Merge branch 'master' into for-linus

1 files changed, 69 insertions, 37 deletions

diff --git a/drivers/lguest/segments.c b/drivers/lguest/segments.c
index 482ed5a1875..951c57b0a7e 100644
--- a/drivers/lguest/segments.c
+++ b/drivers/lguest/segments.c
@@ -1,4 +1,5 @@
-/*P:600 The x86 architecture has segments, which involve a table of descriptors
+/*P:600
+ * The x86 architecture has segments, which involve a table of descriptors
  * which can be used to do funky things with virtual address interpretation.
  * We originally used to use segments so the Guest couldn't alter the
  * Guest<->Host Switcher, and then we had to trim Guest segments, and restore
@@ -8,7 +9,8 @@
  *
  * In these modern times, the segment handling code consists of simple sanity
  * checks, and the worst you'll experience reading this code is butterfly-rash
- * from frolicking through its parklike serenity. :*/
+ * from frolicking through its parklike serenity.
+:*/
 #include "lg.h"
 
 /*H:600
@@ -41,10 +43,12 @@
  * begin.
  */
 
-/* There are several entries we don't let the Guest set.  The TSS entry is the
+/*
+ * There are several entries we don't let the Guest set.  The TSS entry is the
  * "Task State Segment" which controls all kinds of delicate things.  The
  * LGUEST_CS and LGUEST_DS entries are reserved for the Switcher, and the
- * the Guest can't be trusted to deal with double faults. */
+ * the Guest can't be trusted to deal with double faults.
+ */
 static bool ignored_gdt(unsigned int num)
 {
 	return (num == GDT_ENTRY_TSS
@@ -53,42 +57,52 @@ static bool ignored_gdt(unsigned int num)
 		|| num == GDT_ENTRY_DOUBLEFAULT_TSS);
 }
 
-/*H:630 Once the Guest gave us new GDT entries, we fix them up a little.  We
+/*H:630
+ * Once the Guest gave us new GDT entries, we fix them up a little.  We
  * don't care if they're invalid: the worst that can happen is a General
  * Protection Fault in the Switcher when it restores a Guest segment register
  * which tries to use that entry.  Then we kill the Guest for causing such a
- * mess: the message will be "unhandled trap 256". */
+ * mess: the message will be "unhandled trap 256".
+ */
 static void fixup_gdt_table(struct lg_cpu *cpu, unsigned start, unsigned end)
 {
 	unsigned int i;
 
 	for (i = start; i < end; i++) {
-		/* We never copy these ones to real GDT, so we don't care what
-		 * they say */
+		/*
+		 * We never copy these ones to real GDT, so we don't care what
+		 * they say
+		 */
 		if (ignored_gdt(i))
 			continue;
 
-		/* Segment descriptors contain a privilege level: the Guest is
+		/*
+		 * Segment descriptors contain a privilege level: the Guest is
 		 * sometimes careless and leaves this as 0, even though it's
-		 * running at privilege level 1.  If so, we fix it here. */
+		 * running at privilege level 1.  If so, we fix it here.
+		 */
 		if ((cpu->arch.gdt[i].b & 0x00006000) == 0)
 			cpu->arch.gdt[i].b |= (GUEST_PL << 13);
 
-		/* Each descriptor has an "accessed" bit.  If we don't set it
+		/*
+		 * Each descriptor has an "accessed" bit.  If we don't set it
 		 * now, the CPU will try to set it when the Guest first loads
 		 * that entry into a segment register.  But the GDT isn't
-		 * writable by the Guest, so bad things can happen. */
+		 * writable by the Guest, so bad things can happen.
+		 */
 		cpu->arch.gdt[i].b |= 0x00000100;
 	}
 }
 
-/*H:610 Like the IDT, we never simply use the GDT the Guest gives us.  We keep
+/*H:610
+ * Like the IDT, we never simply use the GDT the Guest gives us.  We keep
  * a GDT for each CPU, and copy across the Guest's entries each time we want to
  * run the Guest on that CPU.
  *
  * This routine is called at boot or modprobe time for each CPU to set up the
  * constant GDT entries: the ones which are the same no matter what Guest we're
- * running. */
+ * running.
+ */
 void setup_default_gdt_entries(struct lguest_ro_state *state)
 {
 	struct desc_struct *gdt = state->guest_gdt;
@@ -98,30 +112,37 @@ void setup_default_gdt_entries(struct lguest_ro_state *state)
 	gdt[GDT_ENTRY_LGUEST_CS] = FULL_EXEC_SEGMENT;
 	gdt[GDT_ENTRY_LGUEST_DS] = FULL_SEGMENT;
 
-	/* The TSS segment refers to the TSS entry for this particular CPU.
+	/*
+	 * The TSS segment refers to the TSS entry for this particular CPU.
 	 * Forgive the magic flags: the 0x8900 means the entry is Present, it's
 	 * privilege level 0 Available 386 TSS system segment, and the 0x67
-	 * means Saturn is eclipsed by Mercury in the twelfth house. */
+	 * means Saturn is eclipsed by Mercury in the twelfth house.
+	 */
 	gdt[GDT_ENTRY_TSS].a = 0x00000067 | (tss << 16);
 	gdt[GDT_ENTRY_TSS].b = 0x00008900 | (tss & 0xFF000000)
 		| ((tss >> 16) & 0x000000FF);
 }
 
-/* This routine sets up the initial Guest GDT for booting.  All entries start
- * as 0 (unusable). */
+/*
+ * This routine sets up the initial Guest GDT for booting.  All entries start
+ * as 0 (unusable).
+ */
 void setup_guest_gdt(struct lg_cpu *cpu)
 {
-	/* Start with full 0-4G segments... */
+	/*
+	 * Start with full 0-4G segments...except the Guest is allowed to use
+	 * them, so set the privilege level appropriately in the flags.
+	 */
 	cpu->arch.gdt[GDT_ENTRY_KERNEL_CS] = FULL_EXEC_SEGMENT;
 	cpu->arch.gdt[GDT_ENTRY_KERNEL_DS] = FULL_SEGMENT;
-	/* ...except the Guest is allowed to use them, so set the privilege
-	 * level appropriately in the flags. */
 	cpu->arch.gdt[GDT_ENTRY_KERNEL_CS].b |= (GUEST_PL << 13);
 	cpu->arch.gdt[GDT_ENTRY_KERNEL_DS].b |= (GUEST_PL << 13);
 }
 
-/*H:650 An optimization of copy_gdt(), for just the three "thead-local storage"
- * entries. */
+/*H:650
+ * An optimization of copy_gdt(), for just the three "thead-local storage"
+ * entries.
+ */
 void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt)
 {
 	unsigned int i;
@@ -130,26 +151,34 @@ void copy_gdt_tls(const struct lg_cpu *cpu, struct desc_struct *gdt)
 		gdt[i] = cpu->arch.gdt[i];
 }
 
-/*H:640 When the Guest is run on a different CPU, or the GDT entries have
- * changed, copy_gdt() is called to copy the Guest's GDT entries across to this
- * CPU's GDT. */
+/*H:640
+ * When the Guest is run on a different CPU, or the GDT entries have changed,
+ * copy_gdt() is called to copy the Guest's GDT entries across to this CPU's
+ * GDT.
+ */
 void copy_gdt(const struct lg_cpu *cpu, struct desc_struct *gdt)
 {
 	unsigned int i;
 
-	/* The default entries from setup_default_gdt_entries() are not
-	 * replaced.  See ignored_gdt() above. */
+	/*
+	 * The default entries from setup_default_gdt_entries() are not
+	 * replaced.  See ignored_gdt() above.
+	 */
 	for (i = 0; i < GDT_ENTRIES; i++)
 		if (!ignored_gdt(i))
 			gdt[i] = cpu->arch.gdt[i];
 }
 
-/*H:620 This is where the Guest asks us to load a new GDT entry
- * (LHCALL_LOAD_GDT_ENTRY).  We tweak the entry and copy it in. */
+/*H:620
+ * This is where the Guest asks us to load a new GDT entry
+ * (LHCALL_LOAD_GDT_ENTRY).  We tweak the entry and copy it in.
+ */
 void load_guest_gdt_entry(struct lg_cpu *cpu, u32 num, u32 lo, u32 hi)
 {
-	/* We assume the Guest has the same number of GDT entries as the
-	 * Host, otherwise we'd have to dynamically allocate the Guest GDT. */
+	/*
+	 * We assume the Guest has the same number of GDT entries as the
+	 * Host, otherwise we'd have to dynamically allocate the Guest GDT.
+	 */
 	if (num >= ARRAY_SIZE(cpu->arch.gdt))
 		kill_guest(cpu, "too many gdt entries %i", num);
 
@@ -157,15 +186,19 @@ void load_guest_gdt_entry(struct lg_cpu *cpu, u32 num, u32 lo, u32 hi)
 	cpu->arch.gdt[num].a = lo;
 	cpu->arch.gdt[num].b = hi;
 	fixup_gdt_table(cpu, num, num+1);
-	/* Mark that the GDT changed so the core knows it has to copy it again,
-	 * even if the Guest is run on the same CPU. */
+	/*
+	 * Mark that the GDT changed so the core knows it has to copy it again,
+	 * even if the Guest is run on the same CPU.
+	 */
 	cpu->changed |= CHANGED_GDT;
 }
 
-/* This is the fast-track version for just changing the three TLS entries.
+/*
+ * This is the fast-track version for just changing the three TLS entries.
  * Remember that this happens on every context switch, so it's worth
  * optimizing.  But wouldn't it be neater to have a single hypercall to cover
- * both cases? */
+ * both cases?
+ */
 void guest_load_tls(struct lg_cpu *cpu, unsigned long gtls)
 {
 	struct desc_struct *tls = &cpu->arch.gdt[GDT_ENTRY_TLS_MIN];
@@ -175,7 +208,6 @@ void guest_load_tls(struct lg_cpu *cpu, unsigned long gtls)
 	/* Note that just the TLS entries have changed. */
 	cpu->changed |= CHANGED_GDT_TLS;
 }
-/*:*/
 
 /*H:660
  * With this, we have finished the Host.