From e5c7df720147528ab310fe5ac983cc5115b998da Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sun, 9 Jan 2005 08:03:38 +0000
Subject: [PATCH] Save and restore user processes' FS and GS registers.
---
src/threads/interrupt.h | 2 ++
src/threads/intr-stubs.pl | 4 ++++
src/userprog/process.c | 2 ++
3 files changed, 8 insertions(+)
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;
--
2.30.2