x86/purgatory: Omit use of bin2c

The .incbin assembler directive is much faster than bin2c + $(CC).

Do similar refactoring as in

  4c0f032d ("s390/purgatory: Omit use of bin2c").

Please note the .quad directive matches to size_t in C (both 8
byte) because the purgatory is compiled only for the 64-bit kernel.
(KEXEC_FILE depends on X86_64).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220725020812.622255-2-masahiroy@kernel.org

arch/x86/.gitignore

@@ -3,6 +3,4 @@ boot/compressed/vmlinux
 tools/test_get_len
 tools/insn_sanity
 tools/insn_decoder_test
-purgatory/kexec-purgatory.c
 purgatory/purgatory.ro
-

arch/x86/Kconfig

@@ -2032,7 +2032,6 @@ config KEXEC
 config KEXEC_FILE
 	bool "kexec file based system call"
 	select KEXEC_CORE
-	select BUILD_BIN2C
 	depends on X86_64
 	depends on CRYPTO=y
 	depends on CRYPTO_SHA256=y

arch/x86/purgatory/Makefile

@@ -73,12 +73,6 @@ $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
 $(obj)/purgatory.chk: $(obj)/purgatory.ro FORCE
 		$(call if_changed,ld)
 
-targets += kexec-purgatory.c
-
-quiet_cmd_bin2c = BIN2C   $@
-      cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@
-
-$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro $(obj)/purgatory.chk FORCE
-	$(call if_changed,bin2c)
+$(obj)/kexec-purgatory.o: $(obj)/purgatory.ro $(obj)/purgatory.chk
 
 obj-y += kexec-purgatory.o

arch/x86/purgatory/kexec-purgatory.S

+/* SPDX-License-Identifier: GPL-2.0 */
+
+	.section .rodata, "a"
+
+	.align	8
+kexec_purgatory:
+	.globl	kexec_purgatory
+	.incbin	"arch/x86/purgatory/purgatory.ro"
+.Lkexec_purgatory_end:
+
+	.align	8
+kexec_purgatory_size:
+	.globl	kexec_purgatory_size
+	.quad	.Lkexec_purgatory_end - kexec_purgatory

scripts/remove-stale-files

@@ -41,3 +41,5 @@ if [ -n "${building_out_of_srctree}" ]; then
 fi
 
 rm -f scripts/extract-cert
+
+rm -f arch/x86/purgatory/kexec-purgatory.c