linux/arch/x86/kernel/machine_kexec_64.c
Vivek Goyal 74ca317c26 kexec: create a new config option CONFIG_KEXEC_FILE for new syscall
Currently new system call kexec_file_load() and all the associated code
compiles if CONFIG_KEXEC=y.  But new syscall also compiles purgatory
code which currently uses gcc option -mcmodel=large.  This option seems
to be available only gcc 4.4 onwards.

Hiding new functionality behind a new config option will not break
existing users of old gcc.  Those who wish to enable new functionality
will require new gcc.  Having said that, I am trying to figure out how
can I move away from using -mcmodel=large but that can take a while.

I think there are other advantages of introducing this new config
option.  As this option will be enabled only on x86_64, other arches
don't have to compile generic kexec code which will never be used.  This
new code selects CRYPTO=y and CRYPTO_SHA256=y.  And all other arches had
to do this for CONFIG_KEXEC.  Now with introduction of new config
option, we can remove crypto dependency from other arches.

Now CONFIG_KEXEC_FILE is available only on x86_64.  So whereever I had
CONFIG_X86_64 defined, I got rid of that.

For CONFIG_KEXEC_FILE, instead of doing select CRYPTO=y, I changed it to
"depends on CRYPTO=y".  This should be safer as "select" is not
recursive.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Tested-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-29 16:28:16 -07:00

536 lines
13 KiB
C

/*
* handle transition of Linux booting another kernel
* Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com>
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#define pr_fmt(fmt) "kexec: " fmt
#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/string.h>
#include <linux/gfp.h>
#include <linux/reboot.h>
#include <linux/numa.h>
#include <linux/ftrace.h>
#include <linux/io.h>
#include <linux/suspend.h>
#include <asm/init.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/debugreg.h>
#include <asm/kexec-bzimage64.h>
#ifdef CONFIG_KEXEC_FILE
static struct kexec_file_ops *kexec_file_loaders[] = {
&kexec_bzImage64_ops,
};
#endif
static void free_transition_pgtable(struct kimage *image)
{
free_page((unsigned long)image->arch.pud);
free_page((unsigned long)image->arch.pmd);
free_page((unsigned long)image->arch.pte);
}
static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
{
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
unsigned long vaddr, paddr;
int result = -ENOMEM;
vaddr = (unsigned long)relocate_kernel;
paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
pgd += pgd_index(vaddr);
if (!pgd_present(*pgd)) {
pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
if (!pud)
goto err;
image->arch.pud = pud;
set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
}
pud = pud_offset(pgd, vaddr);
if (!pud_present(*pud)) {
pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
if (!pmd)
goto err;
image->arch.pmd = pmd;
set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
}
pmd = pmd_offset(pud, vaddr);
if (!pmd_present(*pmd)) {
pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
if (!pte)
goto err;
image->arch.pte = pte;
set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
}
pte = pte_offset_kernel(pmd, vaddr);
set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
return 0;
err:
free_transition_pgtable(image);
return result;
}
static void *alloc_pgt_page(void *data)
{
struct kimage *image = (struct kimage *)data;
struct page *page;
void *p = NULL;
page = kimage_alloc_control_pages(image, 0);
if (page) {
p = page_address(page);
clear_page(p);
}
return p;
}
static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
{
struct x86_mapping_info info = {
.alloc_pgt_page = alloc_pgt_page,
.context = image,
.pmd_flag = __PAGE_KERNEL_LARGE_EXEC,
};
unsigned long mstart, mend;
pgd_t *level4p;
int result;
int i;
level4p = (pgd_t *)__va(start_pgtable);
clear_page(level4p);
for (i = 0; i < nr_pfn_mapped; i++) {
mstart = pfn_mapped[i].start << PAGE_SHIFT;
mend = pfn_mapped[i].end << PAGE_SHIFT;
result = kernel_ident_mapping_init(&info,
level4p, mstart, mend);
if (result)
return result;
}
/*
* segments's mem ranges could be outside 0 ~ max_pfn,
* for example when jump back to original kernel from kexeced kernel.
* or first kernel is booted with user mem map, and second kernel
* could be loaded out of that range.
*/
for (i = 0; i < image->nr_segments; i++) {
mstart = image->segment[i].mem;
mend = mstart + image->segment[i].memsz;
result = kernel_ident_mapping_init(&info,
level4p, mstart, mend);
if (result)
return result;
}
return init_transition_pgtable(image, level4p);
}
static void set_idt(void *newidt, u16 limit)
{
struct desc_ptr curidt;
/* x86-64 supports unaliged loads & stores */
curidt.size = limit;
curidt.address = (unsigned long)newidt;
__asm__ __volatile__ (
"lidtq %0\n"
: : "m" (curidt)
);
};
static void set_gdt(void *newgdt, u16 limit)
{
struct desc_ptr curgdt;
/* x86-64 supports unaligned loads & stores */
curgdt.size = limit;
curgdt.address = (unsigned long)newgdt;
__asm__ __volatile__ (
"lgdtq %0\n"
: : "m" (curgdt)
);
};
static void load_segments(void)
{
__asm__ __volatile__ (
"\tmovl %0,%%ds\n"
"\tmovl %0,%%es\n"
"\tmovl %0,%%ss\n"
"\tmovl %0,%%fs\n"
"\tmovl %0,%%gs\n"
: : "a" (__KERNEL_DS) : "memory"
);
}
#ifdef CONFIG_KEXEC_FILE
/* Update purgatory as needed after various image segments have been prepared */
static int arch_update_purgatory(struct kimage *image)
{
int ret = 0;
if (!image->file_mode)
return 0;
/* Setup copying of backup region */
if (image->type == KEXEC_TYPE_CRASH) {
ret = kexec_purgatory_get_set_symbol(image, "backup_dest",
&image->arch.backup_load_addr,
sizeof(image->arch.backup_load_addr), 0);
if (ret)
return ret;
ret = kexec_purgatory_get_set_symbol(image, "backup_src",
&image->arch.backup_src_start,
sizeof(image->arch.backup_src_start), 0);
if (ret)
return ret;
ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
&image->arch.backup_src_sz,
sizeof(image->arch.backup_src_sz), 0);
if (ret)
return ret;
}
return ret;
}
#else /* !CONFIG_KEXEC_FILE */
static inline int arch_update_purgatory(struct kimage *image)
{
return 0;
}
#endif /* CONFIG_KEXEC_FILE */
int machine_kexec_prepare(struct kimage *image)
{
unsigned long start_pgtable;
int result;
/* Calculate the offsets */
start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
/* Setup the identity mapped 64bit page table */
result = init_pgtable(image, start_pgtable);
if (result)
return result;
/* update purgatory as needed */
result = arch_update_purgatory(image);
if (result)
return result;
return 0;
}
void machine_kexec_cleanup(struct kimage *image)
{
free_transition_pgtable(image);
}
/*
* Do not allocate memory (or fail in any way) in machine_kexec().
* We are past the point of no return, committed to rebooting now.
*/
void machine_kexec(struct kimage *image)
{
unsigned long page_list[PAGES_NR];
void *control_page;
int save_ftrace_enabled;
#ifdef CONFIG_KEXEC_JUMP
if (image->preserve_context)
save_processor_state();
#endif
save_ftrace_enabled = __ftrace_enabled_save();
/* Interrupts aren't acceptable while we reboot */
local_irq_disable();
hw_breakpoint_disable();
if (image->preserve_context) {
#ifdef CONFIG_X86_IO_APIC
/*
* We need to put APICs in legacy mode so that we can
* get timer interrupts in second kernel. kexec/kdump
* paths already have calls to disable_IO_APIC() in
* one form or other. kexec jump path also need
* one.
*/
disable_IO_APIC();
#endif
}
control_page = page_address(image->control_code_page) + PAGE_SIZE;
memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
page_list[PA_TABLE_PAGE] =
(unsigned long)__pa(page_address(image->control_code_page));
if (image->type == KEXEC_TYPE_DEFAULT)
page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
<< PAGE_SHIFT);
/*
* The segment registers are funny things, they have both a
* visible and an invisible part. Whenever the visible part is
* set to a specific selector, the invisible part is loaded
* with from a table in memory. At no other time is the
* descriptor table in memory accessed.
*
* I take advantage of this here by force loading the
* segments, before I zap the gdt with an invalid value.
*/
load_segments();
/*
* The gdt & idt are now invalid.
* If you want to load them you must set up your own idt & gdt.
*/
set_gdt(phys_to_virt(0), 0);
set_idt(phys_to_virt(0), 0);
/* now call it */
image->start = relocate_kernel((unsigned long)image->head,
(unsigned long)page_list,
image->start,
image->preserve_context);
#ifdef CONFIG_KEXEC_JUMP
if (image->preserve_context)
restore_processor_state();
#endif
__ftrace_enabled_restore(save_ftrace_enabled);
}
void arch_crash_save_vmcoreinfo(void)
{
VMCOREINFO_SYMBOL(phys_base);
VMCOREINFO_SYMBOL(init_level4_pgt);
#ifdef CONFIG_NUMA
VMCOREINFO_SYMBOL(node_data);
VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
#endif
vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
(unsigned long)&_text - __START_KERNEL);
}
/* arch-dependent functionality related to kexec file-based syscall */
#ifdef CONFIG_KEXEC_FILE
int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
unsigned long buf_len)
{
int i, ret = -ENOEXEC;
struct kexec_file_ops *fops;
for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
fops = kexec_file_loaders[i];
if (!fops || !fops->probe)
continue;
ret = fops->probe(buf, buf_len);
if (!ret) {
image->fops = fops;
return ret;
}
}
return ret;
}
void *arch_kexec_kernel_image_load(struct kimage *image)
{
vfree(image->arch.elf_headers);
image->arch.elf_headers = NULL;
if (!image->fops || !image->fops->load)
return ERR_PTR(-ENOEXEC);
return image->fops->load(image, image->kernel_buf,
image->kernel_buf_len, image->initrd_buf,
image->initrd_buf_len, image->cmdline_buf,
image->cmdline_buf_len);
}
int arch_kimage_file_post_load_cleanup(struct kimage *image)
{
if (!image->fops || !image->fops->cleanup)
return 0;
return image->fops->cleanup(image->image_loader_data);
}
int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
unsigned long kernel_len)
{
if (!image->fops || !image->fops->verify_sig) {
pr_debug("kernel loader does not support signature verification.");
return -EKEYREJECTED;
}
return image->fops->verify_sig(kernel, kernel_len);
}
/*
* Apply purgatory relocations.
*
* ehdr: Pointer to elf headers
* sechdrs: Pointer to section headers.
* relsec: section index of SHT_RELA section.
*
* TODO: Some of the code belongs to generic code. Move that in kexec.c.
*/
int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
Elf64_Shdr *sechdrs, unsigned int relsec)
{
unsigned int i;
Elf64_Rela *rel;
Elf64_Sym *sym;
void *location;
Elf64_Shdr *section, *symtabsec;
unsigned long address, sec_base, value;
const char *strtab, *name, *shstrtab;
/*
* ->sh_offset has been modified to keep the pointer to section
* contents in memory
*/
rel = (void *)sechdrs[relsec].sh_offset;
/* Section to which relocations apply */
section = &sechdrs[sechdrs[relsec].sh_info];
pr_debug("Applying relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
/* Associated symbol table */
symtabsec = &sechdrs[sechdrs[relsec].sh_link];
/* String table */
if (symtabsec->sh_link >= ehdr->e_shnum) {
/* Invalid strtab section number */
pr_err("Invalid string table section index %d\n",
symtabsec->sh_link);
return -ENOEXEC;
}
strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
/* section header string table */
shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
/*
* rel[i].r_offset contains byte offset from beginning
* of section to the storage unit affected.
*
* This is location to update (->sh_offset). This is temporary
* buffer where section is currently loaded. This will finally
* be loaded to a different address later, pointed to by
* ->sh_addr. kexec takes care of moving it
* (kexec_load_segment()).
*/
location = (void *)(section->sh_offset + rel[i].r_offset);
/* Final address of the location */
address = section->sh_addr + rel[i].r_offset;
/*
* rel[i].r_info contains information about symbol table index
* w.r.t which relocation must be made and type of relocation
* to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
* these respectively.
*/
sym = (Elf64_Sym *)symtabsec->sh_offset +
ELF64_R_SYM(rel[i].r_info);
if (sym->st_name)
name = strtab + sym->st_name;
else
name = shstrtab + sechdrs[sym->st_shndx].sh_name;
pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
name, sym->st_info, sym->st_shndx, sym->st_value,
sym->st_size);
if (sym->st_shndx == SHN_UNDEF) {
pr_err("Undefined symbol: %s\n", name);
return -ENOEXEC;
}
if (sym->st_shndx == SHN_COMMON) {
pr_err("symbol '%s' in common section\n", name);
return -ENOEXEC;
}
if (sym->st_shndx == SHN_ABS)
sec_base = 0;
else if (sym->st_shndx >= ehdr->e_shnum) {
pr_err("Invalid section %d for symbol %s\n",
sym->st_shndx, name);
return -ENOEXEC;
} else
sec_base = sechdrs[sym->st_shndx].sh_addr;
value = sym->st_value;
value += sec_base;
value += rel[i].r_addend;
switch (ELF64_R_TYPE(rel[i].r_info)) {
case R_X86_64_NONE:
break;
case R_X86_64_64:
*(u64 *)location = value;
break;
case R_X86_64_32:
*(u32 *)location = value;
if (value != *(u32 *)location)
goto overflow;
break;
case R_X86_64_32S:
*(s32 *)location = value;
if ((s64)value != *(s32 *)location)
goto overflow;
break;
case R_X86_64_PC32:
value -= (u64)address;
*(u32 *)location = value;
break;
default:
pr_err("Unknown rela relocation: %llu\n",
ELF64_R_TYPE(rel[i].r_info));
return -ENOEXEC;
}
}
return 0;
overflow:
pr_err("Overflow in relocation type %d value 0x%lx\n",
(int)ELF64_R_TYPE(rel[i].r_info), value);
return -ENOEXEC;
}
#endif /* CONFIG_KEXEC_FILE */