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From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org, willy@infradead.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	aarcange@redhat.com, kirill.shutemov@linux.intel.com,
	jroedel@suse.de, peterz@infradead.org
Subject: [RFC][PATCH 7/9] x86/mm/pae: Dont (ab)use atomic64
Date: Mon, 30 Nov 2020 12:27:12 +0100
Message-ID: <20201130113603.205586001@infradead.org> (raw)
In-Reply-To: <20201130112705.900705277@infradead.org>

PAE implies CX8, write readable code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/include/asm/pgtable-3level.h |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -2,8 +2,6 @@
 #ifndef _ASM_X86_PGTABLE_3LEVEL_H
 #define _ASM_X86_PGTABLE_3LEVEL_H
 
-#include <asm/atomic64_32.h>
-
 /*
  * Intel Physical Address Extension (PAE) Mode - three-level page
  * tables on PPro+ CPUs.
@@ -96,11 +94,13 @@ static inline void pud_clear(pud_t *pudp
 #ifdef CONFIG_SMP
 static inline pte_t native_ptep_get_and_clear(pte_t *ptep)
 {
-	pte_t res;
+	pte_t old;
 
-	res.pte = (pteval_t)arch_atomic64_xchg((atomic64_t *)ptep, 0);
+	do {
+		old = *ptep;
+	} while (cmpxchg64(&ptep->pte, old.pte, 0ULL) != old.pte);
 
-	return res;
+	return old;
 }
 #else
 #define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)




  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-30 11:27 [RFC][PATCH 0/9] Clean up i386-PAE Peter Zijlstra
2020-11-30 11:27 ` [RFC][PATCH 1/9] mm: Update ptep_get_lockless()s comment Peter Zijlstra
2020-11-30 11:27 ` [RFC][PATCH 2/9] x86/mm/pae: Make pmd_t similar to pte_t Peter Zijlstra
2020-11-30 11:27 ` [RFC][PATCH 3/9] sh/mm: " Peter Zijlstra
2020-11-30 14:10   ` David Laight
2020-11-30 14:21     ` Peter Zijlstra
2020-11-30 11:27 ` [RFC][PATCH 4/9] mm: Fix pmd_read_atomic() Peter Zijlstra
2020-11-30 11:27 ` [RFC][PATCH 5/9] mm: Rename pmd_read_atomic() Peter Zijlstra
2020-11-30 15:31   ` Jason Gunthorpe
2020-12-01  8:57     ` Peter Zijlstra
2020-11-30 11:27 ` [RFC][PATCH 6/9] mm/gup: Fix the lockless walkers Peter Zijlstra
2020-11-30 11:27 ` Peter Zijlstra [this message]
2020-11-30 11:27 ` [RFC][PATCH 8/9] x86/mm/pae: Use WRITE_ONCE() Peter Zijlstra
2020-11-30 11:27 ` [RFC][PATCH 9/9] x86/mm/pae: Be consistent with pXXp_get_and_clear() Peter Zijlstra

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