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authorJeff Dike <jdike@addtoit.com>2008-02-05 01:31:01 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 12:44:29 -0500
commit3963333fe6767f15141ab2dc3b933721c636c212 (patch)
tree62fbec62adf1796709dfa197e12dd725911e0fc9 /arch/um/kernel/tlb.c
parent42a2b54ce8c7b9d4f418995a7950e7e2e15e52ce (diff)
uml: cover stubs with a VMA
Give the stubs a VMA. This allows the removal of a truly nasty kludge to make sure that mm->nr_ptes was correct in exit_mmap. The underlying problem was always that the stubs, which have ptes, and thus allocated a page table, weren't covered by a VMA. This patch fixes that by using install_special_mapping in arch_dup_mmap and activate_context to create the VMA. The stubs have to be moved, since shift_arg_pages seems to assume that the stack is the only VMA present at that point during exec, and uses vma_adjust to fiddle its VMA. However, that extends the stub VMA by the amount removed from the stack VMA. To avoid this problem, the stubs were moved to a different fixed location at the start of the address space. The init_stub_pte calls were moved from init_new_context to arch_dup_mmap because I was occasionally seeing arch_dup_mmap not being called, causing exit_mmap to die. Rather than figure out what was really happening, I decided it was cleaner to just move the calls so that there's no doubt that both the pte and VMA creation happen, no matter what. arch_exit_mmap is used to clear the stub ptes at exit time. The STUB_* constants in as-layout.h no longer depend on UM_TASK_SIZE, that that definition is removed, along with the comments complaining about gcc. Because the stubs are no longer at the top of the address space, some care is needed while flushing TLBs. update_pte_range checks for addresses in the stub range and skips them. flush_thread now issues two unmaps, one for the range before STUB_START and one for the range after STUB_END. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um/kernel/tlb.c')
-rw-r--r--arch/um/kernel/tlb.c11
1 files changed, 4 insertions, 7 deletions
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 429fed2f66b2..ef5a2a20d351 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -184,6 +184,9 @@ static inline int update_pte_range(pmd_t *pmd, unsigned long addr,
184 184
185 pte = pte_offset_kernel(pmd, addr); 185 pte = pte_offset_kernel(pmd, addr);
186 do { 186 do {
187 if ((addr >= STUB_START) && (addr < STUB_END))
188 continue;
189
187 r = pte_read(*pte); 190 r = pte_read(*pte);
188 w = pte_write(*pte); 191 w = pte_write(*pte);
189 x = pte_exec(*pte); 192 x = pte_exec(*pte);
@@ -486,9 +489,6 @@ void __flush_tlb_one(unsigned long addr)
486static void fix_range(struct mm_struct *mm, unsigned long start_addr, 489static void fix_range(struct mm_struct *mm, unsigned long start_addr,
487 unsigned long end_addr, int force) 490 unsigned long end_addr, int force)
488{ 491{
489 if (!proc_mm && (end_addr > STUB_START))
490 end_addr = STUB_START;
491
492 fix_range_common(mm, start_addr, end_addr, force); 492 fix_range_common(mm, start_addr, end_addr, force);
493} 493}
494 494
@@ -502,8 +502,6 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
502 502
503void flush_tlb_mm(struct mm_struct *mm) 503void flush_tlb_mm(struct mm_struct *mm)
504{ 504{
505 unsigned long end;
506
507 /* 505 /*
508 * Don't bother flushing if this address space is about to be 506 * Don't bother flushing if this address space is about to be
509 * destroyed. 507 * destroyed.
@@ -511,8 +509,7 @@ void flush_tlb_mm(struct mm_struct *mm)
511 if (atomic_read(&mm->mm_users) == 0) 509 if (atomic_read(&mm->mm_users) == 0)
512 return; 510 return;
513 511
514 end = proc_mm ? TASK_SIZE : STUB_START; 512 fix_range(mm, 0, TASK_SIZE, 0);
515 fix_range(mm, 0, end, 0);
516} 513}
517 514
518void force_flush_all(void) 515void force_flush_all(void)