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[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 <u.luckas@road.de>

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Uli Luckas <u.luckas@road.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
hifive-unleashed-5.1
Richard Purdie 2008-01-02 00:56:46 +01:00 committed by Russell King
parent ae9458d6a0
commit 4cd9d6f774
8 changed files with 110 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/arm/Kconfig
View File

@ -894,6 +894,13 @@ config KEXEC
initially work for you. It may help to enable device hotplugging
support.
config ATAGS_PROC
bool "Export atags in procfs"
default n
help
Should the atags used to boot the kernel be exported in an "atags"
file in procfs. Useful with kexec.
endmenu
if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_IMX || ARCH_PXA)

1
arch/arm/kernel/Makefile
View File

@ -20,6 +20,7 @@ obj-$(CONFIG_PCI) += bios32.o isa.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
obj-$(CONFIG_KPROBES) += kprobes.o kprobes-decode.o
obj-$(CONFIG_ATAGS_PROC) += atags.o
obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o
obj-$(CONFIG_CRUNCH) += crunch.o crunch-bits.o

86
arch/arm/kernel/atags.c 100644
View File

@ -0,0 +1,86 @@
#include <linux/slab.h>
#include <linux/kexec.h>
#include <linux/proc_fs.h>
#include <asm/setup.h>
#include <asm/types.h>
#include <asm/page.h>
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);

5
arch/arm/kernel/atags.h 100644
View File

@ -0,0 +1,5 @@
#ifdef CONFIG_ATAGS_PROC
extern void save_atags(struct tag *tags);
#else
static inline void save_atags(struct tag *tags) { }
#endif

2
arch/arm/kernel/machine_kexec.c
View File

@ -21,6 +21,7 @@ extern void setup_mm_for_reboot(char mode);
extern unsigned long kexec_start_address;
extern unsigned long kexec_indirection_page;
extern unsigned long kexec_mach_type;
extern unsigned long kexec_boot_atags;
/*
* Provide a dummy crash_notes definition while crash dump arrives to arm.
@ -62,6 +63,7 @@ void machine_kexec(struct kimage *image)
kexec_start_address = image->start;
kexec_indirection_page = page_list;
kexec_mach_type = machine_arch_type;
kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET;
/* copy our kernel relocation code to the control code page */
memcpy(reboot_code_buffer,

30
arch/arm/kernel/relocate_kernel.S
View File

@ -7,23 +7,6 @@
.globl relocate_new_kernel
relocate_new_kernel:
/* Move boot params back to where the kernel expects them */
ldr r0,kexec_boot_params_address
teq r0,#0
beq 8f
ldr r1,kexec_boot_params_copy
mov r6,#KEXEC_BOOT_PARAMS_SIZE/4
7:
ldr r5,[r1],#4
str r5,[r0],#4
subs r6,r6,#1
bne 7b
8:
/* Boot params moved, now go on with the kernel */
ldr r0,kexec_indirection_page
ldr r1,kexec_start_address
@ -67,7 +50,7 @@ relocate_new_kernel:
mov lr,r1
mov r0,#0
ldr r1,kexec_mach_type
ldr r2,kexec_boot_params_address
ldr r2,kexec_boot_atags
mov pc,lr
.globl kexec_start_address
@ -82,14 +65,9 @@ kexec_indirection_page:
kexec_mach_type:
.long 0x0
/* phy addr where new kernel will expect to find boot params */
.globl kexec_boot_params_address
kexec_boot_params_address:
.long 0x0
/* phy addr where old kernel put a copy of orig boot params */
.globl kexec_boot_params_copy
kexec_boot_params_copy:
/* phy addr of the atags for the new kernel */
.globl kexec_boot_atags
kexec_boot_atags:
.long 0x0
relocate_new_kernel_end:

32
arch/arm/kernel/setup.c
View File

@ -24,7 +24,6 @@
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/fs.h>
#include <linux/kexec.h>
#include <asm/cpu.h>
#include <asm/elf.h>
@ -39,6 +38,7 @@
#include <asm/mach/time.h>
#include "compat.h"
#include "atags.h"
#ifndef MEM_SIZE
#define MEM_SIZE (16*1024*1024)
@ -784,23 +784,6 @@ static int __init customize_machine(void)
}
arch_initcall(customize_machine);
#ifdef CONFIG_KEXEC
/* Physical addr of where the boot params should be for this machine */
extern unsigned long kexec_boot_params_address;
/* Physical addr of the buffer into which the boot params are copied */
extern unsigned long kexec_boot_params_copy;
/* Pointer to the boot params buffer, for manipulation and display */
unsigned long kexec_boot_params;
EXPORT_SYMBOL(kexec_boot_params);
/* The buffer itself - make sure it is sized correctly */
static unsigned long kexec_boot_params_buf[(KEXEC_BOOT_PARAMS_SIZE + 3) / 4];
#endif
void __init setup_arch(char **cmdline_p)
{
struct tag *tags = (struct tag *)&init_tags;
@ -819,18 +802,6 @@ void __init setup_arch(char **cmdline_p)
else if (mdesc->boot_params)
tags = phys_to_virt(mdesc->boot_params);
#ifdef CONFIG_KEXEC
kexec_boot_params_copy = virt_to_phys(kexec_boot_params_buf);
kexec_boot_params = (unsigned long)kexec_boot_params_buf;
if (__atags_pointer) {
kexec_boot_params_address = __atags_pointer;
memcpy((void *)kexec_boot_params, tags, KEXEC_BOOT_PARAMS_SIZE);
} else if (mdesc->boot_params) {
kexec_boot_params_address = mdesc->boot_params;
memcpy((void *)kexec_boot_params, tags, KEXEC_BOOT_PARAMS_SIZE);
}
#endif
/*
* If we have the old style parameters, convert them to
* a tag list.
@ -846,6 +817,7 @@ void __init setup_arch(char **cmdline_p)
if (tags->hdr.tag == ATAG_CORE) {
if (meminfo.nr_banks != 0)
squash_mem_tags(tags);
save_atags(tags);
parse_tags(tags);
}

3
include/asm-arm/kexec.h
View File

@ -16,6 +16,9 @@
#define KEXEC_BOOT_PARAMS_SIZE 1536
#define KEXEC_ARM_ATAGS_OFFSET 0x1000
#define KEXEC_ARM_ZIMAGE_OFFSET 0x8000
#ifndef __ASSEMBLY__
struct kimage;