kernel/linux.git/arch/powerpc/include/asm/code-patching.h, branch v6.12.80

powerpc/code-patching: Add data patch alignment check

2024-08-21T10:15:12+00:00

The new data patching still needs to be aligned within a cacheline too for the flushes to work correctly. To simplify this requirement, we just say data patches must be aligned. Detect when data patching is not aligned, returning an invalid argument error. Signed-off-by: Benjamin Gray Reviewed-by: Hari Bathini Acked-by: Naveen N Rao Signed-off-by: Michael Ellerman Link: https://msgid.link/20240515024445.236364-3-bgray@linux.ibm.com

powerpc/code-patching: Add generic memory patching

2024-08-21T10:15:12+00:00

patch_instruction() is designed for patching instructions in otherwise readonly memory. Other consumers also sometimes need to patch readonly memory, so have abused patch_instruction() for arbitrary data patches. This is a problem on ppc64 as patch_instruction() decides on the patch width using the 'instruction' opcode to see if it's a prefixed instruction. Data that triggers this can lead to larger writes, possibly crossing a page boundary and failing the write altogether. Introduce patch_uint(), and patch_ulong(), with aliases patch_u32(), and patch_u64() (on ppc64) designed for aligned data patches. The patch size is now determined by the called function, and is passed as an additional parameter to generic internals. While the instruction flushing is not required for data patches, it remains unconditional in this patch. A followup series is possible if benchmarking shows fewer flushes gives an improvement in some data-patching workload. ppc32 does not support prefixed instructions, so is unaffected by the original issue. Care is taken in not exposing the size parameter in the public (non-static) interface, so the compiler can const-propagate it away. Signed-off-by: Benjamin Gray Reviewed-by: Hari Bathini Signed-off-by: Michael Ellerman Link: https://msgid.link/20240515024445.236364-2-bgray@linux.ibm.com

powerpc/code-patching: introduce patch_instructions()

2023-10-23T09:33:19+00:00

patch_instruction() entails setting up pte, patching the instruction, clearing the pte and flushing the tlb. If multiple instructions need to be patched, every instruction would have to go through the above drill unnecessarily. Instead, introduce patch_instructions() function that sets up the pte, clears the pte and flushes the tlb only once per page range of instructions to be patched. Duplicate most of the patch_instruction() code instead of merging with it, to avoid the performance degradation observed on ppc32, for patch_instruction(), with the code path merged. Also, setup poking_init() always as BPF expects poking_init() to be setup even when STRICT_KERNEL_RWX is off. Signed-off-by: Hari Bathini Acked-by: Song Liu Signed-off-by: Michael Ellerman Link: https://msgid.link/20231020141358.643575-2-hbathini@linux.ibm.com

powerpc/code-patching: Remove protection against patching init addresses after init

2022-12-02T10:59:57+00:00

Once init section is freed, attempting to patch init code ends up in the weed. Commit 51c3c62b58b3 ("powerpc: Avoid code patching freed init sections") protected patch_instruction() against that, but it is the responsibility of the caller to ensure that the patched memory is valid. All callers have now been verified and fixed so the check can be removed. This improves ftrace activation by about 2% on 8xx. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/504310828f473d424e2ed229eff57bf075f52796.1669969781.git.christophe.leroy@csgroup.eu

powerpc/ftrace: Minimise number of #ifdefs

2022-05-22T05:58:26+00:00

A lot of #ifdefs can be replaced by IS_ENABLED() Do so. Signed-off-by: Christophe Leroy [mpe: Fold in changes suggested by Naveen and Christophe on list] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/18ce6708d6f8c71d87436f9c6019f04df4125128.1652074503.git.christophe.leroy@csgroup.eu

powerpc: Replace PPC64_ELF_ABI_v{1/2} by CONFIG_PPC64_ELF_ABI_V{1/2}

2022-05-19T13:11:29+00:00

Replace all uses of PPC64_ELF_ABI_v1 and PPC64_ELF_ABI_v2 by resp CONFIG_PPC64_ELF_ABI_V1 and CONFIG_PPC64_ELF_ABI_V2. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/ba13d59e8c50bc9aa6328f1c7f0c0d0278e0a3a7.1652074503.git.christophe.leroy@csgroup.eu

powerpc/code-patching: Inline create_branch()

2022-05-19T13:11:28+00:00

create_branch() is a good candidate for inlining because: - Flags can be folded in. - Range tests are likely to be already done. Hence reducing the create_branch() to only a set of instructions. So inline it. It improves ftrace activation by 10%. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/69851cc9a7bf8f03d025e6d29e165f2d0bd3bb6e.1652074503.git.christophe.leroy@csgroup.eu

powerpc/code-patching: Inline is_offset_in_{cond}_branch_range()

2022-05-19T13:11:28+00:00

Test in is_offset_in_branch_range() and is_offset_in_cond_branch_range() are simple tests that are worth inlining. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/a05be0ccb7373e6a9789a1988fcd0c810f5f9269.1652074503.git.christophe.leroy@csgroup.eu

powerpc/code-patching: Use jump_label for testing freed initmem

2022-05-11T13:06:39+00:00

Once init is done, initmem is freed forever so no need to test system_state at every call to patch_instruction(). Use jump_label. This reduces by 2% the time needed to activate ftrace on an 8xx. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/0aee964721cab7316cffde21a2ca223cee14d373.1647962456.git.christophe.leroy@csgroup.eu

powerpc: Move and rename func_descr_t

2022-02-16T12:25:10+00:00

There are three architectures with function descriptors, try to have common names for the address they contain in order to refactor some functions into generic functions later. powerpc has 'entry' ia64 has 'ip' parisc has 'addr' Vote for 'addr' and update 'func_descr_t' accordingly. Move it in asm/elf.h to have it at the same place on all three architectures, remove the typedef which hides its real type, and change it to a smoother name 'struct func_desc'. Signed-off-by: Christophe Leroy Reviewed-by: Nicholas Piggin Reviewed-by: Kees Cook Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/529b2ba1d001e8f628ef0d30e8044c9b3d0a4921.1644928018.git.christophe.leroy@csgroup.eu