linux/arch/mips/mm/pgtable-64.c
Ralf Baechle f8829caee3 [MIPS] Fix aliasing bug in copy_to_user_page / copy_from_user_page
The current implementation uses a sequence of a cacheflush and a copy.
This is racy in case of a multithreaded debuggee and renders GDB
virtually unusable.

Aside this fixes a performance hog rendering access to /proc/cmdline very
slow and resulting in a enough cache stalls for the 34K AP/SP programming
model to make the bare metal code on the non-Linux VPE miss RT deadlines.

The main part of this patch was originally written by Ralf Baechle;
Atushi Nemoto did the the debugging.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-10-21 23:17:35 +01:00

69 lines
1.7 KiB
C

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1999, 2000 by Silicon Graphics
* Copyright (C) 2003 by Ralf Baechle
*/
#include <linux/init.h>
#include <linux/mm.h>
#include <asm/fixmap.h>
#include <asm/pgtable.h>
void pgd_init(unsigned long page)
{
unsigned long *p, *end;
p = (unsigned long *) page;
end = p + PTRS_PER_PGD;
while (p < end) {
p[0] = (unsigned long) invalid_pmd_table;
p[1] = (unsigned long) invalid_pmd_table;
p[2] = (unsigned long) invalid_pmd_table;
p[3] = (unsigned long) invalid_pmd_table;
p[4] = (unsigned long) invalid_pmd_table;
p[5] = (unsigned long) invalid_pmd_table;
p[6] = (unsigned long) invalid_pmd_table;
p[7] = (unsigned long) invalid_pmd_table;
p += 8;
}
}
void pmd_init(unsigned long addr, unsigned long pagetable)
{
unsigned long *p, *end;
p = (unsigned long *) addr;
end = p + PTRS_PER_PMD;
while (p < end) {
p[0] = (unsigned long)pagetable;
p[1] = (unsigned long)pagetable;
p[2] = (unsigned long)pagetable;
p[3] = (unsigned long)pagetable;
p[4] = (unsigned long)pagetable;
p[5] = (unsigned long)pagetable;
p[6] = (unsigned long)pagetable;
p[7] = (unsigned long)pagetable;
p += 8;
}
}
void __init pagetable_init(void)
{
unsigned long vaddr;
pgd_t *pgd_base;
/* Initialize the entire pgd. */
pgd_init((unsigned long)swapper_pg_dir);
pmd_init((unsigned long)invalid_pmd_table, (unsigned long)invalid_pte_table);
pgd_base = swapper_pg_dir;
/*
* Fixed mappings:
*/
vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
fixrange_init(vaddr, 0, pgd_base);
}