linux-kernel - [patch V2 11/14] x86/pkru: Provide pkru_get_init

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Date:   Sun, 06 Jun 2021 01:47:53 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [patch V2 11/14] x86/pkru: Provide pkru_get_init_value()

When CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS is disabled then the following
code fails to compile:

     if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
     	u32 pkru = READ_ONCE(init_pkru_value);
	..
     }

because init_pkru_value is defined as '0' which makes READ_ONCE() upset.

Provide an accessor macro to avoid #ifdeffery all over the place.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V2: New patch
---
 arch/x86/include/asm/pgtable.h |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1366,8 +1366,10 @@ static inline pmd_t pmd_swp_clear_uffd_w
 
 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
 extern u32 init_pkru_value;
+#define pkru_get_init_value()	READ_ONCE(init_pkru_value)
 #else
 #define init_pkru_value	0
+#define pkru_get_init_value()	0
 #endif
 
 static inline bool __pkru_allows_read(u32 pkru, u16 pkey)