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

@@ -24,10 +24,11 @@
  * Use is subject to license terms.
  */
 
 /*
  * Copyright (c) 2014, Joyent, Inc. All rights reserved.
+ * Copyright 2023 Oxide Computer Company
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <stddef.h>

@@ -1987,11 +1988,10 @@
 #pragma weak td_thr_getxregsize = __td_thr_getxregsize
 /* ARGSUSED */
 td_err_e
 __td_thr_getxregsize(td_thrhandle_t *th_p, int *xregsize)
 {
-#if defined(__sparc)
         struct ps_prochandle *ph_p;
         td_err_e return_val;
 
         if ((ph_p = ph_lock_th(th_p, &return_val)) == NULL)
                 return (return_val);

@@ -2001,46 +2001,45 @@
         }
 
         if (ps_lgetxregsize(ph_p, thr_to_lwpid(th_p), xregsize) != PS_OK)
                 return_val = TD_DBERR;
 
+        if (*xregsize == 0)
+                return_val = TD_NOXREGS;
+
         (void) ps_pcontinue(ph_p);
         ph_unlock(th_p->th_ta_p);
         return (return_val);
-#else   /* __sparc */
-        return (TD_NOXREGS);
-#endif  /* __sparc */
 }
 
 /*
  * Get a thread's extra state register set.
  */
 #pragma weak td_thr_getxregs = __td_thr_getxregs
-/* ARGSUSED */
 td_err_e
 __td_thr_getxregs(td_thrhandle_t *th_p, void *xregset)
 {
-#if defined(__sparc)
         struct ps_prochandle *ph_p;
         td_err_e return_val;
+        ps_err_e ps_err;
 
         if ((ph_p = ph_lock_th(th_p, &return_val)) == NULL)
                 return (return_val);
         if (ps_pstop(ph_p) != PS_OK) {
                 ph_unlock(th_p->th_ta_p);
                 return (TD_DBERR);
         }
 
-        if (ps_lgetxregs(ph_p, thr_to_lwpid(th_p), (caddr_t)xregset) != PS_OK)
+        ps_err = ps_lgetxregs(ph_p, thr_to_lwpid(th_p), (caddr_t)xregset);
+        if (ps_err == PS_NOXREGS)
+                return_val = TD_NOXREGS;
+        else if (ps_err != PS_OK)
                 return_val = TD_DBERR;
 
         (void) ps_pcontinue(ph_p);
         ph_unlock(th_p->th_ta_p);
         return (return_val);
-#else   /* __sparc */
-        return (TD_NOXREGS);
-#endif  /* __sparc */
 }
 
 /*
  * Set a thread's extra state register set.
  */

@@ -2047,11 +2046,10 @@
 #pragma weak td_thr_setxregs = __td_thr_setxregs
 /* ARGSUSED */
 td_err_e
 __td_thr_setxregs(td_thrhandle_t *th_p, const void *xregset)
 {
-#if defined(__sparc)
         struct ps_prochandle *ph_p;
         td_err_e return_val;
 
         if ((ph_p = ph_lock_th(th_p, &return_val)) == NULL)
                 return (return_val);

@@ -2064,13 +2062,10 @@
                 return_val = TD_DBERR;
 
         (void) ps_pcontinue(ph_p);
         ph_unlock(th_p->th_ta_p);
         return (return_val);
-#else   /* __sparc */
-        return (TD_NOXREGS);
-#endif  /* __sparc */
 }
 
 struct searcher {
         psaddr_t        addr;
         int             status;