The patch titled
get_unmapped_area handles MAP_FIXED on powerpc
has been added to the -mm tree. Its filename is
get_unmapped_area-handles-map_fixed-on-powerpc.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: get_unmapped_area handles MAP_FIXED on powerpc
From: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
The current get_unmapped_area code calls the f_ops->get_unmapped_area or the
arch one (via the mm) only when MAP_FIXED is not passed. That makes it
impossible for archs to impose proper constraints on regions of the virtual
address space. To work around that, get_unmapped_area() then calls some
hugetlbfs specific hacks.
This cause several problems, among others:
- It makes it impossible for a driver or filesystem to do the same thing
that hugetlbfs does (for example, to allow a driver to use larger page sizes
to map external hardware) if that requires applying a constraint on the
addresses (constraining that mapping in certain regions and other mappings
out of those regions).
- Some archs like arm, mips, sparc, sparc64, sh and sh64 already want
MAP_FIXED to be passed down in order to deal with aliasing issues. The code
is there to handle it... but is never called.
This series of patches moves the logic to handle MAP_FIXED down to the various
arch/driver get_unmapped_area() implementations, and then changes the generic
code to always call them. The hugetlbfs hacks then disappear from the generic
code.
Since I need to do some special 64K pages mappings for SPEs on cell, I need to
work around the first problem at least. I have further patches thus
implementing a "slices" layer that handles multiple page sizes through slices
of the address space for use by hugetlbfs, the SPE code, and possibly others,
but it requires that serie of patches first/
There is still a potential (but not practical) issue due to the fact that
filesystems/drivers implemeting g_u_a will effectively bypass all arch checks.
This is not an issue in practice as the only filesystems/drivers using that
hook are doing so for arch specific purposes in the first place.
There is also a problem with mremap that will completely bypass all arch
checks. I'll try to address that separately, I'm not 100% certain yet how,
possibly by making it not work when the vma has a file whose f_ops has a
get_unmapped_area callback, and by making it use is_hugepage_only_range()
before expanding into a new area.
Also, I want to turn is_hugepage_only_range() into a more generic
is_normal_page_range() as that's really what it will end up meaning when used
in stack grow, brk grow and mremap.
None of the above "issues" however are introduced by this patch, they are
already there, so I think the patch can go ini for 2.6.22.
This patch:
Handle MAP_FIXED in powerpc's arch_get_unmapped_area() in all 3
implementations of it.
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Acked-by: William Irwin <bill.irwin@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Cc: Kyle McMartin <kyle@xxxxxxxxxxx>
Cc: Grant Grundler <grundler@xxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Adam Litke <agl@xxxxxxxxxx>
Cc: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/hugetlbpage.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff -puN arch/powerpc/mm/hugetlbpage.c~get_unmapped_area-handles-map_fixed-on-powerpc arch/powerpc/mm/hugetlbpage.c
--- a/arch/powerpc/mm/hugetlbpage.c~get_unmapped_area-handles-map_fixed-on-powerpc
+++ a/arch/powerpc/mm/hugetlbpage.c
@@ -566,6 +566,13 @@ unsigned long arch_get_unmapped_area(str
if (len > TASK_SIZE)
return -ENOMEM;
+ /* handle fixed mapping: prevent overlap with huge pages */
+ if (flags & MAP_FIXED) {
+ if (is_hugepage_only_range(mm, addr, len))
+ return -EINVAL;
+ return addr;
+ }
+
if (addr) {
addr = PAGE_ALIGN(addr);
vma = find_vma(mm, addr);
@@ -641,6 +648,13 @@ arch_get_unmapped_area_topdown(struct fi
if (len > TASK_SIZE)
return -ENOMEM;
+ /* handle fixed mapping: prevent overlap with huge pages */
+ if (flags & MAP_FIXED) {
+ if (is_hugepage_only_range(mm, addr, len))
+ return -EINVAL;
+ return addr;
+ }
+
/* dont allow allocations above current base */
if (mm->free_area_cache > base)
mm->free_area_cache = base;
@@ -823,6 +837,13 @@ unsigned long hugetlb_get_unmapped_area(
/* Paranoia, caller should have dealt with this */
BUG_ON((addr + len) < addr);
+ /* Handle MAP_FIXED */
+ if (flags & MAP_FIXED) {
+ if (prepare_hugepage_range(addr, len, pgoff))
+ return -EINVAL;
+ return addr;
+ }
+
if (test_thread_flag(TIF_32BIT)) {
curareas = current->mm->context.low_htlb_areas;
_
Patches currently in -mm which might be from benh@xxxxxxxxxxxxxxxxxxx are
git-powerpc.patch
git-powerpc-arch-powerpc-sysdev-timerc-build-fix.patch
ppc4xx_sgdma-needs-dma_mappingh.patch
powerpc-rtas-msi-support.patch
spin_lock_unlocked-cleanup-in-arch-powerpc.patch
macintosh-mediabay-convert-to-kthread-api.patch
macintosh-adb-convert-to-the-kthread-api.patch
macintosh-therm_pm72c-partially-convert-to-kthread-api.patch
s2ram-add-arch-irq-disable-enable-hooks.patch
fix-jdelvare-i2c-i2c-del-driver-returns-void-on-powerpc.patch
slub-core.patch
use-slab_panic-flag-cleanup.patch
get_unmapped_area-handles-map_fixed-on-powerpc.patch
get_unmapped_area-handles-map_fixed-on-alpha.patch
get_unmapped_area-handles-map_fixed-on-arm.patch
get_unmapped_area-handles-map_fixed-on-frv.patch
get_unmapped_area-handles-map_fixed-on-i386.patch
get_unmapped_area-handles-map_fixed-on-ia64.patch
get_unmapped_area-handles-map_fixed-on-parisc.patch
get_unmapped_area-handles-map_fixed-on-sparc64.patch
get_unmapped_area-handles-map_fixed-on-x86_64.patch
get_unmapped_area-handles-map_fixed-in-hugetlbfs.patch
get_unmapped_area-handles-map_fixed-in-generic-code.patch
get_unmapped_area-doesnt-need-hugetlbfs-hacks-anymore.patch
the-scheduled-removal-of-obsolete_oss-options.patch
drivers-macintosh-mac_hidc-make-code-static.patch
fixes-and-cleanups-for-earlyprintk-aka-boot-console.patch
parport-dev-driver-model-support-powerpc-fix.patch
atomich-add-atomic64-cmpxchg-xchg-and-add_unless-to-powerpc.patch
atomich-add-atomic64-cmpxchg-xchg-and-add_unless-to-powerpc-fix.patch
local_t-powerpc-extension.patch
linux-kernel-markers-powerpc-optimization.patch
ps3fb-thread-updates.patch
ps3av-thread-updates.patch
ps3fb-kill-superfluous-zero-initializations.patch
ps3av-misc-updates.patch
aty128fb-fix-blanking.patch
radeonfb-add-support-for-radeon-xpress-200m.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
