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authorSiddha, Suresh B <suresh.b.siddha@intel.com>2005-11-05 17:25:53 +0100
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-14 19:55:14 -0800
commitf6c2e3330d3fdd5474bc3756da46fca889a30e33 (patch)
tree41b7534c39a6aea4ae1f0a75c6eb03f6e4b6312c /include/asm-x86_64/pgtable.h
parent69d81fcde7797342417591ba7affb372b9c86eae (diff)
[PATCH] x86_64: Unmap NULL during early bootup
We should zap the low mappings, as soon as possible, so that we can catch kernel bugs more effectively. Previously early boot had NULL mapped and didn't trap on NULL references. This patch introduces boot_level4_pgt, which will always have low identity addresses mapped. Druing boot, all the processors will use this as their level4 pgt. On BP, we will switch to init_level4_pgt as soon as we enter C code and zap the low mappings as soon as we are done with the usage of identity low mapped addresses. On AP's we will zap the low mappings as soon as we jump to C code. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-x86_64/pgtable.h')
-rw-r--r--include/asm-x86_64/pgtable.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h
index 7a07196a7202..a204efb553dc 100644
--- a/include/asm-x86_64/pgtable.h
+++ b/include/asm-x86_64/pgtable.h
@@ -16,6 +16,7 @@ extern pud_t level3_physmem_pgt[512];
extern pud_t level3_ident_pgt[512];
extern pmd_t level2_kernel_pgt[512];
extern pgd_t init_level4_pgt[];
+extern pgd_t boot_level4_pgt[];
extern unsigned long __supported_pte_mask;
#define swapper_pg_dir init_level4_pgt