[PATCH 4.8 27/37] x86/mm/pkeys: Do not skip PKRU register if debug registers are not used

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>

commit ba6d018e3d2f6a0fad58a668cadf66b2d1f80f59 upstream.

__show_regs() fails to dump the PKRU state when the debug registers are in
their default state because there is a return statement on the debug
register state.

Change the logic to report PKRU value even when debug registers are in
their default state.

Fixes:c0b17b5bd4b7 ("x86/mm/pkeys: Dump PKRU with other kernel registers")
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20160910183045.4618-1-nicolas.iooss_linux@xxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/kernel/process_64.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -110,12 +110,13 @@ void __show_regs(struct pt_regs *regs, i
 	get_debugreg(d7, 7);
 
 	/* Only print out debug registers if they are in their non-default state. */
-	if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) &&
-	    (d6 == DR6_RESERVED) && (d7 == 0x400))
-		return;
-
-	printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
-	printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
+	if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) &&
+	    (d6 == DR6_RESERVED) && (d7 == 0x400))) {
+		printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n",
+		       d0, d1, d2);
+		printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n",
+		       d3, d6, d7);
+	}
 
 	if (boot_cpu_has(X86_FEATURE_OSPKE))
 		printk(KERN_DEFAULT "PKRU: %08x\n", read_pkru());