Messages in this thread Patch in this message | | | Subject | [patch 22/39] remap file pages protection support: use FAULT_SIGSEGV for protection checking, uml bits | From | blaisorblade@yahoo ... | Date | Fri, 12 Aug 2005 19:32:30 +0200 |
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From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
This adapts the changes to the i386 handler to the UML one. It isn't enough to make UML work, however, because UML has some peculiarities. Subsequent patches fix this.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> ---
linux-2.6.git-paolo/arch/um/kernel/trap_kern.c | 32 +++++++++++++++++++++---- 1 files changed, 27 insertions(+), 5 deletions(-)
diff -puN arch/um/kernel/trap_kern.c~rfp-fault-sigsegv-2-uml arch/um/kernel/trap_kern.c --- linux-2.6.git/arch/um/kernel/trap_kern.c~rfp-fault-sigsegv-2-uml 2005-08-11 23:09:32.000000000 +0200 +++ linux-2.6.git-paolo/arch/um/kernel/trap_kern.c 2005-08-11 23:09:32.000000000 +0200 @@ -37,6 +37,7 @@ int handle_page_fault(unsigned long addr pmd_t *pmd; pte_t *pte; int err = -EFAULT; + int access_mask = 0; *code_out = SEGV_MAPERR; down_read(&mm->mmap_sem); @@ -55,14 +56,15 @@ int handle_page_fault(unsigned long addr good_area: *code_out = SEGV_ACCERR; if(is_write && !(vma->vm_flags & VM_WRITE)) - goto out; + goto prot_bad; if(!(vma->vm_flags & (VM_READ | VM_EXEC))) - goto out; + goto prot_bad; + access_mask = is_write ? VM_WRITE : 0; do { -survive: - switch (handle_mm_fault(mm, vma, address, is_write)){ +handle_fault: + switch (__handle_mm_fault(mm, vma, address, access_mask)) { case VM_FAULT_MINOR: current->min_flt++; break; @@ -72,6 +74,9 @@ survive: case VM_FAULT_SIGBUS: err = -EACCES; goto out; + case VM_FAULT_SIGSEGV: + err = -EFAULT; + goto out; case VM_FAULT_OOM: err = -ENOMEM; goto out_of_memory; @@ -87,10 +92,27 @@ survive: *pte = pte_mkyoung(*pte); if(pte_write(*pte)) *pte = pte_mkdirty(*pte); flush_tlb_page(vma, address); + + /* If the PTE is not present, the vma protection are not accurate if + * VM_NONUNIFORM; present PTE's are correct for VM_NONUNIFORM and were + * already handled otherwise. */ out: up_read(&mm->mmap_sem); return(err); +prot_bad: + if (unlikely(vma->vm_flags & VM_NONUNIFORM)) { + access_mask = is_write ? VM_WRITE : 0; + /* Otherwise, on a legitimate read fault on a page mapped as + * exec-only, we get problems. Probably, we should lower + * requirements... we should always test just + * pte_read/write/exec, on vma->vm_page_prot! This way is + * cumbersome. However, for now things should work for UML. */ + access_mask |= vma->vm_flags & VM_EXEC ? VM_EXEC : VM_READ; + goto handle_fault; + } + goto out; + /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. @@ -100,7 +122,7 @@ out_of_memory: up_read(&mm->mmap_sem); yield(); down_read(&mm->mmap_sem); - goto survive; + goto handle_fault; } goto out; } _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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