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Commit a91690dd authored by David S. Miller's avatar David S. Miller
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[SPARC64]: Top-down address space allocation for 32-bit tasks. 



Currently allocations are very constrained for 32-bit processes.
It grows down-up from 0x70000000 to 0xf0000000 which gives about
2GB of stack + dynamic mmap() space.

So support the top-down method, and we need to override the
generic helper function in order to deal with D-cache coloring.

With these changes I was able to squeeze out a mmap() just over
3.6GB in size in a 32-bit process.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b5e7ae5d

arch/sparc64/kernel/binfmt_aout32.c

+2 −0
Original line number Diff line number Diff line
@@ -239,6 +239,8 @@ static int load_aout32_binary(struct linux_binprm * bprm, struct pt_regs * regs) 
		(current->mm->start_data = N_DATADDR(ex));

	current->mm->brk = ex.a_bss +

		(current->mm->start_brk = N_BSSADDR(ex));

	current->mm->free_area_cache = current->mm->mmap_base;

	current->mm->cached_hole_size = 0;



	current->mm->mmap = NULL;

	compute_creds(bprm);

arch/sparc64/kernel/sys_sparc.c

+181 −9
Original line number Diff line number Diff line
@@ -82,9 +82,34 @@ static inline int straddles_64bit_va_hole(unsigned long start, unsigned long end 
	return 1;

}



#define COLOUR_ALIGN(addr,pgoff)		\

	((((addr)+SHMLBA-1)&~(SHMLBA-1)) +	\

	 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))

/* These functions differ from the default implementations in

 * mm/mmap.c in two ways:

 *

 * 1) For file backed MAP_SHARED mmap()'s we D-cache color align,

 *    for fixed such mappings we just validate what the user gave us.

 * 2) For 64-bit tasks we avoid mapping anything within 4GB of

 *    the spitfire/niagara VA-hole.

 */



static inline unsigned long COLOUR_ALIGN(unsigned long addr,

					 unsigned long pgoff)

{

	unsigned long base = (addr+SHMLBA-1)&~(SHMLBA-1);

	unsigned long off = (pgoff<<PAGE_SHIFT) & (SHMLBA-1);



	return base + off;

}



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;

}



unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags)

{
@@ -106,7 +131,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi 


	if (test_thread_flag(TIF_32BIT))

		task_size = 0xf0000000UL;

	if (len > task_size || len >= VA_EXCLUDE_START)

	if (unlikely(len > task_size || len >= VA_EXCLUDE_START))

		return -ENOMEM;



	do_color_align = 0;
@@ -125,11 +150,12 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi 
			return addr;

	}



	if (len <= mm->cached_hole_size) {

	if (len > mm->cached_hole_size) {

	        start_addr = addr = mm->free_area_cache;

	} else {

	        start_addr = addr = TASK_UNMAPPED_BASE;

	        mm->cached_hole_size = 0;

		mm->free_area_cache = TASK_UNMAPPED_BASE;

	}

	start_addr = addr = mm->free_area_cache;



	task_size -= len;
@@ -146,7 +172,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi 
			addr = VA_EXCLUDE_END;

			vma = find_vma(mm, VA_EXCLUDE_END);

		}

		if (task_size < addr) {

		if (unlikely(task_size < addr)) {

			if (start_addr != TASK_UNMAPPED_BASE) {

				start_addr = addr = TASK_UNMAPPED_BASE;

				mm->cached_hole_size = 0;
@@ -154,7 +180,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi 
			}

			return -ENOMEM;

		}

		if (!vma || addr + len <= vma->vm_start) {

		if (likely(!vma || addr + len <= vma->vm_start)) {

			/*

			 * Remember the place where we stopped the search:

			 */
@@ -170,6 +196,121 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi 
	}

}



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 task_size = 0xf0000000UL;

	unsigned long addr = addr0;

	int do_color_align;



	/* This should only ever run for 32-bit processes.  */

	BUG_ON(!test_thread_flag(TIF_32BIT));



	if (flags & MAP_FIXED) {

		/* We do not accept a shared mapping if it would violate

		 * cache aliasing constraints.

		 */

		if ((flags & MAP_SHARED) &&

		    ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))

			return -EINVAL;

		return addr;

	}



	if (unlikely(len > task_size))

		return -ENOMEM;



	do_color_align = 0;

	if (filp || (flags & MAP_SHARED))

		do_color_align = 1;



	/* requesting a specific address */

	if (addr) {

		if (do_color_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_color_align) {

		unsigned long base = COLOUR_ALIGN_DOWN(addr-len, pgoff);



		addr = base + len;

	}



	/* make sure it can fit in the remaining address space */

	if (likely(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 (unlikely(mm->mmap_base < len))

		goto bottomup;



	addr = mm->mmap_base-len;

	if (do_color_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 (likely(!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_color_align)

			addr = COLOUR_ALIGN_DOWN(addr, pgoff);

	} while (likely(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;

}



/* Try to align mapping such that we align it as much as possible. */

unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)

{
@@ -213,6 +354,37 @@ unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, u 
	return addr;

}



/* Essentially the same as PowerPC... */

void arch_pick_mmap_layout(struct mm_struct *mm)

{

	/*

	 * Fall back to the standard layout if the personality

	 * bit is set, or if the expected stack growth is unlimited:

	 */

	if (!test_thread_flag(TIF_32BIT) ||

	    (current->personality & ADDR_COMPAT_LAYOUT) ||

	    current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY ||

	    sysctl_legacy_va_layout) {

		mm->mmap_base = TASK_UNMAPPED_BASE;

		mm->get_unmapped_area = arch_get_unmapped_area;

		mm->unmap_area = arch_unmap_area;

	} else {

		/* We know it's 32-bit */

		unsigned long task_size = 0xf0000000UL;

		unsigned long gap;



		gap = current->signal->rlim[RLIMIT_STACK].rlim_cur;

		if (gap < 128 * 1024 * 1024)

			gap = 128 * 1024 * 1024;

		if (gap > (task_size / 6 * 5))

			gap = (task_size / 6 * 5);



		mm->mmap_base = task_size - (gap & PAGE_MASK);

		mm->get_unmapped_area = arch_get_unmapped_area_topdown;

		mm->unmap_area = arch_unmap_area_topdown;

	}

}



asmlinkage unsigned long sparc_brk(unsigned long brk)

{

	/* People could try to be nasty and use ta 0x6d in 32bit programs */

include/asm-sparc64/pgtable.h

+4 −1
Original line number Diff line number Diff line
@@ -752,8 +752,11 @@ extern int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 


#include <asm-generic/pgtable.h>



/* We provide our own get_unmapped_area to cope with VA holes for userland */

/* We provide our own get_unmapped_area to cope with VA holes and

 * SHM area cache aliasing for userland.

 */

#define HAVE_ARCH_UNMAPPED_AREA

#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN



/* We provide a special get_unmapped_area for framebuffer mmaps to try and use

 * the largest alignment possible such that larget PTEs can be used.

include/asm-sparc64/processor.h

+2 −0
Original line number Diff line number Diff line
@@ -217,6 +217,8 @@ static inline void prefetchw(const void *x) 


#define spin_lock_prefetch(x)	prefetchw(x)



#define HAVE_ARCH_PICK_MMAP_LAYOUT



#endif /* !(__ASSEMBLY__) */



#endif /* !(__ASM_SPARC64_PROCESSOR_H) */