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path: root/include/asm-alpha/pgtable.h
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2008-05-14fix SMP data race in pagetable setup vs walkingNick Piggin
There is a possible data race in the page table walking code. After the split ptlock patches, it actually seems to have been introduced to the core code, but even before that I think it would have impacted some architectures (powerpc and sparc64, at least, walk the page tables without taking locks eg. see find_linux_pte()). The race is as follows: The pte page is allocated, zeroed, and its struct page gets its spinlock initialized. The mm-wide ptl is then taken, and then the pte page is inserted into the pagetables. At this point, the spinlock is not guaranteed to have ordered the previous stores to initialize the pte page with the subsequent store to put it in the page tables. So another Linux page table walker might be walking down (without any locks, because we have split-leaf-ptls), and find that new pte we've inserted. It might try to take the spinlock before the store from the other CPU initializes it. And subsequently it might read a pte_t out before stores from the other CPU have cleared the memory. There are also similar races in higher levels of the page tables. They obviously don't involve the spinlock, but could see uninitialized memory. Arch code and hardware pagetable walkers that walk the pagetables without locks could see similar uninitialized memory problems, regardless of whether split ptes are enabled or not. I prefer to put the barriers in core code, because that's where the higher level logic happens, but the page table accessors are per-arch, and open-coding them everywhere I don't think is an option. I'll put the read-side barriers in alpha arch code for now (other architectures perform data-dependent loads in order). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28mm: introduce pte_special pte bitNick Piggin
s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory model (which is more dynamic than most). Instead, they had proposed to implement it with an additional path through vm_normal_page(), using a bit in the pte to determine whether or not the page should be refcounted: vm_normal_page() { ... if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { if (vma->vm_flags & VM_MIXEDMAP) { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; #else if (!pfn_valid(pfn)) return NULL; #endif goto out; } ... } This is fine, however if we are allowed to use a bit in the pte to determine refcountedness, we can use that to _completely_ replace all the vma based schemes. So instead of adding more cases to the already complex vma-based scheme, we can have a clearly seperate and simple pte-based scheme (and get slightly better code generation in the process): vm_normal_page() { #ifdef s390 if (!mixedmap_refcount_pte(pte)) return NULL; return pte_page(pte); #else ... #endif } And finally, we may rather make this concept usable by any architecture rather than making it s390 only, so implement a new type of pte state for this. Unfortunately the old vma based code must stay, because some architectures may not be able to spare pte bits. This makes vm_normal_page a little bit more ugly than we would like, but the 2 cases are clearly seperate. So introduce a pte_special pte state, and use it in mm/memory.c. It is currently a noop for all architectures, so this doesn't actually result in any compiled code changes to mm/memory.o. BTW: I haven't put vm_normal_page() into arch code as-per an earlier suggestion. The reason is that, regardless of where vm_normal_page is actually implemented, the *abstraction* is still exactly the same. Also, while it depends on whether the architecture has pte_special or not, that is the only two possible cases, and it really isn't an arch specific function -- the role of the arch code should be to provide primitive functions and accessors with which to build the core code; pte_special does that. We do not want architectures to know or care about vm_normal_page itself, and we definitely don't want them being able to invent something new there out of sight of mm/ code. If we made vm_normal_page an arch function, then we have to make vm_insert_mixed (next patch) an arch function too. So I don't think moving it to arch code fundamentally improves any abstractions, while it does practically make the code more difficult to follow, for both mm and arch developers, and easier to misuse. [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Carsten Otte <cotte@de.ibm.com> Cc: Jared Hulbert <jaredeh@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16page table handling cleanupJan Beulich
Kill pte_rdprotect(), pte_exprotect(), pte_mkread(), pte_mkexec(), pte_read(), pte_exec(), and pte_user() except where arch-specific code is making use of them. Signed-off-by: Jan Beulich <jbeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08Clean up mostly unused IOSPACE macrosDavid Gibson
Most architectures defined three macros, MK_IOSPACE_PFN(), GET_IOSPACE() and GET_PFN() in pgtable.h. However, the only callers of any of these macros are in Sparc specific code, either in arch/sparc, arch/sparc64 or drivers/sbus. This patch removes the redundant macros from all architectures except sparc and sparc64. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-09-26[PATCH] Standardize pxx_page macrosDave McCracken
One of the changes necessary for shared page tables is to standardize the pxx_page macros. pte_page and pmd_page have always returned the struct page associated with their entry, while pte_page_kernel and pmd_page_kernel have returned the kernel virtual address. pud_page and pgd_page, on the other hand, return the kernel virtual address. Shared page tables needs pud_page and pgd_page to return the actual page structures. There are very few actual users of these functions, so it is simple to standardize their usage. Since this is basic cleanup, I am submitting these changes as a standalone patch. Per Hugh Dickins' comments about it, I am also changing the pxx_page_kernel macros to pxx_page_vaddr to clarify their meaning. Signed-off-by: Dave McCracken <dmccr@us.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-26Don't include linux/config.h from anywhere else in include/David Woodhouse
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-11-07[PATCH] fix remaining missing includesTim Schmielau
Fix more include file problems that surfaced since I submitted the previous fix-missing-includes.patch. This should now allow not to include sched.h from module.h, which is done by a followup patch. Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-13[PATCH] feature removal of io_remap_page_range()Randy Dunlap
As written in Documentation/feature-removal-schedule.txt, remove the io_remap_page_range() kernel API. Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-12[PATCH] alpha: pgprot_uncached() commentAndrew Morton
Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-07[PATCH] alpha(): pgprot_noncachedAndrew Morton
The infiniband code expects that the arch implements pgprot_noncached(). We're mapping PCI areas anyway, so this probabyl wasn't needed and we should make infiniband stop doing that.. Cc: Roland Dreier <rolandd@cisco.com> Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-19[PATCH] freepgt: arch FIRST_USER_ADDRESS 0Hugh Dickins
Replace misleading definition of FIRST_USER_PGD_NR 0 by definition of FIRST_USER_ADDRESS 0 in all the MMU architectures beyond arm and arm26. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!