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more secret sauce to tease mxcsr out of linux-x86.32 ucontext

db4
Joe Groff 2009-09-14 12:30:10 -05:00
parent 578c977a7e
commit b77d9d2960
1 changed files with 35 additions and 3 deletions
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38
vm/os-linux-x86.32.hpp
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@ -3,6 +3,32 @@
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 void *ucontext_stack_pointer(void *uap)
{
ucontext_t *ucontext = (ucontext_t *)uap;
@ -11,15 +37,21 @@ inline static void *ucontext_stack_pointer(void *uap)
inline static unsigned int uap_fpu_status(void *uap)
{
// XXX mxcsr not available in i386 ucontext
ucontext_t *ucontext = (ucontext_t *)uap;
return ucontext->uc_mcontext.fpregs->sw;
struct _fpstate *fpregs = (struct _fpstate *)uap->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;
ucontext->uc_mcontext.fpregs->sw = 0;
struct _fpstate *fpregs = (struct _fpstate *)uap->uc_mcontext.fpregs;
fpregs->sw = 0;
if (fpregs->magic == X86_FXSR_MAGIC)
fpregs->mxcsr &= 0xffffffc0;
}
#define UAP_PROGRAM_COUNTER(ucontext) \