Commit-ID: ebc8827f75954fe315492883eee5cb3f355d547d Gitweb: http://git.kernel.org/tip/ebc8827f75954fe315492883eee5cb3f355d547d Author: Frederic Weisbecker <fweisbec@xxxxxxxxx> AuthorDate: Mon, 27 Sep 2010 18:50:51 +0200 Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx> CommitDate: Thu, 14 Oct 2010 20:43:36 +0200 x86: Barf when vmalloc and kmemcheck faults happen in NMI In x86, faults exit by executing the iret instruction, which then reenables NMIs if we faulted in NMI context. Then if a fault happens in NMI, another NMI can nest after the fault exits. But we don't yet support nested NMIs because we have only one NMI stack. To prevent from that, check that vmalloc and kmemcheck faults don't happen in this context. Most of the other kernel faults in NMIs can be more easily spotted by finding explicit copy_from,to_user() calls on review. Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> --- arch/x86/mm/fault.c | 4 ++++ arch/x86/mm/kmemcheck/kmemcheck.c | 2 ++ 2 files changed, 6 insertions(+), 0 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 4c4508e..a24c6cf 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -251,6 +251,8 @@ static noinline __kprobes int vmalloc_fault(unsigned long address) if (!(address >= VMALLOC_START && address < VMALLOC_END)) return -1; + WARN_ON_ONCE(in_nmi()); + /* * Synchronize this task's top level page-table * with the 'reference' page table. @@ -369,6 +371,8 @@ static noinline __kprobes int vmalloc_fault(unsigned long address) if (!(address >= VMALLOC_START && address < VMALLOC_END)) return -1; + WARN_ON_ONCE(in_nmi()); + /* * Copy kernel mappings over when needed. This can also * happen within a race in page table update. In the later diff --git a/arch/x86/mm/kmemcheck/kmemcheck.c b/arch/x86/mm/kmemcheck/kmemcheck.c index b3b531a..d87dd6d 100644 --- a/arch/x86/mm/kmemcheck/kmemcheck.c +++ b/arch/x86/mm/kmemcheck/kmemcheck.c @@ -631,6 +631,8 @@ bool kmemcheck_fault(struct pt_regs *regs, unsigned long address, if (!pte) return false; + WARN_ON_ONCE(in_nmi()); + if (error_code & 2) kmemcheck_access(regs, address, KMEMCHECK_WRITE); else -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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