Memory Protection Keys for User pages (pkeys) is a CPU feature
which will first appear on Skylake Servers, but will also be
supported on future non-server parts. It provides a mechanism
for enforcing page-based protections, but without requiring
modification of the page tables when an application changes
wishes to change permissions.
Patches to implement execute-only mapping support using pkeys was
merged in to 4.6. But, to do anything else useful with pkeys, an
application needs to be able to set the pkey field in the PTE
(obviously has to be done in-kernel) and make changes to the
"rights" register (using unprivileged instructions).
An application also needs to have an an allocator for the keys
themselves. If two different parts of an application both want
to protect their data with pkeys, they first need to know which
key to use for their individual purposes.
This set introduces 5 system calls, in 3 logical groups:
1. PTE pkey setting (sys_pkey_mprotect(), patches #1-3)
2. Key allocation (sys_pkey_alloc() / sys_pkey_free(), patch #4)
3. Rights register manipulation (sys_pkey_set/get(), patch #5)
These patches build on top of "core" pkeys support already in
4.6. This set is specifically built on f87e0434a, which is
tip/x86/urgent since it contained a documentation fix.
I have manpages written for some of these syscalls, and have
submitted them for review to the manpages list.
This set is also available here:
git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-pkeys.git pkeys-v031
I've written a set of unit tests for these interfaces, which is
available as the last patch in the series and integrated in to
kselftests.
=== diffstat ===
Dave Hansen (8):
x86, pkeys: add fault handling for PF_PK page fault bit
mm: implement new pkey_mprotect() system call
x86, pkeys: make mprotect_key() mask off additional vm_flags
x86: wire up mprotect_key() system call
x86, pkeys: allocation/free syscalls
x86, pkeys: add pkey set/get syscalls
pkeys: add details of system call use to Documentation/
x86, pkeys: add self-tests
Documentation/x86/protection-keys.txt | 63 +
arch/alpha/include/uapi/asm/mman.h | 5 +
arch/mips/include/uapi/asm/mman.h | 5 +
arch/parisc/include/uapi/asm/mman.h | 5 +
arch/x86/entry/syscalls/syscall_32.tbl | 5 +
arch/x86/entry/syscalls/syscall_64.tbl | 5 +
arch/x86/include/asm/mmu.h | 8 +
arch/x86/include/asm/mmu_context.h | 25 +-
arch/x86/include/asm/pkeys.h | 83 +-
arch/x86/kernel/fpu/xstate.c | 73 +-
arch/x86/mm/fault.c | 9 +
arch/x86/mm/pkeys.c | 38 +-
arch/xtensa/include/uapi/asm/mman.h | 5 +
include/linux/pkeys.h | 39 +-
include/uapi/asm-generic/mman-common.h | 5 +
mm/mprotect.c | 134 +-
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/pkey-helpers.h | 186 +++
tools/testing/selftests/x86/protection_keys.c | 1199 +++++++++++++++++
19 files changed, 1863 insertions(+), 31 deletions(-)
Cc: linux-api@xxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: x86@xxxxxxxxxx
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Cc: akpm@xxxxxxxxxxxxxxxxxxxx
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