[tip: x86/core] kbuild: Fixup the IBT kbuild changes
From: tip-bot2 for Peter Zijlstra
Date: Tue Mar 22 2022 - 16:24:14 EST
The following commit has been merged into the x86/core branch of tip:
Commit-ID: d31ed5d767c0452b4f49846d80a0bfeafa3a4ded
Gitweb: https://git.kernel.org/tip/d31ed5d767c0452b4f49846d80a0bfeafa3a4ded
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 18 Mar 2022 12:19:27 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 22 Mar 2022 21:12:04 +01:00
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 <masahiroy@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/CAK7LNAQ2mYMnOKMQheVi+6byUFE3KEkjm1zcndNUfe0tORGvug@xxxxxxxxxxxxxx
---
scripts/Makefile.build | 66 +++++++++++------------------------------
scripts/Makefile.lib | 4 +-
scripts/mod/modpost.c | 12 +++----
3 files changed, 27 insertions(+), 55 deletions(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 926d254..2173a67 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 = \
$(cmd_update_lto_symversions); \
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 79be57f..8bfc923 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -230,11 +230,11 @@ dtc_cpp_flags = -Wp,-MMD,$(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 6bfa332..09c3ab0 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);
}