On 25 Apr 2016 20:42, Colin Ian King wrote:
> currently, the aarch64 clone() system call requires the stack to be
> aligned at a 16 byte boundary, see arch/arm64/kernel/process.c,
> copy_thread():
>
> if (stack_start) {
> if (is_compat_thread(task_thread_info(p)))
> childregs->compat_sp = stack_start;
> /* 16-byte aligned stack mandatory on AArch64 */
> else if (stack_start & 15)
> return -EINVAL;
> else
> childregs->sp = stack_start;
> }
>
>
> ..and returns -EINVAL if not aligned correctly. This should be added to
> the manual page clone(2) as it took me a while to figure out why clone()
> was failing with -EINVAL for aarch64 but not on x86.
seems weird for the kernel to be enforcing this. is it just because of
the stated ABI ? or is there some weird requirement in the kernel itself
that requires this ? it's not like other arches have this check, and
there are def ABI requirements about stack alignments in C.
-mike
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