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mirror of https://github.com/trezor/trezor-firmware.git synced 2024-10-31 20:39:48 +00:00
trezor-firmware/core/embed/firmware/startup.S

58 lines
1.8 KiB
ArmAsm

.syntax unified
.text
.global reset_handler
.type reset_handler, STT_FUNC
reset_handler:
// The following loading of VTOR address only works if T1 bootloader was built with MEMORY_PROTECT=0
// or the firmware was properly signed. All other variants end up in hard fault due to MPU
// (cf mpu_config_firmware in legacy bootloader)
#if TREZOR_MODEL == 1
ldr r0, =0xE000ED08 // r0 = VTOR address
ldr r1, =0x08010400 // r1 = FLASH_APP_START
str r1, [r0] // assign
ldr r0, =_estack - 8 // r0 = stack pointer, T1 bootloader had 8 bytes reserved at end
msr msp, r0 // set stack pointer
dsb
isb
#endif
// setup environment for subsequent stage of code
ldr r0, =ccmram_start // r0 - point to beginning of CCMRAM
ldr r1, =ccmram_end // r1 - point to byte after the end of CCMRAM
ldr r2, =0 // r2 - the word-sized value to be written
bl memset_reg
ldr r0, =sram_start // r0 - point to beginning of SRAM
ldr r1, =sram_end // r1 - point to byte after the end of SRAM
ldr r2, =0 // r2 - the word-sized value to be written
bl memset_reg
// copy data in from flash
ldr r0, =data_vma // dst addr
ldr r1, =data_lma // src addr
ldr r2, =data_size // size in bytes
bl memcpy
// setup the stack protector (see build script "-fstack-protector-all") with an unpredictable value
bl rng_get
ldr r1, = __stack_chk_guard
str r0, [r1]
// re-enable exceptions
// according to "ARM Cortex-M Programming Guide to Memory Barrier Instructions" Application Note 321, section 4.7:
// "If it is not necessary to ensure that a pended interrupt is recognized immediately before
// subsequent operations, it is not necessary to insert a memory barrier instruction."
cpsie f
// enter the application code
bl main
b shutdown
.end