linux-kernel - [PATCH] ARC: mm: Make virt_to

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Message-Id: <20230914-virt-to-phys-arc-v1-1-9dc0008dc0b0@linaro.org>
Date:   Thu, 14 Sep 2023 08:31:35 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Vineet Gupta <vgupta@...nel.org>
Cc:     linux-snps-arc@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>
Subject: [PATCH] ARC: mm: Make virt_to_pfn() a static inline

Making virt_to_pfn() a static inline taking a strongly typed
(const void *) makes the contract of a passing a pointer of that
type to the function explicit and exposes any misuse of the
macro virt_to_pfn() acting polymorphic and accepting many types
such as (void *), (unitptr_t) or (unsigned long) as arguments
without warnings.

In order to do this we move the virt_to_phys() and
below the definition of the __pa() and __va() macros so it
compiles. The macro version was also able to do recursive
symbol resolution.

Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
---
 arch/arc/include/asm/page.h           | 21 ++++++++++++---------
 arch/arc/include/asm/pgtable-levels.h |  2 +-
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h
index 02b53ad811fb..def0dfb95b43 100644
--- a/arch/arc/include/asm/page.h
+++ b/arch/arc/include/asm/page.h
@@ -84,15 +84,6 @@ typedef struct {
 
 typedef struct page *pgtable_t;
 
-/*
- * Use virt_to_pfn with caution:
- * If used in pte or paddr related macros, it could cause truncation
- * in PAE40 builds
- * As a rule of thumb, only use it in helpers starting with virt_
- * You have been warned !
- */
-#define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
-
 /*
  * When HIGHMEM is enabled we have holes in the memory map so we need
  * pfn_valid() that takes into account the actual extents of the physical
@@ -122,6 +113,18 @@ extern int pfn_valid(unsigned long pfn);
 #define __pa(vaddr)  		((unsigned long)(vaddr))
 #define __va(paddr)  		((void *)((unsigned long)(paddr)))
 
+/*
+ * Use virt_to_pfn with caution:
+ * If used in pte or paddr related macros, it could cause truncation
+ * in PAE40 builds
+ * As a rule of thumb, only use it in helpers starting with virt_
+ * You have been warned !
+ */
+static inline unsigned long virt_to_pfn(const void *kaddr)
+{
+	return __pa(kaddr) >> PAGE_SHIFT;
+}
+
 #define virt_to_page(kaddr)	pfn_to_page(virt_to_pfn(kaddr))
 #define virt_addr_valid(kaddr)  pfn_valid(virt_to_pfn(kaddr))
 
diff --git a/arch/arc/include/asm/pgtable-levels.h b/arch/arc/include/asm/pgtable-levels.h
index fc417c75c24d..86e148226463 100644
--- a/arch/arc/include/asm/pgtable-levels.h
+++ b/arch/arc/include/asm/pgtable-levels.h
@@ -159,7 +159,7 @@
 #define pmd_clear(xp)		do { pmd_val(*(xp)) = 0; } while (0)
 #define pmd_page_vaddr(pmd)	(pmd_val(pmd) & PAGE_MASK)
 #define pmd_pfn(pmd)		((pmd_val(pmd) & PAGE_MASK) >> PAGE_SHIFT)
-#define pmd_page(pmd)		virt_to_page(pmd_page_vaddr(pmd))
+#define pmd_page(pmd)		virt_to_page((void *)pmd_page_vaddr(pmd))
 #define set_pmd(pmdp, pmd)	(*(pmdp) = pmd)
 #define pmd_pgtable(pmd)	((pgtable_t) pmd_page(pmd))
 

---
base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d
change-id: 20230913-virt-to-phys-arc-b0b613c689b0

Best regards,
-- 
Linus Walleij <linus.walleij@...aro.org>