m68k: Add support to export bootinfo in procfs

Add optional support to export the bootinfo used to boot the kernel in a
"bootinfo" file in procfs.  This is useful with kexec.

This is based on the similar feature for ATAGS on ARM.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 178dffa9de803067e48b212e016d8a10ec371028..dbdd2231c75ddc9fab61fd1b2dca7c1cc60a3e3e 100644 (file)
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -104,6 +104,13 @@ config KEXEC
          interface is strongly in flux, so no good recommendation can be
          made.
 
+config BOOTINFO_PROC
+       bool "Export bootinfo in procfs"
+       depends on KEXEC && M68KCLASSIC
+       help
+         Say Y to export the bootinfo used to boot the kernel in a
+         "bootinfo" file in procfs.  This is useful with kexec.
+
 menu "Platform setup"
 
 source arch/m68k/Kconfig.cpu

diff --git a/arch/m68k/include/asm/bootinfo.h b/arch/m68k/include/asm/bootinfo.h
index 9edc31893fb8ca982bc05628b8992c34bdc7bea3..8e213267f8e7165054c35f9d81dab22481467fa4 100644 (file)
--- a/arch/m68k/include/asm/bootinfo.h
+++ b/arch/m68k/include/asm/bootinfo.h
@@ -13,4 +13,16 @@
 
 #include <uapi/asm/bootinfo.h>
 
+
+#ifndef __ASSEMBLY__
+
+#ifdef CONFIG_BOOTINFO_PROC
+extern void save_bootinfo(const struct bi_record *bi);
+#else
+static inline void save_bootinfo(const struct bi_record *bi) {}
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+
 #endif /* _M68K_BOOTINFO_H */

diff --git a/arch/m68k/kernel/Makefile b/arch/m68k/kernel/Makefile
index 7ee5f00a9abb1a42abf832d621525fb1ac9da688..2d5d9be162732dae6ae603622e3572e1d0349523 100644 (file)
--- a/arch/m68k/kernel/Makefile
+++ b/arch/m68k/kernel/Makefile
@@ -23,4 +23,5 @@ obj-$(CONFIG_PCI) += pcibios.o
 obj-$(CONFIG_HAS_DMA)  += dma.o
 
 obj-$(CONFIG_KEXEC)            += machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_BOOTINFO_PROC)    += bootinfo_proc.o
 

diff --git a/arch/m68k/kernel/bootinfo_proc.c b/arch/m68k/kernel/bootinfo_proc.c
new file mode 100644 (file)
index 0000000..7ee853e
--- /dev/null
+++ b/arch/m68k/kernel/bootinfo_proc.c
@@ -0,0 +1,80 @@
+/*
+ * Based on arch/arm/kernel/atags_proc.c
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/printk.h>
+#include <linux/proc_fs.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include <asm/bootinfo.h>
+#include <asm/byteorder.h>
+
+
+static char bootinfo_tmp[1536] __initdata;
+
+static void *bootinfo_copy;
+static size_t bootinfo_size;
+
+static ssize_t bootinfo_read(struct file *file, char __user *buf,
+                         size_t count, loff_t *ppos)
+{
+       return simple_read_from_buffer(buf, count, ppos, bootinfo_copy,
+                                      bootinfo_size);
+}
+
+static const struct file_operations bootinfo_fops = {
+       .read = bootinfo_read,
+       .llseek = default_llseek,
+};
+
+void __init save_bootinfo(const struct bi_record *bi)
+{
+       const void *start = bi;
+       size_t size = sizeof(bi->tag);
+
+       while (be16_to_cpu(bi->tag) != BI_LAST) {
+               uint16_t n = be16_to_cpu(bi->size);
+               size += n;
+               bi = (struct bi_record *)((unsigned long)bi + n);
+       }
+
+       if (size > sizeof(bootinfo_tmp)) {
+               pr_err("Cannot save %zu bytes of bootinfo\n", size);
+               return;
+       }
+
+       pr_info("Saving %zu bytes of bootinfo\n", size);
+       memcpy(bootinfo_tmp, start, size);
+       bootinfo_size = size;
+}
+
+static int __init init_bootinfo_procfs(void)
+{
+       /*
+        * This cannot go into save_bootinfo() because kmalloc and proc don't
+        * work yet when it is called.
+        */
+       struct proc_dir_entry *pde;
+
+       if (!bootinfo_size)
+               return -EINVAL;
+
+       bootinfo_copy = kmalloc(bootinfo_size, GFP_KERNEL);
+       if (!bootinfo_copy)
+               return -ENOMEM;
+
+       memcpy(bootinfo_copy, bootinfo_tmp, bootinfo_size);
+
+       pde = proc_create_data("bootinfo", 0400, NULL, &bootinfo_fops, NULL);
+       if (!pde) {
+               kfree(bootinfo_copy);
+               return -ENOMEM;
+       }
+
+       return 0;
+}
+
+arch_initcall(init_bootinfo_procfs);

diff --git a/arch/m68k/kernel/setup_mm.c b/arch/m68k/kernel/setup_mm.c
index 28abca421974f4a240e203b84afa332b17acd041..5b8ec4d5f8e8d79d1becaa48d489d0117374daa8 100644 (file)
--- a/arch/m68k/kernel/setup_mm.c
+++ b/arch/m68k/kernel/setup_mm.c
@@ -146,6 +146,8 @@ static void __init m68k_parse_bootinfo(const struct bi_record *record)
 {
        uint16_t tag;
 
+       save_bootinfo(record);
+
        while ((tag = be16_to_cpu(record->tag)) != BI_LAST) {
                int unknown = 0;
                const void *data = record->data;