15254 %ymm registers not restored after signal handler
15367 x86 getfpregs() summons corrupting %xmm ghosts
15333 want x86 /proc xregs support (libc_db, libproc, mdb, etc.)
15336 want libc functions for extended ucontext_t
15334 want ps_lwphandle-specific reg routines
15328 FPU_CW_INIT mistreats reserved bit
15335 i86pc fpu_subr.c isn't really platform-specific
15332 setcontext(2) isn't actually noreturn
15331 need <sys/stdalign.h>
Change-Id: I7060aa86042dfb989f77fc3323c065ea2eafa9ad
Conflicts:
    usr/src/uts/common/fs/proc/prcontrol.c
    usr/src/uts/intel/os/archdep.c
    usr/src/uts/intel/sys/ucontext.h
    usr/src/uts/intel/syscall/getcontext.c

*** 39,52 ****
  
  #ifndef _ASM
  typedef struct fpu_ctx {
          kfpu_t          fpu_regs;       /* kernel save area for FPU */
          uint64_t        fpu_xsave_mask; /* xsave mask for FPU/SSE/AVX */
- #if defined(__i386)
-         uint64_t        fpu_padding;    /* fix 32bit libmicro regression */
- #endif
          uint_t          fpu_flags;      /* FPU state flags */
  } fpu_ctx_t;
  
  typedef struct pcb {
          fpu_ctx_t       pcb_fpu;        /* fpu state */
          uint_t          pcb_flags;      /* state flags; cleared on fork */
--- 39,50 ----
  
  #ifndef _ASM
  typedef struct fpu_ctx {
          kfpu_t          fpu_regs;       /* kernel save area for FPU */
          uint64_t        fpu_xsave_mask; /* xsave mask for FPU/SSE/AVX */
          uint_t          fpu_flags;      /* FPU state flags */
+         void            *fpu_signal;    /* copyin area for signal handling */
  } fpu_ctx_t;
  
  typedef struct pcb {
          fpu_ctx_t       pcb_fpu;        /* fpu state */
          uint_t          pcb_flags;      /* state flags; cleared on fork */