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circuitpython/py/nlr.h
Damien George d54208a2ff py/scheduler: Implement VM abort flag and mp_sched_vm_abort(). 
This is intended to be used by the very outer caller of the VM/runtime.  It
allows setting a top-level NLR handler that can be jumped to directly, in
order to forcefully abort the VM/runtime.

Enable using:

    #define MICROPY_ENABLE_VM_ABORT (1)

Set up the handler at the top level using:

    nlr_buf_t nlr;
    nlr.ret_val = NULL;
    if (nlr_push(&nlr) == 0) {
        nlr_set_abort(&nlr);
        // call into the VM/runtime
        ...
        nlr_pop();
    } else {
        if (nlr.ret_val == NULL) {
            // handle abort
            ...
        } else {
            // handle other exception that propagated to the top level
            ...
        }
    }
    nlr_set_abort(NULL);

Schedule an abort, eg from an interrupt handler, using:

    mp_sched_vm_abort();

Signed-off-by: Damien George <damien@micropython.org>
2023-03-21 18:08:57 +11:00

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013, 2014 Damien P. George
*
* 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.
*/
#ifndef MICROPY_INCLUDED_PY_NLR_H
#define MICROPY_INCLUDED_PY_NLR_H
// non-local return
// exception handling, basically a stack of setjmp/longjmp buffers
#include <limits.h>
#include <assert.h>
#include "py/mpconfig.h"
#define MICROPY_NLR_NUM_REGS_X86 (6)
#define MICROPY_NLR_NUM_REGS_X64 (8)
#define MICROPY_NLR_NUM_REGS_X64_WIN (10)
#define MICROPY_NLR_NUM_REGS_ARM_THUMB (10)
#define MICROPY_NLR_NUM_REGS_ARM_THUMB_FP (10 + 6)
#define MICROPY_NLR_NUM_REGS_AARCH64 (13)
#define MICROPY_NLR_NUM_REGS_MIPS (13)
#define MICROPY_NLR_NUM_REGS_XTENSA (10)
#define MICROPY_NLR_NUM_REGS_XTENSAWIN (17)
// *FORMAT-OFF*
// If MICROPY_NLR_SETJMP is not enabled then auto-detect the machine arch
#if !MICROPY_NLR_SETJMP
// A lot of nlr-related things need different treatment on Windows
#if defined(_WIN32) || defined(__CYGWIN__)
#define MICROPY_NLR_OS_WINDOWS 1
#else
#define MICROPY_NLR_OS_WINDOWS 0
#endif
#if defined(__i386__)
#define MICROPY_NLR_X86 (1)
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_X86)
#elif defined(__x86_64__)
#define MICROPY_NLR_X64 (1)
#if MICROPY_NLR_OS_WINDOWS
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_X64_WIN)
#else
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_X64)
#endif
#elif defined(__thumb2__) || defined(__thumb__) || defined(__arm__)
#define MICROPY_NLR_THUMB (1)
#if defined(__SOFTFP__)
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_ARM_THUMB)
#else
// With hardware FP registers s16-s31 are callee save so in principle
// should be saved and restored by the NLR code. gcc only uses s16-s21
// so only save/restore those as an optimisation.
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_ARM_THUMB_FP)
#endif
#elif defined(__aarch64__)
#define MICROPY_NLR_AARCH64 (1)
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_AARCH64)
#elif defined(__xtensa__)
#define MICROPY_NLR_XTENSA (1)
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_XTENSA)
#elif defined(__powerpc__)
#define MICROPY_NLR_POWERPC (1)
// this could be less but using 128 for safety
#define MICROPY_NLR_NUM_REGS (128)
#elif defined(__mips__)
#define MICROPY_NLR_MIPS (1)
#define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_MIPS)
#else
#define MICROPY_NLR_SETJMP (1)
//#warning "No native NLR support for this arch, using setjmp implementation"
#endif
#endif
// *FORMAT-ON*
#if MICROPY_NLR_SETJMP
#include <setjmp.h>
#endif
typedef struct _nlr_buf_t nlr_buf_t;
struct _nlr_buf_t {
// The entries in this struct must all be machine word size.
// Pointer to the previous nlr_buf_t in the chain.
// Or NULL if it's the top-level one.
nlr_buf_t *prev;
// The exception that is being raised:
// - NULL means the jump is because of a VM abort (only if MICROPY_ENABLE_VM_ABORT enabled)
// - otherwise it's always a concrete object (an exception instance)
void *ret_val;
#if MICROPY_NLR_SETJMP
jmp_buf jmpbuf;
#else
void *regs[MICROPY_NLR_NUM_REGS];
#endif
#if MICROPY_ENABLE_PYSTACK
void *pystack;
#endif
};
// Helper macros to save/restore the pystack state
#if MICROPY_ENABLE_PYSTACK
#define MP_NLR_SAVE_PYSTACK(nlr_buf) (nlr_buf)->pystack = MP_STATE_THREAD(pystack_cur)
#define MP_NLR_RESTORE_PYSTACK(nlr_buf) MP_STATE_THREAD(pystack_cur) = (nlr_buf)->pystack
#else
#define MP_NLR_SAVE_PYSTACK(nlr_buf) (void)nlr_buf
#define MP_NLR_RESTORE_PYSTACK(nlr_buf) (void)nlr_buf
#endif
// Helper macro to use at the start of a specific nlr_jump implementation
#define MP_NLR_JUMP_HEAD(val, top) \
nlr_buf_t **_top_ptr = &MP_STATE_THREAD(nlr_top); \
nlr_buf_t *top = *_top_ptr; \
if (top == NULL) { \
nlr_jump_fail(val); \
} \
top->ret_val = val; \
MP_NLR_RESTORE_PYSTACK(top); \
*_top_ptr = top->prev; \
#if MICROPY_NLR_SETJMP
// nlr_push() must be defined as a macro, because "The stack context will be
// invalidated if the function which called setjmp() returns."
// For this case it is safe to call nlr_push_tail() first.
#define nlr_push(buf) (nlr_push_tail(buf), setjmp((buf)->jmpbuf))
#else
unsigned int nlr_push(nlr_buf_t *);
#endif
unsigned int nlr_push_tail(nlr_buf_t *top);
void nlr_pop(void);
NORETURN void nlr_jump(void *val);
#if MICROPY_ENABLE_VM_ABORT
#define nlr_set_abort(buf) MP_STATE_VM(nlr_abort) = buf
#define nlr_get_abort() MP_STATE_VM(nlr_abort)
NORETURN void nlr_jump_abort(void);
#endif
// This must be implemented by a port. It's called by nlr_jump
// if no nlr buf has been pushed. It must not return, but rather
// should bail out with a fatal error.
NORETURN void nlr_jump_fail(void *val);
// use nlr_raise instead of nlr_jump so that debugging is easier
#ifndef MICROPY_DEBUG_NLR
#define nlr_raise(val) nlr_jump(MP_OBJ_TO_PTR(val))
#else
#include "mpstate.h"
#define nlr_raise(val) \
do { \
/*printf("nlr_raise: nlr_top=%p\n", MP_STATE_THREAD(nlr_top)); \
fflush(stdout);*/ \
void *_val = MP_OBJ_TO_PTR(val); \
assert(_val != NULL); \
assert(mp_obj_is_exception_instance(val)); \
nlr_jump(_val); \
} while (0)
#if !MICROPY_NLR_SETJMP
#define nlr_push(val) \
assert(MP_STATE_THREAD(nlr_top) != val), nlr_push(val)
/*
#define nlr_push(val) \
printf("nlr_push: before: nlr_top=%p, val=%p\n", MP_STATE_THREAD(nlr_top), val),assert(MP_STATE_THREAD(nlr_top) != val),nlr_push(val)
*/
#endif
#endif
#endif // MICROPY_INCLUDED_PY_NLR_H
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