arch/tile: don't wait for migrating PTEs in an NMI handler
Doing so raises the possibility of self-deadlock if we are waiting for a backtrace for an oprofile or perf interrupt while we are in the middle of migrating our own stack page. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
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@ -203,9 +203,14 @@ static pgd_t *get_current_pgd(void)
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* interrupt or a critical region, and must do as little as possible.
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* Similarly, we can't use atomic ops here, since we may be handling a
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* fault caused by an atomic op access.
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*
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* If we find a migrating PTE while we're in an NMI context, and we're
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* at a PC that has a registered exception handler, we don't wait,
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* since this thread may (e.g.) have been interrupted while migrating
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* its own stack, which would then cause us to self-deadlock.
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*/
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static int handle_migrating_pte(pgd_t *pgd, int fault_num,
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unsigned long address,
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unsigned long address, unsigned long pc,
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int is_kernel_mode, int write)
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{
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pud_t *pud;
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@ -227,6 +232,8 @@ static int handle_migrating_pte(pgd_t *pgd, int fault_num,
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pte_offset_kernel(pmd, address);
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pteval = *pte;
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if (pte_migrating(pteval)) {
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if (in_nmi() && search_exception_tables(pc))
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return 0;
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wait_for_migration(pte);
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return 1;
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}
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@ -300,7 +307,7 @@ static int handle_page_fault(struct pt_regs *regs,
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* rather than trying to patch up the existing PTE.
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*/
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pgd = get_current_pgd();
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if (handle_migrating_pte(pgd, fault_num, address,
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if (handle_migrating_pte(pgd, fault_num, address, regs->pc,
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is_kernel_mode, write))
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return 1;
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@ -665,7 +672,7 @@ struct intvec_state do_page_fault_ics(struct pt_regs *regs, int fault_num,
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*/
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if (fault_num == INT_DTLB_ACCESS)
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write = 1;
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if (handle_migrating_pte(pgd, fault_num, address, 1, write))
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if (handle_migrating_pte(pgd, fault_num, address, pc, 1, write))
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return state;
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/* Return zero so that we continue on with normal fault handling. */
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