From 095fbca0a94930b58f977284ef1b759b98700f8b Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 26 Oct 2020 23:03:13 +0100 Subject: Makefile.extrawarn: move -Wcast-align to W=3 This warning behaves differently depending on the architecture and compiler. Using x86 gcc, we get no output at all because gcc knows the architecture can handle unaligned accesses. Using x86 clang, or gcc on an architecture that needs to manually deal with unaligned accesses, the build log is completely flooded with these warnings, as they are commonly invoked by inline functions of networking headers, e.g. include/linux/skbuff.h:1426:26: warning: cast increases required alignment of target type [-Wcast-align] The compiler is correct to point this out, as we are dealing with undefined behavior that does cause problems in practice, but there is also no good way to rewrite the code in commonly included headers to a safer method. Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Signed-off-by: Masahiro Yamada --- scripts/Makefile.extrawarn | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts') diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 95e4cdb94fe9..6baee1200615 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -60,7 +60,6 @@ endif # ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) -KBUILD_CFLAGS += -Wcast-align KBUILD_CFLAGS += -Wdisabled-optimization KBUILD_CFLAGS += -Wnested-externs KBUILD_CFLAGS += -Wshadow @@ -80,6 +79,7 @@ endif ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) KBUILD_CFLAGS += -Wbad-function-cast +KBUILD_CFLAGS += -Wcast-align KBUILD_CFLAGS += -Wcast-qual KBUILD_CFLAGS += -Wconversion KBUILD_CFLAGS += -Wpacked -- cgit v1.2.3-70-g09d2 From d5750cd3c5486e9c0fa11100df01de8ca0c13fa7 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Thu, 19 Nov 2020 13:46:58 -0700 Subject: kbuild: Disable CONFIG_LD_ORPHAN_WARN for ld.lld 10.0.1 ld.lld 10.0.1 spews a bunch of various warnings about .rela sections, along with a few others. Newer versions of ld.lld do not have these warnings. As a result, do not add '--orphan-handling=warn' to LDFLAGS_vmlinux if ld.lld's version is not new enough. Link: https://github.com/ClangBuiltLinux/linux/issues/1187 Link: https://github.com/ClangBuiltLinux/linux/issues/1193 Reported-by: Arvind Sankar Reported-by: kernelci.org bot Reported-by: Mark Brown Reviewed-by: Kees Cook Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Signed-off-by: Masahiro Yamada --- MAINTAINERS | 1 + init/Kconfig | 5 +++++ scripts/lld-version.sh | 20 ++++++++++++++++++++ 3 files changed, 26 insertions(+) create mode 100755 scripts/lld-version.sh (limited to 'scripts') diff --git a/MAINTAINERS b/MAINTAINERS index a008b70f3c16..286ed8e6b924 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -4274,6 +4274,7 @@ B: https://github.com/ClangBuiltLinux/linux/issues C: irc://chat.freenode.net/clangbuiltlinux F: Documentation/kbuild/llvm.rst F: scripts/clang-tools/ +F: scripts/lld-version.sh K: \b(?i:clang|llvm)\b CLEANCACHE API diff --git a/init/Kconfig b/init/Kconfig index 92c58b45abb8..b9037d6c5ab3 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -47,6 +47,10 @@ config CLANG_VERSION int default $(shell,$(srctree)/scripts/clang-version.sh $(CC)) +config LLD_VERSION + int + default $(shell,$(srctree)/scripts/lld-version.sh $(LD)) + config CC_CAN_LINK bool default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag)) if 64BIT @@ -1351,6 +1355,7 @@ config LD_DEAD_CODE_DATA_ELIMINATION config LD_ORPHAN_WARN def_bool y depends on ARCH_WANT_LD_ORPHAN_WARN + depends on !LD_IS_LLD || LLD_VERSION >= 110000 depends on $(ld-option,--orphan-handling=warn) config SYSCTL diff --git a/scripts/lld-version.sh b/scripts/lld-version.sh new file mode 100755 index 000000000000..d70edb4d8a4f --- /dev/null +++ b/scripts/lld-version.sh @@ -0,0 +1,20 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# +# Usage: $ ./scripts/lld-version.sh ld.lld +# +# Print the linker version of `ld.lld' in a 5 or 6-digit form +# such as `100001' for ld.lld 10.0.1 etc. + +linker_string="$($* --version)" + +if ! ( echo $linker_string | grep -q LLD ); then + echo 0 + exit 1 +fi + +VERSION=$(echo $linker_string | cut -d ' ' -f 2) +MAJOR=$(echo $VERSION | cut -d . -f 1) +MINOR=$(echo $VERSION | cut -d . -f 2) +PATCHLEVEL=$(echo $VERSION | cut -d . -f 3) +printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL -- cgit v1.2.3-70-g09d2 From 7d32358be8acb119dcfe39b6cf67ec6d94bf1fe7 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 4 Dec 2020 02:55:51 +0900 Subject: kbuild: avoid split lines in .mod files "xargs echo" is not a safe way to remove line breaks because the input may exceed the command line limit and xargs may break it up into multiple invocations of echo. This should never happen because scripts/gen_autoksyms.sh expects all undefined symbols are placed in the second line of .mod files. One possible way is to replace "xargs echo" with "sed ':x;N;$!bx;s/\n/ /g'" or something, but I rewrote the code by using awk because it is more readable. This issue was reported by Sami Tolvanen; in his Clang LTO patch set, $(multi-used-m) is no longer an ELF object, but a thin archive that contains LLVM bitcode files. llvm-nm prints out symbols for each archive member separately, which results a lot of dupications, in some places, beyond the system-defined limit. This problem must be fixed irrespective of LTO, and we must ensure zero possibility of having this issue. Link: https://lkml.org/lkml/2020/12/1/1658 Reported-by: Sami Tolvanen Signed-off-by: Masahiro Yamada Reviewed-by: Sami Tolvanen --- scripts/Makefile.build | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) (limited to 'scripts') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index ae647379b579..4c058f12dd73 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -252,6 +252,9 @@ objtool_dep = $(objtool_obj) \ ifdef CONFIG_TRIM_UNUSED_KSYMS cmd_gen_ksymdeps = \ $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd + +# List module undefined symbols +undefined_syms = $(NM) $< | $(AWK) '$$1 == "U" { printf("%s%s", x++ ? " " : "", $$2) }'; endif define rule_cc_o_c @@ -271,13 +274,6 @@ define rule_as_o_S $(call cmd,modversions_S) endef -# List module undefined symbols (or empty line if not enabled) -ifdef CONFIG_TRIM_UNUSED_KSYMS -cmd_undef_syms = $(NM) $< | sed -n 's/^ *U //p' | xargs echo -else -cmd_undef_syms = echo -endif - # Built-in and composite module parts $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE $(call if_changed_rule,cc_o_c) @@ -285,7 +281,7 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE cmd_mod = { \ echo $(if $($*-objs)$($*-y)$($*-m), $(addprefix $(obj)/, $($*-objs) $($*-y) $($*-m)), $(@:.mod=.o)); \ - $(cmd_undef_syms); \ + $(undefined_syms) echo; \ } > $@ $(obj)/%.mod: $(obj)/%.o FORCE -- cgit v1.2.3-70-g09d2