* Kalesh Singh <kaleshsi...@google.com> [241211 18:28]:
> Introduce arc arch_mmap_hint() and define HAVE_ARCH_MMAP_HINT.
> This is a preparatory patch, no functional change is introduced.
You have changed the order of the map fixed check and the len check.
I *think* what you have done is correct, but your comment is certainly
wrong.
Your generic call also has more checks than exist in this version of the
code - which, again is probably good, but a functional change surely?
>
> Signed-off-by: Kalesh Singh <kaleshsi...@google.com>
> ---
>
> Changes in v2:
> - MAP_FIXED case is also handled in arch_mmap_hint() since this is just a
> special case of the hint addr being "enforced", per Yang Shi.
> - Consolidate error handling in arch_mmap_hint().
>
> arch/arc/include/asm/pgtable.h | 1 +
> arch/arc/mm/mmap.c | 43 +++++++++++++++++-----------------
> 2 files changed, 23 insertions(+), 21 deletions(-)
>
> diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h
> index 4cf45a99fd79..af3210ea4888 100644
> --- a/arch/arc/include/asm/pgtable.h
> +++ b/arch/arc/include/asm/pgtable.h
> @@ -28,6 +28,7 @@ extern pgd_t swapper_pg_dir[] __aligned(PAGE_SIZE);
>
> /* to cope with aliasing VIPT cache */
> #define HAVE_ARCH_UNMAPPED_AREA
> +#define HAVE_ARCH_MMAP_HINT
>
> #endif /* __ASSEMBLY__ */
>
> diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c
> index 2185afe8d59f..df01d4d9964b 100644
> --- a/arch/arc/mm/mmap.c
> +++ b/arch/arc/mm/mmap.c
> @@ -14,6 +14,26 @@
>
> #include <asm/cacheflush.h>
>
> +unsigned long arch_mmap_hint(struct file *filp, unsigned long addr,
> + unsigned long len, unsigned long pgoff,
> + unsigned long flags)
> +{
> + if (len > TASK_SIZE)
> + return -ENOMEM;
> +
> + /*
> + * We enforce the MAP_FIXED case.
> + */
> + if (flags & MAP_FIXED) {
> + if (flags & MAP_SHARED &&
> + (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
> + return -EINVAL;
> + return addr;
> + }
> +
> + return generic_mmap_hint(filp, addr, len, pgoff, flags);
> +}
> +
> /*
> * Ensure that shared mappings are correctly aligned to
> * avoid aliasing issues with VIPT caches.
> @@ -27,30 +47,11 @@ arch_get_unmapped_area(struct file *filp, unsigned long
> addr,
> unsigned long flags, vm_flags_t vm_flags)
> {
> struct mm_struct *mm = current->mm;
> - struct vm_area_struct *vma;
> struct vm_unmapped_area_info info = {};
>
> - /*
> - * We enforce the MAP_FIXED case.
> - */
> - if (flags & MAP_FIXED) {
> - if (flags & MAP_SHARED &&
> - (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
> - return -EINVAL;
> + addr = arch_mmap_hint(filp, addr, len, pgoff, flags);
> + if (addr)
> return addr;
> - }
> -
> - if (len > TASK_SIZE)
> - return -ENOMEM;
> -
> - if (addr) {
> - addr = PAGE_ALIGN(addr);
> -
> - vma = find_vma(mm, addr);
> - if (TASK_SIZE - len >= addr &&
> - (!vma || addr + len <= vm_start_gap(vma)))
> - return addr;
> - }
>
> info.length = len;
> info.low_limit = mm->mmap_base;
> --
> 2.47.0.338.g60cca15819-goog
>
>
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