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Subject[tip:x86/urgent] x86: Cleanup highmap after brk is concluded
Commit-ID:  e5f15b45ddf3afa2bbbb10c7ea34fb32b6de0a0e
Gitweb: http://git.kernel.org/tip/e5f15b45ddf3afa2bbbb10c7ea34fb32b6de0a0e
Author: Yinghai Lu <yinghai@kernel.org>
AuthorDate: Fri, 18 Feb 2011 11:30:30 +0000
Committer: H. Peter Anvin <hpa@zytor.com>
CommitDate: Sat, 19 Mar 2011 11:58:19 -0700

x86: Cleanup highmap after brk is concluded

Now cleanup_highmap actually is in two steps: one is early in head64.c
and only clears above _end; a second one is in init_memory_mapping() and
tries to clean from _brk_end to _end.
It should check if those boundaries are PMD_SIZE aligned but currently
does not.
Also init_memory_mapping() is called several times for numa or memory
hotplug, so we really should not handle initial kernel mappings there.

This patch moves cleanup_highmap() down after _brk_end is settled so
we can do everything in one step.
Also we honor max_pfn_mapped in the implementation of cleanup_highmap.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
LKML-Reference: <alpine.DEB.2.00.1103171739050.3382@kaball-desktop>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
arch/x86/kernel/head64.c | 3 ---
arch/x86/kernel/setup.c | 25 +++----------------------
arch/x86/mm/init_64.c | 11 ++++++-----
3 files changed, 9 insertions(+), 30 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 2d2673c..5655c22 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -77,9 +77,6 @@ void __init x86_64_start_kernel(char * real_mode_data)
/* Make NULL pointers segfault */
zap_identity_mappings();

- /* Cleanup the over mapped high alias */
- cleanup_highmap();
-
max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;

for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b176f2b..4a52a5f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -294,30 +294,11 @@ static void __init init_gbpages(void)
else
direct_gbpages = 0;
}
-
-static void __init cleanup_highmap_brk_end(void)
-{
- pud_t *pud;
- pmd_t *pmd;
-
- mmu_cr4_features = read_cr4();
-
- /*
- * _brk_end cannot change anymore, but it and _end may be
- * located on different 2M pages. cleanup_highmap(), however,
- * can only consider _end when it runs, so destroy any
- * mappings beyond _brk_end here.
- */
- pud = pud_offset(pgd_offset_k(_brk_end), _brk_end);
- pmd = pmd_offset(pud, _brk_end - 1);
- while (++pmd <= pmd_offset(pud, (unsigned long)_end - 1))
- pmd_clear(pmd);
-}
#else
static inline void init_gbpages(void)
{
}
-static inline void cleanup_highmap_brk_end(void)
+static void __init cleanup_highmap(void)
{
}
#endif
@@ -330,8 +311,6 @@ static void __init reserve_brk(void)
/* Mark brk area as locked down and no longer taking any
new allocations */
_brk_start = 0;
-
- cleanup_highmap_brk_end();
}

#ifdef CONFIG_BLK_DEV_INITRD
@@ -950,6 +929,8 @@ void __init setup_arch(char **cmdline_p)
*/
reserve_brk();

+ cleanup_highmap();
+
memblock.current_limit = get_max_mapped();
memblock_x86_fill();

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index a08a62c..7026505 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -51,6 +51,7 @@
#include <asm/numa.h>
#include <asm/cacheflush.h>
#include <asm/init.h>
+#include <asm/setup.h>

static int __init parse_direct_gbpages_off(char *arg)
{
@@ -293,18 +294,18 @@ void __init init_extra_mapping_uc(unsigned long phys, unsigned long size)
* to the compile time generated pmds. This results in invalid pmds up
* to the point where we hit the physaddr 0 mapping.
*
- * We limit the mappings to the region from _text to _end. _end is
- * rounded up to the 2MB boundary. This catches the invalid pmds as
+ * We limit the mappings to the region from _text to _brk_end. _brk_end
+ * is rounded up to the 2MB boundary. This catches the invalid pmds as
* well, as they are located before _text:
*/
void __init cleanup_highmap(void)
{
unsigned long vaddr = __START_KERNEL_map;
- unsigned long end = roundup((unsigned long)_end, PMD_SIZE) - 1;
+ unsigned long vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT);
+ unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;
pmd_t *pmd = level2_kernel_pgt;
- pmd_t *last_pmd = pmd + PTRS_PER_PMD;

- for (; pmd < last_pmd; pmd++, vaddr += PMD_SIZE) {
+ for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) {
if (pmd_none(*pmd))
continue;
if (vaddr < (unsigned long) _text || vaddr > end)

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