STACK_POINTER_RANDOM is not working on ARM for the main thread

[ceolin]

On arm (and possible others arch with custom swap to main) the main stack is not randomized, because arch_switch_to_main_thread() is called with K_THREAD_STACK_SIZEOF(z_main_stack) in switch_to_main_thread(), completely ignoring the value that was previous randomized in z_setup_new_thread(). The problem is that this value is not available anymore, except if it is build with CONFIG_THREAD_STACK_INFO

[ceolin]

Possible solutions:

1. Make STACK_POINTER_RANDOM depends on CONFIG_THREAD_STACK_INFO for this platform.
2. change z_setup_new_thread to return this info
3. randomize stack before call zetup_new_thread -> the worst probably
4. Add stack size to k_thread independently of CONFIG_THREAD_STACK_INFO

Other possibilities ? Thoughts ?

[ceolin]

@andrewboie @andyross @ioannisg

[ioannisg]

(1) and (2) seem OK to me, (4) as well, if we don't care about the extra bytes...
Didn't take a detailed look yet, though

[stephanosio]

I haven't followed this up closely; but at first glance, this seems to be being addressed in #24714, is that correct? @ceolin @andrewboie

[andrewboie]

@stephanosio yes correct, I incorporated @ceolin's idea into my series.

My large stack overhaul PR is not landing until 2.4, so if we strongly desire a fix for 2.3 just use @ceolin's PR that he closed and I'll rebase on it later

[ioannisg]

@stephanosio yes correct, I incorporated @ceolin's idea into my series.

My large stack overhaul PR is not landing until 2.4, so if we strongly desire a fix for 2.3 just use @ceolin's PR that he closed and I'll rebase on it later

That's fine with me.

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[ioannisg]

@andrewboie pls, clarify if this issue can be consider closed after we merged #24714

[andrewboie]

yeah this shouldn't be a problem anymore.