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@xxxxxxxxxxxx> --- arch/parisc/include/uapi/asm/mman.h | 1 + arch/parisc/kernel/sys_parisc.c | 9 +++++++++ tools/arch/parisc/include/uapi/asm/mman.h | 1 + 3 files changed, 11 insertions(+) diff --git a/arch/parisc/include/uapi/asm/mman.h b/arch/parisc/include/uapi/asm/mman.h index 68c44f99bc93..44925ef8ac44 100644 --- a/arch/parisc/include/uapi/asm/mman.h +++ b/arch/parisc/include/uapi/asm/mman.h @@ -26,6 +26,7 @@ #define MAP_HUGETLB 0x80000 /* create a huge page mapping */ #define MAP_FIXED_NOREPLACE 0x100000 /* MAP_FIXED which doesn't unmap underlying mapping */ #define MAP_UNINITIALIZED 0 /* uninitialized anonymous mmap */ +#define MAP_BELOW_HINT 0x200000 /* give out address that is below (inclusive) hint address */ #define MS_SYNC 1 /* synchronous memory sync */ #define MS_ASYNC 2 /* sync memory asynchronously */ diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c index f7722451276e..feccb60cf746 100644 --- a/arch/parisc/kernel/sys_parisc.c +++ b/arch/parisc/kernel/sys_parisc.c @@ -148,6 +148,13 @@ 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)) return addr; @@ -163,6 +170,8 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp, info.low_limit = mm->mmap_base; info.high_limit = mmap_upper_limit(NULL); + if (flags & MAP_BELOW_HINT) + info.high_limit = MIN(info.high_limit, addr + len); return vm_unmapped_area(&info); } diff --git a/tools/arch/parisc/include/uapi/asm/mman.h b/tools/arch/parisc/include/uapi/asm/mman.h index 4cc88a642e10..297acc0f7b2a 100644 --- a/tools/arch/parisc/include/uapi/asm/mman.h +++ b/tools/arch/parisc/include/uapi/asm/mman.h @@ -40,4 +40,5 @@ /* MAP_32BIT is undefined on parisc, fix it for perf */ #define MAP_32BIT 0 #define MAP_UNINITIALIZED 0 +#define MAP_BELOW_MAP 0x200000 #endif -- 2.45.0
