[PATCH 1/1] x86: do not skip PKRU register if debug registers are not used

From: Nicolas Iooss
Date: Sat Sep 10 2016 - 14:31:48 EST


When commit c0b17b5bd4b7 ("x86/mm/pkeys: Dump PKRU with other kernel
registers") made __show_regs() show PKRU, this register was only printed
if the debug registers were not in their default state (there is an
if(...) return; before).

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

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
---
arch/x86/kernel/process_64.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 63236d8f84bf..a21068e49dac 100644
--- 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, int all)
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());
--
2.9.3