s390: support command lines longer than 896 bytes

Currently s390 supports a fixed maximum command line length of 896
bytes. This isn't enough as some installers are trying to pass all
configuration data via kernel command line, and even with zfcp alone
it is easy to generate really long command lines. Therefore extend
the command line to 4 kbytes.

In the parm area where the command line is stored there is no indication
of the maximum allowed length, so a new field which contains the maximum
length is added.

The parm area has always been initialized to zero, so with old kernels
this field would read zero. This is important because tools like zipl
could read this field. If it contains a number larger than zero zipl
knows the maximum length that can be stored in the parm area, otherwise
it must assume that it is booting a legacy kernel and only 896 bytes are
available.

The removing of trailing whitespace in head.S is also removed because
code to do this is already present in setup_boot_command_line().

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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
+	l	%r3,MAX_COMMAND_LINE_SIZE+ARCH_OFFSET-PARMAREA(%r12)
-	bnh	.Lnotrunc
+	ahi	%r3,-1
-	la	%r2,895
+	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
+	lr	%r5,%r2
-	la	%r3,COMMAND_LINE-PARMAREA(%r12) # load adr. of command line
+	la	%r6,COMMAND_LINE-PARMAREA(%r12)
-	mvc	0(256,%r3),0(%r4)
+	lr	%r7,%r2
-	mvc	256(256,%r3),256(%r4)
+	ahi	%r7,1
-	mvc	512(256,%r3),512(%r4)
+	mvcl	%r6,%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
 .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"

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));
 

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 */
+	unsigned long max_command_line_size;		/* 0x10430 */
-	char command_line[ARCH_COMMAND_LINE_SIZE];	/* 0x10480 */
+	char pad1[0x10480-0x10438];			/* 0x10438 - 0x10480 */
+	char command_line[COMMAND_LINE_SIZE];		/* 0x10480 */
 };
 
 extern struct parmarea parmarea;

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 */

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;
 }

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)

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) ||
+	ret = -EINVAL;
-	    image->cmdline_buf_len >= ARCH_COMMAND_LINE_SIZE) {
+	minsize = PARMAREA + offsetof(struct parmarea, command_line);
-		ret = -EINVAL;
+	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);