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Subject[PATCH 1/9] mm: i386 sh sh64 ready for split ptlock
Use pte_offset_map_lock, instead of pte_offset_map (or inappropriate
pte_offset_kernel) and mm-wide page_table_lock, in sundry arch places.

The i386 vm86 mark_screen_rdonly: yes, there was and is an assumption
that the screen fits inside the one page table, as indeed it does.

The sh __do_page_fault: which handles both kernel faults (without lock)
and user mm faults (locked - though it set_pte without locking before).

The sh64 flush_cache_range and helpers: which wrongly thought callers
held page_table_lock before (only its tlb_start_vma did, and no longer
does so); moved the flush loop down, and adjusted the large versus small
range decision to consider a range which spans page tables as large.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
---
arch/i386/kernel/vm86.c | 17 +++++-------
arch/sh/mm/fault.c | 40 ++++++++++++++++-------------
arch/sh64/mm/cache.c | 66 +++++++++++++++++++++---------------------------
3 files changed, 59 insertions(+), 64 deletions(-)
--- mm0/arch/i386/kernel/vm86.c 2005-10-17 12:05:09.000000000 +0100
+++ mm1/arch/i386/kernel/vm86.c 2005-10-22 14:06:01.000000000 +0100
@@ -134,17 +134,16 @@ struct pt_regs * fastcall save_v86_state
return ret;
}

-static void mark_screen_rdonly(struct task_struct * tsk)
+static void mark_screen_rdonly(struct mm_struct *mm)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
- pte_t *pte, *mapped;
+ pte_t *pte;
+ spinlock_t *ptl;
int i;

- preempt_disable();
- spin_lock(&tsk->mm->page_table_lock);
- pgd = pgd_offset(tsk->mm, 0xA0000);
+ pgd = pgd_offset(mm, 0xA0000);
if (pgd_none_or_clear_bad(pgd))
goto out;
pud = pud_offset(pgd, 0xA0000);
@@ -153,16 +152,14 @@ static void mark_screen_rdonly(struct ta
pmd = pmd_offset(pud, 0xA0000);
if (pmd_none_or_clear_bad(pmd))
goto out;
- pte = mapped = pte_offset_map(pmd, 0xA0000);
+ pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
for (i = 0; i < 32; i++) {
if (pte_present(*pte))
set_pte(pte, pte_wrprotect(*pte));
pte++;
}
- pte_unmap(mapped);
+ pte_unmap_unlock(pte, ptl);
out:
- spin_unlock(&tsk->mm->page_table_lock);
- preempt_enable();
flush_tlb();
}

@@ -306,7 +303,7 @@ static void do_sys_vm86(struct kernel_vm

tsk->thread.screen_bitmap = info->screen_bitmap;
if (info->flags & VM86_SCREEN_BITMAP)
- mark_screen_rdonly(tsk);
+ mark_screen_rdonly(tsk->mm);
__asm__ __volatile__(
"xorl %%eax,%%eax; movl %%eax,%%fs; movl %%eax,%%gs\n\t"
"movl %0,%%esp\n\t"
--- mm0/arch/sh/mm/fault.c 2004-10-18 22:56:27.000000000 +0100
+++ mm1/arch/sh/mm/fault.c 2005-10-22 14:06:01.000000000 +0100
@@ -194,10 +194,13 @@ asmlinkage int __do_page_fault(struct pt
unsigned long address)
{
unsigned long addrmax = P4SEG;
- pgd_t *dir;
+ pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
pte_t entry;
+ struct mm_struct *mm;
+ spinlock_t *ptl;
+ int ret = 1;

#ifdef CONFIG_SH_KGDB
if (kgdb_nofault && kgdb_bus_err_hook)
@@ -208,28 +211,28 @@ asmlinkage int __do_page_fault(struct pt
addrmax = P4SEG_STORE_QUE + 0x04000000;
#endif

- if (address >= P3SEG && address < addrmax)
- dir = pgd_offset_k(address);
- else if (address >= TASK_SIZE)
+ if (address >= P3SEG && address < addrmax) {
+ pgd = pgd_offset_k(address);
+ mm = NULL;
+ } else if (address >= TASK_SIZE)
return 1;
- else if (!current->mm)
+ else if (!(mm = current->mm))
return 1;
else
- dir = pgd_offset(current->mm, address);
+ pgd = pgd_offset(mm, address);

- pmd = pmd_offset(dir, address);
- if (pmd_none(*pmd))
+ pmd = pmd_offset(pgd, address);
+ if (pmd_none_or_clear_bad(pmd))
return 1;
- if (pmd_bad(*pmd)) {
- pmd_ERROR(*pmd);
- pmd_clear(pmd);
- return 1;
- }
- pte = pte_offset_kernel(pmd, address);
+ if (mm)
+ pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+ else
+ pte = pte_offset_kernel(pmd, address);
+
entry = *pte;
if (pte_none(entry) || pte_not_present(entry)
|| (writeaccess && !pte_write(entry)))
- return 1;
+ goto unlock;

if (writeaccess)
entry = pte_mkdirty(entry);
@@ -251,8 +254,11 @@ asmlinkage int __do_page_fault(struct pt

set_pte(pte, entry);
update_mmu_cache(NULL, address, entry);
-
- return 0;
+ ret = 0;
+unlock:
+ if (mm)
+ pte_unmap_unlock(pte, ptl);
+ return ret;
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
--- mm0/arch/sh64/mm/cache.c 2005-06-17 20:48:29.000000000 +0100
+++ mm1/arch/sh64/mm/cache.c 2005-10-22 14:06:01.000000000 +0100
@@ -584,32 +584,36 @@ static void sh64_dcache_purge_phy_page(u
}
}

-static void sh64_dcache_purge_user_page(struct mm_struct *mm, unsigned long eaddr)
+static void sh64_dcache_purge_user_pages(struct mm_struct *mm,
+ unsigned long addr, unsigned long end)
{
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
pte_t entry;
+ spinlock_t *ptl;
unsigned long paddr;

- /* NOTE : all the callers of this have mm->page_table_lock held, so the
- following page table traversal is safe even on SMP/pre-emptible. */
-
- if (!mm) return; /* No way to find physical address of page */
- pgd = pgd_offset(mm, eaddr);
- if (pgd_bad(*pgd)) return;
-
- pmd = pmd_offset(pgd, eaddr);
- if (pmd_none(*pmd) || pmd_bad(*pmd)) return;
-
- pte = pte_offset_kernel(pmd, eaddr);
- entry = *pte;
- if (pte_none(entry) || !pte_present(entry)) return;
-
- paddr = pte_val(entry) & PAGE_MASK;
-
- sh64_dcache_purge_coloured_phy_page(paddr, eaddr);
+ if (!mm)
+ return; /* No way to find physical address of page */

+ pgd = pgd_offset(mm, addr);
+ if (pgd_bad(*pgd))
+ return;
+
+ pmd = pmd_offset(pgd, addr);
+ if (pmd_none(*pmd) || pmd_bad(*pmd))
+ return;
+
+ pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ do {
+ entry = *pte;
+ if (pte_none(entry) || !pte_present(entry))
+ continue;
+ paddr = pte_val(entry) & PAGE_MASK;
+ sh64_dcache_purge_coloured_phy_page(paddr, addr);
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+ pte_unmap_unlock(pte - 1, ptl);
}
/****************************************************************************/

@@ -668,7 +672,7 @@ static void sh64_dcache_purge_user_range
int n_pages;

n_pages = ((end - start) >> PAGE_SHIFT);
- if (n_pages >= 64) {
+ if (n_pages >= 64 || ((start ^ (end - 1)) & PMD_MASK)) {
#if 1
sh64_dcache_purge_all();
#else
@@ -707,20 +711,10 @@ static void sh64_dcache_purge_user_range
}
#endif
} else {
- /* 'Small' range */
- unsigned long aligned_start;
- unsigned long eaddr;
- unsigned long last_page_start;
-
- aligned_start = start & PAGE_MASK;
- /* 'end' is 1 byte beyond the end of the range */
- last_page_start = (end - 1) & PAGE_MASK;
-
- eaddr = aligned_start;
- while (eaddr <= last_page_start) {
- sh64_dcache_purge_user_page(mm, eaddr);
- eaddr += PAGE_SIZE;
- }
+ /* Small range, covered by a single page table page */
+ start &= PAGE_MASK; /* should already be so */
+ end = PAGE_ALIGN(end); /* should already be so */
+ sh64_dcache_purge_user_pages(mm, start, end);
}
return;
}
@@ -880,9 +874,7 @@ void flush_cache_range(struct vm_area_st
addresses from the user address space specified by mm, after writing
back any dirty data.

- Note(1), 'end' is 1 byte beyond the end of the range to flush.
-
- Note(2), this is called with mm->page_table_lock held.*/
+ Note, 'end' is 1 byte beyond the end of the range to flush. */

sh64_dcache_purge_user_range(mm, start, end);
sh64_icache_inv_user_page_range(mm, start, end);
@@ -898,7 +890,7 @@ void flush_cache_page(struct vm_area_str
the I-cache must be searched too in case the page in question is
both writable and being executed from (e.g. stack trampolines.)

- Note(1), this is called with mm->page_table_lock held.
+ Note, this is called with pte lock held.
*/

sh64_dcache_purge_phy_page(pfn << PAGE_SHIFT);
-
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