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From: ira.weiny@intel.com
To: Dave Hansen <dave.hansen@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	nvdimm@lists.linux.dev, linux-mm@kvack.org
Subject: [PATCH V7 02/18] x86/fpu: Refactor arch_set_user_pkey_access()
Date: Tue,  3 Aug 2021 21:32:15 -0700	[thread overview]
Message-ID: <20210804043231.2655537-3-ira.weiny@intel.com> (raw)
In-Reply-To: <20210804043231.2655537-1-ira.weiny@intel.com>

From: Ira Weiny <ira.weiny@intel.com>

Both PKU and PKS update their register values in the same way.  They can
therefore share the update code.

Define a helper, update_pkey_val(), which will be used to support both
Protection Key User (PKU) and the new Protection Key for Supervisor
(PKS) in subsequent patches.

Use that helper in arch_set_user_pkey_access().

Co-developed-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 arch/x86/include/asm/pkeys.h |  2 ++
 arch/x86/kernel/fpu/xstate.c | 22 ++++------------------
 arch/x86/mm/pkeys.c          | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
index 5c7bcaa79623..597f19e4525b 100644
--- a/arch/x86/include/asm/pkeys.h
+++ b/arch/x86/include/asm/pkeys.h
@@ -133,4 +133,6 @@ static inline int vma_pkey(struct vm_area_struct *vma)
 	return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
 }
 
+u32 update_pkey_val(u32 pk_reg, int pkey, unsigned int flags);
+
 #endif /*_ASM_X86_PKEYS_H */
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 6af0c80ad425..4f95ab38a23c 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -915,8 +915,7 @@ EXPORT_SYMBOL_GPL(get_xsave_addr);
 int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 			      unsigned long init_val)
 {
-	u32 old_pkru, new_pkru_bits = 0;
-	int pkey_shift;
+	u32 pkru;
 
 	/*
 	 * This check implies XSAVE support.  OSPKE only gets
@@ -933,22 +932,9 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
 	if (WARN_ON_ONCE(pkey >= arch_max_pkey()))
 		return -EINVAL;
 
-	/* Set the bits needed in PKRU:  */
-	if (init_val & PKEY_DISABLE_ACCESS)
-		new_pkru_bits |= PKR_AD_BIT;
-	if (init_val & PKEY_DISABLE_WRITE)
-		new_pkru_bits |= PKR_WD_BIT;
-
-	/* Shift the bits in to the correct place in PKRU for pkey: */
-	pkey_shift = pkey * PKRU_BITS_PER_PKEY;
-	new_pkru_bits <<= pkey_shift;
-
-	/* Get old PKRU and mask off any old bits in place: */
-	old_pkru = read_pkru();
-	old_pkru &= ~((PKR_AD_BIT|PKR_WD_BIT) << pkey_shift);
-
-	/* Write old part along with new part: */
-	write_pkru(old_pkru | new_pkru_bits);
+	pkru = read_pkru();
+	pkru = update_pkey_val(pkru, pkey, init_val);
+	write_pkru(pkru);
 
 	return 0;
 }
diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
index aa7042f272fb..ca2e20b18645 100644
--- a/arch/x86/mm/pkeys.c
+++ b/arch/x86/mm/pkeys.c
@@ -190,3 +190,26 @@ static __init int setup_init_pkru(char *opt)
 	return 1;
 }
 __setup("init_pkru=", setup_init_pkru);
+
+/*
+ * Replace disable bits for @pkey with values from @flags
+ *
+ * Kernel users use the same flags as user space:
+ *     PKEY_DISABLE_ACCESS
+ *     PKEY_DISABLE_WRITE
+ */
+u32 update_pkey_val(u32 pk_reg, int pkey, unsigned int flags)
+{
+	int pkey_shift = pkey * PKR_BITS_PER_PKEY;
+
+	/*  Mask out old bit values */
+	pk_reg &= ~(((1 << PKR_BITS_PER_PKEY) - 1) << pkey_shift);
+
+	/*  Or in new values */
+	if (flags & PKEY_DISABLE_ACCESS)
+		pk_reg |= PKR_AD_BIT << pkey_shift;
+	if (flags & PKEY_DISABLE_WRITE)
+		pk_reg |= PKR_WD_BIT << pkey_shift;
+
+	return pk_reg;
+}
-- 
2.28.0.rc0.12.gb6a658bd00c9


  parent reply	other threads:[~2021-08-04  4:32 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-04  4:32 [PATCH V7 00/18] PKS/PMEM: Add Stray Write Protection ira.weiny
2021-08-04  4:32 ` [PATCH V7 01/18] x86/pkeys: Create pkeys_common.h ira.weiny
2021-08-04  4:32 ` ira.weiny [this message]
2021-08-04  4:32 ` [PATCH V7 03/18] x86/pks: Add additional PKEY helper macros ira.weiny
2021-08-04  4:32 ` [PATCH V7 04/18] x86/pks: Add PKS defines and Kconfig options ira.weiny
2021-08-04  4:32 ` [PATCH V7 05/18] x86/pks: Add PKS setup code ira.weiny
2021-08-04  4:32 ` [PATCH V7 06/18] x86/fault: Adjust WARN_ON for PKey fault ira.weiny
2021-08-04  4:32 ` [PATCH V7 07/18] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2021-08-04  4:32 ` [PATCH V7 08/18] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2021-08-04  4:32 ` [PATCH V7 09/18] x86/pks: Add PKS kernel API ira.weiny
2021-08-04  4:32 ` [PATCH V7 10/18] x86/pks: Introduce pks_abandon_protections() ira.weiny
2021-08-04  4:32 ` [PATCH V7 11/18] x86/pks: Add PKS Test code ira.weiny
2021-08-04  4:32 ` [PATCH V7 12/18] x86/pks: Add PKS fault callbacks ira.weiny
2021-08-11 21:18   ` Edgecombe, Rick P
2021-08-17  3:21     ` Ira Weiny
2021-08-04  4:32 ` [PATCH V7 13/18] memremap_pages: Add access protection via supervisor Protection Keys (PKS) ira.weiny
2021-08-04  4:32 ` [PATCH V7 14/18] memremap_pages: Add memremap.pks_fault_mode ira.weiny
2021-08-04  4:57   ` Randy Dunlap
2021-08-07 19:32     ` Ira Weiny
2021-08-11 19:01   ` Edgecombe, Rick P
2021-08-17  3:12     ` Ira Weiny
2021-08-04  4:32 ` [PATCH V7 15/18] kmap: Add stray access protection for devmap pages ira.weiny
2021-08-04  4:32 ` [PATCH V7 16/18] dax: Stray access protection for dax_direct_access() ira.weiny
2021-08-04  4:32 ` [PATCH V7 17/18] nvdimm/pmem: Enable stray access protection ira.weiny
2021-08-04  4:32 ` [PATCH V7 18/18] devdax: " ira.weiny

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