linux-kernel - [RFC PATCH v1 4/4] arm64/mm: Override ptep_get_lockless

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Message-Id: <20240215121756.2734131-5-ryan.roberts@arm.com>
Date: Thu, 15 Feb 2024 12:17:56 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: David Hildenbrand <david@...hat.com>,
	Mark Rutland <mark.rutland@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Muchun Song <muchun.song@...ux.dev>
Cc: Ryan Roberts <ryan.roberts@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH v1 4/4] arm64/mm: Override ptep_get_lockless_norecency()

Override ptep_get_lockless_norecency() when CONFIG_ARM64_CONTPTE is
enabled. Because this API doesn't require the access and dirty bits to
be accurate, for the contpte case, we can avoid reading all ptes in the
contpte block to collect those bits, in contrast to ptep_get_lockless().

Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
 arch/arm64/include/asm/pgtable.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 401087e8a43d..c0e4ccf74714 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1287,6 +1287,12 @@ static inline pte_t ptep_get_lockless(pte_t *ptep)
 	return contpte_ptep_get_lockless(ptep);
 }

+#define ptep_get_lockless_norecency ptep_get_lockless_norecency
+static inline pte_t ptep_get_lockless_norecency(pte_t *ptep)
+{
+	return __ptep_get(ptep);
+}
+
 static inline void set_pte(pte_t *ptep, pte_t pte)
 {
 	/*
--
2.25.1