mango/arch/x86_64/asm-offset.c

#include <kernel/compiler.h>
#include <kernel/sched.h>
#include <kernel/thread.h>

// size_t THREAD_sp = offsetof(struct thread, tr_sp);

/* Use %a0 instead of %0 to prevent gcc from emitting a $ before the symbol
   value in the generated assembly.

   emitting
     .set TASK_sp, $56

   instead of
     .set TASK_sp, 56

   causes garbage symbols to be generated.
*/

#define DEFINE(sym, val)                                                       \
	asm volatile("\n.global " #sym "\n.type " #sym                         \
	             ", @object"                                               \
	             "\n.set " #sym ", %a0"                                    \
	             :                                                         \
	             : "i"(val))

#define OFFSET(sym, str, mem) DEFINE(sym, offsetof(str, mem))

static void __used common(void)
{
	OFFSET(THREAD_sp, struct thread, tr_sp);
}