kernel/linux.git/tools/objtool, branch linux-5.11.y

static_call: Allow module use without exposing static_call_key

2021-03-30T12:30:12+00:00

[ Upstream commit 73f44fe19d359635a607e8e8daa0da4001c1cfc2 ] When exporting static_call_key; with EXPORT_STATIC_CALL*(), the module can use static_call_update() to change the function called. This is not desirable in general. Not exporting static_call_key however also disallows usage of static_call(), since objtool needs the key to construct the static_call_site. Solve this by allowing objtool to create the static_call_site using the trampoline address when it builds a module and cannot find the static_call_key symbol. The module loader will then try and map the trampole back to a key before it constructs the normal sites list. Doing this requires a trampoline -> key associsation, so add another magic section that keeps those. Originally-by: Peter Zijlstra (Intel) Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lkml.kernel.org/r/20210127231837.ifddpn7rhwdaepiu@treble Signed-off-by: Sasha Levin

objtool: Fix ".cold" section suffix check for newer versions of GCC

2021-03-04T11:14:45+00:00

[ Upstream commit 34ca59e109bdf69704c33b8eeffaa4c9f71076e5 ] With my version of GCC 9.3.1 the ".cold" subfunctions no longer have a numbered suffix, so the trailing period is no longer there. Presumably this doesn't yet trigger a user-visible bug since most of the subfunction detection logic is duplicated. I only found it when testing vmlinux.o validation. Fixes: 54262aa28301 ("objtool: Fix sibling call detection") Signed-off-by: Josh Poimboeuf Link: https://lore.kernel.org/r/ca0b5a57f08a2fbb48538dd915cc253b5edabb40.1611263461.git.jpoimboe@redhat.com Signed-off-by: Sasha Levin

objtool: Fix retpoline detection in asm code

2021-03-04T11:14:45+00:00

[ Upstream commit 1f9a1b74942485a0a29e7c4a9a9f2fe8aea17766 ] The JMP_NOSPEC macro branches to __x86_retpoline_*() rather than the __x86_indirect_thunk_*() wrappers used by C code. Detect jumps to __x86_retpoline_*() as retpoline dynamic jumps. Presumably this doesn't trigger a user-visible bug. I only found it when testing vmlinux.o validation. Fixes: 39b735332cb8 ("objtool: Detect jumps to retpoline thunks") Signed-off-by: Josh Poimboeuf Link: https://lore.kernel.org/r/31f5833e2e4f01e3d755889ac77e3661e906c09f.1611263461.git.jpoimboe@redhat.com Signed-off-by: Sasha Levin

objtool: Fix error handling for STD/CLD warnings

2021-03-04T11:14:45+00:00

[ Upstream commit 6f567c9300a5ebd7b18c26dda1c8d6ffbdd0debd ] Actually return an error (and display a backtrace, if requested) for directional bit warnings. Fixes: 2f0f9e9ad7b3 ("objtool: Add Direction Flag validation") Signed-off-by: Josh Poimboeuf Link: https://lore.kernel.org/r/dc70f2adbc72f09526f7cab5b6feb8bf7f6c5ad4.1611263461.git.jpoimboe@redhat.com Signed-off-by: Sasha Levin

objtool: Don't fail on missing symbol table

2021-01-21T21:49:58+00:00

Thanks to a recent binutils change which doesn't generate unused symbols, it's now possible for thunk_64.o be completely empty without CONFIG_PREEMPTION: no text, no data, no symbols. We could edit the Makefile to only build that file when CONFIG_PREEMPTION is enabled, but that will likely create confusion if/when the thunks end up getting used by some other code again. Just ignore it and move on. Reported-by: Nathan Chancellor Reviewed-by: Nathan Chancellor Reviewed-by: Miroslav Benes Tested-by: Nathan Chancellor Link: https://github.com/ClangBuiltLinux/linux/issues/1254 Signed-off-by: Josh Poimboeuf

objtool: Don't fail the kernel build on fatal errors

2021-01-21T21:49:39+00:00

This is basically a revert of commit 644592d32837 ("objtool: Fail the kernel build on fatal errors"). That change turned out to be more trouble than it's worth. Failing the build is an extreme measure which sometimes gets too much attention and blocks CI build testing. These fatal-type warnings aren't yet as rare as we'd hope, due to the ever-increasing matrix of supported toolchains/plugins and their fast-changing nature as of late. Also, there are more people (and bots) looking for objtool warnings than ever before, so even non-fatal warnings aren't likely to be ignored for long. Suggested-by: Nick Desaulniers Reviewed-by: Miroslav Benes Reviewed-by: Nick Desaulniers Reviewed-by: Kamalesh Babulal Signed-off-by: Josh Poimboeuf

objtool: Don't add empty symbols to the rbtree

2021-01-13T22:56:37+00:00

Building with the Clang assembler shows the following warning: arch/x86/kernel/ftrace_64.o: warning: objtool: missing symbol for insn at offset 0x16 The Clang assembler strips section symbols. That ends up giving objtool's find_func_containing() much more test coverage than normal. Turns out, find_func_containing() doesn't work so well for overlapping symbols: 2: 000000000000000e 0 NOTYPE LOCAL DEFAULT 2 fgraph_trace 3: 000000000000000f 0 NOTYPE LOCAL DEFAULT 2 trace 4: 0000000000000000 165 FUNC GLOBAL DEFAULT 2 __fentry__ 5: 000000000000000e 0 NOTYPE GLOBAL DEFAULT 2 ftrace_stub The zero-length NOTYPE symbols are inside __fentry__(), confusing the rbtree search for any __fentry__() offset coming after a NOTYPE. Try to avoid this problem by not adding zero-length symbols to the rbtree. They're rare and aren't needed in the rbtree anyway. One caveat, this actually might not end up being the right fix. Non-empty overlapping symbols, if they exist, could have the same problem. But that would need bigger changes, let's see if we can get away with the easy fix for now. Reported-by: Arnd Bergmann Acked-by: Peter Zijlstra (Intel) Signed-off-by: Josh Poimboeuf

Merge tag 'objtool-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-12-27T17:08:23+00:00

Pull objtool fix from Ingo Molnar: "Fix a segfault that occurs when built with Clang" * tag 'objtool-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Fix seg fault with Clang non-section symbols

objtool: Fix seg fault with Clang non-section symbols

2020-12-16T13:35:46+00:00

The Clang assembler likes to strip section symbols, which means objtool can't reference some text code by its section. This confuses objtool greatly, causing it to seg fault. The fix is similar to what was done before, for ORC reloc generation: e81e07244325 ("objtool: Support Clang non-section symbols in ORC generation") Factor out that code into a common helper and use it for static call reloc generation as well. Reported-by: Arnd Bergmann Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Nick Desaulniers Reviewed-by: Miroslav Benes Link: https://github.com/ClangBuiltLinux/linux/issues/1207 Link: https://lkml.kernel.org/r/ba6b6c0f0dd5acbba66e403955a967d9fdd1726a.1607983452.git.jpoimboe@redhat.com

tools: Factor HOSTCC, HOSTLD, HOSTAR definitions

2020-11-11T20:18:22+00:00

Several Makefiles in tools/ need to define the host toolchain variables. Move their definition to tools/scripts/Makefile.include Signed-off-by: Jean-Philippe Brucker Signed-off-by: Andrii Nakryiko Acked-by: Jiri Olsa Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org