use linker to align fpu state save area

include/arch/i386/include/archtypes.h

@@ -26,19 +26,10 @@ typedef struct segframe {
 	reg_t p_ldt_sel;    /* selector in gdt with ldt base and limit */
 	reg_t	p_cr3;		/* page table root */
 	u32_t	*p_cr3_v;
+	char	*fpu_state;
 	struct segdesc_s p_ldt[LDT_SIZE]; /* CS, DS and remote */
 } segframe_t;
 
-/* fpu_state_s is used in kernel proc table.
- * Any changes in this structure requires changes in sconst.h,
- * since this structure is used in proc structure. */
-struct fpu_state_s {
-	union fpu_state_u *fpu_save_area_p; /* 16-aligned fpu_save_area */
-	/* fpu_image includes 512 bytes of image itself and
-	 * additional 15 bytes required for manual 16-byte alignment. */
-	char fpu_image[527];
-};
-
 #define INMEMORY(p) (!p->p_seg.p_cr3 || get_cpulocal_var(ptproc) == p)
 
 typedef u32_t atomic_t;	/* access to an aligned 32bit value is atomic on i386 */

kernel/arch/i386/arch_system.c

@@ -275,6 +275,8 @@ void fpu_init(void)
 
 void save_local_fpu(struct proc *pr, int retain)
 {
+	char *state = pr->p_seg.fpu_state;
+
 	/* Save process FPU context. If the 'retain' flag is set, keep the FPU
 	 * state as is. If the flag is not set, the state is undefined upon
 	 * return, and the caller is responsible for reloading a proper state.
@@ -283,12 +285,14 @@ void save_local_fpu(struct proc *pr, int retain)
 	if(!is_fpu())
 		return;
 
+	assert(state);
+
 	if(osfxsr_feature) {
-		fxsave(pr->p_fpu_state.fpu_save_area_p);
+		fxsave(state);
 	} else {
-		fnsave(pr->p_fpu_state.fpu_save_area_p);
+		fnsave(state);
 		if (retain)
-			(void) frstor(pr->p_fpu_state.fpu_save_area_p);
+			(void) frstor(state);
 	}
 }
 
@@ -322,18 +326,41 @@ void save_fpu(struct proc *pr)
 	}
 }
 
+/* reserve a chunk of memory for fpu state; every one has to
+ * be FPUALIGN-aligned.
+ */
+static char fpu_state[NR_PROCS][FPU_XFP_SIZE] __aligned(FPUALIGN);
+
+void arch_proc_init(int nr, struct proc *pr)
+{
+	if(nr < 0) return;
+	char *v;
+
+	assert(nr < NR_PROCS);
+
+	v = fpu_state[nr];
+
+	/* verify alignment */
+	assert(!((vir_bytes)v % FPUALIGN));
+	
+	pr->p_seg.fpu_state = v;
+}
+
 int restore_fpu(struct proc *pr)
 {
 	int failed;
+	char *state = pr->p_seg.fpu_state;
+
+	assert(state);
 
 	if(!proc_used_fpu(pr)) {
 		fninit();
 		pr->p_misc_flags |= MF_FPU_INITIALIZED;
 	} else {
 		if(osfxsr_feature) {
-			failed = fxrstor(pr->p_fpu_state.fpu_save_area_p);
+			failed = fxrstor(state);
 		} else {
-			failed = frstor(pr->p_fpu_state.fpu_save_area_p);
+			failed = frstor(state);
 		}
 
 		if (failed) return EINVAL;

kernel/arch/i386/procoffsets.cf

@@ -21,7 +21,6 @@ member CSREG p_reg.cs
 member PSWREG p_reg.psw
 member SPREG p_reg.sp
 member SSREG p_reg.ss
-member FP_SAVE_AREA_P p_fpu_state
 member P_LDT_SEL p_seg.p_ldt_sel
 member P_CR3 p_seg.p_cr3
 member P_CR3_V p_seg.p_cr3_v

kernel/proc.c

@@ -136,6 +136,9 @@ void proc_init(void)
 		rp->p_scheduler = NULL;		/* no user space scheduler */
 		rp->p_priority = 0;		/* no priority */
 		rp->p_quantum_size_ms = 0;	/* no quantum size */
+
+		/* arch-specific initialization */
+		arch_proc_init(i, rp);
 	}
 	for (sp = BEG_PRIV_ADDR, i = 0; sp < END_PRIV_ADDR; ++sp, ++i) {
 		sp->s_proc_nr = NONE;		/* initialize as free */
@@ -155,25 +158,6 @@ void proc_init(void)
 		ip->p_rts_flags |= RTS_PROC_STOP;
 		set_idle_name(ip->p_name, i);
 	}
-
-#if (_MINIX_CHIP == _CHIP_INTEL)
-	for (rp = BEG_PROC_ADDR; rp < END_PROC_ADDR; ++rp) {
-		/*
-		 * FXSR requires 16-byte alignment of memory image, but
-		 * unfortunately a.out does not preserve the alignment while
-		 * linking.  Thus we have to do manual alignment.
-		 */
-		phys_bytes aligned_fp_area;
-		aligned_fp_area =
-			(phys_bytes) &rp->p_fpu_state.fpu_image;
-		if(aligned_fp_area % FPUALIGN) {
-			aligned_fp_area += FPUALIGN -
-				(aligned_fp_area % FPUALIGN);
-		}
-		rp->p_fpu_state.fpu_save_area_p =
-			(void *) aligned_fp_area;
-	}
-#endif
 }
 
 static void switch_address_space_idle(void)

kernel/proc.h

@@ -21,7 +21,6 @@
 
 struct proc {
   struct stackframe_s p_reg;	/* process' registers saved in stack frame */
-  struct fpu_state_s p_fpu_state;	/* process' fpu_regs saved lazily */
   struct segframe p_seg;	/* segment descriptors */
   proc_nr_t p_nr;		/* number of this process (for fast access) */
   struct priv *p_priv;		/* system privileges structure */

kernel/proto.h

@@ -55,6 +55,7 @@ int mini_notify(const struct proc *src, endpoint_t dst);
 void enqueue(struct proc *rp);
 void dequeue(struct proc *rp);
 void switch_to_user(void);
+void arch_proc_init(int nr, struct proc *rp);
 struct proc * arch_finish_switch_to_user(void);
 struct proc *endpoint_lookup(endpoint_t ep);
 #if DEBUG_ENABLE_IPC_WARNINGS

kernel/system/do_fork.c

@@ -27,7 +27,7 @@ int do_fork(struct proc * caller, message * m_ptr)
 /* Handle sys_fork().  PR_ENDPT has forked.  The child is PR_SLOT. */
 #if (_MINIX_CHIP == _CHIP_INTEL)
   reg_t old_ldt_sel;
-  void *old_fpu_save_area_p;
+  char *old_fpu_save_area_p;
 #endif
   register struct proc *rpc;		/* child process pointer */
   struct proc *rpp;			/* parent process pointer */
@@ -59,16 +59,14 @@ int do_fork(struct proc * caller, message * m_ptr)
   gen = _ENDPOINT_G(rpc->p_endpoint);
 #if (_MINIX_CHIP == _CHIP_INTEL)
   old_ldt_sel = rpc->p_seg.p_ldt_sel;	/* backup local descriptors */
-  old_fpu_save_area_p = rpc->p_fpu_state.fpu_save_area_p;
+  old_fpu_save_area_p = rpc->p_seg.fpu_state;
 #endif
   *rpc = *rpp;				/* copy 'proc' struct */
 #if (_MINIX_CHIP == _CHIP_INTEL)
   rpc->p_seg.p_ldt_sel = old_ldt_sel;	/* restore descriptors */
-  rpc->p_fpu_state.fpu_save_area_p = old_fpu_save_area_p;
+  rpc->p_seg.fpu_state = old_fpu_save_area_p;
   if(proc_used_fpu(rpp))
-	memcpy(rpc->p_fpu_state.fpu_save_area_p,
+	memcpy(rpc->p_seg.fpu_state, rpp->p_seg.fpu_state, FPU_XFP_SIZE);
-	       rpp->p_fpu_state.fpu_save_area_p,
-	       FPU_XFP_SIZE);
 #endif
   if(++gen >= _ENDPOINT_MAX_GENERATION)	/* increase generation */
 	gen = 1;			/* generation number wraparound */

kernel/system/do_mcontext.c

@@ -45,8 +45,7 @@ int do_getmcontext(struct proc * caller, message * m_ptr)
 	/* make sure that the FPU context is saved into proc structure first */
 	save_fpu(rp);
 	mc.mc_fpu_flags = rp->p_misc_flags & MF_FPU_INITIALIZED;
-	memcpy(&(mc.mc_fpu_state), rp->p_fpu_state.fpu_save_area_p,
+	memcpy(&(mc.mc_fpu_state), rp->p_seg.fpu_state, FPU_XFP_SIZE);
-							FPU_XFP_SIZE);
   } 
 #endif
 
@@ -84,8 +83,7 @@ int do_setmcontext(struct proc * caller, message * m_ptr)
   /* Copy FPU state */
   if (mc.mc_fpu_flags & MF_FPU_INITIALIZED) {
 	rp->p_misc_flags |= MF_FPU_INITIALIZED;
-	memcpy(rp->p_fpu_state.fpu_save_area_p, &(mc.mc_fpu_state),
+	memcpy(rp->p_seg.fpu_state, &(mc.mc_fpu_state), FPU_XFP_SIZE);
-								FPU_XFP_SIZE);
   } else
 	rp->p_misc_flags &= ~MF_FPU_INITIALIZED;
   /* force reloading FPU in either case */

kernel/system/do_sigreturn.c

@@ -55,8 +55,7 @@ int do_sigreturn(struct proc * caller, message * m_ptr)
 #if (_MINIX_CHIP == _CHIP_INTEL)
   if(sc.sc_flags & MF_FPU_INITIALIZED)
   {
-	memcpy(rp->p_fpu_state.fpu_save_area_p, &sc.sc_fpu_state,
+	memcpy(rp->p_seg.fpu_state, &sc.sc_fpu_state, FPU_XFP_SIZE);
-		FPU_XFP_SIZE);
 	rp->p_misc_flags |=  MF_FPU_INITIALIZED; /* Restore math usage flag. */
 	/* force reloading FPU */
 	release_fpu(rp);

kernel/system/do_sigsend.c

@@ -46,8 +46,7 @@ int do_sigsend(struct proc * caller, message * m_ptr)
     if(proc_used_fpu(rp)) {
 	    /* save the FPU context before saving it to the sig context */
 	    save_fpu(rp);
-	    memcpy(&sc.sc_fpu_state, rp->p_fpu_state.fpu_save_area_p,
+	    memcpy(&sc.sc_fpu_state, rp->p_seg.fpu_state, FPU_XFP_SIZE);
-	   	 FPU_XFP_SIZE);
     }
   #endif
 

kernel/system/do_update.c

@@ -22,8 +22,6 @@
 static void adjust_proc_slot(struct proc *rp, struct proc *from_rp);
 static void adjust_priv_slot(struct priv *privp, struct priv
 	*from_privp);
-static void swap_fpu_state(struct proc *a_rp, struct proc *b_orig_rp,
-	struct proc *b_copy_rp);
 static void swap_proc_slot_pointer(struct proc **rpp, struct proc
 	*src_rp, struct proc *dst_rp);
 
@@ -110,10 +108,6 @@ int do_update(struct proc * caller, message * m_ptr)
   adjust_priv_slot(priv(src_rp), &orig_src_priv);
   adjust_priv_slot(priv(dst_rp), &orig_dst_priv);
 
-  /* Swap FPU state. Can only be done after adjusting the process slots. */
-  swap_fpu_state(src_rp, dst_rp, &orig_dst_proc);
-  swap_fpu_state(dst_rp, src_rp, &orig_src_proc);
-
   /* Swap global process slot addresses. */
   swap_proc_slot_pointer(get_cpulocal_var_ptr(ptproc), src_rp, dst_rp);
 
@@ -152,11 +146,6 @@ static void adjust_proc_slot(struct proc *rp, struct proc *from_rp)
   priv(rp)->s_proc_nr = from_rp->p_nr;
   rp->p_caller_q = from_rp->p_caller_q;
 
-#if (_MINIX_CHIP == _CHIP_INTEL)
-  /* Preserve FPU pointer. */
-  rp->p_fpu_state.fpu_save_area_p = from_rp->p_fpu_state.fpu_save_area_p;
-#endif
-
   /* preserve scheduling */
   rp->p_scheduler = from_rp->p_scheduler;
 #ifdef CONFIG_SMP
@@ -179,26 +168,6 @@ static void adjust_priv_slot(struct priv *privp, struct priv *from_privp)
   privp->s_alarm_timer = from_privp->s_alarm_timer;
 }
 
-/*===========================================================================*
- *				swap_fpu_state				     *
- *===========================================================================*/
-static void swap_fpu_state(struct proc *a_rp, struct proc *b_orig_rp,
-    struct proc *b_copy_rp)
-{
-  /* Copy the FPU state from process B's copied slot, using B's original FPU
-   * save area alignment, into process A's slot.
-   */
-#if (_MINIX_CHIP == _CHIP_INTEL)
-  int align;
-
-  align = (int) ((char *) b_orig_rp->p_fpu_state.fpu_save_area_p -
-	(char *) &b_orig_rp->p_fpu_state.fpu_image);
-
-  memcpy(a_rp->p_fpu_state.fpu_save_area_p,
-	b_copy_rp->p_fpu_state.fpu_image + align, FPU_XFP_SIZE);
-#endif
-}
-
 /*===========================================================================*
  *			   swap_proc_slot_pointer			     *
  *===========================================================================*/