https://github.com/torvalds/linux
Revision ac53c4fca42c394d8a06c7a470ae2d1d50503717 authored by David Daney on 03 December 2012, 20:44:26 UTC, committed by Ralf Baechle on 04 December 2012, 15:57:54 UTC
Problem: 1) Huge page mapping of anonymous memory is initially invalid. Will be faulted in by copy-on-write mechanism. 2) Userspace attempts store at the end of the huge mapping. 3) TLB Refill exception handler fill TLB with a normal (4K sized) invalid page at the end of the huge mapping virtual address range. 4) Userspace restarted, and re-attempts the store at the end of the huge mapping. 5) Page from #3 is invalid, we get a fault and go to the hugepage fault handler. This tries to map a huge page and calls huge_ptep_set_access_flags() to install the mapping. 6) We just call the generic ptep_set_access_flags() to set up the page tables, but the flush there assumes a normal (4K sized) page and only tries to flush the first part of the huge page virtual address out of the TLB, since the existing entry from step #3 doesn't conflict, nothing is flushed. 7) We attempt to load the mapping into the TLB, but because it conflicts with the entry from step #3, we get a Machine Check exception. The fix: Flush the entire rage covered by the huge page in huge_ptep_set_access_flags(), and remove the optimization in local_flush_tlb_range() so that the flush actually does the correct thing. Signed-off-by: David Daney <david.daney@cavium.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: Hillf Danton <dhillf@gmail.com> Patchwork: https://patchwork.linux-mips.org/patch/4661/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> (cherry picked from commit dd617f258cc39d36be26afee9912624a2d23112c)
1 parent 9489e9d
Tip revision: ac53c4fca42c394d8a06c7a470ae2d1d50503717 authored by David Daney on 03 December 2012, 20:44:26 UTC
MIPS: Avoid mcheck by flushing page range in huge_ptep_set_access_flags()
MIPS: Avoid mcheck by flushing page range in huge_ptep_set_access_flags()
Tip revision: ac53c4f
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crypto | ||
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include | ||
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kernel | ||
lib | ||
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net | ||
samples | ||
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.mailmap | -rw-r--r-- | 4.4 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 92.8 KB |
Kbuild | -rw-r--r-- | 2.5 KB |
Kconfig | -rw-r--r-- | 252 bytes |
MAINTAINERS | -rw-r--r-- | 224.8 KB |
Makefile | -rw-r--r-- | 46.6 KB |
README | -rw-r--r-- | 18.2 KB |
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