LD_PRELOAD glibc wrapper to make sure stacks pointers given to clone(2) wrapper are 16-aligned.

ensure_clone_stack_slign.S

/*
 * Make sure stacks pointers given to clone(2) wrapper are 16-byte aligned.
 *
 * Public Domain / CC0
 *
 * i386 glibc clone.S has:
 *	andl	$0xfffffff0, %ecx
 * x86-64 has no such sort and you hit
 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838
 * and sadness somtimes happens :(. Compile this with:
 * $ gcc -shared ensure_clone_stack_slign.S -o ensure_clone_stack_slign.so
 * and run a program with:
 * $ LD_PRELOAD=/path/to/ensure_clone_stack_slign.so command args
 */
	.globl __clone

	.text
	.globl clone
	.align 4
clone:
#ifdef __x86_64__
	andq 	$-16, %rsi
#endif
	jmp	__clone