core/lib: print_stack_usage_metric called with misaligned stack

[LP-HAW]

Description

On the hifive1b board many tests end in a kernel panic because of an unaligned access to memory.
This is only observable when running make term instead of make test.

I think this is because in main_trampoline the print_stack_usage_metric function is called with a potentially misaligned idle_stack.

RIOT/core/lib/init.c

Line 73 in 4caa3bc

print_stack_usage_metric("idle", idle_stack, THREAD_STACKSIZE_IDLE);

Steps to reproduce the issue

Build tests/bench/thread_yield_pingpong for hifive1b and confirm the stacks are misaligned.

$ cd tests/bench/thread_yield_pingpong
$ BOARD=hifive1b make
$ riscv-none-elf-nm -S bin/hifive1b/tests_thread_yield_pingpong.elf | grep 'idle_stack\|main_stack'
800005dd 00000100 b idle_stack
800006dd 00000500 b main_stack

Run the test with make term

$ BOARD=hifive1b make term
2024-03-20 12:08:41,103 # Help: Press s to start test, r to print it is ready
s
2024-03-20 12:08:48,859 # START
2024-03-20 12:08:48,863 # main(): This is RIOT! (Version: 2024.04-devel-440-ge3ce7)
2024-03-20 12:08:48,864 # main starting
2024-03-20 12:08:49,867 # { "result" : 673289, "ticks" : 475 }
2024-03-20 12:08:49,869 # Unhandled trap:
2024-03-20 12:08:49,870 #   mcause: 0x4
2024-03-20 12:08:49,872 #   mepc:   0x2001056e
2024-03-20 12:08:49,873 #   mtval:  0x800005dd
2024-03-20 12:08:49,875 # *** RIOT kernel panic:
2024-03-20 12:08:49,877 # Unhandled trap
2024-03-20 12:08:49,877 # 
2024-03-20 12:08:49,878 # *** halted.
2024-03-20 12:08:49,878 #

Versions

GCC:

$ riscv-none-elf-gcc --version
riscv-none-elf-gcc (xPack GNU RISC-V Embedded GCC x86_64) 13.2.0