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stm32/modmachine: Create dedicated asm function to branch to bootloader.

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Recent gcc versions (at least 9.1) give a warning about using "sp" in the
clobber list.  Such code is removed by this patch.  A dedicated function is
instead used to set SP and branch to the bootloader so the code has full
control over what happens.

Fixes issue #4785.
This commit is contained in:
Damien George 2019-05-15 16:35:09 +10:00
parent 0557f0b74b
commit e1e3704aa1
1 changed files with 16 additions and 20 deletions
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36
ports/stm32/modmachine.c
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@ -247,6 +247,15 @@ STATIC mp_obj_t machine_soft_reset(void) {
}
MP_DEFINE_CONST_FUN_OBJ_0(machine_soft_reset_obj, machine_soft_reset);
__attribute__((naked)) void branch_to_bootloader(uint32_t r0, uint32_t addr) {
__asm volatile (
"ldr r2, [r1, #0]\n" // get address of stack pointer
"msr msp, r2\n" // get stack pointer
"ldr r2, [r1, #4]\n" // get address of destination
"bx r2\n" // branch to bootloader
);
}
// Activate the bootloader without BOOT* pins.
STATIC NORETURN mp_obj_t machine_bootloader(size_t n_args, const mp_obj_t *args) {
#if MICROPY_HW_ENABLE_USB
@ -271,8 +280,7 @@ STATIC NORETURN mp_obj_t machine_bootloader(size_t n_args, const mp_obj_t *args)
SCB_DisableICache();
SCB_DisableDCache();
#endif
__set_MSP(*(volatile uint32_t*)0x08000000);
((void (*)(uint32_t)) *((volatile uint32_t*)(0x08000000 + 4)))(0x70ad0000);
branch_to_bootloader(0x70ad0000, 0x08000000);
}
if (n_args == 1 && mp_obj_is_str_or_bytes(args[0])) {
@ -285,28 +293,16 @@ STATIC NORETURN mp_obj_t machine_bootloader(size_t n_args, const mp_obj_t *args)
SCB_DisableICache();
SCB_DisableDCache();
#endif
__set_MSP(*(volatile uint32_t*)0x08000000);
((void (*)(uint32_t)) *((volatile uint32_t*)(0x08000000 + 4)))(0x70ad0080);
branch_to_bootloader(0x70ad0080, 0x08000000);
}
#endif
#if defined(STM32F7) || defined(STM32H7)
// arm-none-eabi-gcc 4.9.0 does not correctly inline this
// MSP function, so we write it out explicitly here.
//__set_MSP(*((uint32_t*) 0x1FF00000));
__ASM volatile ("movw r3, #0x0000\nmovt r3, #0x1FF0\nldr r3, [r3, #0]\nMSR msp, r3\n" : : : "r3", "sp");
((void (*)(void)) *((uint32_t*) 0x1FF00004))();
#else
#if defined(STM32F7) || defined(STM32H7)
branch_to_bootloader(0, 0x1ff00000);
#else
__HAL_SYSCFG_REMAPMEMORY_SYSTEMFLASH();
// arm-none-eabi-gcc 4.9.0 does not correctly inline this
// MSP function, so we write it out explicitly here.
//__set_MSP(*((uint32_t*) 0x00000000));
__ASM volatile ("movs r3, #0\nldr r3, [r3, #0]\nMSR msp, r3\n" : : : "r3", "sp");
((void (*)(void)) *((uint32_t*) 0x00000004))();
#endif
branch_to_bootloader(0, 0x00000000);
#endif
while (1);
}