1 files changed, 25 insertions, 18 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index e3f362e8af5b..b45cbf93d439 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -164,7 +164,7 @@ static inline void play_dead(void)
          */
         local_irq_disable();
         while (1)
-                __asm__ __volatile__("hlt":::"memory");
+                halt();
 }
 #else
 static inline void play_dead(void)
@@ -313,16 +313,12 @@ void show_regs(struct pt_regs * regs)
         printk(" DS: %04x ES: %04x\n",
                 0xffff & regs->xds,0xffff & regs->xes);
 
-        __asm__("movl %%cr0, %0": "=r" (cr0));
-        __asm__("movl %%cr2, %0": "=r" (cr2));
-        __asm__("movl %%cr3, %0": "=r" (cr3));
-        /* This could fault if %cr4 does not exist */
-        __asm__("1: movl %%cr4, %0              \n"
-                "2:                             \n"
-                ".section __ex_table,\"a\"      \n"
-                ".long 1b,2b                    \n"
-                ".previous                      \n"
-                : "=r" (cr4): "0" (0));
+        cr0 = read_cr0();
+        cr2 = read_cr2();
+        cr3 = read_cr3();
+        if (current_cpu_data.x86 > 4) {
+                cr4 = read_cr4();
+        }
         printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4);
         show_trace(NULL, &regs->esp);
 }
@@ -682,21 +678,26 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
         __unlazy_fpu(prev_p);
 
         /*
-         * Reload esp0, LDT and the page table pointer:
+         * Reload esp0.
          */
         load_esp0(tss, next);
 
         /*
-         * Load the per-thread Thread-Local Storage descriptor.
+         * Save away %fs and %gs. No need to save %es and %ds, as
+         * those are always kernel segments while inside the kernel.
+         * Doing this before setting the new TLS descriptors avoids
+         * the situation where we temporarily have non-reloadable
+         * segments in %fs and %gs.  This could be an issue if the
+         * NMI handler ever used %fs or %gs (it does not today), or
+         * if the kernel is running inside of a hypervisor layer.
          */
-        load_TLS(next, cpu);
+        savesegment(fs, prev->fs);
+        savesegment(gs, prev->gs);
 
         /*
-         * Save away %fs and %gs. No need to save %es and %ds, as
-         * those are always kernel segments while inside the kernel.
+         * Load the per-thread Thread-Local Storage descriptor.
          */
-        asm volatile("mov %%fs,%0":"=m" (prev->fs));
-        asm volatile("mov %%gs,%0":"=m" (prev->gs));
+        load_TLS(next, cpu);
 
         /*
          * Restore %fs and %gs if needed.
@@ -711,6 +712,12 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
                 loadsegment(gs, next->gs);
 
         /*
+         * Restore IOPL if needed.
+         */
+        if (unlikely(prev->iopl != next->iopl))
+                set_iopl_mask(next->iopl);
+
+        /*
          * Now maybe reload the debug registers
          */
         if (unlikely(next->debugreg[7])) {