From 53f7109ef957315ab53205ba3a3f4f48874c0428 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 8 Mar 2022 16:30:45 +0100 Subject: objtool: Rename --duplicate to --lto In order to prepare for LTO like objtool runs for modules, rename the duplicate argument to lto. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20220308154319.172584233@infradead.org --- scripts/link-vmlinux.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts') diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 666f7bbc13eb..9b08dca26f99 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -115,7 +115,7 @@ objtool_link() objtoolcmd="orc generate" fi - objtoolopt="${objtoolopt} --duplicate" + objtoolopt="${objtoolopt} --lto" if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then objtoolopt="${objtoolopt} --mcount" -- cgit v1.2.3 From ed53a0d971926e484d86cce617ec02a7ee85c3fe Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 8 Mar 2022 16:30:56 +0100 Subject: x86/alternative: Use .ibt_endbr_seal to seal indirect calls Objtool's --ibt option generates .ibt_endbr_seal which lists superfluous ENDBR instructions. That is those instructions for which the function is never indirectly called. Overwrite these ENDBR instructions with a NOP4 such that these function can never be indirect called, reducing the number of viable ENDBR targets in the kernel. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20220308154319.822545231@infradead.org --- scripts/Makefile.build | 47 ++++++++++++++++++++++++++++++++++++++--------- scripts/link-vmlinux.sh | 10 ++++++++-- 2 files changed, 46 insertions(+), 11 deletions(-) (limited to 'scripts') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index a4b89b757287..926d2549a59c 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -86,12 +86,18 @@ ifdef need-builtin targets-for-builtin += $(obj)/built-in.a endif -targets-for-modules := $(patsubst %.o, %.mod, $(filter %.o, $(obj-m))) +targets-for-modules := ifdef CONFIG_LTO_CLANG targets-for-modules += $(patsubst %.o, %.lto.o, $(filter %.o, $(obj-m))) endif +ifdef CONFIG_X86_KERNEL_IBT +targets-for-modules += $(patsubst %.o, %.objtool, $(filter %.o, $(obj-m))) +endif + +targets-for-modules += $(patsubst %.o, %.mod, $(filter %.o, $(obj-m))) + ifdef need-modorder targets-for-modules += $(obj)/modules.order endif @@ -230,6 +236,7 @@ objtool := $(objtree)/tools/objtool/objtool objtool_args = \ $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \ $(if $(part-of-module), --module) \ + $(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \ $(if $(CONFIG_FRAME_POINTER),, --no-fp) \ $(if $(CONFIG_GCOV_KERNEL)$(CONFIG_LTO_CLANG), --no-unreachable)\ $(if $(CONFIG_RETPOLINE), --retpoline) \ @@ -237,8 +244,8 @@ objtool_args = \ $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \ $(if $(CONFIG_SLS), --sls) -cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@) -cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd) +cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $(@:.objtool=.o)) +cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$(@:.objtool=.o): $$(wildcard $(objtool))' ; } >> $(dot-target).cmd) endif # CONFIG_STACK_VALIDATION @@ -247,6 +254,21 @@ ifdef CONFIG_LTO_CLANG # Skip objtool for LLVM bitcode $(obj)/%.o: objtool-enabled := +# objtool was skipped for LLVM bitcode, run it now that we have compiled +# modules into native code +$(obj)/%.lto.o: objtool-enabled = y +$(obj)/%.lto.o: part-of-module := y + +else ifdef CONFIG_X86_KERNEL_IBT + +# Skip objtool on individual files +$(obj)/%.o: objtool-enabled := + +# instead run objtool on the module as a whole, right before +# the final link pass with the linker script. +$(obj)/%.objtool: objtool-enabled = y +$(obj)/%.objtool: part-of-module := y + else # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory @@ -292,18 +314,13 @@ ifdef CONFIG_LTO_CLANG # Module .o files may contain LLVM bitcode, compile them into native code # before ELF processing quiet_cmd_cc_lto_link_modules = LTO [M] $@ -cmd_cc_lto_link_modules = \ + cmd_cc_lto_link_modules = \ $(LD) $(ld_flags) -r -o $@ \ $(shell [ -s $(@:.lto.o=.o.symversions) ] && \ echo -T $(@:.lto.o=.o.symversions)) \ --whole-archive $(filter-out FORCE,$^) \ $(cmd_objtool) -# objtool was skipped for LLVM bitcode, run it now that we have compiled -# modules into native code -$(obj)/%.lto.o: objtool-enabled = y -$(obj)/%.lto.o: part-of-module := y - $(obj)/%.lto.o: $(obj)/%.o FORCE $(call if_changed,cc_lto_link_modules) endif @@ -316,6 +333,18 @@ cmd_mod = { \ $(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o FORCE $(call if_changed,mod) +# +# Since objtool will re-write the file it will change the timestamps, therefore +# it is critical that the %.objtool file gets a timestamp *after* objtool runs. +# +# Additionally, care must be had with ordering this rule against the other rules +# that take %.o as a dependency. +# +cmd_objtool_mod = true $(cmd_objtool) ; touch $@ + +$(obj)/%.objtool: $(obj)/%$(mod-prelink-ext).o FORCE + $(call if_changed,objtool_mod) + quiet_cmd_cc_lst_c = MKLST $@ cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \ $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \ diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 9b08dca26f99..f704034ebbe6 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -108,7 +108,9 @@ objtool_link() local objtoolcmd; local objtoolopt; - if is_enabled CONFIG_LTO_CLANG && is_enabled CONFIG_STACK_VALIDATION; then + if is_enabled CONFIG_STACK_VALIDATION && \ + ( is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ); then + # Don't perform vmlinux validation unless explicitly requested, # but run objtool on vmlinux.o now that we have an object file. if is_enabled CONFIG_UNWINDER_ORC; then @@ -117,6 +119,10 @@ objtool_link() objtoolopt="${objtoolopt} --lto" + if is_enabled CONFIG_X86_KERNEL_IBT; then + objtoolopt="${objtoolopt} --ibt" + fi + if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then objtoolopt="${objtoolopt} --mcount" fi @@ -168,7 +174,7 @@ vmlinux_link() # skip output file argument shift - if is_enabled CONFIG_LTO_CLANG; then + if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then # Use vmlinux.o instead of performing the slow LTO link again. objs=vmlinux.o libs= -- cgit v1.2.3 From d31ed5d767c0452b4f49846d80a0bfeafa3a4ded Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 18 Mar 2022 12:19:27 +0100 Subject: kbuild: Fixup the IBT kbuild changes Masahiro-san deemed my kbuild changes to support whole module objtool runs too terrible to live and gracefully provided an alternative. Suggested-by: Masahiro Yamada Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/CAK7LNAQ2mYMnOKMQheVi+6byUFE3KEkjm1zcndNUfe0tORGvug@mail.gmail.com --- scripts/Makefile.build | 66 +++++++++++++++----------------------------------- scripts/Makefile.lib | 4 +-- scripts/mod/modpost.c | 12 ++++----- 3 files changed, 27 insertions(+), 55 deletions(-) (limited to 'scripts') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 926d2549a59c..2173a6729f30 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -86,18 +86,12 @@ ifdef need-builtin targets-for-builtin += $(obj)/built-in.a endif -targets-for-modules := +targets-for-modules := $(patsubst %.o, %.mod, $(filter %.o, $(obj-m))) -ifdef CONFIG_LTO_CLANG -targets-for-modules += $(patsubst %.o, %.lto.o, $(filter %.o, $(obj-m))) -endif - -ifdef CONFIG_X86_KERNEL_IBT -targets-for-modules += $(patsubst %.o, %.objtool, $(filter %.o, $(obj-m))) +ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) +targets-for-modules += $(patsubst %.o, %.prelink.o, $(filter %.o, $(obj-m))) endif -targets-for-modules += $(patsubst %.o, %.mod, $(filter %.o, $(obj-m))) - ifdef need-modorder targets-for-modules += $(obj)/modules.order endif @@ -244,31 +238,16 @@ objtool_args = \ $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \ $(if $(CONFIG_SLS), --sls) -cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $(@:.objtool=.o)) -cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$(@:.objtool=.o): $$(wildcard $(objtool))' ; } >> $(dot-target).cmd) +cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool_args) $@) +cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(objtool))' ; } >> $(dot-target).cmd) endif # CONFIG_STACK_VALIDATION -ifdef CONFIG_LTO_CLANG +ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) # Skip objtool for LLVM bitcode $(obj)/%.o: objtool-enabled := -# objtool was skipped for LLVM bitcode, run it now that we have compiled -# modules into native code -$(obj)/%.lto.o: objtool-enabled = y -$(obj)/%.lto.o: part-of-module := y - -else ifdef CONFIG_X86_KERNEL_IBT - -# Skip objtool on individual files -$(obj)/%.o: objtool-enabled := - -# instead run objtool on the module as a whole, right before -# the final link pass with the linker script. -$(obj)/%.objtool: objtool-enabled = y -$(obj)/%.objtool: part-of-module := y - else # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory @@ -310,19 +289,24 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE $(call if_changed_rule,cc_o_c) $(call cmd,force_checksrc) -ifdef CONFIG_LTO_CLANG +ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) # Module .o files may contain LLVM bitcode, compile them into native code # before ELF processing -quiet_cmd_cc_lto_link_modules = LTO [M] $@ - cmd_cc_lto_link_modules = \ +quiet_cmd_cc_prelink_modules = LD [M] $@ + cmd_cc_prelink_modules = \ $(LD) $(ld_flags) -r -o $@ \ - $(shell [ -s $(@:.lto.o=.o.symversions) ] && \ - echo -T $(@:.lto.o=.o.symversions)) \ + $(shell [ -s $(@:.prelink.o=.o.symversions) ] && \ + echo -T $(@:.prelink.o=.o.symversions)) \ --whole-archive $(filter-out FORCE,$^) \ $(cmd_objtool) -$(obj)/%.lto.o: $(obj)/%.o FORCE - $(call if_changed,cc_lto_link_modules) +# objtool was skipped for LLVM bitcode, run it now that we have compiled +# modules into native code +$(obj)/%.prelink.o: objtool-enabled = y +$(obj)/%.prelink.o: part-of-module := y + +$(obj)/%.prelink.o: $(obj)/%.o FORCE + $(call if_changed,cc_prelink_modules) endif cmd_mod = { \ @@ -333,18 +317,6 @@ cmd_mod = { \ $(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o FORCE $(call if_changed,mod) -# -# Since objtool will re-write the file it will change the timestamps, therefore -# it is critical that the %.objtool file gets a timestamp *after* objtool runs. -# -# Additionally, care must be had with ordering this rule against the other rules -# that take %.o as a dependency. -# -cmd_objtool_mod = true $(cmd_objtool) ; touch $@ - -$(obj)/%.objtool: $(obj)/%$(mod-prelink-ext).o FORCE - $(call if_changed,objtool_mod) - quiet_cmd_cc_lst_c = MKLST $@ cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \ $(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \ @@ -498,7 +470,7 @@ $(obj)/lib.a: $(lib-y) FORCE # Do not replace $(filter %.o,^) with $(real-prereqs). When a single object # module is turned into a multi object module, $^ will contain header file # dependencies recorded in the .*.cmd file. -ifdef CONFIG_LTO_CLANG +ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) quiet_cmd_link_multi-m = AR [M] $@ cmd_link_multi-m = \ $(cmd_update_lto_symversions); \ diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 79be57fdd32a..8bfc9238237c 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -230,11 +230,11 @@ dtc_cpp_flags = -Wp,-MMD,$(depfile).pre.tmp -nostdinc \ $(addprefix -I,$(DTC_INCLUDE)) \ -undef -D__DTS__ -ifeq ($(CONFIG_LTO_CLANG),y) +ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) # With CONFIG_LTO_CLANG, .o files in modules might be LLVM bitcode, so we # need to run LTO to compile them into native code (.lto.o) before further # processing. -mod-prelink-ext := .lto +mod-prelink-ext := .prelink endif # Useful for describing the dependency of composite objects diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 6bfa33217914..09c3ab0a9b37 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1989,9 +1989,9 @@ static char *remove_dot(char *s) if (m && (s[n + m] == '.' || s[n + m] == 0)) s[n] = 0; - /* strip trailing .lto */ - if (strends(s, ".lto")) - s[strlen(s) - 4] = '\0'; + /* strip trailing .prelink */ + if (strends(s, ".prelink")) + s[strlen(s) - 8] = '\0'; } return s; } @@ -2015,9 +2015,9 @@ static void read_symbols(const char *modname) /* strip trailing .o */ tmp = NOFAIL(strdup(modname)); tmp[strlen(tmp) - 2] = '\0'; - /* strip trailing .lto */ - if (strends(tmp, ".lto")) - tmp[strlen(tmp) - 4] = '\0'; + /* strip trailing .prelink */ + if (strends(tmp, ".prelink")) + tmp[strlen(tmp) - 8] = '\0'; mod = new_module(tmp); free(tmp); } -- cgit v1.2.3