/* | |
* Copyright (c) 2015-2019 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 CONTEXT FRAMES AND MACROS FOR RTOS ASSEMBLER SOURCES | |
* | |
* This header contains definitions and macros for use primarily by Xtensa | |
* RTOS assembly coded source files. It includes and uses the Xtensa hardware | |
* abstraction layer (HAL) to deal with config specifics. It may also be | |
* included in C source files. | |
* | |
* !! Supports only Xtensa Exception Architecture 2 (XEA2). XEA1 not supported. !! | |
* | |
* NOTE: The Xtensa architecture requires stack pointer alignment to 16 bytes. | |
*/ | |
#ifndef XTENSA_CONTEXT_H | |
#define XTENSA_CONTEXT_H | |
#ifdef __ASSEMBLER__ | |
#include <xtensa/coreasm.h> | |
#endif | |
#include <xtensa/config/tie.h> | |
#include <xtensa/corebits.h> | |
#include <xtensa/config/system.h> | |
/* Align a value up to nearest n-byte boundary, where n is a power of 2. */ | |
#define ALIGNUP(n, val) (((val) + (n)-1) & -(n)) | |
/* | |
------------------------------------------------------------------------------- | |
Macros that help define structures for both C and assembler. | |
------------------------------------------------------------------------------- | |
*/ | |
#if defined(_ASMLANGUAGE) || defined(__ASSEMBLER__) | |
#define STRUCT_BEGIN .pushsection .text; .struct 0 | |
#define STRUCT_FIELD(ctype,size,asname,name) asname: .space size | |
#define STRUCT_AFIELD(ctype,size,asname,name,n) asname: .space (size)*(n) | |
#define STRUCT_END(sname) sname##Size:; .popsection | |
#else | |
#define STRUCT_BEGIN typedef struct { | |
#define STRUCT_FIELD(ctype,size,asname,name) ctype name; | |
#define STRUCT_AFIELD(ctype,size,asname,name,n) ctype name[n]; | |
#define STRUCT_END(sname) } sname; | |
#endif //_ASMLANGUAGE || __ASSEMBLER__ | |
/* | |
------------------------------------------------------------------------------- | |
INTERRUPT/EXCEPTION STACK FRAME FOR A THREAD OR NESTED INTERRUPT | |
A stack frame of this structure is allocated for any interrupt or exception. | |
It goes on the current stack. If the RTOS has a system stack for handling | |
interrupts, every thread stack must allow space for just one interrupt stack | |
frame, then nested interrupt stack frames go on the system stack. | |
The frame includes basic registers (explicit) and "extra" registers introduced | |
by user TIE or the use of the MAC16 option in the user's Xtensa config. | |
The frame size is minimized by omitting regs not applicable to user's config. | |
For Windowed ABI, this stack frame includes the interruptee's base save area, | |
another base save area to manage gcc nested functions, and a little temporary | |
space to help manage the spilling of the register windows. | |
------------------------------------------------------------------------------- | |
*/ | |
STRUCT_BEGIN | |
STRUCT_FIELD (long, 4, XT_STK_EXIT, exit) /* exit point for dispatch */ | |
STRUCT_FIELD (long, 4, XT_STK_PC, pc) /* return PC */ | |
STRUCT_FIELD (long, 4, XT_STK_PS, ps) /* return PS */ | |
STRUCT_FIELD (long, 4, XT_STK_A0, a0) | |
STRUCT_FIELD (long, 4, XT_STK_A1, a1) /* stack pointer before interrupt */ | |
STRUCT_FIELD (long, 4, XT_STK_A2, a2) | |
STRUCT_FIELD (long, 4, XT_STK_A3, a3) | |
STRUCT_FIELD (long, 4, XT_STK_A4, a4) | |
STRUCT_FIELD (long, 4, XT_STK_A5, a5) | |
STRUCT_FIELD (long, 4, XT_STK_A6, a6) | |
STRUCT_FIELD (long, 4, XT_STK_A7, a7) | |
STRUCT_FIELD (long, 4, XT_STK_A8, a8) | |
STRUCT_FIELD (long, 4, XT_STK_A9, a9) | |
STRUCT_FIELD (long, 4, XT_STK_A10, a10) | |
STRUCT_FIELD (long, 4, XT_STK_A11, a11) | |
STRUCT_FIELD (long, 4, XT_STK_A12, a12) | |
STRUCT_FIELD (long, 4, XT_STK_A13, a13) | |
STRUCT_FIELD (long, 4, XT_STK_A14, a14) | |
STRUCT_FIELD (long, 4, XT_STK_A15, a15) | |
STRUCT_FIELD (long, 4, XT_STK_SAR, sar) | |
STRUCT_FIELD (long, 4, XT_STK_EXCCAUSE, exccause) | |
STRUCT_FIELD (long, 4, XT_STK_EXCVADDR, excvaddr) | |
#if XCHAL_HAVE_LOOPS | |
STRUCT_FIELD (long, 4, XT_STK_LBEG, lbeg) | |
STRUCT_FIELD (long, 4, XT_STK_LEND, lend) | |
STRUCT_FIELD (long, 4, XT_STK_LCOUNT, lcount) | |
#endif | |
#ifndef __XTENSA_CALL0_ABI__ | |
/* Temporary space for saving stuff during window spill */ | |
STRUCT_FIELD (long, 4, XT_STK_TMP0, tmp0) | |
STRUCT_FIELD (long, 4, XT_STK_TMP1, tmp1) | |
STRUCT_FIELD (long, 4, XT_STK_TMP2, tmp2) | |
#endif | |
#ifdef XT_USE_SWPRI | |
/* Storage for virtual priority mask */ | |
STRUCT_FIELD (long, 4, XT_STK_VPRI, vpri) | |
#endif | |
#ifdef XT_USE_OVLY | |
/* Storage for overlay state */ | |
STRUCT_FIELD (long, 4, XT_STK_OVLY, ovly) | |
#endif | |
STRUCT_END(XtExcFrame) | |
#if defined(_ASMLANGUAGE) || defined(__ASSEMBLER__) | |
#define XT_STK_NEXT1 XtExcFrameSize | |
#else | |
#define XT_STK_NEXT1 sizeof(XtExcFrame) | |
#endif | |
/* Allocate extra storage if needed */ | |
#if XCHAL_EXTRA_SA_SIZE != 0 | |
#if XCHAL_EXTRA_SA_ALIGN <= 16 | |
#define XT_STK_EXTRA ALIGNUP(XCHAL_EXTRA_SA_ALIGN, XT_STK_NEXT1) | |
#else | |
/* If need more alignment than stack, add space for dynamic alignment */ | |
#define XT_STK_EXTRA (ALIGNUP(XCHAL_EXTRA_SA_ALIGN, XT_STK_NEXT1) + XCHAL_EXTRA_SA_ALIGN) | |
#endif | |
#define XT_STK_NEXT2 (XT_STK_EXTRA + XCHAL_EXTRA_SA_SIZE) | |
#else | |
#define XT_STK_NEXT2 XT_STK_NEXT1 | |
#endif | |
/* | |
------------------------------------------------------------------------------- | |
This is the frame size. Add space for 4 registers (interruptee's base save | |
area) and some space for gcc nested functions if any. | |
------------------------------------------------------------------------------- | |
*/ | |
#define XT_STK_FRMSZ (ALIGNUP(0x10, XT_STK_NEXT2) + 0x20) | |
/* | |
------------------------------------------------------------------------------- | |
SOLICITED STACK FRAME FOR A THREAD | |
A stack frame of this structure is allocated whenever a thread enters the | |
RTOS kernel intentionally (and synchronously) to submit to thread scheduling. | |
It goes on the current thread's stack. | |
The solicited frame only includes registers that are required to be preserved | |
by the callee according to the compiler's ABI conventions, some space to save | |
the return address for returning to the caller, and the caller's PS register. | |
For Windowed ABI, this stack frame includes the caller's base save area. | |
Note on XT_SOL_EXIT field: | |
It is necessary to distinguish a solicited from an interrupt stack frame. | |
This field corresponds to XT_STK_EXIT in the interrupt stack frame and is | |
always at the same offset (0). It can be written with a code (usually 0) | |
to distinguish a solicted frame from an interrupt frame. An RTOS port may | |
opt to ignore this field if it has another way of distinguishing frames. | |
------------------------------------------------------------------------------- | |
*/ | |
STRUCT_BEGIN | |
#ifdef __XTENSA_CALL0_ABI__ | |
STRUCT_FIELD (long, 4, XT_SOL_EXIT, exit) | |
STRUCT_FIELD (long, 4, XT_SOL_PC, pc) | |
STRUCT_FIELD (long, 4, XT_SOL_PS, ps) | |
STRUCT_FIELD (long, 4, XT_SOL_NEXT, next) | |
STRUCT_FIELD (long, 4, XT_SOL_A12, a12) /* should be on 16-byte alignment */ | |
STRUCT_FIELD (long, 4, XT_SOL_A13, a13) | |
STRUCT_FIELD (long, 4, XT_SOL_A14, a14) | |
STRUCT_FIELD (long, 4, XT_SOL_A15, a15) | |
#else | |
STRUCT_FIELD (long, 4, XT_SOL_EXIT, exit) | |
STRUCT_FIELD (long, 4, XT_SOL_PC, pc) | |
STRUCT_FIELD (long, 4, XT_SOL_PS, ps) | |
STRUCT_FIELD (long, 4, XT_SOL_NEXT, next) | |
STRUCT_FIELD (long, 4, XT_SOL_A0, a0) /* should be on 16-byte alignment */ | |
STRUCT_FIELD (long, 4, XT_SOL_A1, a1) | |
STRUCT_FIELD (long, 4, XT_SOL_A2, a2) | |
STRUCT_FIELD (long, 4, XT_SOL_A3, a3) | |
#endif | |
STRUCT_END(XtSolFrame) | |
/* Size of solicited stack frame */ | |
#define XT_SOL_FRMSZ ALIGNUP(0x10, XtSolFrameSize) | |
/* | |
------------------------------------------------------------------------------- | |
CO-PROCESSOR STATE SAVE AREA FOR A THREAD | |
The RTOS must provide an area per thread to save the state of co-processors | |
when that thread does not have control. Co-processors are context-switched | |
lazily (on demand) only when a new thread uses a co-processor instruction, | |
otherwise a thread retains ownership of the co-processor even when it loses | |
control of the processor. An Xtensa co-processor exception is triggered when | |
any co-processor instruction is executed by a thread that is not the owner, | |
and the context switch of that co-processor is then peformed by the handler. | |
Ownership represents which thread's state is currently in the co-processor. | |
Co-processors may not be used by interrupt or exception handlers. If an | |
co-processor instruction is executed by an interrupt or exception handler, | |
the co-processor exception handler will trigger a kernel panic and freeze. | |
This restriction is introduced to reduce the overhead of saving and restoring | |
co-processor state (which can be quite large) and in particular remove that | |
overhead from interrupt handlers. | |
The co-processor state save area may be in any convenient per-thread location | |
such as in the thread control block or above the thread stack area. It need | |
not be in the interrupt stack frame since interrupts don't use co-processors. | |
Along with the save area for each co-processor, two bitmasks with flags per | |
co-processor (laid out as in the CPENABLE reg) help manage context-switching | |
co-processors as efficiently as possible: | |
XT_CPENABLE | |
The contents of a non-running thread's CPENABLE register. | |
It represents the co-processors owned (and whose state is still needed) | |
by the thread. When a thread is preempted, its CPENABLE is saved here. | |
When a thread solicits a context-swtich, its CPENABLE is cleared - the | |
compiler has saved the (caller-saved) co-proc state if it needs to. | |
When a non-running thread loses ownership of a CP, its bit is cleared. | |
When a thread runs, it's XT_CPENABLE is loaded into the CPENABLE reg. | |
Avoids co-processor exceptions when no change of ownership is needed. | |
XT_CPSTORED | |
A bitmask with the same layout as CPENABLE, a bit per co-processor. | |
Indicates whether the state of each co-processor is saved in the state | |
save area. When a thread enters the kernel, only the state of co-procs | |
still enabled in CPENABLE is saved. When the co-processor exception | |
handler assigns ownership of a co-processor to a thread, it restores | |
the saved state only if this bit is set, and clears this bit. | |
XT_CP_CS_ST | |
A bitmask with the same layout as CPENABLE, a bit per co-processor. | |
Indicates whether callee-saved state is saved in the state save area. | |
Callee-saved state is saved by itself on a solicited context switch, | |
and restored when needed by the coprocessor exception handler. | |
Unsolicited switches will cause the entire coprocessor to be saved | |
when necessary. | |
XT_CP_ASA | |
Pointer to the aligned save area. Allows it to be aligned more than | |
the overall save area (which might only be stack-aligned or TCB-aligned). | |
Especially relevant for Xtensa cores configured with a very large data | |
path that requires alignment greater than 16 bytes (ABI stack alignment). | |
------------------------------------------------------------------------------- | |
*/ | |
#if XCHAL_CP_NUM > 0 | |
/* Offsets of each coprocessor save area within the 'aligned save area': */ | |
#define XT_CP0_SA 0 | |
#define XT_CP1_SA ALIGNUP(XCHAL_CP1_SA_ALIGN, XT_CP0_SA + XCHAL_CP0_SA_SIZE) | |
#define XT_CP2_SA ALIGNUP(XCHAL_CP2_SA_ALIGN, XT_CP1_SA + XCHAL_CP1_SA_SIZE) | |
#define XT_CP3_SA ALIGNUP(XCHAL_CP3_SA_ALIGN, XT_CP2_SA + XCHAL_CP2_SA_SIZE) | |
#define XT_CP4_SA ALIGNUP(XCHAL_CP4_SA_ALIGN, XT_CP3_SA + XCHAL_CP3_SA_SIZE) | |
#define XT_CP5_SA ALIGNUP(XCHAL_CP5_SA_ALIGN, XT_CP4_SA + XCHAL_CP4_SA_SIZE) | |
#define XT_CP6_SA ALIGNUP(XCHAL_CP6_SA_ALIGN, XT_CP5_SA + XCHAL_CP5_SA_SIZE) | |
#define XT_CP7_SA ALIGNUP(XCHAL_CP7_SA_ALIGN, XT_CP6_SA + XCHAL_CP6_SA_SIZE) | |
#define XT_CP_SA_SIZE ALIGNUP(16, XT_CP7_SA + XCHAL_CP7_SA_SIZE) | |
/* Offsets within the overall save area: */ | |
#define XT_CPENABLE 0 /* (2 bytes) coprocessors active for this thread */ | |
#define XT_CPSTORED 2 /* (2 bytes) coprocessors saved for this thread */ | |
#define XT_CP_CS_ST 4 /* (2 bytes) coprocessor callee-saved regs stored for this thread */ | |
#define XT_CP_ASA 8 /* (4 bytes) ptr to aligned save area */ | |
/* Overall size allows for dynamic alignment: */ | |
#define XT_CP_SIZE (12 + XT_CP_SA_SIZE + XCHAL_TOTAL_SA_ALIGN) | |
#else | |
#define XT_CP_SIZE 0 | |
#endif | |
/* | |
------------------------------------------------------------------------------- | |
MACROS TO HANDLE ABI SPECIFICS OF FUNCTION ENTRY AND RETURN | |
Convenient where the frame size requirements are the same for both ABIs. | |
ENTRY(sz), RET(sz) are for framed functions (have locals or make calls). | |
ENTRY0, RET0 are for frameless functions (no locals, no calls). | |
where size = size of stack frame in bytes (must be >0 and aligned to 16). | |
For framed functions the frame is created and the return address saved at | |
base of frame (Call0 ABI) or as determined by hardware (Windowed ABI). | |
For frameless functions, there is no frame and return address remains in a0. | |
Note: Because CPP macros expand to a single line, macros requiring multi-line | |
expansions are implemented as assembler macros. | |
------------------------------------------------------------------------------- | |
*/ | |
#ifdef __ASSEMBLER__ | |
#ifdef __XTENSA_CALL0_ABI__ | |
/* Call0 */ | |
#define ENTRY(sz) entry1 sz | |
.macro entry1 size=0x10 | |
addi sp, sp, -\size | |
s32i a0, sp, 0 | |
.endm | |
#define ENTRY0 | |
#define RET(sz) ret1 sz | |
.macro ret1 size=0x10 | |
l32i a0, sp, 0 | |
addi sp, sp, \size | |
ret | |
.endm | |
#define RET0 ret | |
#else | |
/* Windowed */ | |
#define ENTRY(sz) entry sp, sz | |
#define ENTRY0 entry sp, 0x10 | |
#define RET(sz) retw | |
#define RET0 retw | |
#endif | |
#endif | |
#endif /* XTENSA_CONTEXT_H */ | |