Changes in kernel/arch/ia32/src/asm.S [8078180:d029434] in mainline

File:

• kernel/arch/ia32/src/asm.S (modified) (8 diffs)

kernel/arch/ia32/src/asm.S

@@ -1 +1 @@
 /*
- * Copyright (c) 2001 Jakub Jermar
+ * Copyright (c) 2010 Jakub Jermar
  * All rights reserved.
  *
@@ -32 +32 @@
 
 #include <arch/pm.h>
+#include <arch/cpu.h>
 #include <arch/mm/page.h>
 
@@ -190 +191 @@
 .global sysenter_handler
 sysenter_handler:
-        sti
         subl $(ISTATE_REAL_SIZE), %esp
 
@@ -227 +227 @@
          * Switch to kernel selectors.
          */
-        movw $16, %ax
+        movw $(gdtselector(KDATA_DES)), %ax
         movw %ax, %ds
         movw %ax, %es
         
-        cld
+        /*
+         * Sanitize EFLAGS.
+         *
+         * SYSENTER does not clear the NT flag, which could thus proliferate
+         * from here to the IRET instruction via a context switch and result
+         * in crash.
+         *
+         * SYSENTER does not clear DF, which the ABI assumes to be cleared.
+         *
+         * SYSENTER clears IF, which we would like to be set for syscalls.
+         *
+         */
+        pushl $(EFLAGS_IF)  /* specify EFLAGS bits that we want to set */
+        popfl               /* set bits from the mask, clear or ignore others */
+
         call syscall_handler
         
@@ -294 +308 @@
          * Switch to kernel selectors.
          */
-        movl $16, %eax
+        movl $(gdtselector(KDATA_DES)), %eax
         movl %eax, %ds
         movl %eax, %es
@@ -358 +372 @@
                 .if (1 << \i) & ERROR_WORD_INTERRUPT_LIST
                         /*
-                         * Exception with error word: do nothing
+                         * Exception with error word.
                          */
+                        subl $ISTATE_SOFT_SIZE, %esp
                 .else
                         /*
                          * Exception without error word: fake up one
                          */
-                        pushl $0
+                        subl $(ISTATE_SOFT_SIZE + 4), %esp
                 .endif
         .else
                 /*
-                 * Interrupt: fake up one
+                 * Interrupt: fake up an error word 
                  */
-                pushl $0
+                subl $(ISTATE_SOFT_SIZE + 4), %esp
         .endif
-        
-        subl $ISTATE_SOFT_SIZE, %esp
         
         /*
@@ -404 +417 @@
          * Switch to kernel selectors.
          */
-        movl $16, %eax
+        movl $(gdtselector(KDATA_DES)), %eax
         movl %eax, %ds
         movl %eax, %es
@@ -413 +426 @@
          */
         xorl %eax, %eax
-        cmpl $8, ISTATE_OFFSET_CS(%esp)
-        cmovl %eax, %ebp
+        cmpl $(gdtselector(KTEXT_DES)), ISTATE_OFFSET_CS(%esp)
+        cmovnzl %eax, %ebp
 
         movl %ebp, ISTATE_OFFSET_EBP_FRAME(%esp)