powerpc/purgatory: Omit use of bin2c

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

Do similar refactoring as in commit 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 PPC64).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220725015619.618070-1-masahiroy@kernel.org

arch/powerpc/Kconfig

@@ -553,7 +553,6 @@ config KEXEC_FILE
 	bool "kexec file based system call"
 	select KEXEC_CORE
 	select HAVE_IMA_KEXEC if IMA
-	select BUILD_BIN2C
 	select KEXEC_ELF
 	depends on PPC64
 	depends on CRYPTO=y

arch/powerpc/purgatory/.gitignore

 # SPDX-License-Identifier: GPL-2.0-only
-kexec-purgatory.c
 purgatory.ro

arch/powerpc/purgatory/Makefile

@@ -2,17 +2,13 @@
 
 KASAN_SANITIZE := n
 
-targets += trampoline_$(BITS).o purgatory.ro kexec-purgatory.c
+targets += trampoline_$(BITS).o purgatory.ro
 
 LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined
 
 $(obj)/purgatory.ro: $(obj)/trampoline_$(BITS).o FORCE
 		$(call if_changed,ld)
 
-quiet_cmd_bin2c = BIN2C   $@
-      cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@
-
-$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
-	$(call if_changed,bin2c)
+$(obj)/kexec-purgatory.o: $(obj)/purgatory.ro
 
 obj-y	+= kexec-purgatory.o

arch/powerpc/purgatory/kexec-purgatory.S

+/* SPDX-License-Identifier: GPL-2.0 */
+
+	.section .rodata, "a"
+
+	.align	8
+kexec_purgatory:
+	.globl	kexec_purgatory
+	.incbin	"arch/powerpc/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

@@ -20,6 +20,8 @@ set -e
 # yard. Stale files stay in this file for a while (for some release cycles?),
 # then will be really dead and removed from the code base entirely.
 
+rm -f arch/powerpc/purgatory/kexec-purgatory.c
+
 # These were previously generated source files. When you are building the kernel
 # with O=, make sure to remove the stale files in the output tree. Otherwise,
 # the build system wrongly compiles the stale ones.