On 20.06.19 07:03, Alexandre Ghiti wrote:
> Bottom-up mmap scheme is used twice:
>
> - for legacy mode, in which mmap_legacy_base and mmap_base are equal.
>
> - in case of mmap failure in top-down mode, where there is no need to go
> through the whole address space again for the bottom-up fallback: the goal
> of this fallback is to find, as a last resort, space between the top-down
> mmap base and the stack, which is the only place not covered by the
> top-down mmap.
>
> Then this commit removes the usage of mmap_legacy_base field from parisc
> code.
>
> Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
Boot-tested on parisc and seems to work nicely, thus:
Acked-by: Helge Deller <deller@xxxxxx>
Helge
> ---
> arch/parisc/kernel/sys_parisc.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
> index 5d458a44b09c..e987f3a8eb0b 100644
> --- a/arch/parisc/kernel/sys_parisc.c
> +++ b/arch/parisc/kernel/sys_parisc.c
> @@ -119,7 +119,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
>
> info.flags = 0;
> info.length = len;
> - info.low_limit = mm->mmap_legacy_base;
> + info.low_limit = mm->mmap_base;
> info.high_limit = mmap_upper_limit(NULL);
> info.align_mask = last_mmap ? (PAGE_MASK & (SHM_COLOUR - 1)) : 0;
> info.align_offset = shared_align_offset(last_mmap, pgoff);
> @@ -240,13 +240,11 @@ static unsigned long mmap_legacy_base(void)
> */
> void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
> {
> - mm->mmap_legacy_base = mmap_legacy_base();
> - mm->mmap_base = mmap_upper_limit(rlim_stack);
> -
> if (mmap_is_legacy()) {
> - mm->mmap_base = mm->mmap_legacy_base;
> + mm->mmap_base = mmap_legacy_base();
> mm->get_unmapped_area = arch_get_unmapped_area;
> } else {
> + mm->mmap_base = mmap_upper_limit(rlim_stack);
> mm->get_unmapped_area = arch_get_unmapped_area_topdown;
> }
> }
>
