTOS. */
call0 XT_RTOS_INT_ENTER /* common RTOS interrupt entry */
/* !! We are now on the RTOS system stack !! */
/* Set up PS for C, enable interrupts above this level and clear EXCM. */
#ifdef __XTENSA_CALL0_ABI__
movi a0, PS_INTLEVEL(6) | PS_UM
#else
movi a0, PS_INTLEVEL(6) | PS_UM | PS_WOE
#endif
wsr a0, PS
rsync
/* OK to call C code at this point, dispatch user ISRs */
dispatch_c_isr 6 XCHAL_INTLEVEL6_MASK
/* Done handling interrupts, transfer control to OS */
call0 XT_RTOS_INT_EXIT /* does not return directly here */
/*
Exit point for dispatch. Saved in interrupt stack frame at XT_STK_EXIT
on entry and used to return to a thread or interrupted interrupt handler.
*/
.global _xt_medint6_exit
.type _xt_medint6_exit,@function
.align 4
_xt_medint6_exit:
/* Restore only level-specific regs (the rest were already restored) */
l32i a0, sp, XT_STK_PS /* retrieve interruptee's PS */
wsr a0, EPS_6
l32i a0, sp, XT_STK_PC /* retrieve interruptee's PC */
wsr a0, EPC_6
l32i a0, sp, XT_STK_A0 /* retrieve interruptee's A0 */
l32i sp, sp, XT_STK_A1 /* remove interrupt stack frame */
rsync /* ensure EPS and EPC written */
rfi 6
#endif /* Level 6 */
/*******************************************************************************
HIGH PRIORITY (LEVEL > XCHAL_EXCM_LEVEL) INTERRUPT VECTORS AND HANDLERS
High priority interrupts are by definition those with priorities greater
than XCHAL_EXCM_LEVEL. This includes non-maskable (NMI). High priority
interrupts cannot interact with the RTOS, that is they must save all regs
they use and not call any RTOS function.
A further restriction imposed by the Xtensa windowed architecture is that
high priority interrupts must not modify the stack area even logically
"above" the top of the interrupted stack (they need to provide their
own stack or static save area).
Cadence Design Systems recommends high priority interrupt handlers be coded in assembly
and used for purposes requiring very short service times.
Here are templates for high priority (level 2+) interrupt vectors.
They assume only one interrupt per level to avoid the burden of identifying
which interrupts at this level are pending and enabled. This allows for
minimum latency and avoids having to save/restore a2 in addition to a0.
If more than one interrupt per high priority level is configured, this burden
is on the handler which in any case must provide a way to save and restore
registers it uses without touching the interrupted stack.
Each vector goes at a predetermined location according to the Xtensa
hardware configuration, which is ensured by its placement in a special
section known to the Xtensa linker support package (LSP). It performs
the minimum necessary before jumping to the handler in the .text section.
*******************************************************************************/
/*
Currently only shells for high priority interrupt handlers are provided
here. However a template and example can be found in the Cadence Design Systems tools
documentation: "Microprocessor Programmer's Guide".
*/
#if XCHAL_NUM_INTLEVELS >=2 && XCHAL_EXCM_LEVEL <2 && XCHAL_DEBUGLEVEL !=2
.begin literal_prefix .Level2InterruptVector
.section .Level2InterruptVector.text, "ax"
.global _Level2Vector
.type _Level2Vector,@function
.align 4
_Level2Vector:
wsr a0, EXCSAVE_2 /* preserve a0 */
call0 _xt_highint2 /* load interrupt handler */
.end literal_prefix
.text
.type _xt_highint2,@function
.align 4
_xt_highint2:
#ifdef XT_INTEXC_HOOKS
/* Call interrupt hook if present to (pre)handle interrupts. */
movi a0, _xt_intexc_hooks
l32i a0, a0, 2<<2
beqz a0, 1f
.Ln_xt_highint2_call_hook:
callx0 a0 /* must NOT disturb stack! */
1:
#endif
/* USER_EDIT:
ADD HIGH PRIORITY LEVEL 2 INTERRUPT HANDLER CODE HERE.
*/
.align 4
.L_xt_highint2_exit:
rsr a0, EXCSAVE_2 /* restore a0 */
rfi 2
#endif /* Level 2 */
#if XCHAL_NUM_INTLEVELS >=3 && XCHAL_EXCM_LEVEL <3 && XCHAL_DEBUGLEVEL !=3
.begin literal_prefix .Level3InterruptVector
.section .Level3InterruptVector.text, "ax"
.global _Level3Vector
.type _Level3Vector,@function
.align 4
_Level3Vector:
wsr a0, EXCSAVE_3 /* preserve a0 */
call0 _xt_highint3 /* load interrupt handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.type _xt_highint3,@function
.align 4
_xt_highint3:
#ifdef XT_INTEXC_HOOKS
/* Call interrupt hook if present to (pre)handle interrupts. */
movi a0, _xt_intexc_hooks
l32i a0, a0, 3<<2
beqz a0, 1f
.Ln_xt_highint3_call_hook:
callx0 a0 /* must NOT disturb stack! */
1:
#endif
/* USER_EDIT:
ADD HIGH PRIORITY LEVEL 3 INTERRUPT HANDLER CODE HERE.
*/
.align 4
.L_xt_highint3_exit:
rsr a0, EXCSAVE_3 /* restore a0 */
rfi 3
#endif /* Level 3 */
#if XCHAL_NUM_INTLEVELS >=4 && XCHAL_EXCM_LEVEL <4 && XCHAL_DEBUGLEVEL !=4
.begin literal_prefix .Level4InterruptVector
.section .Level4InterruptVector.text, "ax"
.global _Level4Vector
.type _Level4Vector,@function
.align 4
_Level4Vector:
wsr a0, EXCSAVE_4 /* preserve a0 */
call0 _xt_highint4 /* load interrupt handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.type _xt_highint4,@function
.align 4
_xt_highint4:
#ifdef XT_INTEXC_HOOKS
/* Call interrupt hook if present to (pre)handle interrupts. */
movi a0, _xt_intexc_hooks
l32i a0, a0, 4<<2
beqz a0, 1f
.Ln_xt_highint4_call_hook:
callx0 a0 /* must NOT disturb stack! */
1:
#endif
/* USER_EDIT:
ADD HIGH PRIORITY LEVEL 4 INTERRUPT HANDLER CODE HERE.
*/
.align 4
.L_xt_highint4_exit:
rsr a0, EXCSAVE_4 /* restore a0 */
rfi 4
#endif /* Level 4 */
#if XCHAL_NUM_INTLEVELS >=5 && XCHAL_EXCM_LEVEL <5 && XCHAL_DEBUGLEVEL !=5
.begin literal_prefix .Level5InterruptVector
.section .Level5InterruptVector.text, "ax"
.global _Level5Vector
.type _Level5Vector,@function
.align 4
_Level5Vector:
wsr a0, EXCSAVE_5 /* preserve a0 */
call0 _xt_highint5 /* load interrupt handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.type _xt_highint5,@function
.align 4
_xt_highint5:
#ifdef XT_INTEXC_HOOKS
/* Call interrupt hook if present to (pre)handle interrupts. */
movi a0, _xt_intexc_hooks
l32i a0, a0, 5<<2
beqz a0, 1f
.Ln_xt_highint5_call_hook:
callx0 a0 /* must NOT disturb stack! */
1:
#endif
/* USER_EDIT:
ADD HIGH PRIORITY LEVEL 5 INTERRUPT HANDLER CODE HERE.
*/
.align 4
.L_xt_highint5_exit:
rsr a0, EXCSAVE_5 /* restore a0 */
rfi 5
#endif /* Level 5 */
#if XCHAL_NUM_INTLEVELS >=6 && XCHAL_EXCM_LEVEL <6 && XCHAL_DEBUGLEVEL !=6
.begin literal_prefix .Level6InterruptVector
.section .Level6InterruptVector.text, "ax"
.global _Level6Vector
.type _Level6Vector,@function
.align 4
_Level6Vector:
wsr a0, EXCSAVE_6 /* preserve a0 */
call0 _xt_highint6 /* load interrupt handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.type _xt_highint6,@function
.align 4
_xt_highint6:
#ifdef XT_INTEXC_HOOKS
/* Call interrupt hook if present to (pre)handle interrupts. */
movi a0, _xt_intexc_hooks
l32i a0, a0, 6<<2
beqz a0, 1f
.Ln_xt_highint6_call_hook:
callx0 a0 /* must NOT disturb stack! */
1:
#endif
/* USER_EDIT:
ADD HIGH PRIORITY LEVEL 6 INTERRUPT HANDLER CODE HERE.
*/
.align 4
.L_xt_highint6_exit:
rsr a0, EXCSAVE_6 /* restore a0 */
rfi 6
#endif /* Level 6 */
#if XCHAL_HAVE_NMI
.begin literal_prefix .NMIExceptionVector
.section .NMIExceptionVector.text, "ax"
.global _NMIExceptionVector
.type _NMIExceptionVector,@function
.align 4
_NMIExceptionVector:
wsr a0, EXCSAVE + XCHAL_NMILEVEL _ /* preserve a0 */
call0 _xt_nmi /* load interrupt handler */
/* never returns here - call0 is used as a jump (see note at top) */
.end literal_prefix
.text
.type _xt_nmi,@function
.align 4
_xt_nmi:
#ifdef XT_INTEXC_HOOKS
/* Call interrupt hook if present to (pre)handle interrupts. */
movi a0, _xt_intexc_hooks
l32i a0, a0, XCHAL_NMILEVEL<<2
beqz a0, 1f
.Ln_xt_nmi_call_hook:
callx0 a0 /* must NOT disturb stack! */
1:
#endif
/* USER_EDIT:
ADD HIGH PRIORITY NON-MASKABLE INTERRUPT (NMI) HANDLER CODE HERE.
*/
.align 4
.L_xt_nmi_exit:
rsr a0, EXCSAVE + XCHAL_NMILEVEL /* restore a0 */
rfi XCHAL_NMILEVEL
#endif /* NMI */
/*******************************************************************************
WINDOW OVERFLOW AND UNDERFLOW EXCEPTION VECTORS AND ALLOCA EXCEPTION HANDLER
Here is the code for each window overflow/underflow exception vector and
(interspersed) efficient code for handling the alloca exception cause.
Window exceptions are handled entirely in the vector area and are very
tight for performance. The alloca exception is also handled entirely in
the window vector area so comes at essentially no cost in code size.
Users should never need to modify them and Cadence Design Systems recommends
they do not.
Window handlers go at predetermined vector locations according to the
Xtensa hardware configuration, which is ensured by their placement in a
special section known to the Xtensa linker support package (LSP). Since
their offsets in that section are always the same, the LSPs do not define
a section per vector.
These things are coded for XEA2 only (XEA1 is not supported).
Note on Underflow Handlers:
The underflow handler for returning from call[i+1] to call[i]
must preserve all the registers from call[i+1]'s window.
In particular, a0 and a1 must be preserved because the RETW instruction
will be reexecuted (and may even underflow if an intervening exception
has flushed call[i]'s registers).
Registers a2 and up may contain return values.
*******************************************************************************/
#if XCHAL_HAVE_WINDOWED
.section .WindowVectors.text, "ax"
/*
--------------------------------------------------------------------------------
Window Overflow Exception for Call4.
Invoked if a call[i] referenced a register (a4-a15)
that contains data from ancestor call[j];
call[j] had done a call4 to call[j+1].
On entry here:
window rotated to call[j] start point;
a0-a3 are registers to be saved;
a4-a15 must be preserved;
a5 is call[j+1]'s stack pointer.
--------------------------------------------------------------------------------
*/
.org 0x0
.global _WindowOverflow4
_WindowOverflow4:
s32e a0, a5, -16 /* save a0 to call[j+1]'s stack frame */
s32e a1, a5, -12 /* save a1 to call[j+1]'s stack frame */
s32e a2, a5, -8 /* save a2 to call[j+1]'s stack frame */
s32e a3, a5, -4 /* save a3 to call[j+1]'s stack frame */
rfwo /* rotates back to call[i] position */
/*
--------------------------------------------------------------------------------
Window Underflow Exception for Call4
Invoked by RETW returning from call[i+1] to call[i]
where call[i]'s registers must be reloaded (not live in ARs);
where call[i] had done a call4 to call[i+1].
On entry here:
window rotated to call[i] start point;
a0-a3 are undefined, must be reloaded with call[i].reg[0..3];
a4-a15 must be preserved (they are call[i+1].reg[0..11]);
a5 is call[i+1]'s stack pointer.
--------------------------------------------------------------------------------
*/
.org 0x40
.global _WindowUnderflow4
_WindowUnderflow4:
l32e a0, a5, -16 /* restore a0 from call[i+1]'s stack frame */
l32e a1, a5, -12 /* restore a1 from call[i+1]'s stack frame */
l32e a2, a5, -8 /* restore a2 from call[i+1]'s stack frame */
l32e a3, a5, -4 /* restore a3 from call[i+1]'s stack frame */
rfwu
/*
--------------------------------------------------------------------------------
Handle alloca exception generated by interruptee executing 'movsp'.
This uses space between the window vectors, so is essentially "free".
All interruptee's regs are intact except a0 which is saved in EXCSAVE_1,
and PS.EXCM has been set by the exception hardware (can't be interrupted).
The fact the alloca exception was taken means the registers associated with
the base-save area have been spilled and will be restored by the underflow
handler, so those 4 registers are available for scratch.
The code is optimized to avoid unaligned branches and minimize cache misses.
--------------------------------------------------------------------------------
*/
.align 4
.global _xt_alloca_exc
_xt_alloca_exc:
rsr a0, WINDOWBASE /* grab WINDOWBASE before rotw changes it */
rotw -1 /* WINDOWBASE goes to a4, new a0-a3 are scratch */
rsr a2, PS
extui a3, a2, XCHAL_PS_OWB_SHIFT, XCHAL_PS_OWB_BITS
xor a3, a3, a4 /* bits changed from old to current windowbase */
rsr a4, EXCSAVE_1 /* restore original a0 (now in a4) */
slli a3, a3, XCHAL_PS_OWB_SHIFT
xor a2, a2, a3 /* flip changed bits in old window base */
wsr a2, PS /* update PS.OWB to new window base */
rsync
_bbci.l a4, 31, _WindowUnderflow4
rotw -1 /* original a0 goes to a8 */
_bbci.l a8, 30, _WindowUnderflow8
rotw -1
j _WindowUnderflow12
/*
--------------------------------------------------------------------------------
Window Overflow Exception for Call8
Invoked if a call[i] referenced a register (a4-a15)
that contains data from ancestor call[j];
call[j] had done a call8 to call[j+1].
On entry here:
window rotated to call[j] start point;
a0-a7 are registers to be saved;
a8-a15 must be preserved;
a9 is call[j+1]'s stack pointer.
--------------------------------------------------------------------------------
*/
.org 0x80
.global _WindowOverflow8
_WindowOverflow8:
s32e a0, a9, -16 /* save a0 to call[j+1]'s stack frame */
l32e a0, a1, -12 /* a0 <- call[j-1]'s sp
(used to find end of call[j]'s frame) */
s32e a1, a9, -12 /* save a1 to call[j+1]'s stack frame */
s32e a2, a9, -8 /* save a2 to call[j+1]'s stack frame */
s32e a3, a9, -4 /* save a3 to call[j+1]'s stack frame */
s32e a4, a0, -32 /* save a4 to call[j]'s stack frame */
s32e a5, a0, -28 /* save a5 to call[j]'s stack frame */
s32e a6, a0, -24 /* save a6 to call[j]'s stack frame */
s32e a7, a0, -20 /* save a7 to call[j]'s stack frame */
rfwo /* rotates back to call[i] position */
/*
--------------------------------------------------------------------------------
Window Underflow Exception for Call8
Invoked by RETW returning from call[i+1] to call[i]
where call[i]'s registers must be reloaded (not live in ARs);
where call[i] had done a call8 to call[i+1].
On entry here:
window rotated to call[i] start point;
a0-a7 are undefined, must be reloaded with call[i].reg[0..7];
a8-a15 must be preserved (they are call[i+1].reg[0..7]);
a9 is call[i+1]'s stack pointer.
--------------------------------------------------------------------------------
*/
.org 0xC0
.global _WindowUnderflow8
_WindowUnderflow8:
l32e a0, a9, -16 /* restore a0 from call[i+1]'s stack frame */
l32e a1, a9, -12 /* restore a1 from call[i+1]'s stack frame */
l32e a2, a9, -8 /* restore a2 from call[i+1]'s stack frame */
l32e a7, a1, -12 /* a7 <- call[i-1]'s sp
(used to find end of call[i]'s frame) */
l32e a3, a9, -4 /* restore a3 from call[i+1]'s stack frame */
l32e a4, a7, -32 /* restore a4 from call[i]'s stack frame */
l32e a5, a7, -28 /* restore a5 from call[i]'s stack frame */
l32e a6, a7, -24 /* restore a6 from call[i]'s stack frame */
l32e a7, a7, -20 /* restore a7 from call[i]'s stack frame */
rfwu
/*
--------------------------------------------------------------------------------
Window Overflow Exception for Call12
Invoked if a call[i] referenced a register (a4-a15)
that contains data from ancestor call[j];
call[j] had done a call12 to call[j+1].
On entry here:
window rotated to call[j] start point;
a0-a11 are registers to be saved;
a12-a15 must be preserved;
a13 is call[j+1]'s stack pointer.
--------------------------------------------------------------------------------
*/
.org 0x100
.global _WindowOverflow12
_WindowOverflow12:
s32e a0, a13, -16 /* save a0 to call[j+1]'s stack frame */
l32e a0, a1, -12 /* a0 <- call[j-1]'s sp
(used to find end of call[j]'s frame) */
s32e a1, a13, -12 /* save a1 to call[j+1]'s stack frame */
s32e a2, a13, -8 /* save a2 to call[j+1]'s stack frame */
s32e a3, a13, -4 /* save a3 to call[j+1]'s stack frame */
s32e a4, a0, -48 /* save a4 to end of call[j]'s stack frame */
s32e a5, a0, -44 /* save a5 to end of call[j]'s stack frame */
s32e a6, a0, -40 /* save a6 to end of call[j]'s stack frame */
s32e a7, a0, -36 /* save a7 to end of call[j]'s stack frame */
s32e a8, a0, -32 /* save a8 to end of call[j]'s stack frame */
s32e a9, a0, -28 /* save a9 to end of call[j]'s stack frame */
s32e a10, a0, -24 /* save a10 to end of call[j]'s stack frame */
s32e a11, a0, -20 /* save a11 to end of call[j]'s stack frame */
rfwo /* rotates back to call[i] position */
/*
--------------------------------------------------------------------------------
Window Underflow Exception for Call12
Invoked by RETW returning from call[i+1] to call[i]
where call[i]'s registers must be reloaded (not live in ARs);
where call[i] had done a call12 to call[i+1].
On entry here:
window rotated to call[i] start point;
a0-a11 are undefined, must be reloaded with call[i].reg[0..11];
a12-a15 must be preserved (they are call[i+1].reg[0..3]);
a13 is call[i+1]'s stack pointer.
--------------------------------------------------------------------------------
*/
.org 0x140
.global _WindowUnderflow12
_WindowUnderflow12:
l32e a0, a13, -16 /* restore a0 from call[i+1]'s stack frame */
l32e a1, a13, -12 /* restore a1 from call[i+1]'s stack frame */
l32e a2, a13, -8 /* restore a2 from call[i+1]'s stack frame */
l32e a11, a1, -12 /* a11 <- call[i-1]'s sp
(used to find end of call[i]'s frame) */
l32e a3, a13, -4 /* restore a3 from call[i+1]'s stack frame */
l32e a4, a11, -48 /* restore a4 from end of call[i]'s stack frame */
l32e a5, a11, -44 /* restore a5 from end of call[i]'s stack frame */
l32e a6, a11, -40 /* restore a6 from end of call[i]'s stack frame */
l32e a7, a11, -36 /* restore a7 from end of call[i]'s stack frame */
l32e a8, a11, -32 /* restore a8 from end of call[i]'s stack frame */
l32e a9, a11, -28 /* restore a9 from end of call[i]'s stack frame */
l32e a10, a11, -24 /* restore a10 from end of call[i]'s stack frame */
l32e a11, a11, -20 /* restore a11 from end of call[i]'s stack frame */
rfwu
#endif /* XCHAL_HAVE_WINDOWED */
.section .UserEnter.text, "ax"
.global call_user_start
.type call_user_start,@function
.align 4
.literal_position
call_user_start:
movi a2, 0x40040000 /* note: absolute symbol, not a ptr */
wsr a2, vecbase
call0 user_start /* user exception handler */
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