[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: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc64/kernel/binfmt_aout32.c b/arch/sparc64/kernel/binfmt_aout32.c
index cb9ecd0..d7caa60 100644
--- a/arch/sparc64/kernel/binfmt_aout32.c
+++ b/arch/sparc64/kernel/binfmt_aout32.c
@@ -239,6 +239,8 @@
(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);
diff --git a/arch/sparc64/kernel/sys_sparc.c b/arch/sparc64/kernel/sys_sparc.c
index 8840415..61dffb9 100644
--- a/arch/sparc64/kernel/sys_sparc.c
+++ b/arch/sparc64/kernel/sys_sparc.c
@@ -82,9 +82,34 @@
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 @@
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 @@
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 @@
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 @@
}
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_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 @@
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 */
diff --git a/include/asm-sparc64/pgtable.h b/include/asm-sparc64/pgtable.h
index d427ce6..ed4124e 100644
--- a/include/asm-sparc64/pgtable.h
+++ b/include/asm-sparc64/pgtable.h
@@ -752,8 +752,11 @@
#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.
diff --git a/include/asm-sparc64/processor.h b/include/asm-sparc64/processor.h
index 685479f..c6896b8 100644
--- a/include/asm-sparc64/processor.h
+++ b/include/asm-sparc64/processor.h
@@ -217,6 +217,8 @@
#define spin_lock_prefetch(x) prefetchw(x)
+#define HAVE_ARCH_PICK_MMAP_LAYOUT
+
#endif /* !(__ASSEMBLY__) */
#endif /* !(__ASM_SPARC64_PROCESSOR_H) */