Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab...

[linux-2.6-omap-h63xx.git] / drivers / lguest / interrupts_and_traps.c

diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 0414ddf875871729c00742c00cb6bf45a558eac8..415fab0125acd8e465e1fe2e6fe8241d75894868 100644 (file)
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -222,11 +222,16 @@ bool check_syscall_vector(struct lguest *lg)
 int init_interrupts(void)
 {
        /* If they want some strange system call vector, reserve it now */
-       if (syscall_vector != SYSCALL_VECTOR
-           && test_and_set_bit(syscall_vector, used_vectors)) {
-               printk("lg: couldn't reserve syscall %u\n", syscall_vector);
-               return -EBUSY;
+       if (syscall_vector != SYSCALL_VECTOR) {
+               if (test_bit(syscall_vector, used_vectors) ||
+                   vector_used_by_percpu_irq(syscall_vector)) {
+                       printk(KERN_ERR "lg: couldn't reserve syscall %u\n",
+                                syscall_vector);
+                       return -EBUSY;
+               }
+               set_bit(syscall_vector, used_vectors);
        }
+
        return 0;
 }
 
@@ -406,7 +411,8 @@ void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int num, u32 lo, u32 hi)
  * deliver_trap() to bounce it back into the Guest. */
 static void default_idt_entry(struct desc_struct *idt,
                              int trap,
-                             const unsigned long handler)
+                             const unsigned long handler,
+                             const struct desc_struct *base)
 {
        /* A present interrupt gate. */
        u32 flags = 0x8e00;
@@ -415,6 +421,10 @@ static void default_idt_entry(struct desc_struct *idt,
         * the Guest to use the "int" instruction to trigger it. */
        if (trap == LGUEST_TRAP_ENTRY)
                flags |= (GUEST_PL << 13);
+       else if (base)
+               /* Copy priv. level from what Guest asked for.  This allows
+                * debug (int 3) traps from Guest userspace, for example. */
+               flags |= (base->b & 0x6000);
 
        /* Now pack it into the IDT entry in its weird format. */
        idt->a = (LGUEST_CS<<16) | (handler&0x0000FFFF);
@@ -428,7 +438,7 @@ void setup_default_idt_entries(struct lguest_ro_state *state,
        unsigned int i;
 
        for (i = 0; i < ARRAY_SIZE(state->guest_idt); i++)
-               default_idt_entry(&state->guest_idt[i], i, def[i]);
+               default_idt_entry(&state->guest_idt[i], i, def[i], NULL);
 }
 
 /*H:240 We don't use the IDT entries in the "struct lguest" directly, instead
@@ -442,6 +452,8 @@ void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
        /* We can simply copy the direct traps, otherwise we use the default
         * ones in the Switcher: they will return to the Host. */
        for (i = 0; i < ARRAY_SIZE(cpu->arch.idt); i++) {
+               const struct desc_struct *gidt = &cpu->arch.idt[i];
+
                /* If no Guest can ever override this trap, leave it alone. */
                if (!direct_trap(i))
                        continue;
@@ -449,12 +461,15 @@ void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
                /* Only trap gates (type 15) can go direct to the Guest.
                 * Interrupt gates (type 14) disable interrupts as they are
                 * entered, which we never let the Guest do.  Not present
-                * entries (type 0x0) also can't go direct, of course. */
-               if (idt_type(cpu->arch.idt[i].a, cpu->arch.idt[i].b) == 0xF)
-                       idt[i] = cpu->arch.idt[i];
+                * entries (type 0x0) also can't go direct, of course.
+                *
+                * If it can't go direct, we still need to copy the priv. level:
+                * they might want to give userspace access to a software
+                * interrupt. */
+               if (idt_type(gidt->a, gidt->b) == 0xF)
+                       idt[i] = *gidt;
                else
-                       /* Reset it to the default. */
-                       default_idt_entry(&idt[i], i, def[i]);
+                       default_idt_entry(&idt[i], i, def[i], gidt);
        }
 }