linux-kernel - [PATCH] x86: fix {pmd,pud}_{set,clear}

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Date:   Mon, 19 Feb 2018 07:48:11 -0700
From:   "Jan Beulich" <JBeulich@...e.com>
To:     <mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc:     "Boris Ostrovsky" <boris.ostrovsky@...cle.com>,
        "Juergen Gross" <jgross@...e.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86: fix {pmd,pud}_{set,clear}_flags()

Just like pte_{set,clear}_flags() their PMD and PUD counterparts should
not do any address translation. This was outright wrong under Xen
(causing a dead boot with no useful output on "suitable" systems), and
produced needlessly more complicated code (even if just slightly) when
paravirt was enabled.

Signed-off-by: Jan Beulich <jbeulich@...e.com>
Cc: stable@...r.kernel.org 
---
 arch/x86/include/asm/pgtable.h       |    8 ++++----
 arch/x86/include/asm/pgtable_types.h |   10 ++++++++++
 2 files changed, 14 insertions(+), 4 deletions(-)

--- 4.16-rc2/arch/x86/include/asm/pgtable.h
+++ 4.16-rc2-x86-pXd_set_flags-no-xlat/arch/x86/include/asm/pgtable.h
@@ -350,14 +350,14 @@ static inline pmd_t pmd_set_flags(pmd_t
 {
 	pmdval_t v = native_pmd_val(pmd);
 
-	return __pmd(v | set);
+	return native_make_pmd(v | set);
 }
 
 static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)
 {
 	pmdval_t v = native_pmd_val(pmd);
 
-	return __pmd(v & ~clear);
+	return native_make_pmd(v & ~clear);
 }
 
 static inline pmd_t pmd_mkold(pmd_t pmd)
@@ -409,14 +409,14 @@ static inline pud_t pud_set_flags(pud_t
 {
 	pudval_t v = native_pud_val(pud);
 
-	return __pud(v | set);
+	return native_make_pud(v | set);
 }
 
 static inline pud_t pud_clear_flags(pud_t pud, pudval_t clear)
 {
 	pudval_t v = native_pud_val(pud);
 
-	return __pud(v & ~clear);
+	return native_make_pud(v & ~clear);
 }
 
 static inline pud_t pud_mkold(pud_t pud)
--- 4.16-rc2/arch/x86/include/asm/pgtable_types.h
+++ 4.16-rc2-x86-pXd_set_flags-no-xlat/arch/x86/include/asm/pgtable_types.h
@@ -323,6 +323,11 @@ static inline pudval_t native_pud_val(pu
 #else
 #include <asm-generic/pgtable-nopud.h>
 
+static inline pud_t native_make_pud(pudval_t val)
+{
+	return (pud_t) { .p4d.pgd = native_make_pgd(val) };
+}
+
 static inline pudval_t native_pud_val(pud_t pud)
 {
 	return native_pgd_val(pud.p4d.pgd);
@@ -344,6 +349,11 @@ static inline pmdval_t native_pmd_val(pm
 #else
 #include <asm-generic/pgtable-nopmd.h>
 
+static inline pmd_t native_make_pmd(pmdval_t val)
+{
+	return (pmd_t) { .pud.p4d.pgd = native_make_pgd(val) };
+}
+
 static inline pmdval_t native_pmd_val(pmd_t pmd)
 {
 	return native_pgd_val(pmd.pud.p4d.pgd);