linux-kernel - [PATCH mm-unstable 03/17] mm: arm: Introduce arch_mmap

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Message-ID: <20241210024119.2488608-4-kaleshsingh@google.com>
Date: Mon,  9 Dec 2024 18:41:05 -0800
From: Kalesh Singh <kaleshsingh@...gle.com>
To: akpm@...ux-foundation.org, vbabka@...e.cz, yang@...amperecomputing.com, 
	riel@...riel.com, david@...hat.com
Cc: linux@...linux.org.uk, tsbogend@...ha.franken.de, 
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	kernel-team@...roid.com, android-mm@...gle.com, 
	Kalesh Singh <kaleshsingh@...gle.com>
Subject: [PATCH mm-unstable 03/17] mm: arm: Introduce arch_mmap_hint()

Introduce arm arch_mmap_hint() and define HAVE_ARCH_MMAP_HINT.
This is a preparatory patch, no functional change is introduced.

Signed-off-by: Kalesh Singh <kaleshsingh@...gle.com>
---
 arch/arm/include/asm/pgtable.h |  1 +
 arch/arm/mm/mmap.c             | 54 +++++++++++++++++++---------------
 2 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index be91e376df79..1433b3ff4caa 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -330,6 +330,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
  */
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+#define HAVE_ARCH_MMAP_HINT
 
 #endif /* !__ASSEMBLY__ */
 
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 3dbb383c26d5..c415410eb64a 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -17,6 +17,31 @@
 	((((addr)+SHMLBA-1)&~(SHMLBA-1)) +	\
 	 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
 
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+			     unsigned long len, unsigned long pgoff,
+			     unsigned long flags)
+{
+	int aliasing = cache_is_vipt_aliasing();
+	int do_align = 0;
+
+	if (!addr)
+		return 0;
+
+	/*
+	 * We only need to do colour alignment if either the I or D
+	 * caches alias.
+	 */
+	if (aliasing)
+		do_align = filp || (flags & MAP_SHARED);
+
+	if (do_align)
+		addr = COLOUR_ALIGN(addr, pgoff);
+	else
+		addr = PAGE_ALIGN(addr);
+
+	return generic_mmap_hint(filp, addr, len, pgoff, flags);
+}
+
 /*
  * We need to ensure that shared mappings are correctly aligned to
  * avoid aliasing issues with VIPT caches.  We need to ensure that
@@ -32,7 +57,6 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long flags, vm_flags_t vm_flags)
 {
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
 	int do_align = 0;
 	int aliasing = cache_is_vipt_aliasing();
 	struct vm_unmapped_area_info info = {};
@@ -57,17 +81,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
-	if (addr) {
-		if (do_align)
-			addr = COLOUR_ALIGN(addr, pgoff);
-		else
-			addr = PAGE_ALIGN(addr);
-
-		vma = find_vma(mm, addr);
-		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vm_start_gap(vma)))
-			return addr;
-	}
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
 
 	info.length = len;
 	info.low_limit = mm->mmap_base;
@@ -82,7 +98,6 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		        const unsigned long len, const unsigned long pgoff,
 		        const unsigned long flags, vm_flags_t vm_flags)
 {
-	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
 	int do_align = 0;
@@ -108,16 +123,9 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	}
 
 	/* requesting a specific address */
-	if (addr) {
-		if (do_align)
-			addr = COLOUR_ALIGN(addr, pgoff);
-		else
-			addr = PAGE_ALIGN(addr);
-		vma = find_vma(mm, addr);
-		if (TASK_SIZE - len >= addr &&
-				(!vma || addr + len <= vm_start_gap(vma)))
-			return addr;
-	}
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
-- 
2.47.0.338.g60cca15819-goog