SW4STM32 and SW4Linux fully supports the STM32MP1 asymmetric multicore Cortex/A7+M4 MPUs

   With System Workbench for Linux, Embedded Linux on the STM32MP1 family of MPUs from ST was never as simple to build and maintain, even for newcomers in the Linux world.
And, if you install System Workbench for Linux in System Workbench for STM32 you can seamlessly develop and debug asymmetric applications running partly on Linux, partly on the Cortex-M4.
You can get more information from the ac6-tools website and download two short videos (registration required) highlighting:

System Workbench for STM32

Load other .text section with gdb

strange normaly by collecting your extra section into text section shall do
the default ld is something like
.text :
. = ALIGN(4);
*(.text) /* .text sections (code) */

// add here your extra section

maybe you already tryied something like this ?
Soemtime KEEP statement like
KEEP (*(.init))

can help if section is scraped by linker cos not referecend anywhere.