factor/vm/os-linux-x86.32.hpp

#include <ucontext.h>

namespace factor
{

// glibc lies about the contents of the fpstate the kernel provides, hiding the FXSR
// environment
struct _fpstate {
	/* Regular FPU environment */
	unsigned long   cw;
	unsigned long   sw;
	unsigned long   tag;
	unsigned long   ipoff;
	unsigned long   cssel;
	unsigned long   dataoff;
	unsigned long   datasel;
	struct _fpreg   _st[8];
	unsigned short  status;
	unsigned short  magic;          /* 0xffff = regular FPU data only */
	
	/* FXSR FPU environment */
	unsigned long   _fxsr_env[6];   /* FXSR FPU env is ignored */
	unsigned long   mxcsr;
	unsigned long   reserved;
	struct _fpxreg  _fxsr_st[8];    /* FXSR FPU reg data is ignored */
	struct _xmmreg  _xmm[8];
	unsigned long   padding[56];
};

#define X86_FXSR_MAGIC          0x0000

inline static unsigned int uap_fpu_status(void *uap)
{
	ucontext_t *ucontext = (ucontext_t *)uap;
	struct _fpstate *fpregs = (struct _fpstate *)ucontext->uc_mcontext.fpregs;
	if (fpregs->magic == X86_FXSR_MAGIC)
	    return fpregs->sw | fpregs->mxcsr;
	else
	    return fpregs->sw;
}

inline static void uap_clear_fpu_status(void *uap)
{
	ucontext_t *ucontext = (ucontext_t *)uap;
	struct _fpstate *fpregs = (struct _fpstate *)ucontext->uc_mcontext.fpregs;
	fpregs->sw = 0;
	if (fpregs->magic == X86_FXSR_MAGIC)
	    fpregs->mxcsr &= 0xffffffc0;
}


#define UAP_STACK_POINTER(ucontext) (((ucontext_t *)ucontext)->uc_mcontext.gregs[7])
#define UAP_PROGRAM_COUNTER(ucontext) (((ucontext_t *)ucontext)->uc_mcontext.gregs[14])

}