linux-kernel - [PATCH mm-unstable v2 12/16] mm: sparc32: Introduce arch_mmap

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Message-ID: <20241211232754.1583023-13-kaleshsingh@google.com>
Date: Wed, 11 Dec 2024 15:27:50 -0800
From: Kalesh Singh <kaleshsingh@...gle.com>
To: akpm@...ux-foundation.org, vbabka@...e.cz, yang@...amperecomputing.com, 
	riel@...riel.com, david@...hat.com, minchan@...nel.org, jyescas@...gle.com
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	Kalesh Singh <kaleshsingh@...gle.com>
Subject: [PATCH mm-unstable v2 12/16] mm: sparc32: Introduce arch_mmap_hint()

Introduce sparc32 arch_mmap_hint() and define HAVE_ARCH_MMAP_HINT.

If a sufficiently sized hole doesn't exist at the hint address,
fallback to searching the entire valid VA space instead of only
the VA space above the hint address.

Signed-off-by: Kalesh Singh <kaleshsingh@...gle.com>
---

Changes in v2:
  - MAP_FIXED case is also handled in arch_mmap_hint() since this is just a
    special case of the hint addr being "enforced", per Yang Shi.
  - Consolidate error handling in arch_mmap_hint().

 arch/sparc/include/asm/pgtable_32.h |  1 +
 arch/sparc/kernel/sys_sparc_32.c    | 33 +++++++++++++++++++----------
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h
index 62bcafe38b1f..95084c4d0b01 100644
--- a/arch/sparc/include/asm/pgtable_32.h
+++ b/arch/sparc/include/asm/pgtable_32.h
@@ -437,6 +437,7 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 
 /* We provide our own get_unmapped_area to cope with VA holes for userland */
 #define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_MMAP_HINT
 
 #define pmd_pgtable(pmd)	((pgtable_t)__pmd_page(pmd))
 
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index fb31bc0c5b48..0cc717755417 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -40,13 +40,17 @@ SYSCALL_DEFINE0(getpagesize)
 	return PAGE_SIZE; /* Possibly older binaries want 8192 on sun4's? */
 }
 
-unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags)
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+			     unsigned long len, unsigned long pgoff,
+			     unsigned long flags)
 {
-	struct vm_unmapped_area_info info = {};
-	bool file_hugepage = false;
+	bool file_hugepage;
+
+	/* See asm-sparc/uaccess.h */
+	if (len > TASK_SIZE - PAGE_SIZE)
+		return -ENOMEM;
 
-	if (filp && is_file_hugepages(filp))
-		file_hugepage = true;
+	file_hugepage = filp && is_file_hugepages(filp);
 
 	if (flags & MAP_FIXED) {
 		/* We do not accept a shared mapping if it would violate
@@ -58,14 +62,21 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 		return addr;
 	}
 
-	/* See asm-sparc/uaccess.h */
-	if (len > TASK_SIZE - PAGE_SIZE)
-		return -ENOMEM;
-	if (!addr)
-		addr = TASK_UNMAPPED_BASE;
+	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, unsigned long flags, vm_flags_t vm_flags)
+{
+	struct vm_unmapped_area_info info = {};
+	bool file_hugepage = false;
+
+	addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+	if (addr)
+		return addr;
 
 	info.length = len;
-	info.low_limit = addr;
+	info.low_limit = TASK_UNMAPPED_BASE;
 	info.high_limit = TASK_SIZE;
 	if (!file_hugepage) {
 		info.align_mask = (flags & MAP_SHARED) ?
-- 
2.47.0.338.g60cca15819-goog