firmware: add crc stub to all dfu apps to ensure reliable loading

DFU flashing of apps sometimes aborts, and although rare this leads to
broken devices if no boot button or serial/jtag access exists, because
the bootloader will keep trying to start a half-flashed app that then
crashes at some point.

The easiest fix that works with existing bootloaders is to prepend a
small 512 byte stub that calculcates the crc and compares it with the
crc calculated at build time, and then either starts the actual app, or
sets the dfu flag and resets. This ensures we either have a working,
running app, or end up in the bootloader, ready to flash again.

For obvious reasons this only applies to dfu apps, and not to flash
targets like the actual bootloader itself.

Change-Id: Id6df0486c8b779889d21800dc2441b3aa9af8a5f
This commit is contained in:
Eric Wild 2021-12-06 21:48:01 +01:00 committed by laforge
parent f721e69bc1
commit cb655f9774
7 changed files with 246 additions and 28 deletions

View File

@ -1,4 +1,4 @@
#!/bin/sh -e
#!/bin/bash -e
# Create copies of binaries with -latest, -$GIT_VERSION (OS#4413, OS#3452)
cd "$(dirname "$0")/.."
@ -9,8 +9,10 @@ echo "Copying binaries with "-latest" and "-$GIT_VERSION" appended..."
cd firmware/bin
for ext in bin elf; do
for file in *."$ext"; do
without_ext="${file%.*}"
cp -v "$file" "$without_ext-latest.$ext"
cp -v "$file" "$without_ext-$GIT_VERSION.$ext"
if ! [[ "$file" =~ ^(.*padded.*|.*nocrcstub.*)$ ]];then
without_ext="${file%.*}"
cp -v "$file" "$without_ext-latest.$ext"
cp -v "$file" "$without_ext-$GIT_VERSION.$ext"
fi
done
done

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@ -117,7 +117,7 @@ C_LIBUSB = USBDescriptors.c USBRequests.c USBD.c USBDCallbacks.c USBDDriver.
C_LIBUSB_RT = dfu.c dfu_runtime.c
C_LIBUSB_DFU = dfu.c dfu_desc.c dfu_driver.c
C_LIBCOMMON = string.c stdio.c fputs.c usb_buf.c ringbuffer.c pseudo_talloc.c host_communication.c \
main_common.c stack_check.c
main_common.c stack_check.c crcstub.c
C_BOARD = $(notdir $(wildcard libboard/common/source/*.c))
C_BOARD += $(notdir $(wildcard libboard/$(BOARD)/source/*.c))
@ -229,12 +229,15 @@ $(BIN)/$(BOARD)-dfu-flash-padded.bin: $(BIN)/$(BOARD)-dfu-flash.bin
$(OUTPUT)-combined.bin: $(BIN)/$(BOARD)-dfu-flash-padded.bin $(OUTPUT)-dfu.bin
cat $^ > $@
$(BIN) $(OBJ): apps/$(APP)/usb_strings_generated.h
$(BIN) $(OBJ): apps/$(APP)/usb_strings_generated.h misc/crctool
mkdir -p $@
usbstring/usbstring: usbstring/usbstring.c
gcc $^ -o $@
misc/crctool: misc/crctool.c
gcc $^ -o $@
.PHONY: apps/$(APP)/usb_strings.txt.patched
apps/$(APP)/usb_strings.txt.patched: apps/$(APP)/usb_strings.txt
sed "s/PRODUCT_STRING/$(shell cat libboard/$(BOARD)/product_string.txt)/" $< > $@
@ -251,7 +254,6 @@ build_$(1): $$(ASM_OBJECTS_$(1)) $$(C_OBJECTS_$(1)) $$(EXTRA_OBJECTS_$(1))
$(SILENT)$(CC) $(CFLAGS) $(LDFLAGS) $(LD_OPTIONAL) -T"libboard/common/resources/$(CHIP)/$(1).ld" -Wl,-Map,$(OUTPUT)-$(1).map -o $(OUTPUT)-$(1).elf $$^ $(LIBS)
$(SILENT)$(NM) $(OUTPUT)-$(1).elf >$(OUTPUT)-$(1).elf.txt
$(SILENT)$(OBJCOPY) -O binary $(OUTPUT)-$(1).elf $(OUTPUT)-$(1).bin
$(SILENT)$(SIZE) $$^ $(OUTPUT)-$(1).elf
$$(C_OBJECTS_$(1)): $(OBJ)/$(1)_%.o: %.c Makefile $(OBJ) $(BIN)
@echo [COMPILING $$<]
@ -261,26 +263,17 @@ $$(ASM_OBJECTS_$(1)): $(OBJ)/$(1)_%.o: %.S Makefile $(OBJ) $(BIN)
@echo [ASSEMBLING $$@]
$(SILENT)$(CC) $(ASFLAGS) -DENVIRONMENT_$(1) -DENVIRONMENT=\"$(1)\" -c -o $$@ $$<
debug_$(1): $(1)
$(GDB) -x "$(BOARD_LIB)/resources/gcc/$(BOARD)_$(1).gdb" -ex "reset" -readnow -se $(OUTPUT)-$(1).elf
endef
ALL_MEMORIES = dfu flash ram
ALL_MEMORIES = flash ram
$(foreach MEMORY, $(ALL_MEMORIES), $(eval $(call RULES,$(MEMORY))))
# files with those names do exist..
.PHONY: ram
.PHONY: dfu
.PHONY: flash
dfu: $(OUTPUT)-dfu.bin
.PHONY: ram
ram: build_ram
dfu: build_dfu
ifeq ($(APP), blupdate)
$(info updating updater section with padded bootloader file..)
$(SILENT)dd if=/dev/zero bs=16384 count=1 of=$(BIN)/$(BOARD)-dfu-flash-padded.bin
$(SILENT)dd if=$(BIN)/$(BOARD)-dfu-flash.bin conv=notrunc of=$(BIN)/$(BOARD)-dfu-flash-padded.bin
$(SILENT)$(OBJCOPY) --update-section .blupdate=bin/$(BOARD)-dfu-flash-padded.bin bin/$(BOARD)-blupdate-dfu.elf
$(SILENT)$(OBJCOPY) -O binary bin/$(BOARD)-blupdate-dfu.elf bin/$(BOARD)-blupdate-dfu.bin
endif
.PHONY: flash
flash: build_flash
#alternate way of embedding: obj file
#ifeq ($(APP), dfu)
@ -288,8 +281,37 @@ flash: build_flash
# $(SILENT)$(OBJCOPY) --rename-section .data=.fwupdate -I binary -O elf32-littlearm bin/$(BOARD)-dfu-flash.bin $(OBJ)/flash_fwupdate.o
#endif
program:
openocd -f openocd/openocd.cfg -c "init" -c "halt" -c "flash write_bank 0 ./bin/project-flash.bin 0" -c "reset" -c "shutdown"
C_OBJECTS_dfu = $(addprefix $(OBJ)/dfu_, $(C_OBJECTS))
ASM_OBJECTS_dfu = $(addprefix $(OBJ)/dfu_, $(ASM_OBJECTS))
EXTRA_OBJECTS_dfu = $(addprefix $(OBJ)/dfu_, $(EXTRA_OBJECTS))
$(OUTPUT)-dfu.bin: $(OUTPUT)-dfu_nocrcstub.bin
$(info updating app with crc..)
$(SILENT)cp $< $@.temp
$(SILENT)misc/crctool 512 $@.temp
$(SILENT)mv $@.temp $@
$(OUTPUT)-dfu_nocrcstub.bin: $(OUTPUT)-dfu_nocrcstub.elf
ifeq ($(APP), blupdate)
$(info updating updater section with padded bootloader file..)
$(SILENT)dd status=none if=/dev/zero bs=16384 count=1 of=$(BIN)/$(BOARD)-dfu-flash-padded.bin
$(SILENT)dd status=none if=$(BIN)/$(BOARD)-dfu-flash.bin conv=notrunc of=$(BIN)/$(BOARD)-dfu-flash-padded.bin
$(SILENT)$(OBJCOPY) --update-section .blupdate=bin/$(BOARD)-dfu-flash-padded.bin $<
endif
$(SILENT)$(OBJCOPY) -O binary $< $@
$(OUTPUT)-dfu_nocrcstub.elf: $(ASM_OBJECTS_dfu) $(C_OBJECTS_dfu) $(EXTRA_OBJECTS_dfu)
$(SILENT)$(CC) $(CFLAGS) $(LDFLAGS) $(LD_OPTIONAL) -T"libboard/common/resources/$(CHIP)/dfu.ld" -Wl,-Map,$(OUTPUT)-dfu_nocrcstub.map -o $@ $^ $(LIBS)
$(SILENT)$(NM) $@ >$@.txt
$(C_OBJECTS_dfu): $(OBJ)/dfu_%.o: %.c Makefile $(OBJ) $(BIN)
@echo [COMPILING $<]
$(SILENT)$(CC) $(CFLAGS) -DENVIRONMENT_dfu -DENVIRONMENT=\"dfu\" -c -o $@ $<
$(ASM_OBJECTS_dfu): $(OBJ)/dfu_%.o: %.S Makefile $(OBJ) $(BIN)
@echo [ASSEMBLING $@]
$(SILENT)$(CC) $(ASFLAGS) -DENVIRONMENT_dfu -DENVIRONMENT=\"dfu\" -c -o$@ $<
SERIAL ?= /dev/ttyUSB0
log:

View File

@ -89,8 +89,14 @@ __attribute__((section(".ramfunc"), noinline, noreturn)) static void erase_first
flash_cmd(EFC_FCMD_EA, 0);
#endif
flash_wait_ready();
for (;;)
NVIC_SystemReset();
for (;;) {
/* no functon call, since NVIC_SystemReset() might not be inlined! */
SCB->AIRCR = ((0x5FA << SCB_AIRCR_VECTKEY_Pos) | (SCB->AIRCR & SCB_AIRCR_PRIGROUP_Msk) |
SCB_AIRCR_SYSRESETREQ_Msk);
__DSB();
while (1)
;
}
}
#define MAX_USB_ITER BOARD_MCK / 72 // This should be around a second

View File

@ -39,7 +39,8 @@ SEARCH_DIR(.)
MEMORY
{
/* reserve the first 16k (= 0x4000) for the DFU bootloader */
rom (rx) : ORIGIN = 0x00400000 + 16K, LENGTH = 256K - 16K /* flash, 256K */
crcstub (rx) : ORIGIN = 0x00400000 + 16K, LENGTH = 512 /* crcstub part */
rom (rx) : ORIGIN = 0x00400000 + 16K + 512, LENGTH = 256K - 16K - 512 /* flash, 256K */
/* note: dfudata will be at the start */
ram (rwx) : ORIGIN = 0x20000000, LENGTH = 48K /* SRAM, 48K */
}
@ -47,9 +48,17 @@ MEMORY
/* Section Definitions */
SECTIONS
{
.text :
{
.crcstub :
{
. = ALIGN(4);
KEEP(*(.crcstub_table))
KEEP(*(.crcstub_code))
} > crcstub = 0xff
.text :
{
. = ALIGN(512);
_sfixed = .;
KEEP(*(.vectors .vectors.*))
*(.text .text.* .gnu.linkonce.t.*)
@ -94,7 +103,7 @@ SECTIONS
. = ALIGN(4);
_efixed = .; /* End of text section */
} > rom
} > rom = 0xff
/DISCARD/ :
{

View File

@ -97,6 +97,8 @@ SECTIONS
/DISCARD/ :
{
*(.ARM.exidx)
*(.crcstub_table)
*(.crcstub_code)
}
. = ALIGN(4);

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@ -0,0 +1,86 @@
/* SIMtrace 2 firmware crc stub
*
* (C) 2021 by sysmocom -s.f.m.c. GmbH, Author: Eric Wild <ewild@sysmocom.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <stdint.h>
#include "board.h"
#include "core_cm3.h"
#include "usb/device/dfu/dfu.h"
/*
* This file is a bit special, everything has to go to specific sections, and no globals are available.
* No external functions may be called, unless inlining is enforced!
*/
static void crc_check_stub();
__attribute__((section(".crcstub_table"))) volatile uint32_t crcstub_dummy_table[] = {
(uint32_t)0xdeadc0de, /* deliberately choose invalid value so unpatched image will not be started */
(uint32_t)crc_check_stub, /* must be valid flash addr */
(uint32_t)0xf1, /* crc value calculated by the host */
(uint32_t)0xf2, /* crc calc start address */
(uint32_t)0xf3 /* crc calc length (byte) */
};
__attribute__((section(".crcstub_code"))) static void do_crc32(int8_t c, uint32_t *crc_reg)
{
int32_t i, mask;
*crc_reg ^= c;
for (unsigned int j = 0; j < 8; j++)
if (*crc_reg & 1)
*crc_reg = (*crc_reg >> 1) ^ 0xEDB88320;
else
*crc_reg = *crc_reg >> 1;
}
__attribute__((section(".crcstub_code"), noinline)) static void crc_check_stub()
{
uint32_t crc_reg = 0xffffffff;
uint32_t expected_crc_val = crcstub_dummy_table[2];
uint8_t *crc_calc_startaddr = (uint8_t *)crcstub_dummy_table[3];
volatile uint32_t *actual_exc_tbl = (volatile uint32_t *)crc_calc_startaddr;
uint32_t crc_len = crcstub_dummy_table[4];
/* 4000ms wdt tickling */
WDT->WDT_MR = WDT_MR_WDRSTEN | WDT_MR_WDDBGHLT | WDT_MR_WDIDLEHLT | (((4000UL << 8) / 1000) << 16) |
((4000UL << 8) / 1000);
for (uint8_t *i = crc_calc_startaddr; i < crc_calc_startaddr + crc_len; i++)
do_crc32(*i, &crc_reg);
crc_reg = ~crc_reg;
if (crc_reg == expected_crc_val) {
/* this looks a bit awkward because we have to ensure the bx does not require a sp-relative load */
__asm__ volatile("\
mov r0, %0;\n\
mov r1, %1;\n\
MSR msp,r0;\n\
bx r1;"
:
: "r"(actual_exc_tbl[0]), "r"(actual_exc_tbl[1]));
} else {
/* no globals ! */
((struct dfudata *)0x20000000)->magic = USB_DFU_MAGIC;
__DSB();
for (;;) {
/* no functon call, since NVIC_SystemReset() might not be inlined! */
SCB->AIRCR = ((0x5FA << SCB_AIRCR_VECTKEY_Pos) | (SCB->AIRCR & SCB_AIRCR_PRIGROUP_Msk) |
SCB_AIRCR_SYSRESETREQ_Msk);
__DSB();
while (1)
;
}
}
}

91
firmware/misc/crctool.c Normal file
View File

@ -0,0 +1,91 @@
/* SIMtrace 2 firmware crc tool
*
* (C) 2021 by sysmocom -s.f.m.c. GmbH, Author: Eric Wild <ewild@sysmocom.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
static void do_crc32(int8_t c, uint32_t *crc_reg)
{
int32_t i, mask;
*crc_reg ^= c;
for (unsigned int j = 0; j < 8; j++)
if (*crc_reg & 1)
*crc_reg = (*crc_reg >> 1) ^ 0xEDB88320;
else
*crc_reg = *crc_reg >> 1;
}
int main(int argc, char *argv[])
{
uint32_t crc_reg = 0xffffffff;
long fsize;
uint8_t *buffer;
uint32_t crc_start_offset;
if (argc < 3) {
perror("usage: crctool startoffset blupdate.bin");
return -1;
}
crc_start_offset = strtoull(argv[1], 0, 10);
FILE *blfile = fopen(argv[2], "rb+");
if (blfile == NULL) {
perror("error opening file!");
return -1;
}
fseek(blfile, 0, SEEK_END);
fsize = ftell(blfile);
if (fsize <= crc_start_offset) {
perror("file size?!");
return -1;
}
fseek(blfile, 0, SEEK_SET);
buffer = malloc(fsize);
fread(buffer, 1, fsize, blfile);
if (*(uint32_t *)buffer != 0xdeadc0de) {
perror("weird magic, not a valid blupdate file?");
free(buffer);
return -1;
}
uint8_t *startaddr = buffer + crc_start_offset;
uint8_t *endaddr = buffer + fsize;
for (uint8_t *i = startaddr; i < endaddr; i++) {
do_crc32(*i, &crc_reg);
}
crc_reg = ~crc_reg;
fprintf(stderr, "len: %ld crc: %.8x\n", fsize - crc_start_offset, crc_reg);
((uint32_t *)buffer)[0] = 0x2000baa0; /* fix magic to valid stack address, checked by BL */
((uint32_t *)buffer)[2] = crc_reg;
((uint32_t *)buffer)[3] = 0x00400000 + 0x4000 + crc_start_offset;
((uint32_t *)buffer)[4] = fsize - crc_start_offset;
fseek(blfile, 0, SEEK_SET);
fwrite(buffer, 4, 5, blfile);
fclose(blfile);
free(buffer);
return 0;
}