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Masahiro Yamada 3216484550 kbuild: use obj-y instead extra-y for objects placed at the head

The objects placed at the head of vmlinux need special treatments:

 - arch/$(SRCARCH)/Makefile adds them to head-y in order to place
   them before other archives in the linker command line.

 - arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of
   obj-y to avoid them going into built-in.a.

This commit gets rid of the latter.

Create vmlinux.a to collect all the objects that are unconditionally
linked to vmlinux. The objects listed in head-y are moved to the head
of vmlinux.a by using 'ar m'.

With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y
for builtin objects.

There is no *.o that is directly linked to vmlinux. Drop unneeded code
in scripts/clang-tools/gen_compile_commands.py.

$(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested
by Nathan Chancellor [1].

[1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

2022-10-02 18:04:05 +09:00

1.8 KiB

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SPDX-License-Identifier: GPL-2.0

Makefile for the Linux/Xtensa kernel.

extra-y := vmlinux.lds

obj-y := head.o align.o coprocessor.o entry.o irq.o platform.o process.o
ptrace.o setup.o signal.o stacktrace.o syscall.o time.o traps.o
vectors.o

obj-$(CONFIG_MMU) += pci-dma.o obj-$(CONFIG_PCI) += pci.o obj-$(CONFIG_MODULES) += xtensa_ksyms.o module.o obj-$(CONFIG_FUNCTION_TRACER) += mcount.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SECONDARY_RESET_VECTOR) += mxhead.o obj-$(CONFIG_XTENSA_VARIANT_HAVE_PERF_EVENTS) += perf_event.o obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_S32C1I_SELFTEST) += s32c1i_selftest.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o obj-$(CONFIG_HIBERNATION) += hibernate.o

In the Xtensa architecture, assembly generates literals which must always

precede the L32R instruction with a relative offset less than 256 kB.

Therefore, the .text and .literal section must be combined in parenthesis

in the linker script, such as: *(.literal .text).

We need to post-process the generated vmlinux.lds scripts to convert

(xxx.text) to (xxx.literal xxx.text) for the following text sections:

.text .ref.text .*init.text .exit.text .text.

Replicate rules in scripts/Makefile.build

sed-y = -e ':a; s/*(([^)]).text.unlikely/(\1.literal.unlikely .{text}.unlikely/; ta; '
-e ':b; s/*(([^)]).text(.[a-z])/(\1.{text}\2.literal .{text}\2/; tb; '
-e ':c; s/*(([^)])(.[a-z]it|.ref).text/(\1\2.literal \2.{text}/; tc; '
-e ':d; s/*(([^)]+ |).text/*(\1.literal .{text}/; td; '
-e 's/.{text}/.text/g'

quiet_cmd__cpp_lds_S = LDS $@ cmd__cpp_lds_S = $(CPP) $(cpp_flags) -P -C -Uxtensa -D__ASSEMBLY__
-DLINKER_SCRIPT $< | sed $(sed-y) >$@

$(obj)/vmlinux.lds: $(src)/vmlinux.lds.S FORCE $(call if_changed_dep,_cpp_lds_S)

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