kernel/tools/testing/selftests/vm/protection_keys.c, branch linux-6.2.y

selftests/vm/pkeys: Add a regression test for setting PKRU through ptrace

2022-11-16T23:07:10Z

This tests PTRACE_SETREGSET with NT_X86_XSTATE modifying PKRU directly and removing the PKRU bit from XSTATE_BV. Signed-off-by: Kyle Huey Signed-off-by: Dave Hansen Link: https://lore.kernel.org/all/20221115230932.7126-7-khuey%40kylehuey.com

selftests/vm/pkeys: fix typo in comment

2022-05-25T17:47:48Z

Spelling mistake (triple letters) in comment. Detected with the help of Coccinelle. Link: https://lkml.kernel.org/r/20220521111145.81697-80-Julia.Lawall@inria.fr Signed-off-by: Julia Lawall Reviewed-by: Muchun Song Signed-off-by: Andrew Morton

selftests/vm/pkeys: exercise x86 XSAVE init state

2021-07-01T18:06:06Z

On x86, there is a set of instructions used to save and restore register state collectively known as the XSAVE architecture. There are about a dozen different features managed with XSAVE. The protection keys register, PKRU, is one of those features. The hardware optimizes XSAVE by tracking when the state has not changed from its initial (init) state. In this case, it can avoid the cost of writing state to memory (it would usually just be a bunch of 0's). When the pkey register is 0x0 the hardware optionally choose to track the register as being in the init state (optimize away the writes). AMD CPUs do this more aggressively compared to Intel. On x86, PKRU is rarely in its (very permissive) init state. Instead, the value defaults to something very restrictive. It is not surprising that bugs have popped up in the rare cases when PKRU reaches its init state. Add a protection key selftest which gets the protection keys register into its init state in a way that should work on Intel and AMD. Then, do a bunch of pkey register reads to watch for inadvertent changes. This adds "-mxsave" to CFLAGS for all the x86 vm selftests in order to allow use of the XSAVE instruction __builtin functions. This will make the builtins available on all of the vm selftests, but is expected to be harmless. Link: https://lkml.kernel.org/r/20210611164202.1849B712@viggo.jf.intel.com Signed-off-by: Dave Hansen Signed-off-by: Thomas Gleixner Tested-by: Aneesh Kumar K.V Cc: Ram Pai Cc: Sandipan Das Cc: Florian Weimer Cc: "Desnes A. Nunes do Rosario" Cc: Ingo Molnar Cc: Thiago Jung Bauermann Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

selftests/vm/pkeys: refill shadow register after implicit kernel write

2021-07-01T18:06:06Z

The pkey test code keeps a "shadow" of the pkey register around. This ensures that any bugs which might write to the register can be caught more quickly. Generally, userspace has a good idea when the kernel is going to write to the register. For instance, alloc_pkey() is passed a permission mask. The caller of alloc_pkey() can update the shadow based on the return value and the mask. But, the kernel can also modify the pkey register in a more sneaky way. For mprotect(PROT_EXEC) mappings, the kernel will allocate a pkey and write the pkey register to create an execute-only mapping. The kernel never tells userspace what key it uses for this. This can cause the test to fail with messages like: protection_keys_64.2: pkey-helpers.h:132: _read_pkey_reg: Assertion `pkey_reg == shadow_pkey_reg' failed. because the shadow was not updated with the new kernel-set value. Forcibly update the shadow value immediately after an mprotect(). Link: https://lkml.kernel.org/r/20210611164200.EF76AB73@viggo.jf.intel.com Fixes: 6af17cf89e99 ("x86/pkeys/selftests: Add PROT_EXEC test") Signed-off-by: Dave Hansen Signed-off-by: Thomas Gleixner Tested-by: Aneesh Kumar K.V Cc: Ram Pai Cc: Sandipan Das Cc: Florian Weimer Cc: "Desnes A. Nunes do Rosario" Cc: Ingo Molnar Cc: Thiago Jung Bauermann Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

selftests/vm/pkeys: handle negative sys_pkey_alloc() return code

2021-07-01T18:06:06Z

The alloc_pkey() sefltest function wraps the sys_pkey_alloc() system call. On success, it updates its "shadow" register value because sys_pkey_alloc() updates the real register. But, the success check is wrong. pkey_alloc() considers any non-zero return code to indicate success where the pkey register will be modified. This fails to take negative return codes into account. Consider only a positive return value as a successful call. Link: https://lkml.kernel.org/r/20210611164157.87AB4246@viggo.jf.intel.com Fixes: 5f23f6d082a9 ("x86/pkeys: Add self-tests") Reported-by: Thomas Gleixner Signed-off-by: Dave Hansen Tested-by: Aneesh Kumar K.V Cc: Ram Pai Cc: Sandipan Das Cc: Florian Weimer Cc: "Desnes A. Nunes do Rosario" Cc: Ingo Molnar Cc: Thiago Jung Bauermann Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random

2021-07-01T18:06:06Z

Patch series "selftests/vm/pkeys: Bug fixes and a new test". There has been a lot of activity on the x86 front around the XSAVE architecture which is used to context-switch processor state (among other things). In addition, AMD has recently joined the protection keys club by adding processor support for PKU. The AMD implementation helped uncover a kernel bug around the PKRU "init state", which actually applied to Intel's implementation but was just harder to hit. This series adds a test which is expected to help find this class of bug both on AMD and Intel. All the work around pkeys on x86 also uncovered a few bugs in the selftest. This patch (of 4): The "random" pkey allocation code currently does the good old: srand((unsigned int)time(NULL)); *But*, it unfortunately does this on every random pkey allocation. There may be thousands of these a second. time() has a one second resolution. So, each time alloc_random_pkey() is called, the PRNG is *RESET* to time(). This is nasty. Normally, if you do: srand(); foo = rand(); bar = rand(); You'll be quite guaranteed that 'foo' and 'bar' are different. But, if you do: srand(1); foo = rand(); srand(1); bar = rand(); You are quite guaranteed that 'foo' and 'bar' are the *SAME*. The recent "fix" effectively forced the test case to use the same "random" pkey for the whole test, unless the test run crossed a second boundary. Only run srand() once at program startup. This explains some very odd and persistent test failures I've been seeing. Link: https://lkml.kernel.org/r/20210611164153.91B76FB8@viggo.jf.intel.com Link: https://lkml.kernel.org/r/20210611164155.192D00FF@viggo.jf.intel.com Fixes: 6e373263ce07 ("selftests/vm/pkeys: fix alloc_random_pkey() to make it really random") Signed-off-by: Dave Hansen Signed-off-by: Thomas Gleixner Tested-by: Aneesh Kumar K.V Cc: Ram Pai Cc: Sandipan Das Cc: Florian Weimer Cc: "Desnes A. Nunes do Rosario" Cc: Ingo Molnar Cc: Thiago Jung Bauermann Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

selftests/vm/keys: fix a broken reference at protection_keys.c

2020-06-26T16:01:12Z

Changeset 1eecbcdca2bd ("docs: move protection-keys.rst to the core-api book") from Jun 7, 2019 converted protection-keys.txt file to ReST. A recent change at protection_keys.c partially reverted such changeset, causing it to point to a non-existing file: - * Tests x86 Memory Protection Keys (see Documentation/core-api/protection-keys.rst) + * Tests Memory Protection Keys (see Documentation/vm/protection-keys.txt) It sounds to me that the changeset that introduced such change 4645e3563673 ("selftests/vm/pkeys: rename all references to pkru to a generic name") could also have other side effects, as it sounds that it was not generated against uptream code, but, instead, against a version older than Jun 7, 2019. Fixes: 4645e3563673 ("selftests/vm/pkeys: rename all references to pkru to a generic name") Signed-off-by: Mauro Carvalho Chehab Link: https://lore.kernel.org/r/cf65aa052669f55b9dc976a5c8026aef5840741d.1592895969.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet

selftests: vm: pkeys: use the correct page size on powerpc

2020-06-05T02:06:27Z

Both 4K and 64K pages are supported on powerpc. Parts of the selftest code perform alignment computations based on the PAGE_SIZE macro which is currently hardcoded to 64K for powerpc. This causes some test failures on kernels configured with 4K page size. In some cases, we need to enforce function alignment on page size. Since this can only be done at build time, 64K is used as the alignment factor as that also ensures 4K alignment. Signed-off-by: Sandipan Das Signed-off-by: Andrew Morton Acked-by: Dave Hansen Cc: "Desnes A. Nunes do Rosario" Cc: Florian Weimer Cc: Ingo Molnar Cc: Ram Pai Cc: Thiago Jung Bauermann Cc: "Aneesh Kumar K.V" Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Link: http://lkml.kernel.org/r/5dcdfbf3353acdc90f315172e800b49f5ca21299.1585646528.git.sandipan@linux.ibm.com Signed-off-by: Linus Torvalds

selftests/vm/pkeys: test correct behaviour of pkey-0

2020-06-05T02:06:27Z

Ensure that pkey-0 is allocated on start and that it can be attached dynamically in various modes, without failures. Signed-off-by: Ram Pai Signed-off-by: Sandipan Das Signed-off-by: Andrew Morton Acked-by: Dave Hansen Cc: Dave Hansen Cc: Florian Weimer Cc: "Desnes A. Nunes do Rosario" Cc: Ingo Molnar Cc: Thiago Jung Bauermann Cc: "Aneesh Kumar K.V" Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Link: http://lkml.kernel.org/r/9b7c54a9b4261894fe0c7e884c70b87214ff8fbb.1585646528.git.sandipan@linux.ibm.com Signed-off-by: Linus Torvalds

selftests/vm/pkeys: introduce a sub-page allocator

2020-06-05T02:06:27Z

This introduces a new allocator that allocates 4K hardware pages to back 64K linux pages. This allocator is available only on powerpc. Signed-off-by: Ram Pai Signed-off-by: Thiago Jung Bauermann Signed-off-by: Sandipan Das Signed-off-by: Andrew Morton Acked-by: Dave Hansen Cc: Dave Hansen Cc: Florian Weimer Cc: "Desnes A. Nunes do Rosario" Cc: Ingo Molnar Cc: "Aneesh Kumar K.V" Cc: Michael Ellerman Cc: Michal Hocko Cc: Michal Suchanek Cc: Shuah Khan Link: http://lkml.kernel.org/r/c4a82fa962ec71015b994fab1aaf83bdfd091553.1585646528.git.sandipan@linux.ibm.com Signed-off-by: Linus Torvalds