Pull more clang LTO updates from Kees Cook: "Clang LTO x86 enablement. Full disclosure: while this has _not_ been in linux-next (since it initially looked like the objtool dependencies weren't going to make v5.12), it has been under daily build and runtime testing by Sami for quite some time. These x86 portions have been discussed on lkml, with Peter, Josh, and others helping nail things down. The bulk of the changes are to get objtool working happily. The rest of the x86 enablement is very small. Summary: - Generate __mcount_loc in objtool (Peter Zijlstra) - Support running objtool against vmlinux.o (Sami Tolvanen) - Clang LTO enablement for x86 (Sami Tolvanen)" Link: https://lore.kernel.org/lkml/20201013003203.4168817-26-samitolvanen@google.com/ Link: https://lore.kernel.org/lkml/cover.1611263461.git.jpoimboe@redhat.com/ * tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: kbuild: lto: force rebuilds when switching CONFIG_LTO x86, build: allow LTO to be selected x86, cpu: disable LTO for cpu.c x86, vdso: disable LTO only for vDSO kbuild: lto: postpone objtool objtool: Split noinstr validation from --vmlinux x86, build: use objtool mcount tracing: add support for objtool mcount objtool: Don't autodetect vmlinux.o objtool: Fix __mcount_loc generation with Clang's assembler objtool: Add a pass for generating __mcount_loc
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| @@ -218,27 +218,11 @@ cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)), · 217 unmodified lines | ||
| 218 | 218 | endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT |
| 219 | 219 | |
| 220 | 220 | ifdef CONFIG_STACK_VALIDATION |
| 221 | +ifndef CONFIG_LTO_CLANG | |
| 221 | 222 | ifneq ($(SKIP_STACK_VALIDATION),1) |
| 222 | 223 | |
| 223 | 224 | __objtool_obj := $(objtree)/tools/objtool/objtool |
| 224 | 225 | |
| 225 | −objtool_args = $(if $(CONFIG_UNWINDER_ORC),orc generate,check) | |
| 226 | − | |
| 227 | −objtool_args += $(if $(part-of-module), --module,) | |
| 228 | − | |
| 229 | −ifndef CONFIG_FRAME_POINTER | |
| 230 | −objtool_args += --no-fp | |
| 231 | −endif | |
| 232 | −ifdef CONFIG_GCOV_KERNEL | |
| 233 | −objtool_args += --no-unreachable | |
| 234 | −endif | |
| 235 | −ifdef CONFIG_RETPOLINE | |
| 236 | − objtool_args += --retpoline | |
| 237 | −endif | |
| 238 | −ifdef CONFIG_X86_SMAP | |
| 239 | − objtool_args += --uaccess | |
| 240 | −endif | |
| 241 | − | |
| 242 | 226 | # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory |
| 243 | 227 | # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file |
| 244 | 228 | # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file |
| @@ -250,6 +234,7 @@ objtool_obj = $(if $(patsubst y%,, \ · 5 unmodified lines | ||
| 250 | 234 | $(__objtool_obj)) |
| 251 | 235 | |
| 252 | 236 | endif # SKIP_STACK_VALIDATION |
| 237 | +endif # CONFIG_LTO_CLANG | |
| 253 | 238 | endif # CONFIG_STACK_VALIDATION |
| 254 | 239 | |
| 255 | 240 | # Rebuild all objects when objtool changes, or is enabled/disabled. |
| @@ -222,6 +222,18 @@ dtc_cpp_flags = -Wp,-MMD,$(depfile).pre.tmp -nostdinc \ · 221 unmodified lines | ||
| 222 | 222 | $(addprefix -I,$(DTC_INCLUDE)) \ |
| 223 | 223 | -undef -D__DTS__ |
| 224 | 224 | |
| 225 | +# Objtool arguments are also needed for modfinal with LTO, so we define | |
| 226 | +# then here to avoid duplication. | |
| 227 | +objtool_args = \ | |
| 228 | + $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \ | |
| 229 | + $(if $(part-of-module), --module,) \ | |
| 230 | + $(if $(CONFIG_FRAME_POINTER),, --no-fp) \ | |
| 231 | + $(if $(or $(CONFIG_GCOV_KERNEL),$(CONFIG_LTO_CLANG)), \ | |
| 232 | + --no-unreachable,) \ | |
| 233 | + $(if $(CONFIG_RETPOLINE), --retpoline,) \ | |
| 234 | + $(if $(CONFIG_X86_SMAP), --uaccess,) \ | |
| 235 | + $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount,) | |
| 236 | + | |
| 225 | 237 | # Useful for describing the dependency of composite objects |
| 226 | 238 | # Usage: |
| 227 | 239 | # $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add) |
| @@ -9,7 +9,7 @@ __modfinal: · 8 unmodified lines | ||
| 9 | 9 | include include/config/auto.conf |
| 10 | 10 | include $(srctree)/scripts/Kbuild.include |
| 11 | 11 | |
| 12 | −# for c_flags | |
| 12 | +# for c_flags and objtool_args | |
| 13 | 13 | include $(srctree)/scripts/Makefile.lib |
| 14 | 14 | |
| 15 | 15 | # find all modules listed in modules.order |
| @@ -34,10 +34,23 @@ ifdef CONFIG_LTO_CLANG · 18 unmodified lines | ||
| 34 | 34 | # With CONFIG_LTO_CLANG, reuse the object file we compiled for modpost to |
| 35 | 35 | # avoid a second slow LTO link |
| 36 | 36 | prelink-ext := .lto |
| 37 | −endif | |
| 37 | + | |
| 38 | +# ELF processing was skipped earlier because we didn't have native code, | |
| 39 | +# so let's now process the prelinked binary before we link the module. | |
| 40 | + | |
| 41 | +ifdef CONFIG_STACK_VALIDATION | |
| 42 | +ifneq ($(SKIP_STACK_VALIDATION),1) | |
| 43 | +cmd_ld_ko_o += \ | |
| 44 | + $(objtree)/tools/objtool/objtool $(objtool_args) \ | |
| 45 | + $(@:.ko=$(prelink-ext).o); | |
| 46 | + | |
| 47 | +endif # SKIP_STACK_VALIDATION | |
| 48 | +endif # CONFIG_STACK_VALIDATION | |
| 49 | + | |
| 50 | +endif # CONFIG_LTO_CLANG | |
| 38 | 51 | |
| 39 | 52 | quiet_cmd_ld_ko_o = LD [M] $@ |
| 40 | − cmd_ld_ko_o = \ | |
| 53 | + cmd_ld_ko_o += \ | |
| 41 | 54 | $(LD) -r $(KBUILD_LDFLAGS) \ |
| 42 | 55 | $(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \ |
| 43 | 56 | -T scripts/module.lds -o $@ $(filter %.o, $^); \ |
| @@ -103,14 +103,36 @@ modpost_link() · 102 unmodified lines | ||
| 103 | 103 | |
| 104 | 104 | objtool_link() |
| 105 | 105 | { |
| 106 | + local objtoolcmd; | |
| 106 | 107 | local objtoolopt; |
| 107 | 108 | |
| 109 | + if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then | |
| 110 | + # Don't perform vmlinux validation unless explicitly requested, | |
| 111 | + # but run objtool on vmlinux.o now that we have an object file. | |
| 112 | + if [ -n "${CONFIG_UNWINDER_ORC}" ]; then | |
| 113 | + objtoolcmd="orc generate" | |
| 114 | + fi | |
| 115 | + | |
| 116 | + objtoolopt="${objtoolopt} --duplicate" | |
| 117 | + | |
| 118 | + if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then | |
| 119 | + objtoolopt="${objtoolopt} --mcount" | |
| 120 | + fi | |
| 121 | + fi | |
| 122 | + | |
| 108 | 123 | if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then |
| 109 | − objtoolopt="check" | |
| 124 | + objtoolopt="${objtoolopt} --noinstr" | |
| 125 | + fi | |
| 126 | + | |
| 127 | + if [ -n "${objtoolopt}" ]; then | |
| 128 | + if [ -z "${objtoolcmd}" ]; then | |
| 129 | + objtoolcmd="check" | |
| 130 | + fi | |
| 131 | + objtoolopt="${objtoolopt} --vmlinux" | |
| 110 | 132 | if [ -z "${CONFIG_FRAME_POINTER}" ]; then |
| 111 | 133 | objtoolopt="${objtoolopt} --no-fp" |
| 112 | 134 | fi |
| 113 | − if [ -n "${CONFIG_GCOV_KERNEL}" ]; then | |
| 135 | + if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then | |
| 114 | 136 | objtoolopt="${objtoolopt} --no-unreachable" |
| 115 | 137 | fi |
| 116 | 138 | if [ -n "${CONFIG_RETPOLINE}" ]; then |
| @@ -120,7 +142,7 @@ objtool_link() · 3 unmodified lines | ||
| 120 | 142 | objtoolopt="${objtoolopt} --uaccess" |
| 121 | 143 | fi |
| 122 | 144 | info OBJTOOL ${1} |
| 123 | − tools/objtool/objtool ${objtoolopt} ${1} | |
| 145 | + tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1} | |
| 124 | 146 | fi |
| 125 | 147 | } |
| 126 | 148 | |