2002-10-03 Roland McGrath <roland@frob.com>

* i386/include/mach/i386/mach_i386.defs (i386_set_gdt, i386_get_gdt):
	New routines.
	* i386/i386/user_ldt.c (i386_set_gdt, i386_get_gdt): New functions.
	* i386/i386/gdt.h (USER_GDT, USER_GDT_SLOTS): New macros.
	* i386/i386/thread.h (struct i386_machine_state): New member user_gdt.
	* i386/i386/pcb.c (switch_ktss): Copy those slots into the GDT.
	Remove magic %gs:0 pseudo-register support.
	* i386/i386/ldt.h (USER_GS): Macro removed.
	* i386/i386/pcb.c (pcb_init): Set gs to USER_DS, not USER_GS.
	(thread_setstatus): Likewise.
	* i386/i386/mp_desc.h (struct mp_desc_table): Remove member
	`user_thread_register'.
	* i386/i386/thread.h (struct i386_machine_state): Likewise.
	* i386/i386/mp_desc.c (mp_desc_init): Don't set up USER_GS in LDT.
	* i386/i386/ldt.c (ldt_init): Likewise.
	* i386/intel/pmap.c (pmap_bootstrap): Don't give users access to
	direct-mapped pages.
	* i386/i386/user_ldt.c (i386_set_ldt): Don't cap segment limits.

3 files changed, 64 insertions, 27 deletions

diff --git a/i386/i386/pcb.c b/i386/i386/pcb.c
index a9937bdc..cd9ecdc6 100644
--- a/i386/i386/pcb.c
+++ b/i386/i386/pcb.c
@@ -126,13 +126,9 @@ vm_offset_t stack_detach(thread)
 #if	NCPUS > 1
 #define	curr_gdt(mycpu)		(mp_gdt[mycpu])
 #define	curr_ktss(mycpu)	(mp_ktss[mycpu])
-#define curr_user_thread_reg(mycpu)	\
-  (mp_desc_table[mycpu].user_thread_register)
 #else
 #define	curr_gdt(mycpu)		(gdt)
 #define	curr_ktss(mycpu)	((struct task_tss *)&base_tss)
-#define curr_user_thread_reg(mycpu) (user_thread_register)
-natural_t user_thread_register;
 #endif
 
 #define	gdt_desc_p(mycpu,sel) \
@@ -182,9 +178,11 @@ switch_ktss(pcb_t old_pcb, pcb_t pcb)
 	}
       }
 
-    if (old_pcb)
-      old_pcb->ims.user_thread_register = curr_user_thread_reg(mycpu);
-    curr_user_thread_reg(mycpu) = pcb->ims.user_thread_register;
+	/* Copy in the per-thread GDT slots.  No reloading is necessary
+	   because just restoring the segment registers on the way back to
+	   user mode reloads the shadow registers from the in-memory GDT.  */
+	memcpy (gdt_desc_p (mycpu, USER_GDT),
+		pcb->ims.user_gdt, sizeof pcb->ims.user_gdt);
 
 	/*
 	 * Load the floating-point context, if necessary.
@@ -363,7 +361,7 @@ void pcb_init(thread)
 	pcb->iss.ds = USER_DS;
 	pcb->iss.es = USER_DS;
 	pcb->iss.fs = USER_DS;
-	pcb->iss.gs = USER_GS;
+	pcb->iss.gs = USER_DS;
 	pcb->iss.eflags = EFL_USER_SET;
 
 	thread->pcb = pcb;
@@ -497,7 +495,7 @@ kern_return_t thread_setstatus(thread, flavor, tstate, count)
 		    saved_state->ds = USER_DS;
 		    saved_state->es = USER_DS;
 		    saved_state->fs = USER_DS;
-		    saved_state->gs = USER_GS;
+		    saved_state->gs = USER_DS;
 		}
 		else {
 		    /*
diff --git a/i386/i386/thread.h b/i386/i386/thread.h
index c5ae3c51..f653eed5 100644
--- a/i386/i386/thread.h
+++ b/i386/i386/thread.h
@@ -36,6 +36,7 @@
 #include <mach/boolean.h>
 #include <mach/machine/vm_types.h>
 #include <mach/machine/fp_reg.h>
+#include "gdt.h"
 
 #include <kern/lock.h>
 
@@ -130,7 +131,7 @@ struct i386_machine_state {
 	struct user_ldt	*	ldt;
 	struct i386_fpsave_state *ifps;
 	struct v86_assist_state	v86s;
-  	natural_t user_thread_register;
+	struct x86_desc user_gdt[USER_GDT_SLOTS];
 };
 
 typedef struct pcb {
diff --git a/i386/i386/user_ldt.c b/i386/i386/user_ldt.c
index 9db6da5d..a59b1769 100644
--- a/i386/i386/user_ldt.c
+++ b/i386/i386/user_ldt.c
@@ -170,23 +170,6 @@ i386_set_ldt(thread, first_selector, desc_list, count, desc_list_inline)
 		case ACC_P | ACC_PL_U | ACC_CODE_CR:
 		case ACC_P | ACC_PL_U | ACC_CALL_GATE_16:
 		case ACC_P | ACC_PL_U | ACC_CALL_GATE:
-		  /* Silently cap the segment's limit at VM_MAX_ADDRESS. */
-		  {
-		    unsigned base = ((dp->base_high << 24)
-				     | (dp->base_med << 16) | dp->base_low);
-		    unsigned limit
-		      = ((dp->limit_high << 16) | dp->limit_low);
-		    if (dp->granularity & SZ_G)
-		      limit <<= 12;
-		    if (base > VM_MAX_ADDRESS)
-		      {
-			fill_descriptor_base(dp, 0);
-			fill_descriptor_limit(dp, 0);
-		      }
-		    else if (base + limit > VM_MAX_ADDRESS
-			     || base + limit < base)
-		      fill_descriptor_limit(dp, VM_MAX_ADDRESS - base);
-		  }
 		  break;
 		default:
 		    return KERN_INVALID_ARGUMENT;
@@ -416,3 +399,58 @@ user_ldt_free(user_ldt)
 		user_ldt->desc.limit_low + 1
 		+ sizeof(struct x86_desc));
 }
+
+
+kern_return_t
+i386_set_gdt (thread_t thread, int *selector, struct x86_desc *desc)
+{
+  int idx;
+
+  if (thread == THREAD_NULL)
+    return KERN_INVALID_ARGUMENT;
+
+  if (*selector == -1)
+    {
+      for (idx = sel_idx (USER_GDT); idx < sel_idx (USER_GDT) + USER_GDT_SLOTS;
+	   ++idx)
+	if ((thread->pcb->ims.user_gdt[idx].access & ACC_P) == 0)
+	  {
+	    *selector = (idx << 3) | SEL_PL_U;
+	    break;
+	  }
+      if (idx == sel_idx (USER_GDT) + USER_GDT_SLOTS)
+	return KERN_NO_SPACE;	/* ? */
+    }
+  else if ((*selector & (SEL_LDT|SEL_PL)) != SEL_PL_U
+	   || sel_idx (*selector) < USER_GDT
+	   || sel_idx (*selector) >= USER_GDT + USER_GDT_SLOTS)
+    return KERN_INVALID_ARGUMENT;
+  else
+    idx = sel_idx (*selector);
+
+  if ((desc->access & ACC_P) == 0)
+    memset (&thread->pcb->ims.user_gdt[idx], 0,
+	    sizeof thread->pcb->ims.user_gdt[idx]);
+  else if ((desc->access & (ACC_TYPE|ACC_PL)) != (ACC_TYPE_USER|ACC_PL_U))
+    return KERN_INVALID_ARGUMENT;
+  else
+    thread->pcb->ims.user_gdt[idx] = *desc;
+
+  return KERN_SUCCESS;
+}
+
+kern_return_t
+i386_get_gdt (thread_t thread, int selector, struct x86_desc *desc)
+{
+  if (thread == THREAD_NULL)
+    return KERN_INVALID_ARGUMENT;
+
+  if ((selector & (SEL_LDT|SEL_PL)) != SEL_PL_U
+      || sel_idx (selector) < USER_GDT
+      || sel_idx (selector) >= USER_GDT + USER_GDT_SLOTS)
+    return KERN_INVALID_ARGUMENT;
+
+  *desc = thread->pcb->ims.user_gdt[sel_idx (selector)];
+
+  return KERN_SUCCESS;
+}