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tannewttannewt
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Mark pointers in cpu registers as in use.
This prevents bugs where gc_collect is called from C code that did a recent allocation.
1 parent 252aacd commit ec78d3c

5 files changed

Lines changed: 105 additions & 4 deletions

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‎main.c‎

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Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -44,6 +44,7 @@
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#include "lib/utils/pyexec.h"
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#include "mpconfigboard.h"
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#include "supervisor/cpu.h"
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#include "supervisor/port.h"
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#include "supervisor/filesystem.h"
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// TODO(tannewt): Figure out how to choose language at compile time.
@@ -381,16 +382,17 @@ int __attribute__((used)) main(void) {
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}
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void gc_collect(void) {
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// WARNING: This gc_collect implementation doesn't try to get root
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// pointers from CPU registers, and thus may function incorrectly.
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void *dummy;
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gc_collect_start();
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mp_uint_t regs[10];
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mp_uint_t sp = cpu_get_regs_and_sp(regs);
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// This collects root pointers from the VFS mount table. Some of them may
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// have lost their references in the VM even though they are mounted.
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gc_collect_root((void**)&MP_STATE_VM(vfs_mount_table), sizeof(mp_vfs_mount_t) / sizeof(mp_uint_t));
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// This naively collects all object references from an approximate stack
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// range.
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gc_collect_root(&dummy, ((mp_uint_t)&_estack - (mp_uint_t)&dummy) / sizeof(mp_uint_t));
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gc_collect_root((void**)sp, ((uint32_t)&_estack - sp) / sizeof(uint32_t));
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gc_collect_end();
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}
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‎ports/atmel-samd/Makefile‎

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@@ -412,13 +412,16 @@ endif
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SRC_SHARED_MODULE_EXPANDED = $(addprefix shared-bindings/, $(SRC_SHARED_MODULE)) \
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$(addprefix shared-module/, $(SRC_SHARED_MODULE))
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SRC_O = supervisor/$(CHIP_FAMILY)_cpu.o
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OBJ = $(PY_O) $(SUPERVISOR_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
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OBJ += $(addprefix $(BUILD)/, $(SRC_ASF:.c=.o))
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OBJ += $(addprefix $(BUILD)/, $(SRC_COMMON_HAL_EXPANDED:.c=.o))
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OBJ += $(addprefix $(BUILD)/, $(SRC_SHARED_MODULE_EXPANDED:.c=.o))
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ifeq ($(INTERNAL_LIBM),1)
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OBJ += $(addprefix $(BUILD)/, $(SRC_LIBM:.c=.o))
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endif
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OBJ += $(addprefix $(BUILD)/, $(SRC_O))
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SRC_QSTR += $(SRC_C) $(SRC_SUPERVISOR) $(SRC_COMMON_HAL_EXPANDED) $(SRC_SHARED_MODULE_EXPANDED) $(STM_SRC_C)
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‎ports/atmel-samd/supervisor/samd21_cpu.s‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,35 @@
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.syntax unified
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.cpu cortex-m0
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.thumb
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.text
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.align 2
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@ uint cpu_get_regs_and_sp(r0=uint regs[10])
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.global cpu_get_regs_and_sp
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.thumb
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.thumb_func
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.type cpu_get_regs_and_sp, %function
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cpu_get_regs_and_sp:
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@ store registers into given array
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str r4, [r0, #0]
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str r5, [r0, #4]
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str r6, [r0, #8]
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str r7, [r0, #12]
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push {r1}
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mov r1, r8
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str r1, [r0, #16]
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mov r1, r9
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str r1, [r0, #20]
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mov r1, r10
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str r1, [r0, #24]
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mov r1, r11
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str r1, [r0, #28]
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mov r1, r12
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str r1, [r0, #32]
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mov r1, r13
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str r1, [r0, #36]
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pop {r1}
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@ return the sp
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mov r0, sp
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bx lr

‎ports/atmel-samd/supervisor/samd51_cpu.s‎

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@@ -0,0 +1,27 @@
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.syntax unified
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.cpu cortex-m4
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.thumb
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.text
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.align 2
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@ uint cpu_get_regs_and_sp(r0=uint regs[10])
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.global cpu_get_regs_and_sp
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.thumb
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.thumb_func
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.type cpu_get_regs_and_sp, %function
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cpu_get_regs_and_sp:
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@ store registers into given array
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str r4, [r0], #4
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str r5, [r0], #4
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str r6, [r0], #4
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str r7, [r0], #4
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str r8, [r0], #4
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str r9, [r0], #4
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str r10, [r0], #4
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str r11, [r0], #4
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str r12, [r0], #4
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str r13, [r0], #4
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@ return the sp
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mov r0, sp
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bx lr

‎supervisor/cpu.h‎

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/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef MICROPY_INCLUDED_SUPERVISOR_CPU_H
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#define MICROPY_INCLUDED_SUPERVISOR_CPU_H
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// Adds up to 10 pointers from the CPUs registers to regs. This is used to make sure no actively
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// used heap memory is freed. Its usually implemented in assembly.
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mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs);
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#endif // MICROPY_INCLUDED_SUPERVISOR_CPU_H

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