Introduce x86 arch_mmap_hint() and define HAVE_ARCH_MMAP_HINT.
This is a preparatory patch, no functional change is introduced.
Fallback to generic_mmap_hint() if an architecture doesn't
provide HAVE_ARCH_MMAP_HINT.
Signed-off-by: Kalesh Singh <kaleshsi...@google.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 most of the error handling in arch_mmap_hint().
- Fallback to generic_mmap_hint() if arch_mmap_hint() is not provided.
arch/x86/include/asm/pgtable_64.h | 1 +
arch/x86/kernel/sys_x86_64.c | 64 +++++++++++++++----------------
include/linux/sched/mm.h | 5 +++
mm/mmap.c | 9 +++++
4 files changed, 45 insertions(+), 34 deletions(-)
diff --git a/arch/x86/include/asm/pgtable_64.h
b/arch/x86/include/asm/pgtable_64.h
index d1426b64c1b9..4472fd0040c3 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -245,6 +245,7 @@ extern void cleanup_highmap(void);
#define HAVE_ARCH_UNMAPPED_AREA
#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+#define HAVE_ARCH_MMAP_HINT
#define PAGE_AGP PAGE_KERNEL_NOCACHE
#define HAVE_PAGE_AGP 1
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 776ae6fa7f2d..008c6d19bd02 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -123,31 +123,44 @@ static inline unsigned long
stack_guard_placement(vm_flags_t vm_flags)
return 0;
}
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ unsigned long begin, end;
+
+ find_start_end(addr, flags, &begin, &end);
+
+ /* requested length too big for entire address space */
+ if (len > end || len > TASK_SIZE)
+ return -ENOMEM;
+
+ /* No address checking. See comment at mmap_address_hint_valid() */
+ if (flags & MAP_FIXED)
+ return addr;
+
+ addr = PAGE_ALIGN(addr);
+
+ /* Fallback to VA space search? */
+ if (!mmap_address_hint_valid(addr, len))
+ 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, unsigned long flags, vm_flags_t
vm_flags)
{
- struct mm_struct *mm = current->mm;
- struct vm_area_struct *vma;
struct vm_unmapped_area_info info = {};
unsigned long begin, end;
- if (flags & MAP_FIXED)
+ addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+ if (addr)
return addr;
find_start_end(addr, flags, &begin, &end);
- if (len > end)
- return -ENOMEM;
-
- if (addr) {
- addr = PAGE_ALIGN(addr);
- vma = find_vma(mm, addr);
- if (end - len >= addr &&
- (!vma || addr + len <= vm_start_gap(vma)))
- return addr;
- }
-
info.length = len;
info.low_limit = begin;
info.high_limit = end;
@@ -168,34 +181,17 @@ arch_get_unmapped_area_topdown(struct file *filp,
unsigned long addr0,
unsigned long len, unsigned long pgoff,
unsigned long flags, vm_flags_t vm_flags)
{
- struct vm_area_struct *vma;
- struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
struct vm_unmapped_area_info info = {};
- /* requested length too big for entire address space */
- if (len > TASK_SIZE)
- return -ENOMEM;
-
- /* No address checking. See comment at mmap_address_hint_valid() */
- if (flags & MAP_FIXED)
- return addr;
-
/* for MAP_32BIT mappings we force the legacy mmap base */
if (!in_32bit_syscall() && (flags & MAP_32BIT))
goto bottomup;
/* requesting a specific address */
- if (addr) {
- addr &= PAGE_MASK;
- if (!mmap_address_hint_valid(addr, len))
- goto get_unmapped_area;
-
- vma = find_vma(mm, addr);
- if (!vma || addr + len <= vm_start_gap(vma))
- return addr;
- }
-get_unmapped_area:
+ addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
+ if (addr)
+ return addr;
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index edeec19d1708..f4143703f234 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -205,6 +205,11 @@ unsigned long generic_mmap_hint(struct file *filp,
unsigned long addr,
unsigned long len, unsigned long pgoff,
unsigned long flags);
+/* See generic_mmap_hint() */
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags);
+
unsigned long
generic_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff,
diff --git a/mm/mmap.c b/mm/mmap.c
index 382b4eac5406..76dd6acdf051 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -705,6 +705,15 @@ arch_get_unmapped_area(struct file *filp, unsigned long
addr,
}
#endif
+#ifndef HAVE_ARCH_MMAP_HINT
+unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ return generic_mmap_hint(filp, addr, len, pgoff, flags);
+}
+#endif
+
/*
* This mmap-allocator allocates new areas top-down from below the
* stack's low limit (the base):
--
2.47.0.338.g60cca15819-goog
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