Messages in this thread Patch in this message | | | Subject | [patch 24/39] remap_file_pages protection support: adapt to uml peculiarities | From | blaisorblade@yahoo ... | Date | Fri, 12 Aug 2005 20:35:57 +0200 |
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From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Uml is particular in respect with other architectures (and possibly this is to fix) in the fact that our arch fault handler handles indifferently both TLB and page faults. In particular, we may get to call handle_mm_fault() when the PTE is already correct, but simply it's not flushed.
And rfp-fault-sigsegv-2 breaks this, because when getting a fault on a pte_present PTE and non-uniform VMA, it assumes the fault is due to a protection fault, and signals the caller a SIGSEGV must be sent.
This isn't the final fix for UML, that's the next one.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> ---
linux-2.6.git-paolo/arch/um/kernel/trap_kern.c | 19 +++++++++++++++---- 1 files changed, 15 insertions(+), 4 deletions(-)
diff -puN arch/um/kernel/trap_kern.c~rfp-sigsegv-uml-3 arch/um/kernel/trap_kern.c --- linux-2.6.git/arch/um/kernel/trap_kern.c~rfp-sigsegv-uml-3 2005-08-11 23:13:06.000000000 +0200 +++ linux-2.6.git-paolo/arch/um/kernel/trap_kern.c 2005-08-11 23:14:26.000000000 +0200 @@ -75,8 +75,21 @@ handle_fault: err = -EACCES; goto out; case VM_FAULT_SIGSEGV: - err = -EFAULT; - goto out; + /* Duplicate this code here. */ + pgd = pgd_offset(mm, address); + pud = pud_offset(pgd, address); + pmd = pmd_offset(pud, address); + pte = pte_offset_kernel(pmd, address); + if (likely (pte_newpage(*pte) || pte_newprot(*pte))) { + /* This wasn't done by __handle_mm_fault(), and + * the page hadn't been flushed. */ + *pte = pte_mkyoung(*pte); + if(pte_write(*pte)) *pte = pte_mkdirty(*pte); + break; + } else { + err = -EFAULT; + goto out; + } case VM_FAULT_OOM: err = -ENOMEM; goto out_of_memory; @@ -89,8 +102,6 @@ handle_fault: pte = pte_offset_kernel(pmd, address); } while(!pte_present(*pte)); err = 0; - *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 _ - 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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