[PATCH 1/3] s390: add variable command line size

[Sven Schnelle <svens@linux.ibm.com>]

Newer s390 kernels support a command line size longer than 896
bytes. Such kernels contain a new member in the parameter area,
which might be utilized by tools like kexec. Older kernels have
the location initialized to zero, so we check whether there's a
non-zero number present and use that. If there isn't, we fallback
to the legacy command line size of 896 bytes.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
---
 kexec/arch/s390/kexec-image.c | 53 ++++++++++++++++++++++++-----------
 kexec/arch/s390/kexec-s390.h  | 19 +++++++------
 2 files changed, 46 insertions(+), 26 deletions(-)

diff --git a/kexec/arch/s390/kexec-image.c b/kexec/arch/s390/kexec-image.c
index 3c24fdfe3c7c..7747d02399db 100644
--- a/kexec/arch/s390/kexec-image.c
+++ b/kexec/arch/s390/kexec-image.c
@@ -25,7 +25,7 @@
 #include <fcntl.h>
 
 static uint64_t crash_base, crash_end;
-static char command_line[COMMAND_LINESIZE];
+static char *command_line;
 
 static void add_segment_check(struct kexec_info *info, const void *buf,
 			      size_t bufsz, unsigned long base, size_t memsz)
@@ -38,11 +38,16 @@ static void add_segment_check(struct kexec_info *info, const void *buf,
 
 int command_line_add(const char *str)
 {
-	if (strlen(command_line) + strlen(str) + 1 > COMMAND_LINESIZE) {
-		fprintf(stderr, "Command line too long.\n");
+	char *tmp = NULL;
+
+	tmp = concat_cmdline(command_line, str);
+	if (!tmp) {
+		fprintf(stderr, "out of memory\n");
 		return -1;
 	}
-	strcat(command_line, str);
+
+	free(command_line);
+	command_line = tmp;
 	return 0;
 }
 
@@ -78,6 +83,8 @@ int image_s390_load_file(int argc, char **argv, struct kexec_info *info)
 		if (info->initrd_fd == -1) {
 			fprintf(stderr, "Could not open initrd file %s:%s\n",
 					ramdisk, strerror(errno));
+			free(command_line);
+			command_line = NULL;
 			return -1;
 		}
 	}
@@ -97,7 +104,7 @@ image_s390_load(int argc, char **argv, const char *kernel_buf,
 	const char *ramdisk;
 	off_t ramdisk_len;
 	unsigned int ramdisk_origin;
-	int opt;
+	int opt, ret = -1;
 
 	if (info->file_mode)
 		return image_s390_load_file(argc, argv, info);
@@ -112,7 +119,6 @@ image_s390_load(int argc, char **argv, const char *kernel_buf,
 		};
 	static const char short_options[] = KEXEC_OPT_STR "";
 
-	command_line[0] = 0;
 	ramdisk = NULL;
 	ramdisk_len = 0;
 	ramdisk_origin = 0;
@@ -132,7 +138,7 @@ image_s390_load(int argc, char **argv, const char *kernel_buf,
 	if (info->kexec_flags & KEXEC_ON_CRASH) {
 		if (parse_iomem_single("Crash kernel\n", &crash_base,
 				       &crash_end))
-			return -1;
+			goto out;
 	}
 
 	/* Add kernel segment */
@@ -151,7 +157,7 @@ image_s390_load(int argc, char **argv, const char *kernel_buf,
 		rd_buffer = slurp_file_mmap(ramdisk, &ramdisk_len);
 		if (rd_buffer == NULL) {
 			fprintf(stderr, "Could not read ramdisk.\n");
-			return -1;
+			goto out;
 		}
 		ramdisk_origin = MAX(RAMDISK_ORIGIN_ADDR, kernel_size);
 		ramdisk_origin = _ALIGN_UP(ramdisk_origin, 0x100000);
@@ -160,7 +166,7 @@ image_s390_load(int argc, char **argv, const char *kernel_buf,
 	}
 	if (info->kexec_flags & KEXEC_ON_CRASH) {
 		if (load_crashdump_segments(info, crash_base, crash_end))
-			return -1;
+			goto out;
 	} else {
 		info->entry = (void *) IMAGE_READ_OFFSET;
 	}
@@ -183,15 +189,28 @@ image_s390_load(int argc, char **argv, const char *kernel_buf,
 			*tmp = crash_end - crash_base + 1;
 		}
 	}
-	/*
-	 * We will write a probably given command line.
-	 * First, erase the old area, then setup the new parameters:
-	 */
-	if (strlen(command_line) != 0) {
-		memset(krnl_buffer + COMMAND_LINE_OFFS, 0, COMMAND_LINESIZE);
-		memcpy(krnl_buffer + COMMAND_LINE_OFFS, command_line, strlen(command_line));
+
+	if (command_line) {
+		unsigned long maxsize;
+		char *dest = krnl_buffer + COMMAND_LINE_OFFS;
+
+		maxsize = *(unsigned long *)(krnl_buffer + MAX_COMMAND_LINESIZE_OFFS);
+		if (!maxsize)
+			maxsize = LEGACY_COMMAND_LINESIZE;
+
+		if (strlen(command_line) > maxsize-1) {
+			fprintf(stderr, "command line too long, maximum allowed size %ld\n",
+				maxsize-1);
+			goto out;
+		}
+		strncpy(dest, command_line, maxsize-1);
+		dest[maxsize-1] = '\0';
 	}
-	return 0;
+	ret = 0;
+out:
+	free(command_line);
+	command_line = NULL;
+	return ret;
 }
 
 int 
diff --git a/kexec/arch/s390/kexec-s390.h b/kexec/arch/s390/kexec-s390.h
index ef53b111e167..1b0e04848460 100644
--- a/kexec/arch/s390/kexec-s390.h
+++ b/kexec/arch/s390/kexec-s390.h
@@ -10,16 +10,17 @@
 #ifndef KEXEC_S390_H
 #define KEXEC_S390_H
 
-#define IMAGE_READ_OFFSET     0x10000
+#define IMAGE_READ_OFFSET           0x10000
 
-#define RAMDISK_ORIGIN_ADDR   0x800000
-#define INITRD_START_OFFS     0x408
-#define INITRD_SIZE_OFFS      0x410
-#define OLDMEM_BASE_OFFS      0x418
-#define OLDMEM_SIZE_OFFS      0x420
-#define COMMAND_LINE_OFFS     0x480
-#define COMMAND_LINESIZE      896
-#define MAX_MEMORY_RANGES     1024
+#define RAMDISK_ORIGIN_ADDR         0x800000
+#define INITRD_START_OFFS           0x408
+#define INITRD_SIZE_OFFS            0x410
+#define OLDMEM_BASE_OFFS            0x418
+#define OLDMEM_SIZE_OFFS            0x420
+#define MAX_COMMAND_LINESIZE_OFFS   0x430
+#define COMMAND_LINE_OFFS           0x480
+#define LEGACY_COMMAND_LINESIZE     896
+#define MAX_MEMORY_RANGES           1024
 
 #define MAX(x, y) ((x) > (y) ? (x) : (y))
 #define MIN(x, y) ((x) < (y) ? (x) : (y))
-- 
2.25.1


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