linux-kernel - [PATCH 24/37] x86, pkeys: dump PKRU with other kernel registers

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Message-Id: <20151117033544.A730AE35@viggo.jf.intel.com>
Date:	Mon, 16 Nov 2015 19:35:44 -0800
From:	Dave Hansen <dave@...1.net>
To:	linux-kernel@...r.kernel.org
Cc:	x86@...nel.org, Dave Hansen <dave@...1.net>,
	dave.hansen@...ux.intel.com
Subject: [PATCH 24/37] x86, pkeys: dump PKRU with other kernel registers


From: Dave Hansen <dave.hansen@...ux.intel.com>

I'm a bit ambivalent about whether this is needed or not.

Protection Keys never affect kernel mappings.  But, they can
affect whether the kernel will fault when it touches a user
mapping.  But, the kernel doesn't touch user mappings without
some careful choreography and these accesses don't generally
result in oopses.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
---

 b/arch/x86/kernel/process_64.c |    2 ++
 1 file changed, 2 insertions(+)

diff -puN arch/x86/kernel/process_64.c~pkeys-30-kernel-error-dumps arch/x86/kernel/process_64.c
--- a/arch/x86/kernel/process_64.c~pkeys-30-kernel-error-dumps	2015-11-16 12:35:46.445675988 -0800
+++ b/arch/x86/kernel/process_64.c	2015-11-16 12:35:46.449676170 -0800
@@ -116,6 +116,8 @@ void __show_regs(struct pt_regs *regs, i
 	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());
 }
 
 void release_thread(struct task_struct *dead_task)
_
--
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