x86/microcode: Use the firmware_loader built-in API

The microcode loader has been looping through __start_builtin_fw down to
__end_builtin_fw to look for possibly built-in firmware for microcode
updates.

Now that the firmware loader code has exported an API for looping
through the kernel's built-in firmware section, use it and drop the x86
implementation in favor.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20211021155843.1969401-4-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/x86/include/asm/microcode.h

@@ -130,14 +130,11 @@ static inline unsigned int x86_cpuid_family(void)
 extern void __init load_ucode_bsp(void);
 extern void load_ucode_ap(void);
 void reload_early_microcode(void);
-extern bool get_builtin_firmware(struct cpio_data *cd, const char *name);
 extern bool initrd_gone;
 #else
 static inline void __init load_ucode_bsp(void)			{ }
 static inline void load_ucode_ap(void)				{ }
 static inline void reload_early_microcode(void)			{ }
-static inline bool
-get_builtin_firmware(struct cpio_data *cd, const char *name)	{ return false; }
 #endif
 
 #endif /* _ASM_X86_MICROCODE_H */

arch/x86/kernel/cpu/microcode/amd.c

@@ -456,17 +456,23 @@ apply_microcode_early_amd(u32 cpuid_1_eax, void *ucode, size_t size, bool save_p
 
 static bool get_builtin_microcode(struct cpio_data *cp, unsigned int family)
 {
-#ifdef CONFIG_X86_64
 	char fw_name[36] = "amd-ucode/microcode_amd.bin";
+	struct firmware fw;
+
+	if (IS_ENABLED(CONFIG_X86_32))
+		return false;
 
 	if (family >= 0x15)
 		snprintf(fw_name, sizeof(fw_name),
 			 "amd-ucode/microcode_amd_fam%.2xh.bin", family);
 
-	return get_builtin_firmware(cp, fw_name);
-#else
+	if (firmware_request_builtin(&fw, fw_name)) {
+		cp->size = fw.size;
+		cp->data = (void *)fw.data;
+		return true;
+	}
+
 	return false;
-#endif
 }
 
 static void __load_ucode_amd(unsigned int cpuid_1_eax, struct cpio_data *ret)

arch/x86/kernel/cpu/microcode/core.c

@@ -140,23 +140,6 @@ static bool __init check_loader_disabled_bsp(void)
 	return *res;
 }
 
-extern struct builtin_fw __start_builtin_fw[];
-extern struct builtin_fw __end_builtin_fw[];
-
-bool get_builtin_firmware(struct cpio_data *cd, const char *name)
-{
-	struct builtin_fw *b_fw;
-
-	for (b_fw = __start_builtin_fw; b_fw != __end_builtin_fw; b_fw++) {
-		if (!strcmp(name, b_fw->name)) {
-			cd->size = b_fw->size;
-			cd->data = b_fw->data;
-			return true;
-		}
-	}
-	return false;
-}
-
 void __init load_ucode_bsp(void)
 {
 	unsigned int cpuid_1_eax;

arch/x86/kernel/cpu/microcode/intel.c

@@ -456,6 +456,7 @@ static void save_mc_for_early(struct ucode_cpu_info *uci, u8 *mc, unsigned int s
 static bool load_builtin_intel_microcode(struct cpio_data *cp)
 {
 	unsigned int eax = 1, ebx, ecx = 0, edx;
+	struct firmware fw;
 	char name[30];
 
 	if (IS_ENABLED(CONFIG_X86_32))
@@ -466,7 +467,13 @@ static bool load_builtin_intel_microcode(struct cpio_data *cp)
 	sprintf(name, "intel-ucode/%02x-%02x-%02x",
 		      x86_family(eax), x86_model(eax), x86_stepping(eax));
 
-	return get_builtin_firmware(cp, name);
+	if (firmware_request_builtin(&fw, name)) {
+		cp->size = fw.size;
+		cp->data = (void *)fw.data;
+		return true;
+	}
+
+	return false;
 }
 
 /*