From 4cd9d6f774c7e0578bbc4409d4490d8f2097d40a Mon Sep 17 00:00:00 2001 From: Richard Purdie Date: Wed, 2 Jan 2008 00:56:46 +0100 Subject: [PATCH] [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/Kconfig | 7 +++ arch/arm/kernel/Makefile | 1 + arch/arm/kernel/atags.c | 86 +++++++++++++++++++++++++++++++ arch/arm/kernel/atags.h | 5 ++ arch/arm/kernel/machine_kexec.c | 2 + arch/arm/kernel/relocate_kernel.S | 30 ++--------- arch/arm/kernel/setup.c | 32 +----------- include/asm-arm/kexec.h | 3 ++ 8 files changed, 110 insertions(+), 56 deletions(-) create mode 100644 arch/arm/kernel/atags.c create mode 100644 arch/arm/kernel/atags.h diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 4b1a8e3d29..4bd8952eef 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -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) diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index faa7619211..00d44c6fbf 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -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 diff --git a/arch/arm/kernel/atags.c b/arch/arm/kernel/atags.c new file mode 100644 index 0000000000..e2e934c380 --- /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); diff --git a/arch/arm/kernel/atags.h b/arch/arm/kernel/atags.h new file mode 100644 index 0000000000..e5f028d214 --- /dev/null +++ b/arch/arm/kernel/atags.h @@ -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 diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 863c66454f..db8f54a345 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -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, diff --git a/arch/arm/kernel/relocate_kernel.S b/arch/arm/kernel/relocate_kernel.S index 062c111c57..61930eb090 100644 --- a/arch/arm/kernel/relocate_kernel.S +++ b/arch/arm/kernel/relocate_kernel.S @@ -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: diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index bf56eb337d..ae3712d39a 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -24,7 +24,6 @@ #include #include #include -#include #include #include @@ -39,6 +38,7 @@ #include #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); } diff --git a/include/asm-arm/kexec.h b/include/asm-arm/kexec.h index 46dcc4d0b9..1ee17b6951 100644 --- a/include/asm-arm/kexec.h +++ b/include/asm-arm/kexec.h @@ -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; -- 2.39.5