mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![Magnus Damm](/assets/img/avatar_default.png)
kexec: Avoid overwriting the current pgd (V4, i386) This patch upgrades the i386-specific kexec code to avoid overwriting the current pgd. Overwriting the current pgd is bad when CONFIG_CRASH_DUMP is used to start a secondary kernel that dumps the memory of the previous kernel. The code introduces a new set of page tables. These tables are used to provide an executable identity mapping without overwriting the current pgd. Signed-off-by: Magnus Damm <magnus@valinux.co.jp> Signed-off-by: Andi Kleen <ak@suse.de>
171 lines
4.5 KiB
C
171 lines
4.5 KiB
C
/*
|
|
* machine_kexec.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.
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/kexec.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/init.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/pgalloc.h>
|
|
#include <asm/tlbflush.h>
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/io.h>
|
|
#include <asm/apic.h>
|
|
#include <asm/cpufeature.h>
|
|
#include <asm/desc.h>
|
|
#include <asm/system.h>
|
|
|
|
#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
|
|
static u32 kexec_pgd[1024] PAGE_ALIGNED;
|
|
#ifdef CONFIG_X86_PAE
|
|
static u32 kexec_pmd0[1024] PAGE_ALIGNED;
|
|
static u32 kexec_pmd1[1024] PAGE_ALIGNED;
|
|
#endif
|
|
static u32 kexec_pte0[1024] PAGE_ALIGNED;
|
|
static u32 kexec_pte1[1024] PAGE_ALIGNED;
|
|
|
|
static void set_idt(void *newidt, __u16 limit)
|
|
{
|
|
struct Xgt_desc_struct curidt;
|
|
|
|
/* ia32 supports unaliged loads & stores */
|
|
curidt.size = limit;
|
|
curidt.address = (unsigned long)newidt;
|
|
|
|
load_idt(&curidt);
|
|
};
|
|
|
|
|
|
static void set_gdt(void *newgdt, __u16 limit)
|
|
{
|
|
struct Xgt_desc_struct curgdt;
|
|
|
|
/* ia32 supports unaligned loads & stores */
|
|
curgdt.size = limit;
|
|
curgdt.address = (unsigned long)newgdt;
|
|
|
|
load_gdt(&curgdt);
|
|
};
|
|
|
|
static void load_segments(void)
|
|
{
|
|
#define __STR(X) #X
|
|
#define STR(X) __STR(X)
|
|
|
|
__asm__ __volatile__ (
|
|
"\tljmp $"STR(__KERNEL_CS)",$1f\n"
|
|
"\t1:\n"
|
|
"\tmovl $"STR(__KERNEL_DS)",%%eax\n"
|
|
"\tmovl %%eax,%%ds\n"
|
|
"\tmovl %%eax,%%es\n"
|
|
"\tmovl %%eax,%%fs\n"
|
|
"\tmovl %%eax,%%gs\n"
|
|
"\tmovl %%eax,%%ss\n"
|
|
::: "eax", "memory");
|
|
#undef STR
|
|
#undef __STR
|
|
}
|
|
|
|
/*
|
|
* A architecture hook called to validate the
|
|
* proposed image and prepare the control pages
|
|
* as needed. The pages for KEXEC_CONTROL_CODE_SIZE
|
|
* have been allocated, but the segments have yet
|
|
* been copied into the kernel.
|
|
*
|
|
* Do what every setup is needed on image and the
|
|
* reboot code buffer to allow us to avoid allocations
|
|
* later.
|
|
*
|
|
* Currently nothing.
|
|
*/
|
|
int machine_kexec_prepare(struct kimage *image)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Undo anything leftover by machine_kexec_prepare
|
|
* when an image is freed.
|
|
*/
|
|
void machine_kexec_cleanup(struct kimage *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.
|
|
*/
|
|
NORET_TYPE void machine_kexec(struct kimage *image)
|
|
{
|
|
unsigned long page_list[PAGES_NR];
|
|
void *control_page;
|
|
|
|
/* Interrupts aren't acceptable while we reboot */
|
|
local_irq_disable();
|
|
|
|
control_page = page_address(image->control_code_page);
|
|
memcpy(control_page, relocate_kernel, PAGE_SIZE);
|
|
|
|
page_list[PA_CONTROL_PAGE] = __pa(control_page);
|
|
page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
|
|
page_list[PA_PGD] = __pa(kexec_pgd);
|
|
page_list[VA_PGD] = (unsigned long)kexec_pgd;
|
|
#ifdef CONFIG_X86_PAE
|
|
page_list[PA_PMD_0] = __pa(kexec_pmd0);
|
|
page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
|
|
page_list[PA_PMD_1] = __pa(kexec_pmd1);
|
|
page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
|
|
#endif
|
|
page_list[PA_PTE_0] = __pa(kexec_pte0);
|
|
page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
|
|
page_list[PA_PTE_1] = __pa(kexec_pte1);
|
|
page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
|
|
|
|
/* 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 */
|
|
relocate_kernel((unsigned long)image->head, (unsigned long)page_list,
|
|
image->start, cpu_has_pae);
|
|
}
|
|
|
|
/* crashkernel=size@addr specifies the location to reserve for
|
|
* a crash kernel. By reserving this memory we guarantee
|
|
* that linux never sets it up as a DMA target.
|
|
* Useful for holding code to do something appropriate
|
|
* after a kernel panic.
|
|
*/
|
|
static int __init parse_crashkernel(char *arg)
|
|
{
|
|
unsigned long size, base;
|
|
size = memparse(arg, &arg);
|
|
if (*arg == '@') {
|
|
base = memparse(arg+1, &arg);
|
|
/* FIXME: Do I want a sanity check
|
|
* to validate the memory range?
|
|
*/
|
|
crashk_res.start = base;
|
|
crashk_res.end = base + size - 1;
|
|
}
|
|
return 0;
|
|
}
|
|
early_param("crashkernel", parse_crashkernel);
|