[PATCH 0/0] RFC: ARM: Thumb-2: Symbol manipulation macros for function body copying

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Tue, Jan 11, 2011 at 06:02:30PM -0600, Dave Martin wrote:
> To make it easier to deal with cases like this, I've had a
> go at writing some macros to make copying function bodies
> easier, while being robust for ARM and Thumb-2.

How about instead providing some infrastructure which coes the
copy too?  Something like:

#define copy_fn_to_sram(to, fn, size) ({		\
	__typeof__(fn) f;				\
	unsigned long ptr;				\
	__asm__("" : "=r" (ptr) : "0" (fn));		\
	memcpy(to, (void *)(ptr & ~1), size);		\
	ptr = (ptr & 1) | (unsigned long)to;		\
	__asm__("" : "=r" (f) : "0" (ptr));		\
	f;						\
})

Used by:
extern void my_func(int foo);
extern int my_func_size;

void call_my_func(void *to, int arg)
{
	void (*fn)(int);

	fn = copy_fn_to_sram(to, my_func, my_func_size);
	fn(arg);
}

Then if you need to fix the way the copies are done for some
architectural reason, there's only one place to do it.

I'm not sure asm/unified.h is the right place - I don't think this has
anything to do with the unified assembler syntax.  Please create a new
header for this.