Memory protection keys enable applications to protect its address space from inadvertent access or corruption from itself. The overall idea: ----------------- A process allocates a key and associates it with an address range within its address space. The process then can dynamically set read/write permissions on the key without involving the kernel. Any code that violates the permissions of the address space; as defined by its associated key, will receive a segmentation fault. This patch series enables the feature on PPC64 HPTE platform. ISA3.0 section 5.7.13 describes the detailed specifications. Highlevel view of the design: --------------------------- When an application associates a key with a address address range, program the key in the Linux PTE. When the MMU detects a page fault, allocate a hash page and program the key into HPTE. And finally when the MMU detects a key violation; due to invalid application access, invoke the registered signal handler and provide the violated key number as well as the state of the key register (AMR), at the time it faulted. Testing: ------- This patch series has passed all the protection key tests available in the selftests directory.The tests are updated to work on both x86 and powerpc. Outstanding issues: ------------------- How will the application know if pkey is enabled, if so how many pkeys are available? Is PKEY_DISABLE_EXECUTE supported? - Ben. History: ------- version v6: (1) selftest changes are broken down into 20 incremental patches. (2) A separate key allocation mask that includes PKEY_DISABLE_EXECUTE is added for powerpc (3) pkey feature is enabled for 64K HPT case only. RPT and 4k HPT is disabled. (4) Documentation is updated to better capture the semantics. (5) introduced arch_pkeys_enabled() to find if an arch enables pkeys. Correspond- ing change the logic that displays key value in smaps. (6) code rearranged in many places based on comments from Dave Hansen, Balbir, Anshuman. (7) fixed one bug where a bogus key could be associated successfully in pkey_mprotect(). version v5: (1) reverted back to the old design -- store the key in the pte, instead of bypassing it. The v4 design slowed down the hash page path. (2) detects key violation when kernel is told to access user pages. (3) further refined the patches into smaller consumable units (4) page faults handlers captures the fault- ing key from the pte instead of the vma. This closes a race between where the key update in the vma and a key fault caused by the key programmed in the pte. (5) a key created with access-denied should also set it up to deny write. Fixed it. (6) protection-key number is displayed in smaps the x86 way. version v4: (1) patches no more depend on the pte bits to program the hpte -- comment by Balbir (2) documentation updates (3) fixed a bug in the selftest. (4) unlike x86, powerpc lets signal handler change key permission bits; the change will persist across signal handler boundaries. Earlier we allowed the signal handler to modify a field in the siginfo structure which would than be used by the kernel to program the key protection register (AMR) -- resolves a issue raised by Ben. "Calls to sys_swapcontext with a made-up context will end up with a crap AMR if done by code who didn't know about that register". (5) these changes enable protection keys on 4k-page kernel aswell. version v3: (1) split the patches into smaller consumable patches. (2) added the ability to disable execute permission on a key at creation. (3) rename calc_pte_to_hpte_pkey_bits() to pte_to_hpte_pkey_bits() -- suggested by Anshuman (4) some code optimization and clarity in do_page_fault() (5) A bug fix while invalidating a hpte slot in __hash_page_4K() -- noticed by Aneesh version v2: (1) documentation and selftest added. (2) fixed a bug in 4k hpte backed 64k pte where page invalidation was not done correctly, and initialization of second-part-of-the-pte was not done correctly if the pte was not yet Hashed with a hpte. -- Reported by Aneesh. (3) Fixed ABI breakage caused in siginfo structure. -- Reported by Anshuman. version v1: Initial version Ram Pai (62): powerpc: Free up four 64K PTE bits in 4K backed HPTE pages powerpc: Free up four 64K PTE bits in 64K backed HPTE pages powerpc: introduce pte_set_hash_slot() helper powerpc: introduce pte_get_hash_gslot() helper powerpc: capture the PTE format changes in the dump pte report powerpc: use helper functions in __hash_page_64K() for 64K PTE powerpc: use helper functions in __hash_page_huge() for 64K PTE powerpc: use helper functions in __hash_page_4K() for 64K PTE powerpc: use helper functions in __hash_page_4K() for 4K PTE powerpc: use helper functions in flush_hash_page() powerpc: initial pkey plumbing mm: introduce an additional vma bit for powerpc pkey powerpc: track allocation status of all pkeys powerpc: helper function to read,write AMR,IAMR,UAMOR registers powerpc: helper functions to initialize AMR, IAMR and UMOR registers powerpc: cleaup AMR,iAMR when a key is allocated or freed powerpc: implementation for arch_set_user_pkey_access() powerpc: sys_pkey_alloc() and sys_pkey_free() system calls powerpc: ability to create execute-disabled pkeys powerpc: store and restore the pkey state across context switches powerpc: introduce execute-only pkey powerpc: ability to associate pkey to a vma powerpc: implementation for arch_override_mprotect_pkey() powerpc: map vma key-protection bits to pte key bits. powerpc: sys_pkey_mprotect() system call powerpc: Program HPTE key protection bits powerpc: helper to validate key-access permissions of a pte powerpc: check key protection for user page access powerpc: Macro the mask used for checking DSI exception powerpc: implementation for arch_vma_access_permitted() powerpc: Handle exceptions caused by pkey violation powerpc: capture AMR register content on pkey violation powerpc: introduce get_pte_pkey() helper powerpc: capture the violated protection key on fault powerpc: Deliver SEGV signal on pkey violation mm: introduce arch_pkeys_enabled() x86: implementation for arch_pkeys_enabled() powerpc: implementation for arch_pkeys_enabled() mm: display pkey in smaps if arch_pkeys_enabled() is true x86: delete arch_show_smap() selftest/x86: Move protecton key selftest to arch neutral directory selftest/vm: rename all references to pkru to a generic name selftest/vm: move generic definitions to header file selftest/vm: typecast the pkey register selftest/vm: generics function to handle shadow key register selftest/vm: fix the wrong assert in pkey_disable_set() selftest/vm: fixed bugs in pkey_disable_clear() selftest/vm: clear the bits in shadow reg when a pkey is freed. selftest/vm: fix alloc_random_pkey() to make it really random selftest/vm: introduce two arch independent abstraction selftest/vm: pkey register should match shadow pkey selftest/vm: generic cleanup selftest/vm: powerpc implementation for generic abstraction selftest/vm: fix an assertion in test_pkey_alloc_exhaust() selftest/vm: associate key on a mapped page and detect access violation selftest/vm: detect no key violation on a freed key selftest/vm: associate key on a mapped page and detect write violation selftest/vm: detect no write key-violation on a freed key selftest/vm: detect write violation on a mapped access-denied-key page selftest/vm: sub-page allocator Documentation/x86: Move protecton key documentation to arch neutral directory Documentation/vm: PowerPC specific updates to memory protection keys Documentation/vm/protection-keys.txt | 125 ++ Documentation/x86/protection-keys.txt | 85 -- arch/powerpc/Kconfig | 16 + arch/powerpc/include/asm/book3s/64/hash-4k.h | 20 + arch/powerpc/include/asm/book3s/64/hash-64k.h | 60 +- arch/powerpc/include/asm/book3s/64/hash.h | 7 +- arch/powerpc/include/asm/book3s/64/mmu-hash.h | 10 + arch/powerpc/include/asm/book3s/64/mmu.h | 10 + arch/powerpc/include/asm/book3s/64/pgtable.h | 64 +- arch/powerpc/include/asm/mman.h | 16 +- arch/powerpc/include/asm/mmu_context.h | 14 + arch/powerpc/include/asm/paca.h | 4 + arch/powerpc/include/asm/pkeys.h | 226 ++++ arch/powerpc/include/asm/processor.h | 5 + arch/powerpc/include/asm/reg.h | 8 +- arch/powerpc/include/asm/systbl.h | 3 + arch/powerpc/include/asm/unistd.h | 6 +- arch/powerpc/include/uapi/asm/ptrace.h | 1 + arch/powerpc/include/uapi/asm/unistd.h | 3 + arch/powerpc/kernel/asm-offsets.c | 6 + arch/powerpc/kernel/exceptions-64s.S | 2 +- arch/powerpc/kernel/process.c | 18 + arch/powerpc/kernel/setup_64.c | 4 + arch/powerpc/kernel/signal_32.c | 5 + arch/powerpc/kernel/signal_64.c | 4 + arch/powerpc/kernel/traps.c | 15 + arch/powerpc/mm/Makefile | 1 + arch/powerpc/mm/dump_linuxpagetables.c | 3 +- arch/powerpc/mm/fault.c | 31 + arch/powerpc/mm/hash64_4k.c | 14 +- arch/powerpc/mm/hash64_64k.c | 124 ++- arch/powerpc/mm/hash_utils_64.c | 65 +- arch/powerpc/mm/hugetlbpage-hash64.c | 16 +- arch/powerpc/mm/mmu_context_book3s64.c | 2 + arch/powerpc/mm/pkeys.c | 279 +++++ arch/x86/include/asm/pkeys.h | 1 + arch/x86/kernel/fpu/xstate.c | 5 + arch/x86/kernel/setup.c | 8 - fs/proc/task_mmu.c | 15 +- include/linux/mm.h | 20 +- include/linux/pkeys.h | 5 + tools/testing/selftests/vm/Makefile | 1 + tools/testing/selftests/vm/pkey-helpers.h | 394 +++++++ tools/testing/selftests/vm/protection_keys.c | 1500 +++++++++++++++++++++++++ tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/pkey-helpers.h | 219 ---- tools/testing/selftests/x86/protection_keys.c | 1395 ----------------------- 47 files changed, 2993 insertions(+), 1844 deletions(-) create mode 100644 Documentation/vm/protection-keys.txt delete mode 100644 Documentation/x86/protection-keys.txt create mode 100644 arch/powerpc/include/asm/pkeys.h create mode 100644 arch/powerpc/mm/pkeys.c create mode 100644 tools/testing/selftests/vm/pkey-helpers.h create mode 100644 tools/testing/selftests/vm/protection_keys.c delete mode 100644 tools/testing/selftests/x86/pkey-helpers.h delete mode 100644 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