Peter and myself spent quite some time to figure out how to make CPUs cope with a RO mapped LDT. While the initial trick of writing the ACCESS bit in a special fault handler covers most cases, the tricky problem of CS/SS in return to user space (IRET ...) was giving us quite some headache. Peter finally found a way to do so. Touching the CS/SS selectors with LAR on the way out to user space makes it work w/o trouble. Contrary to the approach Andy was taking with storing the LDT in a special map area, the following series uses a special mapping which is mapped without the user bit and read only. This just ties the LDT to the process which is the most natural way to do it, removes the requirement for special pagetable code and works independent of pagetable isolation. This was tested on quite a range of Intel and AMD machines, but the test coverage on 32bit is quite meager. I'll resurrect a few dust bricks tomorrow. The patch series also includes an updated version of the: do not inherit LDT on exec changes. There are some extensions to the VMA code, which need scrunity of the mm folks. Thanks, tglx --- arch/powerpc/include/asm/mmu_context.h | 5 arch/powerpc/platforms/Kconfig.cputype | 1 arch/s390/Kconfig | 1 arch/x86/entry/common.c | 8 arch/x86/include/asm/desc.h | 2 arch/x86/include/asm/mmu.h | 7 arch/x86/include/asm/thread_info.h | 4 arch/x86/include/uapi/asm/mman.h | 4 arch/x86/kernel/cpu/common.c | 4 arch/x86/kernel/ldt.c | 573 ++++++++++++++++++++++------- arch/x86/mm/fault.c | 19 arch/x86/mm/tlb.c | 2 arch/x86/power/cpu.c | 2 b/arch/um/include/asm/mmu_context.h | 3 b/arch/unicore32/include/asm/mmu_context.h | 5 b/arch/x86/include/asm/mmu_context.h | 93 +++- b/include/linux/mman.h | 4 include/asm-generic/mm_hooks.h | 5 include/linux/mm.h | 21 - include/linux/mm_types.h | 3 kernel/fork.c | 3 mm/internal.h | 2 mm/mmap.c | 16 tools/testing/selftests/x86/ldt_gdt.c | 83 +++- 24 files changed, 673 insertions(+), 197 deletions(-) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
