OpenWrt – Rev 1

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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
@@ -10,14 +10,11 @@
 #include <linux/mm.h>
 #include <linux/delay.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"
 
 int (*_machine_kexec_prepare)(struct kimage *) = NULL;
 void (*_machine_kexec_shutdown)(void) = NULL;
@@ -28,6 +25,99 @@ atomic_t kexec_ready_to_reboot = ATOMIC_
 void (*_crash_smp_send_stop)(void) = NULL;
 #endif
 
+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 */
+       copy_from_user(kexec_argv_buf, buf, size);
+       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;
@@ -52,6 +142,18 @@ int
 machine_kexec_prepare(struct kimage *kimage)
 {
        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);
@@ -89,10 +191,12 @@ 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 =
@@ -100,9 +204,19 @@ 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
@@ -124,15 +238,16 @@ machine_kexec(struct kimage *image)
        /*
         * we do not want to be bothered.
         */
+       pr_info("Before irq_disable.\n");
        local_irq_disable();
 
-       printk("Will call new kernel at %08lx\n", image->start);
-       printk("Bye ...\n");
+       pr_info("Will call new kernel at %08lx\n", image->start);
+       pr_info("Bye ...\n");
        __flush_cache_all();
 #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
@@ -12,8 +12,9 @@
 #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
@@ -98,7 +99,7 @@ done:
 #endif
        /* jump to kexec_start_address */
        j               s1
-       END(relocate_new_kernel)
+       END(kexec_relocate_new_kernel)
 
 #ifdef CONFIG_SMP
 /*
@@ -184,9 +185,15 @@ 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)

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