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Date: Fri, 22 Jun 2012 23:27:56 +0100
From: Russell King - ARM Linux <linux@....linux.org.uk>
To: Rik van Riel <riel@...riel.com>
Cc: linux-mm@...ck.org, akpm@...ux-foundation.org, aarcange@...hat.com,
peterz@...radead.org, minchan@...il.com, kosaki.motohiro@...il.com,
andi@...stfloor.org, hannes@...xchg.org, mel@....ul.ie,
linux-kernel@...r.kernel.org, Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH -mm v2 10/11] mm: remove ARM arch_get_unmapped_area
functions
On Thu, Jun 21, 2012 at 05:57:14PM -0400, Rik van Riel wrote:
> Remove the ARM special variants of arch_get_unmapped_area since the
> generic functions should now be able to handle everything.
>
> ARM only needs page colouring if cache_is_vipt_aliasing; leave
> shm_align_mask at PAGE_SIZE-1 unless we need colouring.
>
> Untested because I have no ARM hardware.
And I'll need other bits of the patch set to be able to test this for you...
> Cc: Russell King <linux@....linux.org.uk>
> Signed-off-by: Rik van Riel <riel@...hat.com>
> ---
> arch/arm/include/asm/pgtable.h | 6 -
> arch/arm/mm/init.c | 4 +
> arch/arm/mm/mmap.c | 217 ----------------------------------------
> 3 files changed, 4 insertions(+), 223 deletions(-)
>
> diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
> index f66626d..6754183 100644
> --- a/arch/arm/include/asm/pgtable.h
> +++ b/arch/arm/include/asm/pgtable.h
> @@ -296,12 +296,6 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
> #include <asm-generic/pgtable.h>
>
> /*
> - * We provide our own arch_get_unmapped_area to cope with VIPT caches.
> - */
> -#define HAVE_ARCH_UNMAPPED_AREA
> -#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
> -
> -/*
> * remap a physical page `pfn' of size `size' with page protection `prot'
> * into virtual address `from'
> */
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index f54d592..abaf862 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -600,6 +600,10 @@ void __init mem_init(void)
> extern u32 itcm_end;
> #endif
>
> + /* Tell the page colouring code what we need. */
> + if (cache_is_vipt_aliasing())
> + shm_align_mask = SHMLBA - 1;
> +
> max_mapnr = pfn_to_page(max_pfn + PHYS_PFN_OFFSET) - mem_map;
>
> /* this will put all unused low memory onto the freelists */
> diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
> index ce8cb19..d90969b 100644
> --- a/arch/arm/mm/mmap.c
> +++ b/arch/arm/mm/mmap.c
> @@ -11,22 +11,6 @@
> #include <linux/random.h>
> #include <asm/cachetype.h>
>
> -static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
> - unsigned long pgoff)
> -{
> - unsigned long base = addr & ~(SHMLBA-1);
> - unsigned long off = (pgoff << PAGE_SHIFT) & (SHMLBA-1);
> -
> - if (base + off <= addr)
> - return base + off;
> -
> - return base - off;
> -}
> -
> -#define COLOUR_ALIGN(addr,pgoff) \
> - ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
> - (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
> -
> /* gap between mmap and stack */
> #define MIN_GAP (128*1024*1024UL)
> #define MAX_GAP ((TASK_SIZE)/6*5)
> @@ -54,207 +38,6 @@ static unsigned long mmap_base(unsigned long rnd)
> return PAGE_ALIGN(TASK_SIZE - gap - rnd);
> }
>
> -/*
> - * We need to ensure that shared mappings are correctly aligned to
> - * avoid aliasing issues with VIPT caches. We need to ensure that
> - * a specific page of an object is always mapped at a multiple of
> - * SHMLBA bytes.
> - *
> - * We unconditionally provide this function for all cases, however
> - * in the VIVT case, we optimise out the alignment rules.
> - */
> -unsigned long
> -arch_get_unmapped_area(struct file *filp, unsigned long addr,
> - unsigned long len, unsigned long pgoff, unsigned long flags)
> -{
> - struct mm_struct *mm = current->mm;
> - struct vm_area_struct *vma;
> - unsigned long start_addr;
> - int do_align = 0;
> - int aliasing = cache_is_vipt_aliasing();
> -
> - /*
> - * We only need to do colour alignment if either the I or D
> - * caches alias.
> - */
> - if (aliasing)
> - do_align = filp || (flags & MAP_SHARED);
> -
> - /*
> - * We enforce the MAP_FIXED case.
> - */
> - if (flags & MAP_FIXED) {
> - if (aliasing && flags & MAP_SHARED &&
> - (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
> - return -EINVAL;
> - return addr;
> - }
> -
> - if (len > TASK_SIZE)
> - return -ENOMEM;
> -
> - if (addr) {
> - if (do_align)
> - addr = COLOUR_ALIGN(addr, pgoff);
> - else
> - addr = PAGE_ALIGN(addr);
> -
> - vma = find_vma(mm, addr);
> - if (TASK_SIZE - len >= addr &&
> - (!vma || addr + len <= vma->vm_start))
> - return addr;
> - }
> - if (len > mm->cached_hole_size) {
> - start_addr = addr = mm->free_area_cache;
> - } else {
> - start_addr = addr = mm->mmap_base;
> - mm->cached_hole_size = 0;
> - }
> -
> -full_search:
> - if (do_align)
> - addr = COLOUR_ALIGN(addr, pgoff);
> - else
> - addr = PAGE_ALIGN(addr);
> -
> - for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
> - /* At this point: (!vma || addr < vma->vm_end). */
> - if (TASK_SIZE - len < addr) {
> - /*
> - * Start a new search - just in case we missed
> - * some holes.
> - */
> - if (start_addr != TASK_UNMAPPED_BASE) {
> - start_addr = addr = TASK_UNMAPPED_BASE;
> - mm->cached_hole_size = 0;
> - goto full_search;
> - }
> - return -ENOMEM;
> - }
> - if (!vma || addr + len <= vma->vm_start) {
> - /*
> - * Remember the place where we stopped the search:
> - */
> - mm->free_area_cache = addr + len;
> - return addr;
> - }
> - if (addr + mm->cached_hole_size < vma->vm_start)
> - mm->cached_hole_size = vma->vm_start - addr;
> - addr = vma->vm_end;
> - if (do_align)
> - addr = COLOUR_ALIGN(addr, pgoff);
> - }
> -}
> -
> -unsigned long
> -arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> - const unsigned long len, const unsigned long pgoff,
> - const unsigned long flags)
> -{
> - struct vm_area_struct *vma;
> - struct mm_struct *mm = current->mm;
> - unsigned long addr = addr0;
> - int do_align = 0;
> - int aliasing = cache_is_vipt_aliasing();
> -
> - /*
> - * We only need to do colour alignment if either the I or D
> - * caches alias.
> - */
> - if (aliasing)
> - do_align = filp || (flags & MAP_SHARED);
> -
> - /* requested length too big for entire address space */
> - if (len > TASK_SIZE)
> - return -ENOMEM;
> -
> - if (flags & MAP_FIXED) {
> - if (aliasing && flags & MAP_SHARED &&
> - (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
> - return -EINVAL;
> - return addr;
> - }
> -
> - /* requesting a specific address */
> - if (addr) {
> - if (do_align)
> - addr = COLOUR_ALIGN(addr, pgoff);
> - else
> - addr = PAGE_ALIGN(addr);
> - vma = find_vma(mm, addr);
> - if (TASK_SIZE - len >= addr &&
> - (!vma || addr + len <= vma->vm_start))
> - return addr;
> - }
> -
> - /* check if free_area_cache is useful for us */
> - if (len <= mm->cached_hole_size) {
> - mm->cached_hole_size = 0;
> - mm->free_area_cache = mm->mmap_base;
> - }
> -
> - /* either no address requested or can't fit in requested address hole */
> - addr = mm->free_area_cache;
> - if (do_align) {
> - unsigned long base = COLOUR_ALIGN_DOWN(addr - len, pgoff);
> - addr = base + len;
> - }
> -
> - /* make sure it can fit in the remaining address space */
> - if (addr > len) {
> - vma = find_vma(mm, addr-len);
> - if (!vma || addr <= vma->vm_start)
> - /* remember the address as a hint for next time */
> - return (mm->free_area_cache = addr-len);
> - }
> -
> - if (mm->mmap_base < len)
> - goto bottomup;
> -
> - addr = mm->mmap_base - len;
> - if (do_align)
> - addr = COLOUR_ALIGN_DOWN(addr, pgoff);
> -
> - do {
> - /*
> - * Lookup failure means no vma is above this address,
> - * else if new region fits below vma->vm_start,
> - * return with success:
> - */
> - vma = find_vma(mm, addr);
> - if (!vma || addr+len <= vma->vm_start)
> - /* remember the address as a hint for next time */
> - return (mm->free_area_cache = addr);
> -
> - /* remember the largest hole we saw so far */
> - if (addr + mm->cached_hole_size < vma->vm_start)
> - mm->cached_hole_size = vma->vm_start - addr;
> -
> - /* try just below the current vma->vm_start */
> - addr = vma->vm_start - len;
> - if (do_align)
> - addr = COLOUR_ALIGN_DOWN(addr, pgoff);
> - } while (len < vma->vm_start);
> -
> -bottomup:
> - /*
> - * A failed mmap() very likely causes application failure,
> - * so fall back to the bottom-up function here. This scenario
> - * can happen with large stack limits and large mmap()
> - * allocations.
> - */
> - mm->cached_hole_size = ~0UL;
> - mm->free_area_cache = TASK_UNMAPPED_BASE;
> - addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
> - /*
> - * Restore the topdown base:
> - */
> - mm->free_area_cache = mm->mmap_base;
> - mm->cached_hole_size = ~0UL;
> -
> - return addr;
> -}
> -
> void arch_pick_mmap_layout(struct mm_struct *mm)
> {
> unsigned long random_factor = 0UL;
> --
> 1.7.7.6
>
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