[RFC v4 00/17] powerpc: Memory Protection Keys

From: Ram Pai
Date: Tue Jun 27 2017 - 06:12:26 EST

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
a address range within its address space.
The process than can dynamically set read/write
permissions on the key without involving the
kernel. Any code that violates the permissions
off 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.


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.

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 (17):
mm: introduce an additional vma bit for powerpc pkey
mm: ability to disable execute permission on a key at creation
x86: key creation with PKEY_DISABLE_EXECUTE disallowed
powerpc: Implement sys_pkey_alloc and sys_pkey_free system call
powerpc: store and restore the pkey state across context switches
powerpc: Implementation for sys_mprotect_pkey() system call
powerpc: make the hash functions protection-key aware
powerpc: Program HPTE key protection bits
powerpc: call the hash functions with the correct pkey value
powerpc: Macro the mask used for checking DSI exception
powerpc: Handle exceptions caused by pkey violation
powerpc: Deliver SEGV signal on pkey violation
selftest: Move protecton key selftest to arch neutral directory
selftest: PowerPC specific test updates to memory protection keys
Documentation: Move protecton key documentation to arch neutral
directory
Documentation: PowerPC specific updates to memory protection keys
procfs: display the protection-key number associated with a vma

Documentation/filesystems/proc.txt | 3 +-
Documentation/vm/protection-keys.txt | 134 +++
Documentation/x86/protection-keys.txt | 85 --
Makefile | 2 +-
arch/powerpc/Kconfig | 15 +
arch/powerpc/include/asm/book3s/64/hash.h | 2 +-
arch/powerpc/include/asm/book3s/64/mmu-hash.h | 19 +-
arch/powerpc/include/asm/book3s/64/mmu.h | 10 +
arch/powerpc/include/asm/book3s/64/pgtable.h | 62 ++
arch/powerpc/include/asm/mman.h | 8 +-
arch/powerpc/include/asm/mmu_context.h | 12 +
arch/powerpc/include/asm/paca.h | 1 +
arch/powerpc/include/asm/pkeys.h | 159 +++
arch/powerpc/include/asm/processor.h | 5 +
arch/powerpc/include/asm/reg.h | 7 +-
arch/powerpc/include/asm/systbl.h | 3 +
arch/powerpc/include/asm/unistd.h | 6 +-
arch/powerpc/include/uapi/asm/ptrace.h | 3 +-
arch/powerpc/include/uapi/asm/unistd.h | 3 +
arch/powerpc/kernel/asm-offsets.c | 5 +
arch/powerpc/kernel/exceptions-64s.S | 18 +-
arch/powerpc/kernel/process.c | 18 +
arch/powerpc/kernel/signal_32.c | 5 +
arch/powerpc/kernel/signal_64.c | 4 +
arch/powerpc/kernel/traps.c | 49 +
arch/powerpc/mm/Makefile | 1 +
arch/powerpc/mm/fault.c | 22 +
arch/powerpc/mm/hash64_4k.c | 4 +-
arch/powerpc/mm/hash64_64k.c | 8 +-
arch/powerpc/mm/hash_utils_64.c | 42 +-
arch/powerpc/mm/hugepage-hash64.c | 4 +-
arch/powerpc/mm/hugetlbpage-hash64.c | 5 +-
arch/powerpc/mm/mem.c | 7 +
arch/powerpc/mm/mmu_context_book3s64.c | 5 +
arch/powerpc/mm/mmu_decl.h | 5 +-
arch/powerpc/mm/pkeys.c | 256 +++++
arch/x86/kernel/fpu/xstate.c | 3 +
fs/proc/task_mmu.c | 18 +-
include/linux/mm.h | 18 +-
include/uapi/asm-generic/mman-common.h | 4 +-
tools/testing/selftests/vm/Makefile | 1 +
tools/testing/selftests/vm/pkey-helpers.h | 365 ++++++
tools/testing/selftests/vm/protection_keys.c | 1488 +++++++++++++++++++++++++
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/pkey-helpers.h | 219 ----
tools/testing/selftests/x86/protection_keys.c | 1395 -----------------------
46 files changed, 2755 insertions(+), 1755 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 tools/testing/selftests/x86/protection_keys.c

--
1.8.3.1