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

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Date:   Sat, 10 Sep 2016 20:30:45 +0200
From:   Nicolas Iooss <nicolas.iooss_linux@....org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Nicolas Iooss <nicolas.iooss_linux@....org>
Subject: [PATCH 1/1] x86: do not skip PKRU register if debug registers are not used

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@....org>
---
 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