[LTP] ltp_clone

["Will Deacon" <will.deacon@arm.com>]

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




------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev 
_______________________________________________
Ltp-list mailing list
Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list