3566561bfa
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>
104 lines
3.4 KiB
C
104 lines
3.4 KiB
C
#ifndef _I386_KEXEC_H
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#define _I386_KEXEC_H
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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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#ifdef CONFIG_X86_PAE
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#define PA_PMD_0 8
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#define VA_PMD_0 9
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#define PA_PMD_1 10
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#define VA_PMD_1 11
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#define PAGES_NR 12
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#else
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#define PAGES_NR 8
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#endif
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#ifndef __ASSEMBLY__
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#include <asm/fixmap.h>
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#include <asm/ptrace.h>
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#include <asm/string.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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* Someone correct me if FIXADDR_START - PAGEOFFSET is not the correct
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* calculation for the amount of memory directly mappable into the
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* kernel memory space.
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*/
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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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#define MAX_NOTE_BYTES 1024
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/* CPU does not save ss and esp 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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memcpy(newregs, oldregs, sizeof(*newregs));
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newregs->esp = (unsigned long)&(oldregs->esp);
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__asm__ __volatile__(
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"xorl %%eax, %%eax\n\t"
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"movw %%ss, %%ax\n\t"
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:"=a"(newregs->xss));
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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 esp 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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crash_fixup_ss_esp(newregs, oldregs);
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else {
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__asm__ __volatile__("movl %%ebx,%0" : "=m"(newregs->ebx));
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__asm__ __volatile__("movl %%ecx,%0" : "=m"(newregs->ecx));
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__asm__ __volatile__("movl %%edx,%0" : "=m"(newregs->edx));
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__asm__ __volatile__("movl %%esi,%0" : "=m"(newregs->esi));
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__asm__ __volatile__("movl %%edi,%0" : "=m"(newregs->edi));
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__asm__ __volatile__("movl %%ebp,%0" : "=m"(newregs->ebp));
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__asm__ __volatile__("movl %%eax,%0" : "=m"(newregs->eax));
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__asm__ __volatile__("movl %%esp,%0" : "=m"(newregs->esp));
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__asm__ __volatile__("movw %%ss, %%ax;" :"=a"(newregs->xss));
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__asm__ __volatile__("movw %%cs, %%ax;" :"=a"(newregs->xcs));
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__asm__ __volatile__("movw %%ds, %%ax;" :"=a"(newregs->xds));
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__asm__ __volatile__("movw %%es, %%ax;" :"=a"(newregs->xes));
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__asm__ __volatile__("pushfl; popl %0" :"=m"(newregs->eflags));
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newregs->eip = (unsigned long)current_text_addr();
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}
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}
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asmlinkage NORET_TYPE void
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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) ATTRIB_NORET;
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#endif /* __ASSEMBLY__ */
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#endif /* _I386_KEXEC_H */
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