System Workbench for STM32

> arm-none-eabi-objcopy -O binary boot.elf boot.bin
> xxd -eg4 boot.bin | head

Many thanks to Peter Shook for his hint with startup option.

Alternative way is to fetch this address from output.map file. Search for line "Reset_Hanlder" and you'll find

 .text.Reset_Handler
                0x000000000800d5d0       0x50 startup/startup_stm32f103xb.o
                0x000000000800d5d0                Reset_Handler

Here 0800d5d0 is the PC value you'll need.
Moreover, in my case, these addresses differed by 1 (which is very strange), and only the value from output.map worked, whereas the first one did not.