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Commit a5eff725 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Borislav Petkov
Browse files

x86/pkeys: Add PKRU value to init_fpstate 



The task's initial PKRU value is set partly for fpu__clear()/
copy_init_pkru_to_fpregs(). It is not part of init_fpstate.xsave and
instead it is set explicitly.

If the user removes the PKRU state from XSAVE in the signal handler then
__fpu__restore_sig() will restore the missing bits from `init_fpstate'
and initialize the PKRU value to 0.

Add the `init_pkru_value' to `init_fpstate' so it is set to the init
value in such a case.

In theory copy_init_pkru_to_fpregs() could be removed because restoring
the PKRU at return-to-userland should be enough.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarDave Hansen <dave.hansen@intel.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Chang S. Bae" <chang.seok.bae@intel.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190403164156.19645-28-bigeasy@linutronix.de
parent 06b251df

arch/x86/kernel/cpu/common.c

+5 −0
Original line number Diff line number Diff line
@@ -372,6 +372,8 @@ static bool pku_disabled; 


static __always_inline void setup_pku(struct cpuinfo_x86 *c)

{

	struct pkru_state *pk;



	/* check the boot processor, plus compile options for PKU: */

	if (!cpu_feature_enabled(X86_FEATURE_PKU))

		return;
@@ -382,6 +384,9 @@ static __always_inline void setup_pku(struct cpuinfo_x86 *c) 
		return;



	cr4_set_bits(X86_CR4_PKE);

	pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU);

	if (pk)

		pk->pkru = init_pkru_value;

	/*

	 * Seting X86_CR4_PKE will cause the X86_FEATURE_OSPKE

	 * cpuid bit to be set.  We need to ensure that we

arch/x86/mm/pkeys.c

+6 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 


#include <asm/cpufeature.h>             /* boot_cpu_has, ...            */

#include <asm/mmu_context.h>            /* vma_pkey()                   */

#include <asm/fpu/internal.h>		/* init_fpstate			*/



int __execute_only_pkey(struct mm_struct *mm)

{
@@ -161,6 +162,7 @@ static ssize_t init_pkru_read_file(struct file *file, char __user *user_buf, 
static ssize_t init_pkru_write_file(struct file *file,

		 const char __user *user_buf, size_t count, loff_t *ppos)

{

	struct pkru_state *pk;

	char buf[32];

	ssize_t len;

	u32 new_init_pkru;
@@ -183,6 +185,10 @@ static ssize_t init_pkru_write_file(struct file *file, 
		return -EINVAL;



	WRITE_ONCE(init_pkru_value, new_init_pkru);

	pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU);

	if (!pk)

		return -EINVAL;

	pk->pkru = new_init_pkru;

	return count;

}