strace/linux/x86_64/arch_regs.h - nest-cam/4320010/strace - Git at Google

 extern uint32_t *const i386_esp_ptr;
 extern uint64_t *const x86_64_rsp_ptr;
	extern uint32_t *const i386_esp_ptr;
	extern uint64_t *const x86_64_rsp_ptr;