linux-kernel - [PATCH mm-unstable 04/17] mm: alpha: Introduce arch_mmap

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Message-ID: <20241210024119.2488608-5-kaleshsingh@google.com>
Date: Mon,  9 Dec 2024 18:41:06 -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 04/17] mm: alpha: Introduce arch_mmap_hint()

Introduce alpha 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/alpha/include/asm/pgtable.h |  1 +
 arch/alpha/kernel/osf_sys.c      | 29 ++++++++++++++++++++++++-----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
index 635f0a5f5bbd..372885a01abd 100644
--- a/arch/alpha/include/asm/pgtable.h
+++ b/arch/alpha/include/asm/pgtable.h
@@ -362,5 +362,6 @@ extern void paging_init(void);
 
 /* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
 #define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_MMAP_HINT
 
 #endif /* _ALPHA_PGTABLE_H */
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 86185021f75a..68e61dece537 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -1225,6 +1225,27 @@ arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
 	return vm_unmapped_area(&info);
 }
 
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+			     unsigned long len, unsigned long pgoff,
+			     unsigned long flags)
+{
+	unsigned long limit;
+
+	if (!addr)
+		return 0;
+
+	/* "32 bit" actually means 31 bit, since pointers sign extend.  */
+	if (current->personality & ADDR_LIMIT_32BIT)
+		limit = 0x80000000;
+	else
+		limit = TASK_SIZE;
+
+	if (limit - len < addr)
+		return 0;
+
+	return generic_mmap_hint(filp, addr, len, pgoff, flags);
+}
+
 unsigned long
 arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		       unsigned long len, unsigned long pgoff,
@@ -1254,11 +1275,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	   merely specific addresses, but regions of memory -- perhaps
 	   this feature should be incorporated into all ports?  */
 
-	if (addr) {
-		addr = arch_get_unmapped_area_1 (PAGE_ALIGN(addr), len, limit);
-		if (addr != (unsigned long) -ENOMEM)
-			return addr;
-	}
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return hint;
 
 	/* Next, try allocating at TASK_UNMAPPED_BASE.  */
 	addr = arch_get_unmapped_area_1 (PAGE_ALIGN(TASK_UNMAPPED_BASE),
-- 
2.47.0.338.g60cca15819-goog