linux-kernel - [PATCH 3.2 101/153] x86/mm: Fix {pmd,pud}_{set,clear}

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Date:   Wed, 30 May 2018 11:52:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Josh Poimboeuf" <jpoimboe@...hat.com>,
        "Boris Ostrovsky" <boris.ostrovsky@...cle.com>,
        "Andy Lutomirski" <luto@...nel.org>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Jan Beulich" <JBeulich@...e.com>,
        "Juergen Gross" <jgross@...e.com>,
        "Jan Beulich" <jbeulich@...e.com>,
        "Ingo Molnar" <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        "Brian Gerst" <brgerst@...il.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Borislav Petkov" <bp@...en8.de>,
        "Denys Vlasenko" <dvlasenk@...hat.com>
Subject: [PATCH 3.2 101/153] x86/mm: Fix {pmd,pud}_{set,clear}_flags()

3.2.102-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Beulich <JBeulich@...e.com>

commit 842cef9113c2120f74f645111ded1e020193d84c upstream.

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>
Reviewed-by: Juergen Gross <jgross@...e.com>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/5A8AF1BB02000078001A91C3@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
[bwh: Backported to 3.2:
 - There aren't any pud_{set,clear}_flags() functions
 - There's no p4d level]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -254,14 +254,14 @@ 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)
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -271,6 +271,11 @@ 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.pgd = native_make_pgd(val) };
+}
+
 static inline pmdval_t native_pmd_val(pmd_t pmd)
 {
 	return native_pgd_val(pmd.pud.pgd);