[RFC v3 09/13] firmware: port built-in section to linker table

["Luis R. Rodriguez" <mcgrof@kernel.org>]

This ports built-in firmware to use linker tables,
this replaces the custom section solution with a
generic solution.

This also demos the use of the .rodata (SECTION_RO)
linker tables.

Tested with 0 built-in firmware, 1 and 2 built-in
firmwares successfully.

v3:
o explicitly include tables.h as we no longer include
  tables.h from sections.h

o use new section_tbl_asmtype() helper on firmware/Makefile
  to enable having to unfold things on our own.

v2: introduced this file in this version of the series

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 arch/x86/kernel/cpu/microcode/core.c |  8 ++++----
 drivers/base/firmware_class.c        | 12 ++++++------
 firmware/Makefile                    |  4 +++-
 include/asm-generic/vmlinux.lds.h    |  7 -------
 4 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index df04b2d033f6..3e7c08d99601 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -31,6 +31,7 @@
 #include <linux/cpu.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/tables.h>
 
 #include <asm/microcode_intel.h>
 #include <asm/cpu_device_id.h>
@@ -91,15 +92,14 @@ static bool __init check_loader_disabled_bsp(void)
 	return *res;
 }
 
-extern struct builtin_fw __start_builtin_fw[];
-extern struct builtin_fw __end_builtin_fw[];
+DECLARE_LINKTABLE_RO(struct builtin_fw, builtin_fw);
 
 bool get_builtin_firmware(struct cpio_data *cd, const char *name)
 {
 #ifdef CONFIG_FW_LOADER
-	struct builtin_fw *b_fw;
+	const struct builtin_fw *b_fw;
 
-	for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
+	LINKTABLE_FOR_EACH(b_fw, builtin_fw) {
 		if (!strcmp(name, b_fw->name)) {
 			cd->size = b_fw->size;
 			cd->data = b_fw->data;
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 22d1760a4278..8fbf03c3e4c2 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -30,6 +30,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/reboot.h>
 #include <linux/security.h>
+#include <linux/tables.h>
 
 #include <generated/utsrelease.h>
 
@@ -43,15 +44,14 @@ MODULE_LICENSE("GPL");
 
 #ifdef CONFIG_FW_LOADER
 
-extern struct builtin_fw __start_builtin_fw[];
-extern struct builtin_fw __end_builtin_fw[];
+DEFINE_LINKTABLE_RO(struct builtin_fw, builtin_fw);
 
 static bool fw_get_builtin_firmware(struct firmware *fw, const char *name,
 				    void *buf, size_t size)
 {
-	struct builtin_fw *b_fw;
+	const struct builtin_fw *b_fw;
 
-	for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
+	LINKTABLE_FOR_EACH(b_fw, builtin_fw) {
 		if (strcmp(name, b_fw->name) == 0) {
 			fw->size = b_fw->size;
 			fw->data = b_fw->data;
@@ -67,9 +67,9 @@ static bool fw_get_builtin_firmware(struct firmware *fw, const char *name,
 
 static bool fw_is_builtin_firmware(const struct firmware *fw)
 {
-	struct builtin_fw *b_fw;
+	const struct builtin_fw *b_fw;
 
-	for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++)
+	LINKTABLE_FOR_EACH(b_fw, builtin_fw)
 		if (fw->data == b_fw->data)
 			return true;
 
diff --git a/firmware/Makefile b/firmware/Makefile
index fa3e81c2a97b..32304a227f09 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -155,6 +155,8 @@ quiet_cmd_fwbin = MK_FW   $@
 		  ASM_ALIGN=$(if $(CONFIG_64BIT),3,2);			     \
 		  PROGBITS=$(if $(CONFIG_ARM),%,@)progbits;		     \
 		  echo "/* Generated by firmware/Makefile */"		> $@;\
+		  echo "\#include <asm/sections.h>"			>>$@;\
+		  echo "\#include <asm/tables.h>"			>>$@;\
 		  echo "    .section .rodata"				>>$@;\
 		  echo "    .p2align $${ASM_ALIGN}"			>>$@;\
 		  echo "_fw_$${FWSTR}_bin:"				>>$@;\
@@ -164,7 +166,7 @@ quiet_cmd_fwbin = MK_FW   $@
 		  echo "    .p2align $${ASM_ALIGN}"			>>$@;\
 		  echo "_fw_$${FWSTR}_name:"				>>$@;\
 		  echo "    .string \"$$FWNAME\""			>>$@;\
-		  echo "    .section .builtin_fw,\"a\",$${PROGBITS}"	>>$@;\
+		  echo "    section_tbl_asmtype(SECTION_RODATA, builtin_fw, SECTION_ORDER_ANY, a,$${PROGBITS})"	>>$@;\
 		  echo "    .p2align $${ASM_ALIGN}"			>>$@;\
 		  echo "    $${ASM_WORD} _fw_$${FWSTR}_name"		>>$@;\
 		  echo "    $${ASM_WORD} _fw_$${FWSTR}_bin"		>>$@;\
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b3a9cd7bc947..8e31a4454841 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -313,13 +313,6 @@
 		VMLINUX_SYMBOL(__end_pci_fixups_suspend_late) = .;	\
 	}								\
 									\
-	/* Built-in firmware blobs */					\
-	.builtin_fw        : AT(ADDR(.builtin_fw) - LOAD_OFFSET) {	\
-		VMLINUX_SYMBOL(__start_builtin_fw) = .;			\
-		*(.builtin_fw)						\
-		VMLINUX_SYMBOL(__end_builtin_fw) = .;			\
-	}								\
-									\
 	TRACEDATA							\
 									\
 	/* Kernel symbol table: Normal symbols */			\
-- 
2.8.4