From 49c19e58aa14fba779bfe331b1ebaba62d31dfa5 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 11 Nov 2006 14:25:16 +0000
Subject: [PATCH] Add memory clobbers to several asm statements, to prevent
 reordering.

---
 src/threads/init.c      | 2 +-
 src/threads/interrupt.c | 2 +-
 src/threads/thread.c    | 2 +-
 src/userprog/pagedir.c  | 2 +-
 src/userprog/process.c  | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/threads/init.c b/src/threads/init.c
index 2931704..5961deb 100644
--- a/src/threads/init.c
+++ b/src/threads/init.c
@@ -382,7 +382,7 @@ power_off (void)
 
   for (p = s; *p != '\0'; p++)
     outb (0x8900, *p);
-  asm ("cli; hlt");
+  asm volatile ("cli; hlt" : : : "memory");
   printf ("still running...\n");
   for (;;);
 }
diff --git a/src/threads/interrupt.c b/src/threads/interrupt.c
index 72b3783..3e37213 100644
--- a/src/threads/interrupt.c
+++ b/src/threads/interrupt.c
@@ -95,7 +95,7 @@ intr_disable (void)
   /* Disable interrupts by clearing the interrupt flag.
      See [IA32-v2b] "CLI" and [IA32-v3a] 5.8.1 "Masking Maskable
      Hardware Interrupts". */
-  asm volatile ("cli");
+  asm volatile ("cli" : : : "memory");
 
   return old_level;
 }
diff --git a/src/threads/thread.c b/src/threads/thread.c
index 938d7f8..1dc34ad 100644
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -389,7 +389,7 @@ idle (void *idle_started_ UNUSED)
 
          See [IA32-v2a] "HLT", [IA32-v2b] "STI", and [IA32-v3a]
          7.11.1 "HLT Instruction". */
-      asm ("sti; hlt");
+      asm volatile ("sti; hlt" : : : "memory");
     }
 }
 
diff --git a/src/userprog/pagedir.c b/src/userprog/pagedir.c
index 7d99375..30bdfe2 100644
--- a/src/userprog/pagedir.c
+++ b/src/userprog/pagedir.c
@@ -227,7 +227,7 @@ pagedir_activate (uint32_t *pd)
      new page tables immediately.  See [IA32-v2a] "MOV--Move
      to/from Control Registers" and [IA32-v3a] 3.7.5 "Base
      Address of the Page Directory". */
-  asm volatile ("movl %0, %%cr3" :: "r" (vtop (pd)));
+  asm volatile ("movl %0, %%cr3" : : "r" (vtop (pd)) : "memory");
 }
 
 /* Returns the currently active page directory. */
diff --git a/src/userprog/process.c b/src/userprog/process.c
index bece1fe..675dc25 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -72,7 +72,7 @@ execute_thread (void *file_name_)
      arguments on the stack in the form of a `struct intr_frame',
      we just point the stack pointer (%esp) to our stack frame
      and jump to it. */
-  asm ("movl %0, %%esp; jmp intr_exit" :: "g" (&if_));
+  asm volatile ("movl %0, %%esp; jmp intr_exit" : : "g" (&if_) : "memory");
   NOT_REACHED ();
 }
 
-- 
2.30.2