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Put persistent variables at end of stack

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Two variables of the bootloader are persistent:
- __stack_chk_guard is used by interrupt handlers
- system_millis is used by timer interrupt and service routines

Note that currently __stack_chk_guard is shared between unprivileged
firmware and bootloader.

If we get more variables later it may make sense to make a section for
this.
This commit is contained in:
Jochen Hoenicke 2018-03-26 23:35:40 +02:00 committed by Pavol Rusnak
parent ed7a8bfa6c
commit be64864efc
No known key found for this signature in database
GPG Key ID: 91F3B339B9A02A3D
5 changed files with 11 additions and 6 deletions
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3
memory.ld
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@ -18,5 +18,8 @@ INCLUDE libopencm3_stm32f2.ld
_ram_start = ORIGIN(ram);
_ram_end = ORIGIN(ram) + LENGTH(ram);
_stack = _ram_end - 8;
__stack_chk_guard = _ram_end - 8;
system_millis = _ram_end - 4;
_data_size = SIZEOF(.data);

3
memory_app_1.0.0.ld
View File

@ -18,5 +18,8 @@ INCLUDE libopencm3_stm32f2.ld
_ram_start = ORIGIN(ram);
_ram_end = ORIGIN(ram) + LENGTH(ram);
_stack = _ram_end - 8;
__stack_chk_guard = _ram_end - 8;
system_millis = _ram_end - 4;
_data_size = SIZEOF(.data);

2
setup.c
View File

@ -29,8 +29,6 @@
#include "layout.h"
#include "util.h"
uint32_t __stack_chk_guard;
static inline void __attribute__((noreturn)) fault_handler(const char *line1) {
layoutDialog(&bmp_icon_error, NULL, NULL, NULL, line1, "detected.", NULL, "Please unplug", "the device.", NULL);
for (;;) {} // loop forever

2
timer.c
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@ -25,7 +25,7 @@
#include <libopencm3/cm3/vector.h>
/* 1 tick = 1 ms */
volatile uint32_t system_millis;
extern volatile uint32_t system_millis;
/*
* Initialise the Cortex-M3 SysTick timer

7
util.h
View File

@ -48,6 +48,7 @@ extern void __attribute__((noreturn)) shutdown(void);
#if !EMULATOR
// defined in memory.ld
extern uint8_t _ram_start[], _ram_end[];
extern uint8_t _stack[];
// defined in startup.s
extern void memset_reg(void *start, void *stop, uint32_t val);
@ -59,13 +60,13 @@ static inline void __attribute__((noreturn)) jump_to_firmware(const vector_table
{
if (FW_SIGNED == trust) { // trusted signed firmware
SCB_VTOR = (uint32_t)vector_table; // * relocate vector table
// Set stack pointer
__asm__ volatile("msr msp, %0" :: "r" (vector_table->initial_sp_value));
} else { // untrusted firmware
mpu_config(); // * configure MPU
__asm__ volatile("msr msp, %0" :: "r" (_stack));
}
// Set stack pointer
__asm__ volatile("msr msp, %0" :: "r" (vector_table->initial_sp_value));
// Jump to address
vector_table->reset();