forked from Minki/linux
93fab1b22e
Patch series "Generic page walk and ptdump", v17. Many architectures current have a debugfs file for dumping the kernel page tables. Currently each architecture has to implement custom functions for this because the details of walking the page tables used by the kernel are different between architectures. This series extends the capabilities of walk_page_range() so that it can deal with the page tables of the kernel (which have no VMAs and can contain larger huge pages than exist for user space). A generic PTDUMP implementation is the implemented making use of the new functionality of walk_page_range() and finally arm64 and x86 are switch to using it, removing the custom table walkers. To enable a generic page table walker to walk the unusual mappings of the kernel we need to implement a set of functions which let us know when the walker has reached the leaf entry. After a suggestion from Will Deacon I've chosen the name p?d_leaf() as this (hopefully) describes the purpose (and is a new name so has no historic baggage). Some architectures have p?d_large macros but this is easily confused with "large pages". This series ends with a generic PTDUMP implemention for arm64 and x86. Mostly this is a clean up and there should be very little functional change. The exceptions are: * arm64 PTDUMP debugfs now displays pages which aren't present (patch 22). * arm64 has the ability to efficiently process KASAN pages (which previously only x86 implemented). This means that the combination of KASAN and DEBUG_WX is now useable. This patch (of 23): Exposing the pud/pgd levels of the page tables to walk_page_range() means we may come across the exotic large mappings that come with large areas of contiguous memory (such as the kernel's linear map). For architectures that don't provide all p?d_leaf() macros, provide generic do nothing default that are suitable where there cannot be leaf pages at that level. Futher patches will add implementations for individual architectures. The name p?d_leaf() is chosen to minimize the confusion with existing uses of "large" pages and "huge" pages which do not necessary mean that the entry is a leaf (for example it may be a set of contiguous entries that only take 1 TLB slot). For the purpose of walking the page tables we don't need to know how it will be represented in the TLB, but we do need to know for sure if it is a leaf of the tree. Link: http://lkml.kernel.org/r/20191218162402.45610-2-steven.price@arm.com Signed-off-by: Steven Price <steven.price@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morse <james.morse@arm.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Liang, Kan" <kan.liang@linux.intel.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexandre Ghiti <alex@ghiti.fr> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: James Hogan <jhogan@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Burton <paul.burton@mips.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Zong Li <zong.li@sifive.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| linux | ||
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