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Groups > linux.kernel > #1291488

[PATCH 14/32] x86, pkeys: add functions to fetch PKRU

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

This adds the raw instruction to access PKRU as well as some
accessor functions that correctly handle when the CPU does not
support the instruction.  We don't use it here, but we will use
read_pkru() in the next patch.

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

 b/arch/x86/include/asm/pgtable.h       |    8 ++++++++
 b/arch/x86/include/asm/special_insns.h |   22 ++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff -puN arch/x86/include/asm/pgtable.h~pkeys-10-kernel-pkru-instructions arch/x86/include/asm/pgtable.h
--- a/arch/x86/include/asm/pgtable.h~pkeys-10-kernel-pkru-instructions	2015-12-14 10:42:44.861895284 -0800
+++ b/arch/x86/include/asm/pgtable.h	2015-12-14 10:42:44.866895508 -0800
@@ -102,6 +102,14 @@ static inline int pte_dirty(pte_t pte)
 	return pte_flags(pte) & _PAGE_DIRTY;
 }
 
+
+static inline u32 read_pkru(void)
+{
+	if (boot_cpu_has(X86_FEATURE_OSPKE))
+		return __read_pkru();
+	return 0;
+}
+
 static inline int pte_young(pte_t pte)
 {
 	return pte_flags(pte) & _PAGE_ACCESSED;
diff -puN arch/x86/include/asm/special_insns.h~pkeys-10-kernel-pkru-instructions arch/x86/include/asm/special_insns.h
--- a/arch/x86/include/asm/special_insns.h~pkeys-10-kernel-pkru-instructions	2015-12-14 10:42:44.863895373 -0800
+++ b/arch/x86/include/asm/special_insns.h	2015-12-14 10:42:44.867895553 -0800
@@ -98,6 +98,28 @@ static inline void native_write_cr8(unsi
 }
 #endif
 
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+static inline u32 __read_pkru(void)
+{
+	u32 ecx = 0;
+	u32 edx, pkru;
+
+	/*
+	 * "rdpkru" instruction.  Places PKRU contents in to EAX,
+	 * clears EDX and requires that ecx=0.
+	 */
+	asm volatile(".byte 0x0f,0x01,0xee\n\t"
+		     : "=a" (pkru), "=d" (edx)
+		     : "c" (ecx));
+	return pkru;
+}
+#else
+static inline u32 __read_pkru(void)
+{
+	return 0;
+}
+#endif
+
 static inline void native_wbinvd(void)
 {
 	asm volatile("wbinvd": : :"memory");
_
--
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[PATCH 00/32] x86: Memory Protection Keys (v7) Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 06/32] x86, pkeys: add PKRU xsave fields and data structure(s) Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 17/32] x86, pkeys: check VMAs and PTEs for protection keys Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 14/32] x86, pkeys: add functions to fetch PKRU Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
    Re: [PATCH 14/32] x86, pkeys: add functions to fetch PKRU Thomas Gleixner <tglx@linutronix.de> - 2015-12-14 21:00 +0100
  [PATCH 19/32] x86, pkeys: optimize fault handling in access_error() Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 10/32] x86, pkeys: arch-specific protection bits Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 13/32] x86, pkeys: fill in pkey field in siginfo Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 20/32] x86, pkeys: differentiate instruction fetches Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 05/32] x86, pkeys: define new CR4 bit Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 01/32] mm, gup: introduce concept of "foreign" get_user_pages() Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 08/32] x86, pkeys: new page fault error code bit: PF_PK Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 11/32] x86, pkeys: pass VMA down in to fault signal generation code Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  [PATCH 23/32] x86, pkeys: add Kconfig prompt to existing config option Dave Hansen <dave@sr71.net> - 2015-12-14 20:20 +0100
  Re: [PATCH 00/32] x86: Memory Protection Keys (v7) "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2015-12-24 12:40 +0100

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