From: Yousong Zhou <yszhou4tech@gmail.com>
Subject: MIPS: kexec: Accept command line parameters from userspace.

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
---
 arch/mips/kernel/machine_kexec.c   |  153 +++++++++++++++++++++++++++++++-----
 arch/mips/kernel/machine_kexec.h   |   20 +++++
 arch/mips/kernel/relocate_kernel.S |   21 +++--
 3 files changed, 167 insertions(+), 27 deletions(-)
 create mode 100644 arch/mips/kernel/machine_kexec.h

--- a/arch/mips/kernel/machine_kexec.c
+++ b/arch/mips/kernel/machine_kexec.c
@@ -9,14 +9,11 @@
 #include <linux/delay.h>
 #include <linux/libfdt.h>
 
+#include <asm/bootinfo.h>
 #include <asm/cacheflush.h>
 #include <asm/page.h>
-
-extern const unsigned char relocate_new_kernel[];
-extern const size_t relocate_new_kernel_size;
-
-extern unsigned long kexec_start_address;
-extern unsigned long kexec_indirection_page;
+#include <linux/uaccess.h>
+#include "machine_kexec.h"
 
 static unsigned long reboot_code_buffer;
 
@@ -30,6 +27,101 @@ void (*_crash_smp_send_stop)(void) = NUL
 void (*_machine_kexec_shutdown)(void) = NULL;
 void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
 
+static void machine_kexec_print_args(void)
+{
+	unsigned long argc = (int)kexec_args[0];
+	int i;
+
+	pr_info("kexec_args[0] (argc): %lu\n", argc);
+	pr_info("kexec_args[1] (argv): %p\n", (void *)kexec_args[1]);
+	pr_info("kexec_args[2] (env ): %p\n", (void *)kexec_args[2]);
+	pr_info("kexec_args[3] (desc): %p\n", (void *)kexec_args[3]);
+
+	for (i = 0; i < argc; i++) {
+		pr_info("kexec_argv[%d] = %p, %s\n",
+				i, kexec_argv[i], kexec_argv[i]);
+	}
+}
+
+static void machine_kexec_init_argv(struct kimage *image)
+{
+	void __user *buf = NULL;
+	size_t bufsz;
+	size_t size;
+	int i;
+
+	bufsz = 0;
+	for (i = 0; i < image->nr_segments; i++) {
+		struct kexec_segment *seg;
+
+		seg = &image->segment[i];
+		if (seg->bufsz < 6)
+			continue;
+
+		if (strncmp((char *) seg->buf, "kexec ", 6))
+			continue;
+
+		buf = seg->buf;
+		bufsz = seg->bufsz;
+		break;
+	}
+
+	if (!buf)
+		return;
+
+	size = KEXEC_COMMAND_LINE_SIZE;
+	size = min(size, bufsz);
+	if (size < bufsz)
+		pr_warn("kexec command line truncated to %zd bytes\n", size);
+
+	/* Copy to kernel space */
+	if (copy_from_user(kexec_argv_buf, buf, size))
+		pr_warn("kexec command line copy to kernel space failed\n");
+
+	kexec_argv_buf[size - 1] = 0;
+}
+
+static void machine_kexec_parse_argv(struct kimage *image)
+{
+	char *reboot_code_buffer;
+	int reloc_delta;
+	char *ptr;
+	int argc;
+	int i;
+
+	ptr = kexec_argv_buf;
+	argc = 0;
+
+	/*
+	 * convert command line string to array of parameters
+	 * (as bootloader does).
+	 */
+	while (ptr && *ptr && (KEXEC_MAX_ARGC > argc)) {
+		if (*ptr == ' ') {
+			*ptr++ = '\0';
+			continue;
+		}
+
+		kexec_argv[argc++] = ptr;
+		ptr = strchr(ptr, ' ');
+	}
+
+	if (!argc)
+		return;
+
+	kexec_args[0] = argc;
+	kexec_args[1] = (unsigned long)kexec_argv;
+	kexec_args[2] = 0;
+	kexec_args[3] = 0;
+
+	reboot_code_buffer = page_address(image->control_code_page);
+	reloc_delta = reboot_code_buffer - (char *)kexec_relocate_new_kernel;
+
+	kexec_args[1] += reloc_delta;
+	for (i = 0; i < argc; i++)
+		kexec_argv[i] += reloc_delta;
+}
+
 static void kexec_image_info(const struct kimage *kimage)
 {
 	unsigned long i;
@@ -99,6 +191,18 @@ machine_kexec_prepare(struct kimage *kim
 #endif
 
 	kexec_image_info(kimage);
+	/*
+	 * Whenever arguments passed from kexec-tools, Init the arguments as
+	 * the original ones to try avoiding booting failure.
+	 */
+
+	kexec_args[0] = fw_arg0;
+	kexec_args[1] = fw_arg1;
+	kexec_args[2] = fw_arg2;
+	kexec_args[3] = fw_arg3;
+
+	machine_kexec_init_argv(kimage);
+	machine_kexec_parse_argv(kimage);
 
 	if (_machine_kexec_prepare)
 		return _machine_kexec_prepare(kimage);
@@ -161,7 +265,7 @@ machine_crash_shutdown(struct pt_regs *r
 void kexec_nonboot_cpu_jump(void)
 {
 	local_flush_icache_range((unsigned long)relocated_kexec_smp_wait,
-				 reboot_code_buffer + relocate_new_kernel_size);
+				 reboot_code_buffer + KEXEC_RELOCATE_NEW_KERNEL_SIZE);
 
 	relocated_kexec_smp_wait(NULL);
 }
@@ -199,7 +303,7 @@ void kexec_reboot(void)
 	 * machine_kexec() CPU.
 	 */
 	local_flush_icache_range(reboot_code_buffer,
-				 reboot_code_buffer + relocate_new_kernel_size);
+				 reboot_code_buffer + KEXEC_RELOCATE_NEW_KERNEL_SIZE);
 
 	do_kexec = (void *)reboot_code_buffer;
 	do_kexec();
@@ -212,10 +316,12 @@ machine_kexec(struct kimage *image)
 	unsigned long *ptr;
 
 	reboot_code_buffer =
-	  (unsigned long)page_address(image->control_code_page);
+		(unsigned long)page_address(image->control_code_page);
+	pr_info("reboot_code_buffer = %p\n", (void *)reboot_code_buffer);
 
 	kexec_start_address =
 		(unsigned long) phys_to_virt(image->start);
+	pr_info("kexec_start_address = %p\n", (void *)kexec_start_address);
 
 	if (image->type == KEXEC_TYPE_DEFAULT) {
 		kexec_indirection_page =
@@ -223,9 +329,19 @@ machine_kexec(struct kimage *image)
 	} else {
 		kexec_indirection_page = (unsigned long)&image->head;
 	}
+	pr_info("kexec_indirection_page = %p\n", (void *)kexec_indirection_page);
 
-	memcpy((void*)reboot_code_buffer, relocate_new_kernel,
-	       relocate_new_kernel_size);
+	pr_info("Where is memcpy: %p\n", memcpy);
+	pr_info("kexec_relocate_new_kernel = %p, kexec_relocate_new_kernel_end = %p\n",
+		(void *)kexec_relocate_new_kernel, &kexec_relocate_new_kernel_end);
+	pr_info("Copy %lu bytes from %p to %p\n", KEXEC_RELOCATE_NEW_KERNEL_SIZE,
+		(void *)kexec_relocate_new_kernel, (void *)reboot_code_buffer);
+	memcpy((void*)reboot_code_buffer, kexec_relocate_new_kernel,
+	       KEXEC_RELOCATE_NEW_KERNEL_SIZE);
+
+	pr_info("Before _print_args().\n");
+	machine_kexec_print_args();
+	pr_info("Before eval loop.\n");
 
 	/*
 	 * The generic kexec code builds a page list with physical
@@ -256,7 +372,7 @@ machine_kexec(struct kimage *image)
 #ifdef CONFIG_SMP
 	/* All secondary cpus now may jump to kexec_wait cycle */
 	relocated_kexec_smp_wait = reboot_code_buffer +
-		(void *)(kexec_smp_wait - relocate_new_kernel);
+		(void *)(kexec_smp_wait - kexec_relocate_new_kernel);
 	smp_wmb();
 	atomic_set(&kexec_ready_to_reboot, 1);
 #endif
--- /dev/null
+++ b/arch/mips/kernel/machine_kexec.h
@@ -0,0 +1,20 @@
+#ifndef _MACHINE_KEXEC_H
+#define _MACHINE_KEXEC_H
+
+#ifndef __ASSEMBLY__
+extern const unsigned char kexec_relocate_new_kernel[];
+extern unsigned long kexec_relocate_new_kernel_end;
+extern unsigned long kexec_start_address;
+extern unsigned long kexec_indirection_page;
+
+extern char kexec_argv_buf[];
+extern char *kexec_argv[];
+
+#define KEXEC_RELOCATE_NEW_KERNEL_SIZE	((unsigned long)&kexec_relocate_new_kernel_end - (unsigned long)kexec_relocate_new_kernel)
+#endif /* !__ASSEMBLY__ */
+
+#define KEXEC_COMMAND_LINE_SIZE		256
+#define KEXEC_ARGV_SIZE			(KEXEC_COMMAND_LINE_SIZE / 16)
+#define KEXEC_MAX_ARGC			(KEXEC_ARGV_SIZE / sizeof(long))
+
+#endif
--- a/arch/mips/kernel/relocate_kernel.S
+++ b/arch/mips/kernel/relocate_kernel.S
@@ -10,8 +10,9 @@
 #include <asm/mipsregs.h>
 #include <asm/stackframe.h>
 #include <asm/addrspace.h>
+#include "machine_kexec.h"
 
-LEAF(relocate_new_kernel)
+LEAF(kexec_relocate_new_kernel)
 	PTR_L a0,	arg0
 	PTR_L a1,	arg1
 	PTR_L a2,	arg2
@@ -96,7 +97,7 @@ done:
 #endif
 	/* jump to kexec_start_address */
 	j		s1
-	END(relocate_new_kernel)
+	END(kexec_relocate_new_kernel)
 
 #ifdef CONFIG_SMP
 /*
@@ -182,9 +183,15 @@ kexec_indirection_page:
 	PTR		0
 	.size		kexec_indirection_page, PTRSIZE
 
-relocate_new_kernel_end:
+kexec_argv_buf:
+	EXPORT(kexec_argv_buf)
+	.skip		KEXEC_COMMAND_LINE_SIZE
+	.size		kexec_argv_buf, KEXEC_COMMAND_LINE_SIZE
+
+kexec_argv:
+	EXPORT(kexec_argv)
+	.skip		KEXEC_ARGV_SIZE
+	.size		kexec_argv, KEXEC_ARGV_SIZE
 
-relocate_new_kernel_size:
-	EXPORT(relocate_new_kernel_size)
-	PTR		relocate_new_kernel_end - relocate_new_kernel
-	.size		relocate_new_kernel_size, PTRSIZE
+kexec_relocate_new_kernel_end:
+	EXPORT(kexec_relocate_new_kernel_end)