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Message-ID: <20120621123743.GA7121@aftab.osrc.amd.com>
Date: Thu, 21 Jun 2012 14:37:43 +0200
From: Borislav Petkov <bp@...64.org>
To: Rik van Riel <riel@...hat.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@...riel.com>
Subject: Re: [PATCH -mm 4/7] mm: make page colouring code generic
On Mon, Jun 18, 2012 at 06:05:23PM -0400, Rik van Riel wrote:
> From: Rik van Riel <riel@...riel.com>
>
> Fix the x86-64 page colouring code to take pgoff into account.
> Use the x86 and MIPS page colouring code as the basis for a generic
> page colouring function.
>
> Teach the generic arch_get_unmapped_area(_topdown) code to call the
> page colouring code.
>
> Make sure that ALIGN_DOWN always aligns down, and ends up at the
> right page colour.
>
> Signed-off-by: Rik van Riel <riel@...hat.com>
> ---
> arch/mips/include/asm/page.h | 2 -
> arch/mips/include/asm/pgtable.h | 1 +
> arch/x86/include/asm/elf.h | 3 -
> arch/x86/include/asm/pgtable_64.h | 1 +
> arch/x86/kernel/sys_x86_64.c | 35 +++++++++-----
> arch/x86/vdso/vma.c | 2 +-
> include/linux/sched.h | 8 +++-
> mm/mmap.c | 91 ++++++++++++++++++++++++++++++++-----
> 8 files changed, 111 insertions(+), 32 deletions(-)
>
> diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
> index da9bd7d..459cc25 100644
> --- a/arch/mips/include/asm/page.h
> +++ b/arch/mips/include/asm/page.h
> @@ -63,8 +63,6 @@ extern void build_copy_page(void);
> extern void clear_page(void * page);
> extern void copy_page(void * to, void * from);
>
> -extern unsigned long shm_align_mask;
> -
> static inline unsigned long pages_do_alias(unsigned long addr1,
> unsigned long addr2)
> {
> diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
> index b2202a6..f133a4c 100644
> --- a/arch/mips/include/asm/pgtable.h
> +++ b/arch/mips/include/asm/pgtable.h
> @@ -415,6 +415,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
> */
> #define HAVE_ARCH_UNMAPPED_AREA
> #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
> +#define HAVE_ARCH_ALIGN_ADDR
>
> /*
> * No page table caches to initialise
> diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
> index 5939f44..dc2d0bf 100644
> --- a/arch/x86/include/asm/elf.h
> +++ b/arch/x86/include/asm/elf.h
> @@ -358,8 +358,6 @@ static inline int mmap_is_ia32(void)
> enum align_flags {
> ALIGN_VA_32 = BIT(0),
> ALIGN_VA_64 = BIT(1),
> - ALIGN_VDSO = BIT(2),
> - ALIGN_TOPDOWN = BIT(3),
> };
>
> struct va_alignment {
> @@ -368,5 +366,4 @@ struct va_alignment {
> } ____cacheline_aligned;
>
> extern struct va_alignment va_align;
> -extern unsigned long align_addr(unsigned long, struct file *, enum align_flags);
> #endif /* _ASM_X86_ELF_H */
> diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
> index 8af36f6..8408ccd 100644
> --- a/arch/x86/include/asm/pgtable_64.h
> +++ b/arch/x86/include/asm/pgtable_64.h
> @@ -170,6 +170,7 @@ extern void cleanup_highmap(void);
> #define HAVE_ARCH_UNMAPPED_AREA
> #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
> #define HAVE_ARCH_GET_ADDRESS_RANGE
> +#define HAVE_ARCH_ALIGN_ADDR
>
> #define pgtable_cache_init() do { } while (0)
> #define check_pgt_cache() do { } while (0)
> diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
> index 2595a5e..ac0afb8 100644
> --- a/arch/x86/kernel/sys_x86_64.c
> +++ b/arch/x86/kernel/sys_x86_64.c
> @@ -25,31 +25,40 @@
> * @flags denotes the allocation direction - bottomup or topdown -
> * or vDSO; see call sites below.
> */
> -unsigned long align_addr(unsigned long addr, struct file *filp,
> - enum align_flags flags)
> +unsigned long arch_align_addr(unsigned long addr, struct file *filp,
> + unsigned long pgoff, unsigned long flags,
> + enum mmap_allocation_direction direction)
Arguments vertical alignment too, not only addr alignment :-)
> {
> - unsigned long tmp_addr;
> + unsigned long tmp_addr = PAGE_ALIGN(addr);
I'm guessing addr coming from arch_get_unmapped_area(_topdown) might not
be page-aligned in all cases?
>
> /* handle 32- and 64-bit case with a single conditional */
> if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
> - return addr;
> + return tmp_addr;
>
> - if (!(current->flags & PF_RANDOMIZE))
> - return addr;
> + /* Always allow MAP_FIXED. Colouring is a performance thing only. */
> + if (flags & MAP_FIXED)
> + return tmp_addr;
Why here? Maybe we should push this MAP_FIXED check up in the
arch_get_unmapped_area(_topdown) and not call arch_align_addr() for
MAP_FIXED requests?
Or do you want to save some code duplication?
> - if (!((flags & ALIGN_VDSO) || filp))
> - return addr;
> + if (!(current->flags & PF_RANDOMIZE))
> + return tmp_addr;
>
> - tmp_addr = addr;
> + if (!(filp || direction == ALLOC_VDSO))
> + return tmp_addr;
>
> /*
> * We need an address which is <= than the original
> * one only when in topdown direction.
> */
> - if (!(flags & ALIGN_TOPDOWN))
> + if (direction == ALLOC_UP)
> tmp_addr += va_align.mask;
>
> tmp_addr &= ~va_align.mask;
> + tmp_addr += ((pgoff << PAGE_SHIFT) & va_align.mask);
> +
> + if (direction == ALLOC_DOWN && tmp_addr > addr) {
> + tmp_addr -= va_align.mask;
> + tmp_addr &= ~va_align.mask;
> + }
>
> return tmp_addr;
> }
> @@ -159,7 +168,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
>
> full_search:
>
> - addr = align_addr(addr, filp, 0);
> + addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
>
> for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
> /* At this point: (!vma || addr < vma->vm_end). */
> @@ -186,7 +195,7 @@ full_search:
> mm->cached_hole_size = vma->vm_start - addr;
>
> addr = vma->vm_end;
> - addr = align_addr(addr, filp, 0);
> + addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
> }
> }
>
> @@ -235,7 +244,7 @@ try_again:
>
> addr -= len;
> do {
> - addr = align_addr(addr, filp, ALIGN_TOPDOWN);
> + addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
>
> /*
> * Lookup failure means no vma is above this address,
> diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
> index 00aaf04..83e0355 100644
> --- a/arch/x86/vdso/vma.c
> +++ b/arch/x86/vdso/vma.c
> @@ -141,7 +141,7 @@ static unsigned long vdso_addr(unsigned long start, unsigned len)
> * unaligned here as a result of stack start randomization.
> */
> addr = PAGE_ALIGN(addr);
> - addr = align_addr(addr, NULL, ALIGN_VDSO);
> + addr = arch_align_addr(addr, NULL, 0, 0, ALLOC_VDSO);
>
> return addr;
> }
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index fc76318..18f9326 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -390,12 +390,18 @@ extern int sysctl_max_map_count;
> #ifdef CONFIG_MMU
> enum mmap_allocation_direction {
> ALLOC_UP,
> - ALLOC_DOWN
> + ALLOC_DOWN,
> + ALLOC_VDSO,
> };
> extern void arch_pick_mmap_layout(struct mm_struct *mm);
> extern void
> arch_get_address_range(unsigned long flags, unsigned long *begin,
> unsigned long *end, enum mmap_allocation_direction direction);
> +extern unsigned long shm_align_mask;
> +extern unsigned long
> +arch_align_addr(unsigned long addr, struct file *filp,
> + unsigned long pgoff, unsigned long flags,
> + enum mmap_allocation_direction direction);
> extern unsigned long
> arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
> unsigned long, unsigned long);
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 92cf0bf..0314cb1 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1465,6 +1465,51 @@ unacct_error:
> return error;
> }
>
> +#ifndef HAVE_ARCH_ALIGN_ADDR
> +/* Each architecture is responsible for setting this to the required value. */
> +unsigned long shm_align_mask = PAGE_SIZE - 1;
> +EXPORT_SYMBOL(shm_align_mask);
> +
> +unsigned long arch_align_addr(unsigned long addr, struct file *filp,
> + unsigned long pgoff, unsigned long flags,
> + enum mmap_allocation_direction direction)
Ditto on arguments alignment as above.
> +{
> + unsigned long tmp_addr = PAGE_ALIGN(addr);
> +
> + if (shm_align_mask <= PAGE_SIZE)
> + return tmp_addr;
> +
> + /* Allow MAP_FIXED without MAP_SHARED at any address. */
> + if ((flags & (MAP_FIXED|MAP_SHARED)) == MAP_FIXED)
> + return tmp_addr;
> +
> + /* Enforce page colouring for any file or MAP_SHARED mapping. */
> + if (!(filp || (flags & MAP_SHARED)))
> + return tmp_addr;
> +
> + /*
> + * We need an address which is <= than the original
> + * one only when in topdown direction.
> + */
> + if (direction == ALLOC_UP)
> + tmp_addr += shm_align_mask;
> +
> + tmp_addr &= ~shm_align_mask;
> + tmp_addr += ((pgoff << PAGE_SHIFT) & shm_align_mask);
> +
> + /*
> + * When aligning down, make sure we did not accidentally go up.
> + * The caller will check for underflow.
> + */
Can we add this comment to the x86-64 version of arch_align_addr too pls?
> + if (direction == ALLOC_DOWN && tmp_addr > addr) {
> + tmp_addr -= shm_align_mask;
> + tmp_addr &= ~shm_align_mask;
> + }
> +
> + return tmp_addr;
> +}
> +#endif
> +
> #ifndef HAVE_ARCH_GET_ADDRESS_RANGE
> void arch_get_address_range(unsigned long flags, unsigned long *begin,
> unsigned long *end, enum mmap_allocation_direction direction)
> @@ -1513,18 +1558,22 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
> struct mm_struct *mm = current->mm;
> struct vm_area_struct *vma = NULL;
> struct rb_node *rb_node;
> - unsigned long lower_limit, upper_limit;
> + unsigned long lower_limit, upper_limit, tmp_addr;
>
> arch_get_address_range(flags, &lower_limit, &upper_limit, ALLOC_UP);
>
> if (len > TASK_SIZE)
> return -ENOMEM;
>
> - if (flags & MAP_FIXED)
> + if (flags & MAP_FIXED) {
> + tmp_addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
> + if (tmp_addr != PAGE_ALIGN(addr))
> + return -EINVAL;
> return addr;
> + }
>
> if (addr) {
> - addr = PAGE_ALIGN(addr);
> + addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
> vma = find_vma(mm, addr);
> if (TASK_SIZE - len >= addr &&
> (!vma || addr + len <= vma->vm_start))
> @@ -1533,7 +1582,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
>
> /* Find the left-most free area of sufficient size. */
> for (addr = 0, rb_node = mm->mm_rb.rb_node; rb_node; ) {
> - unsigned long vma_start;
> + unsigned long vma_start, tmp_addr;
> int found_here = 0;
>
> vma = rb_to_vma(rb_node);
> @@ -1541,13 +1590,17 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
> if (vma->vm_start > len) {
> if (!vma->vm_prev) {
> /* This is the left-most VMA. */
> - if (vma->vm_start - len >= lower_limit) {
> - addr = lower_limit;
> + tmp_addr = arch_align_addr(lower_limit, filp,
> + pgoff, flags, ALLOC_UP);
> + if (vma->vm_start - len >= tmp_addr) {
> + addr = tmp_addr;
> goto found_addr;
> }
> } else {
> /* Is this hole large enough? Remember it. */
> vma_start = max(vma->vm_prev->vm_end, lower_limit);
> + vma_start = arch_align_addr(vma_start, filp,
> + pgoff, flags, ALLOC_UP);
> if (vma->vm_start - len >= vma_start) {
> addr = vma_start;
> found_here = 1;
> @@ -1599,6 +1652,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
> if (addr < lower_limit)
> addr = lower_limit;
>
> + addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_UP);
> +
> found_addr:
> if (TASK_SIZE - len < addr)
> return -ENOMEM;
> @@ -1656,12 +1711,17 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> if (len > TASK_SIZE)
> return -ENOMEM;
>
> - if (flags & MAP_FIXED)
> + if (flags & MAP_FIXED) {
> + unsigned long tmp_addr;
> + tmp_addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
> + if (tmp_addr != PAGE_ALIGN(addr))
> + return -EINVAL;
> return addr;
> + }
>
> /* requesting a specific address */
> if (addr) {
> - addr = PAGE_ALIGN(addr);
> + addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
> vma = find_vma(mm, addr);
> if (TASK_SIZE - len >= addr &&
> (!vma || addr + len <= vma->vm_start))
> @@ -1678,7 +1738,9 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> */
> if (upper_limit - len > mm->highest_vma) {
> addr = upper_limit - len;
> - goto found_addr;
> + addr = arch_align_addr(addr, filp, pgoff, flags, ALLOC_DOWN);
> + if (addr > mm->highest_vma);
> + goto found_addr;
> }
>
> /* Find the right-most free area of sufficient size. */
> @@ -1691,9 +1753,14 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
> /* Is this hole large enough? Remember it. */
> vma_start = min(vma->vm_start, upper_limit);
> if (vma_start > len) {
> - if (!vma->vm_prev ||
> - (vma_start - len >= vma->vm_prev->vm_end)) {
> - addr = vma_start - len;
> + unsigned long tmp_addr = vma_start - len;
> + tmp_addr = arch_align_addr(tmp_addr, filp,
> + pgoff, flags, ALLOC_DOWN);
> + /* No underflow? Does it still fit the hole? */
> + if (tmp_addr && tmp_addr <= vma_start - len &&
> + (!vma->vm_prev ||
> + tmp_addr >= vma->vm_prev->vm_end)) {
> + addr = tmp_addr;
> found_here = 1;
> }
> }
> --
> 1.7.7.6
>
> --
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--
Regards/Gruss,
Boris.
Advanced Micro Devices GmbH
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