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Re: Stack alignment with pthreads
On Friday, at 22:49, Anthony Mallet wrote:
| - The only thing that had some effect was to artificially substract 4 bytes
| from the sp in makecontext, just before 'pushing' the args. (i.e. replaced
| ``sp -= argc + 1'' by ``sp -= argc + 2'' in arch/i386/gen/makecontext.c).
Following up on myself...
I found more interesting info here:
Mimicking this patch to our i386/makecontext() gives this:
sp = (unsigned int *)((uintptr_t)sp & ~0x3);
sp -= argc; /* Make room for args. */
sp = (unsigned int *)((uintptr_t)sp & ~0xf);
sp --; /* Make room for ret */
(I can provide a real diff if this is not clear :)
What I understand is that the first arg should be aligned on 16 bytes, and this
effectively fixes the problem.
So what do you think about this change?
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