From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sun, 9 Jan 2005 08:03:38 +0000 (+0000)
Subject: Save and restore user processes' FS and GS registers.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=90284ecf98313edfd34d8e3f30a2b00a0065bf38;p=pintos-anon

Save and restore user processes' FS and GS registers.
---

diff --git a/TODO b/TODO
index b4e216e..15902a2 100644
--- a/TODO
+++ b/TODO
@@ -1,15 +1,5 @@
 -*- text -*-
 
-* FS and GS:
-
-  - struct intr_frame: Add members.
-  
-  - intr_entry(): Save, reset.
-
-  - intr_exit(): Restore.
-
-  - execute_thread(): Initialize.
-
 * Userprog project:
 
   - Move `join' implementation here, from `threads' project, to help
diff --git a/src/threads/interrupt.h b/src/threads/interrupt.h
index d54b7ef..99abf8e 100644
--- a/src/threads/interrupt.h
+++ b/src/threads/interrupt.h
@@ -29,6 +29,8 @@ struct intr_frame
     uint32_t edx;               /* Saved EDX. */
     uint32_t ecx;               /* Saved ECX. */
     uint32_t eax;               /* Saved EAX. */
+    uint16_t gs, :16;           /* Saved GS segment register. */
+    uint16_t fs, :16;           /* Saved FS segment register. */
     uint16_t es, :16;           /* Saved ES segment register. */
     uint16_t ds, :16;           /* Saved DS segment register. */
 
diff --git a/src/threads/intr-stubs.pl b/src/threads/intr-stubs.pl
index a5ad9b0..75cde7b 100755
--- a/src/threads/intr-stubs.pl
+++ b/src/threads/intr-stubs.pl
@@ -35,6 +35,8 @@ intr_entry:
 	# Save caller's registers.
 	push ds
 	push es
+	push fs
+	push gs
 	pusha
 
 	# Set up kernel environment.
@@ -53,6 +55,8 @@ intr_entry:
 intr_exit:
 	# Restore caller's registers.
 	popa
+	pop gs
+	pop fs
 	pop es
 	pop ds
 	add esp, 8
diff --git a/src/userprog/process.c b/src/userprog/process.c
index b9a199e..c0a6547 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -54,6 +54,8 @@ execute_thread (void *filename_)
 
   /* Initialize interrupt frame and load executable. */
   memset (&if_, 0, sizeof if_);
+  if_.gs = SEL_UDSEG;
+  if_.fs = SEL_UDSEG;
   if_.es = SEL_UDSEG;
   if_.ds = SEL_UDSEG;
   if_.cs = SEL_UCSEG;