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s390/pageattr: do a single TLB flush for change_page_attr
The change of the access rights for an address range in the kernel address space is currently done with a loop of IPTE + a store of the modified PTE. Between the IPTE and the store the PTE will be invalid, this intermediate state can cause problems with concurrent accesses. Consider a change of a kernel area from read-write to read-only, a concurrent reader of that area should be fine but with the invalid PTE it might get an unexpected exception. Remove the IPTEs for each PTE and do a global flush after all PTEs have been modified. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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1 changed files with 3 additions and 5 deletions
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@ -65,19 +65,17 @@ static pte_t *walk_page_table(unsigned long addr)
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static void change_page_attr(unsigned long addr, int numpages,
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pte_t (*set) (pte_t))
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{
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pte_t *ptep, pte;
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pte_t *ptep;
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int i;
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for (i = 0; i < numpages; i++) {
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ptep = walk_page_table(addr);
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if (WARN_ON_ONCE(!ptep))
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break;
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pte = *ptep;
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pte = set(pte);
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__ptep_ipte(addr, ptep);
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*ptep = pte;
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*ptep = set(*ptep);
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addr += PAGE_SIZE;
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}
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__tlb_flush_kernel();
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}
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int set_memory_ro(unsigned long addr, int numpages)
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