From 4cd9d6f774c7e0578bbc4409d4490d8f2097d40a Mon Sep 17 00:00:00 2001 From: Richard Purdie Date: Wed, 2 Jan 2008 00:56:46 +0100 Subject: [ARM] 4736/1: Export atags to userspace and allow kexec to use customised atags Currently, the atags used by kexec are fixed to the ones originally used to boot the kernel. This is less than ideal as changing the commandline, initrd and other options would be a useful feature. This patch exports the atags used for the current kernel to userspace through an "atags" file in procfs. The presence of the file is controlled by its own Kconfig option and cleans up several ifdef blocks into a separate file. The tags for the new kernel are assumed to be at a fixed location before the kernel image itself. The location of the tags used to boot the original kernel is unimportant and no longer saved. Based on a patch from Uli Luckas Signed-off-by: Richard Purdie Acked-by: Uli Luckas Signed-off-by: Russell King --- arch/arm/kernel/atags.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 arch/arm/kernel/atags.c (limited to 'arch/arm/kernel/atags.c') diff --git a/arch/arm/kernel/atags.c b/arch/arm/kernel/atags.c new file mode 100644 index 00000000000..e2e934c3808 --- /dev/null +++ b/arch/arm/kernel/atags.c @@ -0,0 +1,86 @@ +#include +#include +#include +#include +#include +#include + +struct buffer { + size_t size; + char *data; +}; +static struct buffer tags_buffer; + +static int +read_buffer(char* page, char** start, off_t off, int count, + int* eof, void* data) +{ + struct buffer *buffer = (struct buffer *)data; + + if (off >= buffer->size) { + *eof = 1; + return 0; + } + + count = min((int) (buffer->size - off), count); + + memcpy(page, &buffer->data[off], count); + + return count; +} + + +static int +create_proc_entries(void) +{ + struct proc_dir_entry* tags_entry; + + tags_entry = create_proc_read_entry("atags", 0400, &proc_root, read_buffer, &tags_buffer); + if (!tags_entry) + return -ENOMEM; + + return 0; +} + + +static char __initdata atags_copy_buf[KEXEC_BOOT_PARAMS_SIZE]; +static char __initdata *atags_copy; + +void __init save_atags(const struct tag *tags) +{ + atags_copy = atags_copy_buf; + memcpy(atags_copy, tags, KEXEC_BOOT_PARAMS_SIZE); +} + + +static int __init init_atags_procfs(void) +{ + struct tag *tag; + int error; + + if (!atags_copy) { + printk(KERN_WARNING "Exporting ATAGs: No saved tags found\n"); + return -EIO; + } + + for (tag = (struct tag *) atags_copy; tag->hdr.size; tag = tag_next(tag)) + ; + + tags_buffer.size = ((char *) tag - atags_copy) + sizeof(tag->hdr); + tags_buffer.data = kmalloc(tags_buffer.size, GFP_KERNEL); + if (tags_buffer.data == NULL) + return -ENOMEM; + memcpy(tags_buffer.data, atags_copy, tags_buffer.size); + + error = create_proc_entries(); + if (error) { + printk(KERN_ERR "Exporting ATAGs: not enough memory\n"); + kfree(tags_buffer.data); + tags_buffer.size = 0; + tags_buffer.data = NULL; + } + + return error; +} + +arch_initcall(init_atags_procfs); -- cgit v1.2.3