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kbuild: add arch specific post-link Makefile

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Allow architectures to create arch/xxx/Makefile.postlink with targets
for vmlinux, modules.ko, and clean, which will be invoked after final
linking of vmlinux and modules.

powerpc will use this to check vmlinux linker relocations for sanity,
and may use it to fix up alternate instruction patch branch addresses.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
This commit is contained in:
Nicholas Piggin 2016-08-24 22:29:21 +10:00 committed by Michal Marek
parent b67067f117
commit fbe6e37dab
3 changed files with 32 additions and 8 deletions
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16
Documentation/kbuild/makefiles.txt
View file

@ -41,6 +41,7 @@ This document describes the Linux kernel Makefiles.
--- 6.8 Custom kbuild commands
--- 6.9 Preprocessing linker scripts
--- 6.10 Generic header files
--- 6.11 Post-link pass
=== 7 Kbuild syntax for exported headers
--- 7.1 header-y
@ -1237,6 +1238,21 @@ When kbuild executes, the following steps are followed (roughly):
to list the file in the Kbuild file.
See "7.4 generic-y" for further info on syntax etc.
--- 6.11 Post-link pass
If the file arch/xxx/Makefile.postlink exists, this makefile
will be invoked for post-link objects (vmlinux and modules.ko)
for architectures to run post-link passes on. Must also handle
the clean target.
This pass runs after kallsyms generation. If the architecture
needs to modify symbol locations, rather than manipulate the
kallsyms, it may be easier to add another postlink target for
.tmp_vmlinux? targets to be called from link-vmlinux.sh.
For example, powerpc uses this to check relocation sanity of
the linked vmlinux file.
=== 7 Kbuild syntax for exported headers
The kernel includes a set of headers that is exported to userspace.

10
Makefile
View file

@ -957,9 +957,12 @@ endif
include/generated/autoksyms.h: FORCE
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh true
# Final link of vmlinux
cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)
quiet_cmd_link-vmlinux = LINK $@
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
# Final link of vmlinux with optional arch pass after final link
cmd_link-vmlinux = \
$(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) ; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
vmlinux: scripts/link-vmlinux.sh vmlinux_prereq $(vmlinux-deps) FORCE
+$(call if_changed,link-vmlinux)
@ -1286,6 +1289,7 @@ $(clean-dirs):
vmlinuxclean:
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean
$(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)
clean: archclean vmlinuxclean

14
scripts/Makefile.modpost
View file

@ -115,14 +115,18 @@ $(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
targets += $(modules:.ko=.mod.o)
# Step 6), final link of the modules
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
# Step 6), final link of the modules with optional arch pass after final link
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o = $(LD) -r $(LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-o $@ $(filter-out FORCE,$^)
cmd_ld_ko_o = \
$(LD) -r $(LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-o $@ $(filter-out FORCE,$^) ; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
$(modules): %.ko :%.o %.mod.o FORCE
$(call if_changed,ld_ko_o)
+$(call if_changed,ld_ko_o)
targets += $(modules)