measure_stack_free_internal(): don't try to align end of stack

[benpicco]

Contribution description

The end-of stack alignment causes the function to fail measuring the stack size.

Testing procedure

A new test was added to verify the stack measurement.

ps also shows the stack usage again

2024-06-04 16:56:22,086 # ps
2024-06-04 16:56:22,089 # 	pid | name                 | state    Q | pri | stack  ( used) ( free) | base addr  | current     
2024-06-04 16:56:22,091 # 	  - | isr_stack            | -        - |   - |   8192 (   -1) ( 8193) |  0x8085880 |  0x8085880
2024-06-04 16:56:22,093 # 	  1 | idle                 | pending  Q |  15 |   8192 (  436) ( 7756) |  0x8080180 |  0x8081fdc 
2024-06-04 16:56:22,095 # 	  2 | main                 | running  Q |   7 |  12288 ( 2792) ( 9496) |  0x8082180 |  0x8084fdc 
2024-06-04 16:56:22,097 # 	  3 | pktdump              | bl rx    _ |   6 |  12224 (  896) (11328) |  0x808da40 |  0x809085c 
2024-06-04 16:56:22,098 # 	  4 | ipv6                 | bl rx    _ |   4 |   8128 ( 1464) ( 6664) |  0x8087c80 |  0x8089a9c 
2024-06-04 16:56:22,100 # 	  5 | udp                  | bl rx    _ |   5 |   4032 (  960) ( 3072) |  0x8092ce0 |  0x8093afc 
2024-06-04 16:56:22,102 # 	  6 | gnrc_netdev_tap      | bl anyfl _ |   2 |   8064 ( 2216) ( 5848) |  0x808a220 |  0x808bffc 
2024-06-04 16:56:22,105 # 	  7 | RPL                  | bl rx    _ |   5 |   8192 (  896) ( 7296) |  0x8090c80 |  0x8092adc 
2024-06-04 16:56:22,106 # 	    | SUM                  |            |     |  69312 ( 9660) (59652)

Issues/PRs references

fixes the issue from #18942 (comment)

[benpicco]

superseded by #20724

[maribu]

Let's go with this. The stack size is sanitized before any arch code is called, I don't think there is value in keeping the extra alignment code:

RIOT/core/thread.c

Lines 220 to 221 in 2576649

	/* round down the stacksize to a multiple of thread_t alignments (usually 16/32bit) */
	stacksize -= stacksize % alignof(thread_t);

[riot-ci]

Murdock results

✔️ PASSED

5b73294 tests/core/thread_stack_alignment: also test for stack usage

Success	Failures	Total	Runtime
10160	0	10161	17m:17s

Artifacts

• Documentation preview