Спасибо. Нашёл. Из комплектного STM32CubeIDE, startup_stm32f107vctx.s, начало кода: .syntax unified
.cpu cortex-m3
.fpu softvfp
.thumb
.global g_pfnVectors
.global Default_Handler
и ниже
g_pfnVectors:
.word _estack
.word Reset_Handler
.word NMI_Handler
.word HardFault_Handler
.word MemManage_Handler
.word BusFault_Handler
.word UsageFault_Handler
В STM32F107VCTX_FLASH.ld:
/* Highest address of the user mode stack */
_estack = ORIGIN(RAM) + LENGTH(RAM); /* end of "RAM" Ram type memory */