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sh: Handle fixmap TLB eviction more coherently.

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There was a race in the kmap_coherent() implementation. While we
guarded against preemption, there was nothing preventing eviction of
the pre-faulted fixmap entry from the UTLB. Under certain workloads
this would result in the fixmap entries used for cache colouring being
evicted from the UTLB in the midst of a copy_page().

In addition to pre-faulting, we also make sure to preserve the PTEs
in the kernel page table and introduce a cached PTE for kmap_coherent()
usage. This follows a similar change on MIPS ("[MIPS] Fix aliasing bug
in copy_to_user_page / copy_from_user_page").

Reported-by: Hideo Saito <saito@densan.co.jp>
Reported-by: CHIKAMA Masaki <masaki.chikama@gmail.com>
Tested-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Paul Mundt 2008-11-10 20:00:45 +09:00
parent f7160c7573
commit acca4f4d9b
3 changed files with 32 additions and 3 deletions
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6
arch/sh/include/asm/pgtable.h
View file

@ -148,6 +148,12 @@ extern void paging_init(void);
extern void page_table_range_init(unsigned long start, unsigned long end,
pgd_t *pgd);
#if !defined(CONFIG_CACHE_OFF) && defined(CONFIG_CPU_SH4) && defined(CONFIG_MMU)
extern void kmap_coherent_init(void);
#else
#define kmap_coherent_init() do { } while (0)
#endif
#include <asm-generic/pgtable.h>
#endif /* __ASM_SH_PGTABLE_H */

12
arch/sh/mm/init.c
View file

@ -137,6 +137,7 @@ void __init page_table_range_init(unsigned long start, unsigned long end,
void __init paging_init(void)
{
unsigned long max_zone_pfns[MAX_NR_ZONES];
unsigned long vaddr;
int nid;
/* We don't need to map the kernel through the TLB, as
@ -148,10 +149,15 @@ void __init paging_init(void)
* check for a null value. */
set_TTB(swapper_pg_dir);
/* Populate the relevant portions of swapper_pg_dir so that
/*
* Populate the relevant portions of swapper_pg_dir so that
* we can use the fixmap entries without calling kmalloc.
* pte's will be filled in by __set_fixmap(). */
page_table_range_init(FIXADDR_START, FIXADDR_TOP, swapper_pg_dir);
* pte's will be filled in by __set_fixmap().
*/
vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
page_table_range_init(vaddr, 0, swapper_pg_dir);
kmap_coherent_init();
memset(max_zone_pfns, 0, sizeof(max_zone_pfns));

17
arch/sh/mm/pg-sh4.c
View file

@ -7,6 +7,7 @@
* Released under the terms of the GNU GPL v2.0.
*/
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <linux/highmem.h>
@ -16,6 +17,20 @@
#define CACHE_ALIAS (current_cpu_data.dcache.alias_mask)
#define kmap_get_fixmap_pte(vaddr) \
pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), (vaddr))
static pte_t *kmap_coherent_pte;
void __init kmap_coherent_init(void)
{
unsigned long vaddr;
/* cache the first coherent kmap pte */
vaddr = __fix_to_virt(FIX_CMAP_BEGIN);
kmap_coherent_pte = kmap_get_fixmap_pte(vaddr);
}
static inline void *kmap_coherent(struct page *page, unsigned long addr)
{
enum fixed_addresses idx;
@ -34,6 +49,8 @@ static inline void *kmap_coherent(struct page *page, unsigned long addr)
update_mmu_cache(NULL, vaddr, pte);
set_pte(kmap_coherent_pte - (FIX_CMAP_END - idx), pte);
return (void *)vaddr;
}