kernel.git/arch/powerpc/kernel/optprobes.c, branch linux-5.9.y

powerpc: Add ppc_inst_as_u64()

2020-05-26T13:36:57Z

The code patching code wants to get the value of a struct ppc_inst as a u64 when the instruction is prefixed, so we can pass the u64 down to __put_user_asm() and write it with a single store. The optprobes code wants to load a struct ppc_inst as an immediate into a register so it is useful to have it as a u64 to use the existing helper function. Currently this is a bit awkward because the value differs based on the CPU endianness, so add a helper to do the conversion. This fixes the usage in arch_prepare_optimized_kprobe() which was previously incorrect on big endian. Fixes: 650b55b707fd ("powerpc: Add prefixed instructions to instruction data type") Signed-off-by: Michael Ellerman Tested-by: Jordan Niethe Link: https://lore.kernel.org/r/20200526072630.2487363-1-mpe@ellerman.id.au

powerpc: Add prefixed instructions to instruction data type

2020-05-18T14:10:39Z

For powerpc64, redefine the ppc_inst type so both word and prefixed instructions can be represented. On powerpc32 the type will remain the same. Update places which had assumed instructions to be 4 bytes long. Signed-off-by: Jordan Niethe Reviewed-by: Alistair Popple [mpe: Rework the get_user_inst() macros to be parameterised, and don't assign to the dest if an error occurred. Use CONFIG_PPC64 not __powerpc64__ in a few places. Address other comments from Christophe. Fix some sparse complaints.] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200506034050.24806-24-jniethe5@gmail.com

powerpc/optprobes: Add register argument to patch_imm64_load_insns()

2020-05-18T14:10:38Z

Currently patch_imm32_load_insns() is used to load an instruction to r4 to be emulated by emulate_step(). For prefixed instructions we would like to be able to load a 64bit immediate to r4. To prepare for this make patch_imm64_load_insns() take an argument that decides which register to load an immediate to - rather than hardcoding r3. Signed-off-by: Jordan Niethe Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200516115449.4168796-1-mpe@ellerman.id.au

powerpc: Use a function for reading instructions

2020-05-18T14:10:37Z

Prefixed instructions will mean there are instructions of different length. As a result dereferencing a pointer to an instruction will not necessarily give the desired result. Introduce a function for reading instructions from memory into the instruction data type. Signed-off-by: Jordan Niethe Signed-off-by: Michael Ellerman Reviewed-by: Alistair Popple Link: https://lore.kernel.org/r/20200506034050.24806-13-jniethe5@gmail.com

powerpc: Use a datatype for instructions

2020-05-18T14:10:37Z

Currently unsigned ints are used to represent instructions on powerpc. This has worked well as instructions have always been 4 byte words. However, ISA v3.1 introduces some changes to instructions that mean this scheme will no longer work as well. This change is Prefixed Instructions. A prefixed instruction is made up of a word prefix followed by a word suffix to make an 8 byte double word instruction. No matter the endianness of the system the prefix always comes first. Prefixed instructions are only planned for powerpc64. Introduce a ppc_inst type to represent both prefixed and word instructions on powerpc64 while keeping it possible to exclusively have word instructions on powerpc32. Signed-off-by: Jordan Niethe [mpe: Fix compile error in emulate_spe()] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200506034050.24806-12-jniethe5@gmail.com

powerpc: Use a macro for creating instructions from u32s

2020-05-18T14:10:36Z

In preparation for instructions having a more complex data type start using a macro, ppc_inst(), for making an instruction out of a u32. A macro is used so that instructions can be used as initializer elements. Currently this does nothing, but it will allow for creating a data type that can represent prefixed instructions. Signed-off-by: Jordan Niethe [mpe: Change include guard to _ASM_POWERPC_INST_H] Signed-off-by: Michael Ellerman Reviewed-by: Alistair Popple Link: https://lore.kernel.org/r/20200506034050.24806-7-jniethe5@gmail.com

powerpc: Change calling convention for create_branch() et. al.

2020-05-18T14:10:36Z

create_branch(), create_cond_branch() and translate_branch() return the instruction that they create, or return 0 to signal an error. Separate these concerns in preparation for an instruction type that is not just an unsigned int. Fill the created instruction to a pointer passed as the first parameter to the function and use a non-zero return value to signify an error. Signed-off-by: Jordan Niethe Signed-off-by: Michael Ellerman Reviewed-by: Alistair Popple Link: https://lore.kernel.org/r/20200506034050.24806-6-jniethe5@gmail.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

powerpc/kprobes: Do not disable interrupts for optprobes and kprobes_on_ftrace

2017-11-12T12:51:41Z

Per Documentation/kprobes.txt, we don't necessarily need to disable interrupts before invoking the kprobe handlers. Masami submitted similar changes for x86 via commit a19b2e3d783964 ("kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes"). Do the same for powerpc. Signed-off-by: Naveen N. Rao Acked-by: Masami Hiramatsu Signed-off-by: Michael Ellerman

powerpc/kprobes: Disable preemption before invoking probe handler for optprobes

2017-11-12T12:51:40Z

Per Documentation/kprobes.txt, probe handlers need to be invoked with preemption disabled. Update optimized_callback() to do so. Also move get_kprobe_ctlblk() invocation post preemption disable, since it accesses pre-cpu data. This was not an issue so far since optprobes wasn't selected if CONFIG_PREEMPT was enabled. Commit a30b85df7d599f ("kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT=y") changes this. Signed-off-by: Naveen N. Rao Acked-by: Masami Hiramatsu Signed-off-by: Michael Ellerman