[PATCH v3 2/2] m68k: Add support to export bootinfo in procfs

Geert Uytterhoeven
2013-12-01T11:30:35Z

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>
---
v2:
- No changes
v3:
- Rebased on top of current m68k tree

arch/m68k/Kconfig | 7 ++++
arch/m68k/include/asm/bootinfo.h | 12 ++++++
arch/m68k/kernel/Makefile | 1 +
arch/m68k/kernel/bootinfo_proc.c | 80 ++++++++++++++++++++++++++++++++++++++
arch/m68k/kernel/setup_mm.c | 2 +
5 files changed, 102 insertions(+)
create mode 100644 arch/m68k/kernel/bootinfo_proc.c

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 178dffa9de80..dbdd2231c75d 100644
--- 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 9edc31893fb8..8e213267f8e7 100644
--- 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 7ee5f00a9abb..2d5d9be16273 100644
--- 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
index 000000000000..7ee853e1432b
--- /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 28abca421974..5b8ec4d5f8e8 100644
--- 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;
--
1.7.9.5