Re: [PATCH 4.9 85/96] x86/retpoline: Add initial retpoline support
From: Jiri Kosina
Date: Sat Jan 20 2018 - 17:22:30 EST
On Wed, 17 Jan 2018, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> > http://git.infradead.org/retpoline-stable.git/shortlog/refs/heads/linux-4.4.y
>
> And I've now queued up all of these patches, thanks very much for doing
> this work!
The patch below is needed on top of it, otherwise if CONFIG_MODVERSIONS is
enabled, all the _thunk symbols end up with 0x0 checksum and fail to load
due to mismatch.
0x00000000 __x86_indirect_thunk_rcx vmlinux EXPORT_SYMBOL
so please consider queuing it on top; I am queuing it in SLE12 codestreams
now.
From: Nicholas Piggin <npiggin@xxxxxxxxx>
Date: Tue, 1 Nov 2016 12:46:19 +1100
Subject: [PATCH] kbuild: modversions for EXPORT_SYMBOL() for asm
Git-commit: 4efca4ed05cbdfd13ec3e8cb623fb77d6e4ab187
Patch-mainline: 4.9-rc6
[jkosina@xxxxxxx: folded cc6acc11cad1 fixup in as well ]
Allow architectures to create asm/asm-prototypes.h file that
provides C prototypes for exported asm functions, which enables
proper CRC versions to be generated for them.
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Michal Marek <mmarek@xxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---
scripts/Makefile.build | 87 +++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 80 insertions(+), 7 deletions(-)
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -158,7 +158,8 @@ cmd_cc_i_c = $(CPP) $(c_flags) -
$(obj)/%.i: $(src)/%.c FORCE
$(call if_changed_dep,cc_i_c)
-cmd_gensymtypes = \
+# These mirror gensymtypes_S and co below, keep them in synch.
+cmd_gensymtypes_c = \
$(CPP) -D__GENKSYMS__ $(c_flags) $< | \
$(GENKSYMS) $(if $(1), -T $(2)) \
$(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \
@@ -169,7 +170,7 @@ cmd_gensymtypes =
quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
cmd_cc_symtypes_c = \
set -e; \
- $(call cmd_gensymtypes,true,$@) >/dev/null; \
+ $(call cmd_gensymtypes_c,true,$@) >/dev/null; \
test -s $@ || rm -f $@
$(obj)/%.symtypes : $(src)/%.c FORCE
@@ -198,9 +199,10 @@ else
# the actual value of the checksum generated by genksyms
cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
-cmd_modversions = \
+
+cmd_modversions_c = \
if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
- $(call cmd_gensymtypes,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
+ $(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
> $(@D)/.tmp_$(@F:.o=.ver); \
\
$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
@@ -245,7 +247,7 @@ endif
define rule_cc_o_c
$(call echo-cmd,checksrc) $(cmd_checksrc) \
$(call echo-cmd,cc_o_c) $(cmd_cc_o_c); \
- $(cmd_modversions) \
+ $(cmd_modversions_c) \
$(call echo-cmd,record_mcount) \
$(cmd_record_mcount) \
scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' > \
@@ -254,6 +256,15 @@ define rule_cc_o_c
mv -f $(dot-target).tmp $(dot-target).cmd
endef
+define rule_as_o_S
+ $(call echo-cmd,as_o_S) $(cmd_as_o_S); \
+ scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,as_o_S)' > \
+ $(dot-target).tmp; \
+ $(cmd_modversions_S) \
+ rm -f $(depfile); \
+ mv -f $(dot-target).tmp $(dot-target).cmd
+endef
+
# Built-in and composite module parts
$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
$(call cmd,force_checksrc)
@@ -282,6 +293,38 @@ modkern_aflags := $(KBUILD_AFLAGS_KERNEL
$(real-objs-m) : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
$(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
+# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
+# or a file that it includes, in order to get versioned symbols. We build a
+# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
+# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
+#
+# This is convoluted. The .S file must first be preprocessed to run guards and
+# expand names, then the resulting exports must be constructed into plain
+# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
+# to make the genksyms input.
+#
+# These mirror gensymtypes_c and co above, keep them in synch.
+cmd_gensymtypes_S = \
+ (echo "\#include <linux/kernel.h>" ; \
+ echo "\#include <asm/asm-prototypes.h>" ; \
+ $(CPP) $(a_flags) $< | \
+ grep "\<___EXPORT_SYMBOL\>" | \
+ sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
+ $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \
+ $(GENKSYMS) $(if $(1), -T $(2)) \
+ $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \
+ $(if $(KBUILD_PRESERVE),-p) \
+ -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
+
+quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
+cmd_cc_symtypes_S = \
+ set -e; \
+ $(call cmd_gensymtypes_S,true,$@) >/dev/null; \
+ test -s $@ || rm -f $@
+
+$(obj)/%.symtypes : $(src)/%.S FORCE
+ $(call cmd,cc_symtypes_S)
+
quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
cmd_as_s_S = $(CPP) $(a_flags) -o $@ $<
@@ -289,10 +332,40 @@ $(obj)/%.s: $(src)/%.S FORCE
$(call if_changed_dep,as_s_S)
quiet_cmd_as_o_S = AS $(quiet_modtag) $@
-cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
+
+ifndef CONFIG_MODVERSIONS
+cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
+
+else
+
+ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
+
+ifeq ($(ASM_PROTOTYPES),)
+cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
+
+else
+
+# versioning matches the C process described above, with difference that
+# we parse asm-prototypes.h C header to get function definitions.
+
+cmd_as_o_S = $(CC) $(a_flags) -c -o $(@D)/.tmp_$(@F) $<
+
+cmd_modversions_S = \
+ if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then \
+ $(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
+ > $(@D)/.tmp_$(@F:.o=.ver); \
+ \
+ $(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) \
+ -T $(@D)/.tmp_$(@F:.o=.ver); \
+ rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver); \
+ else \
+ mv -f $(@D)/.tmp_$(@F) $@; \
+ fi;
+endif
+endif
$(obj)/%.o: $(src)/%.S FORCE
- $(call if_changed_dep,as_o_S)
+ $(call if_changed_rule,as_o_S)
targets += $(real-objs-y) $(real-objs-m) $(lib-y)
targets += $(extra-y) $(MAKECMDGOALS) $(always)
--
Jiri Kosina
SUSE Labs