101f12af16
Registering a callback handler through register_die_notifier() is obviously
primarily intended for use by modules. However, the way these currently
get called it is basically impossible for them to actually be used by
modules, as there is, on non-PAE configurationes, a good chance (the larger
the module, the better) for the system to crash as a result.
This is because the callback gets invoked
(a) in the page fault path before the top level page table propagation
gets carried out (hence a fault to propagate the top level page table
entry/entries mapping to module's code/data would nest infinitly) and
(b) in the NMI path, where nested faults must absolutely not happen,
since otherwise the IRET from the nested fault re-enables NMIs,
potentially resulting in nested NMI occurences.
Besides the modular aspect, similar problems would even arise for in-
kernel consumers of the API if they touched ioremap()ed or vmalloc()ed
memory inside their handlers.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
66 lines
2 KiB
C
66 lines
2 KiB
C
#ifndef _I386_PGTABLE_2LEVEL_H
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#define _I386_PGTABLE_2LEVEL_H
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#include <asm-generic/pgtable-nopmd.h>
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#define pte_ERROR(e) \
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printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, (e).pte_low)
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#define pgd_ERROR(e) \
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printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
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/*
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* Certain architectures need to do special things when PTEs
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* within a page table are directly modified. Thus, the following
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* hook is made available.
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*/
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#define set_pte(pteptr, pteval) (*(pteptr) = pteval)
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#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
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#define set_pte_atomic(pteptr, pteval) set_pte(pteptr,pteval)
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#define set_pmd(pmdptr, pmdval) (*(pmdptr) = (pmdval))
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#define ptep_get_and_clear(mm,addr,xp) __pte(xchg(&(xp)->pte_low, 0))
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#define pte_same(a, b) ((a).pte_low == (b).pte_low)
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#define pte_page(x) pfn_to_page(pte_pfn(x))
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#define pte_none(x) (!(x).pte_low)
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#define pte_pfn(x) ((unsigned long)(((x).pte_low >> PAGE_SHIFT)))
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#define pfn_pte(pfn, prot) __pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
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#define pfn_pmd(pfn, prot) __pmd(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
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/*
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* All present user pages are user-executable:
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*/
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static inline int pte_exec(pte_t pte)
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{
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return pte_user(pte);
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}
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/*
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* All present pages are kernel-executable:
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*/
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static inline int pte_exec_kernel(pte_t pte)
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{
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return 1;
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}
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/*
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* Bits 0, 6 and 7 are taken, split up the 29 bits of offset
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* into this range:
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*/
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#define PTE_FILE_MAX_BITS 29
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#define pte_to_pgoff(pte) \
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((((pte).pte_low >> 1) & 0x1f ) + (((pte).pte_low >> 8) << 5 ))
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#define pgoff_to_pte(off) \
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((pte_t) { (((off) & 0x1f) << 1) + (((off) >> 5) << 8) + _PAGE_FILE })
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/* Encode and de-code a swap entry */
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#define __swp_type(x) (((x).val >> 1) & 0x1f)
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#define __swp_offset(x) ((x).val >> 8)
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#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 1) | ((offset) << 8) })
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#define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_low })
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#define __swp_entry_to_pte(x) ((pte_t) { (x).val })
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void vmalloc_sync_all(void);
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#endif /* _I386_PGTABLE_2LEVEL_H */
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