STM32 WWDG interrupt firing when not configured

Question

I have an application that I am porting from the Keil IDE to build with the GNU toolchain due to license issues. I have successfully be able to set up, build, flash and run the

Answer 1

In my case, I had a function written in the GCC assembly that was migrated from the ARM assembly. The problem went away after I had added the .thumb_func line to the assembly file.

I was getting this error:

(gdb) c
+c
Continuing.

Program received signal SIGINT, Interrupt.
WWDG_IRQHandler () at ...startup_stm32f40_41xxx.s:121

(gdb) bt
#0  WWDG_IRQHandler () at ...startup_stm32f40_41xxx.s:12
#1  
#2  RTOS_SysTick_Handler () at ...osKernel.s:18
#3  
#4  0x0800021a in task0 () at ...main.cpp:10
#5  0x08000214 in frame_dummy ()
#6  0x00000000 in ?? ()

RTOS_SysTick_Handler is a function written in assembly and the WWDG_IRQHandler was always triggered before any first assembly instructions in that function (tried different instructions and it didn't change anything).

I was doing some tweaks around the C code and at some point, I hit another handler: UsageFault which led me to the .thumb_func hint: ARM Cortex M4 SVC_Handler "UsageFault".