path: root/arch
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authorCatalin Marinas <catalin.marinas@arm.com>2013-04-29 15:07:45 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-07 20:33:07 -0700
commit87855fa699dac0cdd02177905aa0fa1ef485ab07 (patch)
tree4f38ea011757066c4421ac83b7ba8fabea04b378 /arch
parentbe629bd73febd59027cca2fdda42b0eeb13c2de9 (diff)
arm: set the page table freeing ceiling to TASK_SIZE
commit 104ad3b32d7a71941c8ab2dee78eea38e8a23309 upstream. ARM processors with LPAE enabled use 3 levels of page tables, with an entry in the top level (pgd) covering 1GB of virtual space. Because of the branch relocation limitations on ARM, the loadable modules are mapped 16MB below PAGE_OFFSET, making the corresponding 1GB pgd shared between kernel modules and user space. If free_pgtables() is called with the default ceiling 0, free_pgd_range() (and subsequently called functions) also frees the page table shared between user space and kernel modules (which is normally handled by the ARM-specific pgd_free() function). This patch changes defines the ARM USER_PGTABLES_CEILING to TASK_SIZE when CONFIG_ARM_LPAE is enabled. Note that the pgd_free() function already checks the presence of the shared pmd page allocated by pgd_alloc() and frees it, though with ceiling 0 this wasn't necessary. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 80d6fc4dbe4..9bcd262a900 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -61,6 +61,15 @@ extern void __pgd_error(const char *file, int line, pgd_t);
+ * Use TASK_SIZE as the ceiling argument for free_pgtables() and
+ * free_pgd_range() to avoid freeing the modules pmd when LPAE is enabled (pmd
+ * page shared between user and kernel).
+ */
* The pgprot_* and protection_map entries will be fixed up in runtime
* to include the cachable and bufferable bits based on memory policy,
* as well as any architecture dependent bits like global/ASID and SMP