3 files changed, 48 insertions, 35 deletions

diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index f74dfc4..8271466 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -168,6 +168,12 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
 .section .init.text,"ax",@progbits
 #endif
 
+	/* Do an early initialization of the fixmap area */
+	movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
+	movl $(swapper_pg_pmd - __PAGE_OFFSET), %eax
+	addl $0x007, %eax			/* 0x007 = PRESENT+RW+USER */
+	movl %eax, 4092(%edx)
+
 #ifdef CONFIG_SMP
 ENTRY(startup_32_smp)
 	cld
@@ -507,6 +513,8 @@ ENTRY(_stext)
 .section ".bss.page_aligned","w"
 ENTRY(swapper_pg_dir)
 	.fill 1024,4,0
+ENTRY(swapper_pg_pmd)
+	.fill 1024,4,0
 ENTRY(empty_zero_page)
 	.fill 4096,1,0
 
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 06dfa65..6c49acb 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -538,8 +538,31 @@ int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 	return 1;
 }
 
-static noinline void __switch_to_xtra(struct task_struct *next_p,
-				    struct tss_struct *tss)
+#ifdef CONFIG_SECCOMP
+void hard_disable_TSC(void)
+{
+	write_cr4(read_cr4() | X86_CR4_TSD);
+}
+void disable_TSC(void)
+{
+	preempt_disable();
+	if (!test_and_set_thread_flag(TIF_NOTSC))
+		/*
+		 * Must flip the CPU state synchronously with
+		 * TIF_NOTSC in the current running context.
+		 */
+		hard_disable_TSC();
+	preempt_enable();
+}
+void hard_enable_TSC(void)
+{
+	write_cr4(read_cr4() & ~X86_CR4_TSD);
+}
+#endif /* CONFIG_SECCOMP */
+
+static noinline void
+__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
+		 struct tss_struct *tss)
 {
 	struct thread_struct *next;
 
@@ -555,6 +578,17 @@ static noinline void __switch_to_xtra(struct task_struct *next_p,
 		set_debugreg(next->debugreg[7], 7);
 	}
 
+#ifdef CONFIG_SECCOMP
+	if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
+	    test_tsk_thread_flag(next_p, TIF_NOTSC)) {
+		/* prev and next are different */
+		if (test_tsk_thread_flag(next_p, TIF_NOTSC))
+			hard_disable_TSC();
+		else
+			hard_enable_TSC();
+	}
+#endif
+
 	if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
 		/*
 		 * Disable the bitmap via an invalid offset. We still cache
@@ -586,33 +620,6 @@ static noinline void __switch_to_xtra(struct task_struct *next_p,
 }
 
 /*
- * This function selects if the context switch from prev to next
- * has to tweak the TSC disable bit in the cr4.
- */
-static inline void disable_tsc(struct task_struct *prev_p,
-			       struct task_struct *next_p)
-{
-	struct thread_info *prev, *next;
-
-	/*
-	 * gcc should eliminate the ->thread_info dereference if
-	 * has_secure_computing returns 0 at compile time (SECCOMP=n).
-	 */
-	prev = task_thread_info(prev_p);
-	next = task_thread_info(next_p);
-
-	if (has_secure_computing(prev) || has_secure_computing(next)) {
-		/* slow path here */
-		if (has_secure_computing(prev) &&
-		    !has_secure_computing(next)) {
-			write_cr4(read_cr4() & ~X86_CR4_TSD);
-		} else if (!has_secure_computing(prev) &&
-			   has_secure_computing(next))
-			write_cr4(read_cr4() | X86_CR4_TSD);
-	}
-}
-
-/*
  *	switch_to(x,yn) should switch tasks from x to y.
  *
  * We fsave/fwait so that an exception goes off at the right time
@@ -689,11 +696,9 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
 	/*
 	 * Now maybe handle debug registers and/or IO bitmaps
 	 */
-	if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW)
-	    || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)))
-		__switch_to_xtra(next_p, tss);
-
-	disable_tsc(prev_p, next_p);
+	if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
+		     task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
+		__switch_to_xtra(prev_p, next_p, tss);
 
 	/*
 	 * Leave lazy mode, flushing any hypercalls made here.
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 90da057..28bd1c5 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -390,7 +390,7 @@ void die(const char * str, struct pt_regs * regs, long err)
 		unsigned long esp;
 		unsigned short ss;
 
-		report_bug(regs->eip);
+		report_bug(regs->eip, regs);
 
 		printk(KERN_EMERG "%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
 #ifdef CONFIG_PREEMPT