X-Git-Url: http://pilppa.org/gitweb/?a=blobdiff_plain;f=drivers%2Flguest%2Finterrupts_and_traps.c;h=415fab0125acd8e465e1fe2e6fe8241d75894868;hb=f60a0a79846abed04ad5abddb5dafd14b66e1ab0;hp=0414ddf875871729c00742c00cb6bf45a558eac8;hpb=858c52d15f186e055dc33a1872f5b45a66d42296;p=linux-2.6-omap-h63xx.git

diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 0414ddf8758..415fab0125a 100644
--- 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);
 	}
 }