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x86-64: finish cleanup_highmaps()'s job wrt. _brk_end

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With the introduction of the .brk section, special care must be taken
that no unused page table entries remain if _brk_end and _end are
separated by a 2M page boundary. cleanup_highmap() runs very early and
hence cannot take care of that, hence potential entries needing to be
removed past _brk_end must be cleared once the brk allocator has done
its job.

[ Impact: avoids undesirable TLB aliases ]

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Jan Beulich 2009-05-06 13:06:47 +01:00 committed by H. Peter Anvin
parent 6143876651
commit 4983439676
1 changed files with 17 additions and 1 deletions
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18
arch/x86/mm/init.c
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@ -7,6 +7,7 @@
#include <asm/page.h>
#include <asm/page_types.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/system.h>
#include <asm/tlbflush.h>
@ -304,8 +305,23 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
#endif
#ifdef CONFIG_X86_64
if (!after_bootmem)
if (!after_bootmem && !start) {
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);
}
#endif
__flush_tlb_all();