diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index 5d3fc69a505c..3a252d140c55 100644
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -184,35 +184,23 @@ iplstart:
 	bas	%r14,.Lloader		# load parameter file
 	ltr	%r2,%r2 		# got anything ?
 	bz	.Lnopf
-	chi	%r2,895
-	bnh	.Lnotrunc
-	la	%r2,895
+	l	%r3,MAX_COMMAND_LINE_SIZE+ARCH_OFFSET-PARMAREA(%r12)
+	ahi	%r3,-1
+	clr	%r2,%r3
+	bl	.Lnotrunc
+	lr	%r2,%r3
 .Lnotrunc:
 	l	%r4,.Linitrd
 	clc	0(3,%r4),.L_hdr		# if it is HDRx
 	bz	.Lagain1		# skip dataset header
 	clc	0(3,%r4),.L_eof		# if it is EOFx
 	bz	.Lagain1		# skip dateset trailer
-	la	%r5,0(%r4,%r2)
-	lr	%r3,%r2
-	la	%r3,COMMAND_LINE-PARMAREA(%r12) # load adr. of command line
-	mvc	0(256,%r3),0(%r4)
-	mvc	256(256,%r3),256(%r4)
-	mvc	512(256,%r3),512(%r4)
-	mvc	768(122,%r3),768(%r4)
-	slr	%r0,%r0
-	b	.Lcntlp
-.Ldelspc:
-	ic	%r0,0(%r2,%r3)
-	chi	%r0,0x20		# is it a space ?
-	be	.Lcntlp
-	ahi	%r2,1
-	b	.Leolp
-.Lcntlp:
-	brct	%r2,.Ldelspc
-.Leolp:
-	slr	%r0,%r0
-	stc	%r0,0(%r2,%r3)		# terminate buffer
+
+	lr	%r5,%r2
+	la	%r6,COMMAND_LINE-PARMAREA(%r12)
+	lr	%r7,%r2
+	ahi	%r7,1
+	mvcl	%r6,%r4
 .Lnopf:
 
 #
@@ -394,6 +382,7 @@ SYM_DATA_START(parmarea)
 	.quad	0			# OLDMEM_BASE
 	.quad	0			# OLDMEM_SIZE
 	.quad	kernel_version		# points to kernel version string
+	.quad	COMMAND_LINE_SIZE
 
 	.org	COMMAND_LINE
 	.byte	"root=/dev/ram0 ro"
diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c
index 0f84c072625e..9ed7e29c81d9 100644
--- a/arch/s390/boot/ipl_parm.c
+++ b/arch/s390/boot/ipl_parm.c
@@ -170,10 +170,10 @@ static inline int has_ebcdic_char(const char *str)
 
 void setup_boot_command_line(void)
 {
-	parmarea.command_line[ARCH_COMMAND_LINE_SIZE - 1] = 0;
+	parmarea.command_line[COMMAND_LINE_SIZE - 1] = 0;
 	/* convert arch command line to ascii if necessary */
 	if (has_ebcdic_char(parmarea.command_line))
-		EBCASC(parmarea.command_line, ARCH_COMMAND_LINE_SIZE);
+		EBCASC(parmarea.command_line, COMMAND_LINE_SIZE);
 	/* copy arch command line */
 	strcpy(early_command_line, strim(parmarea.command_line));
 
diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h
index 121e1a8c41d7..d718029794e2 100644
--- a/arch/s390/include/asm/setup.h
+++ b/arch/s390/include/asm/setup.h
@@ -42,6 +42,8 @@
 #define STARTUP_NORMAL_OFFSET	0x10000
 #define STARTUP_KDUMP_OFFSET	0x10010
 
+#define LEGACY_COMMAND_LINE_SIZE	896
+
 #ifndef __ASSEMBLY__
 
 #include <asm/lowcore.h>
@@ -54,8 +56,9 @@ struct parmarea {
 	unsigned long oldmem_base;			/* 0x10418 */
 	unsigned long oldmem_size;			/* 0x10420 */
 	unsigned long kernel_version;			/* 0x10428 */
-	char pad1[0x10480 - 0x10430];			/* 0x10430 - 0x10480 */
-	char command_line[ARCH_COMMAND_LINE_SIZE];	/* 0x10480 */
+	unsigned long max_command_line_size;		/* 0x10430 */
+	char pad1[0x10480-0x10438];			/* 0x10438 - 0x10480 */
+	char command_line[COMMAND_LINE_SIZE];		/* 0x10480 */
 };
 
 extern struct parmarea parmarea;
diff --git a/arch/s390/include/uapi/asm/setup.h b/arch/s390/include/uapi/asm/setup.h
index 1f8803a31079..9b685536c31c 100644
--- a/arch/s390/include/uapi/asm/setup.h
+++ b/arch/s390/include/uapi/asm/setup.h
@@ -9,6 +9,4 @@
 
 #define COMMAND_LINE_SIZE	4096
 
-#define ARCH_COMMAND_LINE_SIZE	896
-
 #endif /* _UAPI_ASM_S390_SETUP_H */
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 28177e4f52cc..8e00bb228662 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -164,5 +164,6 @@ int main(void)
 	DEFINE(OLDMEM_BASE, PARMAREA + offsetof(struct parmarea, oldmem_base));
 	DEFINE(OLDMEM_SIZE, PARMAREA + offsetof(struct parmarea, oldmem_size));
 	DEFINE(COMMAND_LINE, PARMAREA + offsetof(struct parmarea, command_line));
+	DEFINE(MAX_COMMAND_LINE_SIZE, PARMAREA + offsetof(struct parmarea, max_command_line_size));
 	return 0;
 }
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index ba3ace5ac73c..3cdf68c53614 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -280,7 +280,7 @@ char __bootdata(early_command_line)[COMMAND_LINE_SIZE];
 static void __init setup_boot_command_line(void)
 {
 	/* copy arch command line */
-	strlcpy(boot_command_line, early_command_line, ARCH_COMMAND_LINE_SIZE);
+	strlcpy(boot_command_line, early_command_line, COMMAND_LINE_SIZE);
 }
 
 static void __init check_image_bootable(void)
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index 55382ffde9d4..528edff085d9 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -216,7 +216,9 @@ void *kexec_file_add_components(struct kimage *image,
 				int (*add_kernel)(struct kimage *image,
 						  struct s390_load_data *data))
 {
+	unsigned long max_command_line_size = LEGACY_COMMAND_LINE_SIZE;
 	struct s390_load_data data = {0};
+	unsigned long minsize;
 	int ret;
 
 	data.report = ipl_report_init(&ipl_block);
@@ -227,11 +229,23 @@ void *kexec_file_add_components(struct kimage *image,
 	if (ret)
 		goto out;
 
-	if (image->kernel_buf_len < PARMAREA + sizeof(struct parmarea) ||
-	    image->cmdline_buf_len >= ARCH_COMMAND_LINE_SIZE) {
-		ret = -EINVAL;
+	ret = -EINVAL;
+	minsize = PARMAREA + offsetof(struct parmarea, command_line);
+	if (image->kernel_buf_len < minsize)
 		goto out;
-	}
+
+	if (data.parm->max_command_line_size)
+		max_command_line_size = data.parm->max_command_line_size;
+
+	if (minsize + max_command_line_size < minsize)
+		goto out;
+
+	if (image->kernel_buf_len < minsize + max_command_line_size)
+		goto out;
+
+	if (image->cmdline_buf_len >= max_command_line_size)
+		goto out;
+
 	memcpy(data.parm->command_line, image->cmdline_buf,
 	       image->cmdline_buf_len);