Merge branch 'linus' into x86/microcode, to pick up merge window changes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/Documentation/x86/early-microcode.txt b/Documentation/x86/early-microcode.txt
index c956d99..07749e7 100644
--- a/Documentation/x86/early-microcode.txt
+++ b/Documentation/x86/early-microcode.txt
@@ -45,7 +45,10 @@
 =================
 
 We can also load builtin microcode supplied through the regular firmware
-builtin method CONFIG_FIRMWARE_IN_KERNEL. Here's an example:
+builtin method CONFIG_FIRMWARE_IN_KERNEL. Only 64-bit is currently
+supported.
+
+Here's an example:
 
 CONFIG_FIRMWARE_IN_KERNEL=y
 CONFIG_EXTRA_FIRMWARE="intel-ucode/06-3a-09 amd-ucode/microcode_amd_fam15h.bin"
diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 9d3a96c..da0d81f 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -133,40 +133,14 @@
 #ifdef CONFIG_MICROCODE
 extern void __init load_ucode_bsp(void);
 extern void load_ucode_ap(void);
-extern int __init save_microcode_in_initrd(void);
 void reload_early_microcode(void);
 extern bool get_builtin_firmware(struct cpio_data *cd, const char *name);
 #else
 static inline void __init load_ucode_bsp(void)			{ }
 static inline void load_ucode_ap(void)				{ }
-static inline int __init save_microcode_in_initrd(void)		{ return 0; }
 static inline void reload_early_microcode(void)			{ }
 static inline bool
 get_builtin_firmware(struct cpio_data *cd, const char *name)	{ return false; }
 #endif
 
-static inline unsigned long get_initrd_start(void)
-{
-#ifdef CONFIG_BLK_DEV_INITRD
-	return initrd_start;
-#else
-	return 0;
-#endif
-}
-
-static inline unsigned long get_initrd_start_addr(void)
-{
-#ifdef CONFIG_BLK_DEV_INITRD
-#ifdef CONFIG_X86_32
-	unsigned long *initrd_start_p = (unsigned long *)__pa_nodebug(&initrd_start);
-
-	return (unsigned long)__pa_nodebug(*initrd_start_p);
-#else
-	return get_initrd_start();
-#endif
-#else /* CONFIG_BLK_DEV_INITRD */
-	return 0;
-#endif
-}
-
 #endif /* _ASM_X86_MICROCODE_H */
diff --git a/arch/x86/include/asm/microcode_amd.h b/arch/x86/include/asm/microcode_amd.h
index adfc847..15eb754 100644
--- a/arch/x86/include/asm/microcode_amd.h
+++ b/arch/x86/include/asm/microcode_amd.h
@@ -62,7 +62,6 @@
 extern enum ucode_state load_microcode_amd(int cpu, u8 family, const u8 *data, size_t size);
 
 #define PATCH_MAX_SIZE PAGE_SIZE
-extern u8 amd_ucode_patch[PATCH_MAX_SIZE];
 
 #ifdef CONFIG_MICROCODE_AMD
 extern void __init load_ucode_amd_bsp(unsigned int family);
diff --git a/arch/x86/include/asm/microcode_intel.h b/arch/x86/include/asm/microcode_intel.h
index 603417f..5e69154 100644
--- a/arch/x86/include/asm/microcode_intel.h
+++ b/arch/x86/include/asm/microcode_intel.h
@@ -70,9 +70,4 @@
 static inline void reload_ucode_intel(void) {}
 #endif
 
-#ifdef CONFIG_HOTPLUG_CPU
-extern int save_mc_for_early(u8 *mc);
-#else
-static inline int save_mc_for_early(u8 *mc) { return 0; }
-#endif
 #endif /* _ASM_X86_MICROCODE_INTEL_H */
diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 8581963..27a0228 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -56,24 +56,24 @@
 static size_t container_size;
 
 static u32 ucode_new_rev;
-u8 amd_ucode_patch[PATCH_MAX_SIZE];
+static u8 amd_ucode_patch[PATCH_MAX_SIZE];
 static u16 this_equiv_id;
 
 static struct cpio_data ucode_cpio;
 
-/*
- * Microcode patch container file is prepended to the initrd in cpio format.
- * See Documentation/x86/early-microcode.txt
- */
-static __initdata char ucode_path[] = "kernel/x86/microcode/AuthenticAMD.bin";
-
 static struct cpio_data __init find_ucode_in_initrd(void)
 {
-	long offset = 0;
+#ifdef CONFIG_BLK_DEV_INITRD
 	char *path;
 	void *start;
 	size_t size;
 
+	/*
+	 * Microcode patch container file is prepended to the initrd in cpio
+	 * format. See Documentation/x86/early-microcode.txt
+	 */
+	static __initdata char ucode_path[] = "kernel/x86/microcode/AuthenticAMD.bin";
+
 #ifdef CONFIG_X86_32
 	struct boot_params *p;
 
@@ -89,9 +89,12 @@
 	path    = ucode_path;
 	start   = (void *)(boot_params.hdr.ramdisk_image + PAGE_OFFSET);
 	size    = boot_params.hdr.ramdisk_size;
-#endif
+#endif /* !CONFIG_X86_32 */
 
-	return find_cpio_data(path, start, size, &offset);
+	return find_cpio_data(path, start, size, NULL);
+#else
+	return (struct cpio_data){ NULL, 0, "" };
+#endif
 }
 
 static size_t compute_container_size(u8 *data, u32 total_size)
@@ -289,11 +292,11 @@
 	size = &ucode_cpio.size;
 #endif
 
-	cp = find_ucode_in_initrd();
-	if (!cp.data) {
-		if (!load_builtin_amd_microcode(&cp, family))
-			return;
-	}
+	if (!load_builtin_amd_microcode(&cp, family))
+		cp = find_ucode_in_initrd();
+
+	if (!(cp.data && cp.size))
+		return;
 
 	*data = cp.data;
 	*size = cp.size;
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index ac360bf..df04b2d 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -60,7 +60,6 @@
 static DEFINE_MUTEX(microcode_mutex);
 
 struct ucode_cpu_info		ucode_cpu_info[NR_CPUS];
-EXPORT_SYMBOL_GPL(ucode_cpu_info);
 
 /*
  * Operations that are run on a target cpu:
@@ -175,24 +174,24 @@
 	}
 }
 
-int __init save_microcode_in_initrd(void)
+static int __init save_microcode_in_initrd(void)
 {
 	struct cpuinfo_x86 *c = &boot_cpu_data;
 
 	switch (c->x86_vendor) {
 	case X86_VENDOR_INTEL:
 		if (c->x86 >= 6)
-			save_microcode_in_initrd_intel();
+			return save_microcode_in_initrd_intel();
 		break;
 	case X86_VENDOR_AMD:
 		if (c->x86 >= 0x10)
-			save_microcode_in_initrd_amd();
+			return save_microcode_in_initrd_amd();
 		break;
 	default:
 		break;
 	}
 
-	return 0;
+	return -EINVAL;
 }
 
 void reload_early_microcode(void)
@@ -691,4 +690,5 @@
 	return error;
 
 }
+fs_initcall(save_microcode_in_initrd);
 late_initcall(microcode_init);
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 65cbbcd..0f97ae9 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -40,9 +40,13 @@
 #include <asm/msr.h>
 
 /*
- * Temporary microcode blobs pointers storage. We note here the pointers to
- * microcode blobs we've got from whatever storage (detached initrd, builtin).
- * Later on, we put those into final storage mc_saved_data.mc_saved.
+ * Temporary microcode blobs pointers storage. We note here during early load
+ * the pointers to microcode blobs we've got from whatever storage (detached
+ * initrd, builtin). Later on, we put those into final storage
+ * mc_saved_data.mc_saved.
+ *
+ * Important: those are offsets from the beginning of initrd or absolute
+ * addresses within the kernel image when built-in.
  */
 static unsigned long mc_tmp_ptrs[MAX_UCODE_COUNT];
 
@@ -51,8 +55,15 @@
 	struct microcode_intel **mc_saved;
 } mc_saved_data;
 
+/* Microcode blobs within the initrd. 0 if builtin. */
+static struct ucode_blobs {
+	unsigned long start;
+	bool valid;
+} blobs;
+
+/* Go through saved patches and find the one suitable for the current CPU. */
 static enum ucode_state
-load_microcode_early(struct microcode_intel **saved,
+find_microcode_patch(struct microcode_intel **saved,
 		     unsigned int num_saved, struct ucode_cpu_info *uci)
 {
 	struct microcode_intel *ucode_ptr, *new_mc = NULL;
@@ -121,13 +132,13 @@
 	if (!mcs->mc_saved) {
 		copy_ptrs(mc_saved_tmp, mc_ptrs, offset, count);
 
-		return load_microcode_early(mc_saved_tmp, count, uci);
+		return find_microcode_patch(mc_saved_tmp, count, uci);
 	} else {
 #ifdef CONFIG_X86_32
 		microcode_phys(mc_saved_tmp, mcs);
-		return load_microcode_early(mc_saved_tmp, count, uci);
+		return find_microcode_patch(mc_saved_tmp, count, uci);
 #else
-		return load_microcode_early(mcs->mc_saved, count, uci);
+		return find_microcode_patch(mcs->mc_saved, count, uci);
 #endif
 	}
 }
@@ -450,8 +461,6 @@
 #endif
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-static DEFINE_MUTEX(x86_cpu_microcode_mutex);
 /*
  * Save this mc into mc_saved_data. So it will be loaded early when a CPU is
  * hot added or resumes.
@@ -459,19 +468,18 @@
  * Please make sure this mc should be a valid microcode patch before calling
  * this function.
  */
-int save_mc_for_early(u8 *mc)
+static void save_mc_for_early(u8 *mc)
 {
+#ifdef CONFIG_HOTPLUG_CPU
+	/* Synchronization during CPU hotplug. */
+	static DEFINE_MUTEX(x86_cpu_microcode_mutex);
+
 	struct microcode_intel *mc_saved_tmp[MAX_UCODE_COUNT];
 	unsigned int mc_saved_count_init;
 	unsigned int num_saved;
 	struct microcode_intel **mc_saved;
-	int ret = 0;
-	int i;
+	int ret, i;
 
-	/*
-	 * Hold hotplug lock so mc_saved_data is not accessed by a CPU in
-	 * hotplug.
-	 */
 	mutex_lock(&x86_cpu_microcode_mutex);
 
 	mc_saved_count_init = mc_saved_data.num_saved;
@@ -509,11 +517,8 @@
 
 out:
 	mutex_unlock(&x86_cpu_microcode_mutex);
-
-	return ret;
-}
-EXPORT_SYMBOL_GPL(save_mc_for_early);
 #endif
+}
 
 static bool __init load_builtin_intel_microcode(struct cpio_data *cp)
 {
@@ -532,37 +537,6 @@
 #endif
 }
 
-static __initdata char ucode_name[] = "kernel/x86/microcode/GenuineIntel.bin";
-static __init enum ucode_state
-scan_microcode(struct mc_saved_data *mcs, unsigned long *mc_ptrs,
-	       unsigned long start, unsigned long size,
-	       struct ucode_cpu_info *uci)
-{
-	struct cpio_data cd;
-	long offset = 0;
-#ifdef CONFIG_X86_32
-	char *p = (char *)__pa_nodebug(ucode_name);
-#else
-	char *p = ucode_name;
-#endif
-
-	cd.data = NULL;
-	cd.size = 0;
-
-	/* try built-in microcode if no initrd */
-	if (!size) {
-		if (!load_builtin_intel_microcode(&cd))
-			return UCODE_ERROR;
-	} else {
-		cd = find_cpio_data(p, (void *)start, size, &offset);
-		if (!cd.data)
-			return UCODE_ERROR;
-	}
-
-	return get_matching_model_microcode(start, cd.data, cd.size,
-					    mcs, mc_ptrs, uci);
-}
-
 /*
  * Print ucode update info.
  */
@@ -680,38 +654,117 @@
  */
 int __init save_microcode_in_initrd_intel(void)
 {
-	unsigned int count = mc_saved_data.num_saved;
 	struct microcode_intel *mc_saved[MAX_UCODE_COUNT];
-	int ret = 0;
+	unsigned int count = mc_saved_data.num_saved;
+	unsigned long offset = 0;
+	int ret;
 
 	if (!count)
-		return ret;
+		return 0;
 
-	copy_ptrs(mc_saved, mc_tmp_ptrs, get_initrd_start(), count);
+	/*
+	 * We have found a valid initrd but it might've been relocated in the
+	 * meantime so get its updated address.
+	 */
+	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && blobs.valid)
+		offset = initrd_start;
+
+	copy_ptrs(mc_saved, mc_tmp_ptrs, offset, count);
 
 	ret = save_microcode(&mc_saved_data, mc_saved, count);
 	if (ret)
 		pr_err("Cannot save microcode patches from initrd.\n");
-
-	show_saved_mc();
+	else
+		show_saved_mc();
 
 	return ret;
 }
 
+static __init enum ucode_state
+__scan_microcode_initrd(struct cpio_data *cd, struct ucode_blobs *blbp)
+{
+#ifdef CONFIG_BLK_DEV_INITRD
+	static __initdata char ucode_name[] = "kernel/x86/microcode/GenuineIntel.bin";
+	char *p = IS_ENABLED(CONFIG_X86_32) ? (char *)__pa_nodebug(ucode_name)
+						    : ucode_name;
+# ifdef CONFIG_X86_32
+	unsigned long start = 0, size;
+	struct boot_params *params;
+
+	params = (struct boot_params *)__pa_nodebug(&boot_params);
+	size   = params->hdr.ramdisk_size;
+
+	/*
+	 * Set start only if we have an initrd image. We cannot use initrd_start
+	 * because it is not set that early yet.
+	 */
+	start = (size ? params->hdr.ramdisk_image : 0);
+
+# else /* CONFIG_X86_64 */
+	unsigned long start = 0, size;
+
+	size  = (u64)boot_params.ext_ramdisk_size << 32;
+	size |= boot_params.hdr.ramdisk_size;
+
+	if (size) {
+		start  = (u64)boot_params.ext_ramdisk_image << 32;
+		start |= boot_params.hdr.ramdisk_image;
+
+		start += PAGE_OFFSET;
+	}
+# endif
+
+	*cd = find_cpio_data(p, (void *)start, size, NULL);
+	if (cd->data) {
+		blbp->start = start;
+		blbp->valid = true;
+
+		return UCODE_OK;
+	} else
+#endif /* CONFIG_BLK_DEV_INITRD */
+		return UCODE_ERROR;
+}
+
+static __init enum ucode_state
+scan_microcode(struct mc_saved_data *mcs, unsigned long *mc_ptrs,
+	       struct ucode_cpu_info *uci, struct ucode_blobs *blbp)
+{
+	struct cpio_data cd = { NULL, 0, "" };
+	enum ucode_state ret;
+
+	/* try built-in microcode first */
+	if (load_builtin_intel_microcode(&cd))
+		/*
+		 * Invalidate blobs as we might've gotten an initrd too,
+		 * supplied by the boot loader, by mistake or simply forgotten
+		 * there. That's fine, we ignore it since we've found builtin
+		 * microcode already.
+		 */
+		blbp->valid = false;
+	else {
+		ret = __scan_microcode_initrd(&cd, blbp);
+		if (ret != UCODE_OK)
+			return ret;
+	}
+
+	return get_matching_model_microcode(blbp->start, cd.data, cd.size,
+					    mcs, mc_ptrs, uci);
+}
+
 static void __init
 _load_ucode_intel_bsp(struct mc_saved_data *mcs, unsigned long *mc_ptrs,
-		      unsigned long start, unsigned long size)
+		      struct ucode_blobs *blbp)
 {
 	struct ucode_cpu_info uci;
 	enum ucode_state ret;
 
 	collect_cpu_info_early(&uci);
 
-	ret = scan_microcode(mcs, mc_ptrs, start, size, &uci);
+	ret = scan_microcode(mcs, mc_ptrs, &uci, blbp);
 	if (ret != UCODE_OK)
 		return;
 
-	ret = load_microcode(mcs, mc_ptrs, start, &uci);
+	ret = load_microcode(mcs, mc_ptrs, blbp->start, &uci);
 	if (ret != UCODE_OK)
 		return;
 
@@ -720,54 +773,62 @@
 
 void __init load_ucode_intel_bsp(void)
 {
-	u64 start, size;
+	struct ucode_blobs *blobs_p;
+	struct mc_saved_data *mcs;
+	unsigned long *ptrs;
+
 #ifdef CONFIG_X86_32
-	struct boot_params *p;
-
-	p	= (struct boot_params *)__pa_nodebug(&boot_params);
-	size	= p->hdr.ramdisk_size;
-
-	/*
-	 * Set start only if we have an initrd image. We cannot use initrd_start
-	 * because it is not set that early yet.
-	 */
-	start	= (size ? p->hdr.ramdisk_image : 0);
-
-	_load_ucode_intel_bsp((struct mc_saved_data *)__pa_nodebug(&mc_saved_data),
-			      (unsigned long *)__pa_nodebug(&mc_tmp_ptrs),
-			      start, size);
+	mcs	= (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
+	ptrs	= (unsigned long *)__pa_nodebug(&mc_tmp_ptrs);
+	blobs_p	= (struct ucode_blobs *)__pa_nodebug(&blobs);
 #else
-	size	= boot_params.hdr.ramdisk_size;
-	start	= (size ? boot_params.hdr.ramdisk_image + PAGE_OFFSET : 0);
-
-	_load_ucode_intel_bsp(&mc_saved_data, mc_tmp_ptrs, start, size);
+	mcs	= &mc_saved_data;
+	ptrs	= mc_tmp_ptrs;
+	blobs_p = &blobs;
 #endif
+
+	_load_ucode_intel_bsp(mcs, ptrs, blobs_p);
 }
 
 void load_ucode_intel_ap(void)
 {
-	unsigned long *mcs_tmp_p;
-	struct mc_saved_data *mcs_p;
+	struct ucode_blobs *blobs_p;
+	unsigned long *ptrs, start = 0;
+	struct mc_saved_data *mcs;
 	struct ucode_cpu_info uci;
 	enum ucode_state ret;
-#ifdef CONFIG_X86_32
 
-	mcs_tmp_p = (unsigned long *)__pa_nodebug(mc_tmp_ptrs);
-	mcs_p = (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
+#ifdef CONFIG_X86_32
+	mcs	= (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
+	ptrs	= (unsigned long *)__pa_nodebug(mc_tmp_ptrs);
+	blobs_p	= (struct ucode_blobs *)__pa_nodebug(&blobs);
 #else
-	mcs_tmp_p = mc_tmp_ptrs;
-	mcs_p = &mc_saved_data;
+	mcs	= &mc_saved_data;
+	ptrs	= mc_tmp_ptrs;
+	blobs_p = &blobs;
 #endif
 
 	/*
 	 * If there is no valid ucode previously saved in memory, no need to
 	 * update ucode on this AP.
 	 */
-	if (!mcs_p->num_saved)
+	if (!mcs->num_saved)
 		return;
 
+	if (blobs_p->valid) {
+		start = blobs_p->start;
+
+#ifdef CONFIG_RANDOMIZE_MEMORY
+		/*
+		 * Pay attention to CONFIG_RANDOMIZE_MEMORY=y as it shuffles
+		 * physmem mapping too and there we have the initrd.
+		 */
+		start += PAGE_OFFSET - __PAGE_OFFSET_BASE;
+#endif
+	}
+
 	collect_cpu_info_early(&uci);
-	ret = load_microcode(mcs_p, mcs_tmp_p, get_initrd_start_addr(), &uci);
+	ret = load_microcode(mcs, ptrs, start, &uci);
 	if (ret != UCODE_OK)
 		return;
 
@@ -784,7 +845,7 @@
 
 	collect_cpu_info_early(&uci);
 
-	ret = load_microcode_early(mc_saved_data.mc_saved,
+	ret = find_microcode_patch(mc_saved_data.mc_saved,
 				   mc_saved_data.num_saved, &uci);
 	if (ret != UCODE_OK)
 		return;
@@ -794,6 +855,7 @@
 
 static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
+	static struct cpu_signature prev;
 	struct cpuinfo_x86 *c = &cpu_data(cpu_num);
 	unsigned int val[2];
 
@@ -808,8 +870,13 @@
 	}
 
 	csig->rev = c->microcode;
-	pr_info("CPU%d sig=0x%x, pf=0x%x, revision=0x%x\n",
-		cpu_num, csig->sig, csig->pf, csig->rev);
+
+	/* No extra locking on prev, races are harmless. */
+	if (csig->sig != prev.sig || csig->pf != prev.pf || csig->rev != prev.rev) {
+		pr_info("sig=0x%x, pf=0x%x, revision=0x%x\n",
+			csig->sig, csig->pf, csig->rev);
+		prev = *csig;
+	}
 
 	return 0;
 }
@@ -838,6 +905,7 @@
 	struct ucode_cpu_info *uci;
 	struct cpuinfo_x86 *c;
 	unsigned int val[2];
+	static int prev_rev;
 
 	/* We should bind the task to the CPU */
 	if (WARN_ON(raw_smp_processor_id() != cpu))
@@ -872,11 +940,14 @@
 		return -1;
 	}
 
-	pr_info("CPU%d updated to revision 0x%x, date = %04x-%02x-%02x\n",
-		cpu, val[1],
-		mc->hdr.date & 0xffff,
-		mc->hdr.date >> 24,
-		(mc->hdr.date >> 16) & 0xff);
+	if (val[1] != prev_rev) {
+		pr_info("updated to revision 0x%x, date = %04x-%02x-%02x\n",
+			val[1],
+			mc->hdr.date & 0xffff,
+			mc->hdr.date >> 24,
+			(mc->hdr.date >> 16) & 0xff);
+		prev_rev = val[1];
+	}
 
 	c = &cpu_data(cpu);
 
diff --git a/arch/x86/kernel/cpu/microcode/intel_lib.c b/arch/x86/kernel/cpu/microcode/intel_lib.c
index 2ce1a7d..406cb6c 100644
--- a/arch/x86/kernel/cpu/microcode/intel_lib.c
+++ b/arch/x86/kernel/cpu/microcode/intel_lib.c
@@ -141,7 +141,6 @@
 	}
 	return 0;
 }
-EXPORT_SYMBOL_GPL(microcode_sanity_check);
 
 /*
  * Returns 1 if update has been found, 0 otherwise.
@@ -183,4 +182,3 @@
 
 	return find_matching_signature(mc, csig, cpf);
 }
-EXPORT_SYMBOL_GPL(has_newer_microcode);
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index cc82830..fb4c1b4 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -700,13 +700,6 @@
 void __init free_initrd_mem(unsigned long start, unsigned long end)
 {
 	/*
-	 * Remember, initrd memory may contain microcode or other useful things.
-	 * Before we lose initrd mem, we need to find a place to hold them
-	 * now that normal virtual memory is enabled.
-	 */
-	save_microcode_in_initrd();
-
-	/*
 	 * end could be not aligned, and We can not align that,
 	 * decompresser could be confused by aligned initrd_end
 	 * We already reserve the end partial page before in
diff --git a/lib/earlycpio.c b/lib/earlycpio.c
index 3eb3e47..db283ba 100644
--- a/lib/earlycpio.c
+++ b/lib/earlycpio.c
@@ -125,7 +125,10 @@
 		if ((ch[C_MODE] & 0170000) == 0100000 &&
 		    ch[C_NAMESIZE] >= mypathsize &&
 		    !memcmp(p, path, mypathsize)) {
-			*nextoff = (long)nptr - (long)data;
+
+			if (nextoff)
+				*nextoff = (long)nptr - (long)data;
+
 			if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
 				pr_warn(
 				"File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",