[PATCH 15/16] sparc: mm: Support MAP_BELOW_HINT

Charlie Jenkins
2024-08-28T08:15:45Z

Add support for MAP_BELOW_HINT to mmap by restricting high_limit to addr
when the flag is enabled.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
arch/sparc/kernel/sys_sparc_64.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index d9c3b34ca744..b9ce9988551a 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -129,6 +129,8 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
info.length = len;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = min(task_size, VA_EXCLUDE_START);
+ if (flags & MAP_BELOW_HINT)
+ info.high_limit = MIN(info.high_limit, addr + len);
info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
info.align_offset = pgoff << PAGE_SHIFT;
addr = vm_unmapped_area(&info);
@@ -137,6 +139,8 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
VM_BUG_ON(addr != -ENOMEM);
info.low_limit = VA_EXCLUDE_END;
info.high_limit = task_size;
+ if (flags & MAP_BELOW_HINT)
+ info.high_limit = MIN(info.high_limit, addr + len);
addr = vm_unmapped_area(&info);
}

@@ -192,6 +196,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
info.length = len;
info.low_limit = PAGE_SIZE;
info.high_limit = mm->mmap_base;
+ if (flags & MAP_BELOW_HINT)
+ info.high_limit = MIN(info.high_limit, addr + len);
info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
info.align_offset = pgoff << PAGE_SHIFT;
addr = vm_unmapped_area(&info);
@@ -207,6 +213,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
info.flags = 0;
info.low_limit = TASK_UNMAPPED_BASE;
info.high_limit = STACK_TOP32;
+ if (flags & MAP_BELOW_HINT)
+ info.high_limit = MIN(info.high_limit, addr + len);
addr = vm_unmapped_area(&info);
}

--
2.45.0