3ab8352137
This patch provides an enhancement to kexec/kdump. It implements the
following features:
- Backup/restore memory used by the original kernel before/after
kexec.
- Save/restore CPU state before/after kexec.
The features of this patch can be used as a general method to call program in
physical mode (paging turning off). This can be used to call BIOS code under
Linux.
kexec-tools needs to be patched to support kexec jump. The patches and
the precompiled kexec can be download from the following URL:
source: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-src_git_kh10.tar.bz2
patches: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec-tools-patches_git_kh10.tar.bz2
binary: http://khibernation.sourceforge.net/download/release_v10/kexec-tools/kexec_git_kh10
Usage example of calling some physical mode code and return:
1. Compile and install patched kernel with following options selected:
CONFIG_X86_32=y
CONFIG_KEXEC=y
CONFIG_PM=y
CONFIG_KEXEC_JUMP=y
2. Build patched kexec-tool or download the pre-built one.
3. Build some physical mode executable named such as "phy_mode"
4. Boot kernel compiled in step 1.
5. Load physical mode executable with /sbin/kexec. The shell command
line can be as follow:
/sbin/kexec --load-preserve-context --args-none phy_mode
6. Call physical mode executable with following shell command line:
/sbin/kexec -e
Implementation point:
To support jumping without reserving memory. One shadow backup page (source
page) is allocated for each page used by kexeced code image (destination
page). When do kexec_load, the image of kexeced code is loaded into source
pages, and before executing, the destination pages and the source pages are
swapped, so the contents of destination pages are backupped. Before jumping
to the kexeced code image and after jumping back to the original kernel, the
destination pages and the source pages are swapped too.
C ABI (calling convention) is used as communication protocol between
kernel and called code.
A flag named KEXEC_PRESERVE_CONTEXT for sys_kexec_load is added to
indicate that the loaded kernel image is used for jumping back.
Now, only the i386 architecture is supported.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
171 lines
5.2 KiB
C
171 lines
5.2 KiB
C
#ifndef _KEXEC_H
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#define _KEXEC_H
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#ifdef CONFIG_X86_32
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# define PA_CONTROL_PAGE 0
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# define VA_CONTROL_PAGE 1
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# define PA_PGD 2
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# define VA_PGD 3
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# define PA_PTE_0 4
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# define VA_PTE_0 5
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# define PA_PTE_1 6
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# define VA_PTE_1 7
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# define PA_SWAP_PAGE 8
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# ifdef CONFIG_X86_PAE
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# define PA_PMD_0 9
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# define VA_PMD_0 10
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# define PA_PMD_1 11
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# define VA_PMD_1 12
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# define PAGES_NR 13
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# else
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# define PAGES_NR 9
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# endif
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#else
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# define PA_CONTROL_PAGE 0
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# define VA_CONTROL_PAGE 1
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# define PA_PGD 2
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# define VA_PGD 3
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# define PA_PUD_0 4
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# define VA_PUD_0 5
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# define PA_PMD_0 6
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# define VA_PMD_0 7
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# define PA_PTE_0 8
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# define VA_PTE_0 9
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# define PA_PUD_1 10
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# define VA_PUD_1 11
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# define PA_PMD_1 12
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# define VA_PMD_1 13
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# define PA_PTE_1 14
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# define VA_PTE_1 15
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# define PA_TABLE_PAGE 16
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# define PAGES_NR 17
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#endif
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#ifndef __ASSEMBLY__
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#include <linux/string.h>
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#include <asm/page.h>
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#include <asm/ptrace.h>
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/*
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* KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return.
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* I.e. Maximum page that is mapped directly into kernel memory,
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* and kmap is not required.
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*
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* So far x86_64 is limited to 40 physical address bits.
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*/
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#ifdef CONFIG_X86_32
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/* Maximum physical address we can use pages from */
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# define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
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/* Maximum address we can reach in physical address mode */
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# define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
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/* Maximum address we can use for the control code buffer */
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# define KEXEC_CONTROL_MEMORY_LIMIT TASK_SIZE
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# define KEXEC_CONTROL_CODE_SIZE 4096
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/* The native architecture */
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# define KEXEC_ARCH KEXEC_ARCH_386
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/* We can also handle crash dumps from 64 bit kernel. */
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# define vmcore_elf_check_arch_cross(x) ((x)->e_machine == EM_X86_64)
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#else
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/* Maximum physical address we can use pages from */
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# define KEXEC_SOURCE_MEMORY_LIMIT (0xFFFFFFFFFFUL)
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/* Maximum address we can reach in physical address mode */
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# define KEXEC_DESTINATION_MEMORY_LIMIT (0xFFFFFFFFFFUL)
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/* Maximum address we can use for the control pages */
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# define KEXEC_CONTROL_MEMORY_LIMIT (0xFFFFFFFFFFUL)
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/* Allocate one page for the pdp and the second for the code */
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# define KEXEC_CONTROL_CODE_SIZE (4096UL + 4096UL)
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/* The native architecture */
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# define KEXEC_ARCH KEXEC_ARCH_X86_64
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#endif
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/*
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* CPU does not save ss and sp on stack if execution is already
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* running in kernel mode at the time of NMI occurrence. This code
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* fixes it.
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*/
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static inline void crash_fixup_ss_esp(struct pt_regs *newregs,
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struct pt_regs *oldregs)
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{
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#ifdef CONFIG_X86_32
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newregs->sp = (unsigned long)&(oldregs->sp);
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asm volatile("xorl %%eax, %%eax\n\t"
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"movw %%ss, %%ax\n\t"
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:"=a"(newregs->ss));
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#endif
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}
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/*
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* This function is responsible for capturing register states if coming
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* via panic otherwise just fix up the ss and sp if coming via kernel
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* mode exception.
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*/
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static inline void crash_setup_regs(struct pt_regs *newregs,
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struct pt_regs *oldregs)
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{
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if (oldregs) {
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memcpy(newregs, oldregs, sizeof(*newregs));
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crash_fixup_ss_esp(newregs, oldregs);
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} else {
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#ifdef CONFIG_X86_32
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asm volatile("movl %%ebx,%0" : "=m"(newregs->bx));
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asm volatile("movl %%ecx,%0" : "=m"(newregs->cx));
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asm volatile("movl %%edx,%0" : "=m"(newregs->dx));
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asm volatile("movl %%esi,%0" : "=m"(newregs->si));
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asm volatile("movl %%edi,%0" : "=m"(newregs->di));
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asm volatile("movl %%ebp,%0" : "=m"(newregs->bp));
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asm volatile("movl %%eax,%0" : "=m"(newregs->ax));
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asm volatile("movl %%esp,%0" : "=m"(newregs->sp));
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asm volatile("movl %%ss, %%eax;" :"=a"(newregs->ss));
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asm volatile("movl %%cs, %%eax;" :"=a"(newregs->cs));
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asm volatile("movl %%ds, %%eax;" :"=a"(newregs->ds));
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asm volatile("movl %%es, %%eax;" :"=a"(newregs->es));
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asm volatile("pushfl; popl %0" :"=m"(newregs->flags));
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#else
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asm volatile("movq %%rbx,%0" : "=m"(newregs->bx));
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asm volatile("movq %%rcx,%0" : "=m"(newregs->cx));
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asm volatile("movq %%rdx,%0" : "=m"(newregs->dx));
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asm volatile("movq %%rsi,%0" : "=m"(newregs->si));
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asm volatile("movq %%rdi,%0" : "=m"(newregs->di));
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asm volatile("movq %%rbp,%0" : "=m"(newregs->bp));
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asm volatile("movq %%rax,%0" : "=m"(newregs->ax));
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asm volatile("movq %%rsp,%0" : "=m"(newregs->sp));
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asm volatile("movq %%r8,%0" : "=m"(newregs->r8));
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asm volatile("movq %%r9,%0" : "=m"(newregs->r9));
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asm volatile("movq %%r10,%0" : "=m"(newregs->r10));
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asm volatile("movq %%r11,%0" : "=m"(newregs->r11));
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asm volatile("movq %%r12,%0" : "=m"(newregs->r12));
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asm volatile("movq %%r13,%0" : "=m"(newregs->r13));
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asm volatile("movq %%r14,%0" : "=m"(newregs->r14));
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asm volatile("movq %%r15,%0" : "=m"(newregs->r15));
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asm volatile("movl %%ss, %%eax;" :"=a"(newregs->ss));
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asm volatile("movl %%cs, %%eax;" :"=a"(newregs->cs));
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asm volatile("pushfq; popq %0" :"=m"(newregs->flags));
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#endif
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newregs->ip = (unsigned long)current_text_addr();
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}
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}
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#ifdef CONFIG_X86_32
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asmlinkage unsigned long
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relocate_kernel(unsigned long indirection_page,
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unsigned long control_page,
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unsigned long start_address,
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unsigned int has_pae,
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unsigned int preserve_context);
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#else
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NORET_TYPE void
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relocate_kernel(unsigned long indirection_page,
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unsigned long page_list,
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unsigned long start_address) ATTRIB_NORET;
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#endif
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#endif /* __ASSEMBLY__ */
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#endif /* _KEXEC_H */
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