linux/tools/objtool/arch.h, branch v5.8

objtool: Fix noinstr vs KCOV

2020-06-18T15:36:33Z

Since many compilers cannot disable KCOV with a function attribute, help it to NOP out any __sanitizer_cov_*() calls injected in noinstr code. This turns: 12: e8 00 00 00 00 callq 17 13: R_X86_64_PLT32 __sanitizer_cov_trace_pc-0x4 into: 12: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 13: R_X86_64_NONE __sanitizer_cov_trace_pc-0x4 Just like recordmcount does. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Dmitry Vyukov

objtool: Enable compilation of objtool for all architectures

2020-05-20T14:17:28Z

Objtool currently only compiles for x86 architectures. This is fine as it presently does not support tooling for other architectures. However, we would like to be able to convert other kernel tools to run as objtool sub commands because they too process ELF object files. This will allow us to convert tools such as recordmcount to use objtool's ELF code. Since much of recordmcount's ELF code is copy-paste code to/from a variety of other kernel tools (look at modpost for example) this means that if we can convert recordmcount we can convert more. We define weak definitions for subcommand entry functions and other weak definitions for shared functions critical to building existing subcommands. These return 127 when the command is missing which signify tools that do not exist on all architectures. In this case the "check" and "orc" tools do not exist on all architectures so we only add them for x86. Future changes adding support for "check", to arm64 for example, can then modify the SUBCMD_CHECK variable when building for arm64. Objtool is not currently wired in to KConfig to be built for other architectures because it's not needed for those architectures and there are no commands it supports other than those for x86. As more command support is enabled on various architectures the necessary KConfig changes can be made (e.g. adding "STACK_VALIDATION") to trigger building objtool. [ jpoimboe: remove aliases, add __weak macro, add error messages ] Cc: Julien Thierry Signed-off-by: Matt Helsley Signed-off-by: Josh Poimboeuf

objtool: Move the IRET hack into the arch decoder

2020-04-30T18:14:33Z

Quoting Julien: "And the other suggestion is my other email was that you don't even need to add INSN_EXCEPTION_RETURN. You can keep IRET as INSN_CONTEXT_SWITCH by default and x86 decoder lookups the symbol conaining an iret. If it's a function symbol, it can just set the type to INSN_OTHER so that it caries on to the next instruction after having handled the stack_op." Suggested-by: Julien Thierry Signed-off-by: Miroslav Benes Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200428191659.913283807@infradead.org

objtool: Remove INSN_STACK

2020-04-30T18:14:33Z

With the unconditional use of handle_insn_ops(), INSN_STACK has lost its purpose. Remove it. Suggested-by: Julien Thierry Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200428191659.854203028@infradead.org

objtool: Constify arch_decode_instruction()

2020-04-23T06:34:18Z

Mostly straightforward constification, except that WARN_FUNC() needs a writable pointer while we have read-only pointers, so deflect this to WARN(). Acked-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Sami Tolvanen Cc: Thomas Gleixner Link: https://lore.kernel.org/r/20200422103205.61900-4-mingo@kernel.org

objtool: Rename struct cfi_state

2020-04-22T08:53:50Z

There's going to be a new struct cfi_state, rename this one to make place. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Reviewed-by: Alexandre Chartre Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200416115118.986441913@infradead.org Signed-off-by: Ingo Molnar

objtool: Better handle IRET

2020-04-22T08:53:50Z

Teach objtool a little more about IRET so that we can avoid using the SAVE/RESTORE annotation. In particular, make the weird corner case in insn->restore go away. The purpose of that corner case is to deal with the fact that UNWIND_HINT_RESTORE lands on the instruction after IRET, but that instruction can end up being outside the basic block, consider: if (cond) sync_core() foo(); Then the hint will land on foo(), and we'll encounter the restore hint without ever having seen the save hint. By teaching objtool about the arch specific exception frame size, and assuming that any IRET in an STT_FUNC symbol is an exception frame sized POP, we can remove the use of save/restore hints for this code. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Reviewed-by: Alexandre Chartre Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200416115118.631224674@infradead.org Signed-off-by: Ingo Molnar

objtool: Support multiple stack_op per instruction

2020-04-22T08:53:50Z

Instruction sets can include more or less complex operations which might not fit the currently defined set of stack_ops. Combining more than one stack_op provides more flexibility to describe the behaviour of an instruction. This also reduces the need to define new stack_ops specific to a single instruction set. Allow instruction decoders to generate multiple stack_op per instruction. Signed-off-by: Julien Thierry Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Reviewed-by: Alexandre Chartre Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200327152847.15294-11-jthierry@redhat.com Signed-off-by: Ingo Molnar

objtool: Add abstraction for destination offsets

2020-04-22T08:53:49Z

The jump and call destination relocation offsets are x86-specific. Abstract them by calling arch-specific implementations. [ jthierry: Remove superfluous comment; replace other addend offsets with arch_dest_rela_offset() ] Signed-off-by: Raphael Gault Signed-off-by: Julien Thierry Acked-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar

objtool: Support conditional retpolines

2019-07-18T19:01:10Z

A Clang-built kernel is showing the following warning: arch/x86/kernel/platform-quirks.o: warning: objtool: x86_early_init_platform_quirks()+0x84: unreachable instruction That corresponds to this code: 7e: 0f 85 00 00 00 00 jne 84 80: R_X86_64_PC32 __x86_indirect_thunk_r11-0x4 84: c3 retq This is a conditional retpoline sibling call, which is now possible thanks to retpolines. Objtool hasn't seen that before. It's incorrectly interpreting the conditional jump as an unconditional dynamic jump. Reported-by: Nick Desaulniers Signed-off-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Tested-by: Nick Desaulniers Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/30d4c758b267ef487fb97e6ecb2f148ad007b554.1563413318.git.jpoimboe@redhat.com