[PATCH v4] kexec-tools: mips: Pass initrd parameter via cmdline

[Hui Li]

Under loongson platform, use command:
kexec -l vmlinux... --append="root=UUID=28e1..." --initrd=...
kexec -e
quick restart failed like this:

********************************************************************
[    3.420791] VFS: Cannot open root device "UUID=6462a8a4-02fb-49..."
[    3.431262] Please append a correct "root=" boot option; ...
...
...
...
[    3.543175]   0801         4194304 sda1 554e69cc-01
[    3.543175]
[    3.549494]   0802        62914560 sda2 554e69cc-02
[    3.549495]
[    3.555818]   0803         8388608 sda3 554e69cc-03
[    3.555819]
[    3.562139]   0804       174553229 sda4 554e69cc-04
[    3.562139]
[    3.568463] 0b00         1048575 sr0
[    3.568464]  driver: sr
[    3.574524] Kernel panic - not syncing: VFS: Unable to mount root fs...
[    3.582750] ---[ end Kernel panic - not syncing: VFS:...
*******************************************************************

The kernel cannot parse the UUID, the UUID is parsed in the initrd.
For compatibility with previous platforms, loongson platform obtain
initrd parameter through cmdline in kernel, the kernel supports use
cmdline to parse initrd. But under the mips architecture, kexec-tools
pass the initrd through DTB.

So some modifications as follows:

(1) in kexec/arch/mips/kexec-elf-mips.c
    Add patch_initrd_info(), at runtime to distinguish different cpu,
    only for loongson cpu, add initrd parameter to cmdline.

(2) in kexec/arch/mips/crashdump-mips.c
    Because loongson uses a different page_offset, it should be modified
    to ensure that crashdump functionality is correct and reliable.

Signed-off-by: Hui Li <lihui at loongson.cn>
---
 kexec/arch/mips/crashdump-mips.c |  3 ++
 kexec/arch/mips/kexec-elf-mips.c | 73 +++++++++++++++++++++++++++++++-
 2 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/kexec/arch/mips/crashdump-mips.c b/kexec/arch/mips/crashdump-mips.c
index aa09c83..548aeff 100644
--- a/kexec/arch/mips/crashdump-mips.c
+++ b/kexec/arch/mips/crashdump-mips.c
@@ -335,6 +335,9 @@ static int patch_elf_info(void)
 			/* OCTEON uses a different page_offset. */
 			if (strstr(line, "Octeon"))
 				elf_info64.page_offset = 0x8000000000000000ULL;
+			/* LOONGSON uses a different page_offset. */
+			else if (strstr(line, "Loongson"))
+				elf_info64.page_offset = 0xffffffff80000000ULL;
 			break;
 		}
 	}
diff --git a/kexec/arch/mips/kexec-elf-mips.c b/kexec/arch/mips/kexec-elf-mips.c
index a2d11fc..b9e0341 100644
--- a/kexec/arch/mips/kexec-elf-mips.c
+++ b/kexec/arch/mips/kexec-elf-mips.c
@@ -40,6 +40,74 @@ static const int probe_debug = 0;
 #define CMDLINE_PREFIX "kexec "
 static char cmdline_buf[COMMAND_LINE_SIZE] = CMDLINE_PREFIX;
 
+/* Converts unsigned long to ascii string. */
+static void ultoa(unsigned long i, char *str)
+{
+	int j = 0, k;
+	char tmp;
+
+	do {
+		str[j++] = i % 10 + '0';
+	} while ((i /= 10) > 0);
+	str[j] = '\0';
+
+	/* Reverse the string. */
+	for (j = 0, k = strlen(str) - 1; j < k; j++, k--) {
+		tmp = str[k];
+		str[k] = str[j];
+		str[j] = tmp;
+	}
+}
+
+/* Adds initrd parameters to command line. */
+static int cmdline_add_initrd(char *cmdline, unsigned long addr, char *new_para)
+{
+	int cmdlen, len;
+	char str[30], *ptr;
+
+	ptr = str;
+	strcpy(str, new_para);
+	ptr += strlen(str);
+	ultoa(addr, ptr);
+	len = strlen(str);
+	cmdlen = strlen(cmdline) + len;
+	if (cmdlen > (COMMAND_LINE_SIZE - 1))
+		die("Command line overflow\n");
+	strcat(cmdline, str);
+
+	return 0;
+}
+
+/* add initrd to cmdline to compatible with previous platforms. */
+static int patch_initrd_info(char *cmdline, unsigned long initrd_base, unsigned long initrd_size)
+{
+	const char cpuinfo[] = "/proc/cpuinfo";
+	char line[MAX_LINE];
+	FILE *fp;
+	unsigned long page_offset = PAGE_OFFSET;
+
+	fp = fopen(cpuinfo, "r");
+	if (!fp) {
+		fprintf(stderr, "Cannot open %s: %s\n",
+		cpuinfo, strerror(errno));
+		return -1;
+	}
+	while (fgets(line, sizeof(line), fp) != 0) {
+		if (strncmp(line, "cpu model", 9) == 0) {
+			/* LOONGSON64  uses a different page_offset. */
+		if (strstr(line, "Loongson")) {
+				if (arch_options.core_header_type == CORE_TYPE_ELF64)
+					page_offset = (unsigned long)0xffffffff80000000ULL;
+				cmdline_add_initrd(cmdline, page_offset + initrd_base, " rd_start=");
+				cmdline_add_initrd(cmdline, initrd_size, " rd_size=");
+				break;
+			}
+		}
+	}
+	fclose(fp);
+	return 0;
+}
+
 int elf_mips_probe(const char *buf, off_t len)
 {
 	struct mem_ehdr ehdr;
@@ -171,9 +239,10 @@ int elf_mips_load(int argc, char **argv, const char *buf, off_t len,
 		/* Now that the buffer for initrd is prepared, update the dtb
 		 * with an appropriate location */
 		dtb_set_initrd(&dtb_buf, &dtb_length, initrd_base, initrd_base + initrd_size);
-	}
-
 
+		/* Add the initrd parameters to cmdline */
+		patch_initrd_info(cmdline_buf, initrd_base, initrd_size);
+	}
 	/* This is a legacy method for commandline passing used
 	 * currently by Octeon CPUs only */
 	add_buffer(info, cmdline_buf, sizeof(cmdline_buf),
-- 
2.20.1