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/mips/mm/mmap.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index 7e11d7b58761..1595fda284cd 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -79,6 +79,13 @@ 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(info.high_limit, + (addr + len) - (STACK_TOP - mm->mmap_base)); addr = vm_unmapped_area(&info);
if (!(addr & ~PAGE_MASK)) @@ -94,6 +101,8 @@ 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); }