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/loongarch/mm/mmap.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/arch/loongarch/mm/mmap.c b/arch/loongarch/mm/mmap.c index 889030985135..66a5badf849b 100644 --- a/arch/loongarch/mm/mmap.c +++ b/arch/loongarch/mm/mmap.c @@ -70,6 +70,13 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp, info.flags = VM_UNMAPPED_AREA_TOPDOWN; info.low_limit = PAGE_SIZE; info.high_limit = mm->mmap_base; + if (flags & MAP_BELOW_HINT) + /* + * Subtract (STACK_TOP - mm->mmap_base) to get random + * offset defined in mmap_base() in mm/util.c + */ + info.high_limit = MIN(mm->mmap_base, + (addr + len) - (STACK_TOP - mm->mmap_base)) addr = vm_unmapped_area(&info);
if (!(addr & ~PAGE_MASK)) @@ -84,7 +91,11 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp, }
info.low_limit = mm->mmap_base; + info.high_limit = TASK_SIZE; + if (flags & MAP_BELOW_HINT) + info.high_limit = MIN(info.high_limit, addr + len); + return vm_unmapped_area(&info); }