linux-kernel - [RFC PATCH v4 02/16] mm: Define __pte_leaf

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Date: Mon, 27 May 2024 15:30:00 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Jason Gunthorpe <jgg@...dia.com>,
	Peter Xu <peterx@...hat.com>,
	Oscar Salvador <osalvador@...e.de>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v4 02/16] mm: Define __pte_leaf_size() to also take a PMD entry

On powerpc 8xx, when a page is 8M size, the information is in the PMD
entry. So allow architectures to provide __pte_leaf_size() instead of
pte_leaf_size() and provide the PMD entry to that function.

When __pte_leaf_size() is not defined, define it as a pte_leaf_size()
so that architectures not interested in the PMD arguments are not
impacted.

Only define a default pte_leaf_size() when __pte_leaf_size() is not
defined to make sure nobody adds new calls to pte_leaf_size() in the
core.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
---
v3: Don't change pte_leaf_size() to not impact other architectures
---
 include/linux/pgtable.h | 3 +++
 kernel/events/core.c    | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 18019f037bae..3080e7cde3de 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1888,9 +1888,12 @@ typedef unsigned int pgtbl_mod_mask;
 #ifndef pmd_leaf_size
 #define pmd_leaf_size(x) PMD_SIZE
 #endif
+#ifndef __pte_leaf_size
 #ifndef pte_leaf_size
 #define pte_leaf_size(x) PAGE_SIZE
 #endif
+#define __pte_leaf_size(x,y) pte_leaf_size(y)
+#endif
 
 /*
  * We always define pmd_pfn for all archs as it's used in lots of generic
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f0128c5ff278..880df84ce07c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7596,7 +7596,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
 
 	pte = ptep_get_lockless(ptep);
 	if (pte_present(pte))
-		size = pte_leaf_size(pte);
+		size = __pte_leaf_size(pmd, pte);
 	pte_unmap(ptep);
 #endif /* CONFIG_HAVE_GUP_FAST */
 
-- 
2.44.0