lkml.org 
[lkml]   [2002]   [Jul]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] fix x86 page table init
The recent changes to the x86 page table init reintroduced a bug with 
the 4k pagetables. The page table must be filled with entries before it
is inserted into the pmd or else you risk a tlb miss on a kernel code
page causing an oops. This patch takes a different approach than before
- it allows for reuse of the boot pagetable pages instead of allocating
new ones.

--
Brian Gerst
diff -urN linux-bk/arch/i386/mm/init.c linux/arch/i386/mm/init.c
--- linux-bk/arch/i386/mm/init.c Tue Jul 30 20:59:27 2002
+++ linux/arch/i386/mm/init.c Tue Jul 30 21:02:41 2002
@@ -70,10 +70,14 @@
*/
static pte_t * __init one_page_table_init(pmd_t *pmd)
{
- pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
- set_pmd(pmd, __pmd(__pa(page_table) | _KERNPG_TABLE));
- if (page_table != pte_offset_kernel(pmd, 0))
- BUG();
+ pte_t *page_table;
+ page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+ if (pmd_none(*pmd)) {
+ set_pmd(pmd, __pmd(__pa(page_table) | _KERNPG_TABLE));
+ if (page_table != pte_offset_kernel(pmd, 0))
+ BUG();
+ } else
+ page_table = pte_offset_kernel(pmd, 0);

return page_table;
}
@@ -107,9 +111,7 @@

pmd = pmd_offset(pgd, vaddr);
for (; (pmd_ofs < PTRS_PER_PMD) && (vaddr != end); pmd++, pmd_ofs++) {
- if (pmd_none(*pmd))
- one_page_table_init(pmd);
-
+ one_page_table_init(pmd);
vaddr += PMD_SIZE;
}
pmd_ofs = 0;
\
 
 \ /
  Last update: 2005-03-22 13:27    [from the cache]
©2003-2011 Jasper Spaans