On 25/02/11 11:11 +0000, ext Will Deacon wrote:
> Hello,
>
> The definition of ltp_clone looks like this:
>
>
> int
> ltp_clone(unsigned long clone_flags, int (*fn)(void *arg), void *arg,
> size_t stack_size, void *stack)
> {
> int ret;
>
> #if defined(__hppa__)
> ret = clone(fn, stack, clone_flags, arg);
> #elif defined(__ia64__)
> ret = clone2(fn, stack, stack_size, clone_flags, arg, NULL, NULL, NULL);
> #elif defined(__arm__)
> /*
> * Stack size should be a multiple of 32 bit words
> * & stack limit must be aligned to a 32 bit boundary
> */
> ret = clone(fn, (stack ? stack + stack_size : NULL),
> clone_flags, arg);
> #else
> ret = clone(fn, (stack ? stack + stack_size - 1 : NULL),
> clone_flags, arg);
> #endif
>
> return ret;
> }
>
>
> I believe the __arm__ case is to ensure that we pass an aligned
> stack pointer to the syscall (as required by the architecture).
> What I don't understand, is why we pass an unaligned address in
> the #else case? Given that a stack push decrements the sp before
> writing on every architecture I know of, it seems that the __arm__
> case should be used as the default rather than forcing a misaligned
> stack on other architectures.
>
> Will
>
Hi,
have you fetched the latest from the git tree:
git://ltp.git.sourceforge.net/gitroot/ltp/ltp ?
Lines are:
int
ltp_clone(unsigned long clone_flags, int (*fn)(void *arg), void *arg,
size_t stack_size, void *stack)
{
int ret;
#if defined(__hppa__)
ret = clone(fn, stack, clone_flags, arg);
#elif defined(__ia64__)
ret = clone2(fn, stack, stack_size, clone_flags, arg, NULL, NULL,
NULL);
#else
/*
* For archs where stack grows downwards, stack points to the topmost
* address of the memory space set up for the child stack.
*/
ret = clone(fn, (stack ? stack + stack_size : NULL),
clone_flags, arg);
#endif
return ret;
}
br,
Hannu
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