1 files changed, 45 insertions, 0 deletions

diff --git a/include/asm-i386/kexec.h b/include/asm-i386/kexec.h
index d80d446498fb..8fb1defd98c6 100644
--- a/include/asm-i386/kexec.h
+++ b/include/asm-i386/kexec.h
@@ -2,6 +2,7 @@
 #define _I386_KEXEC_H
 
 #include <asm/fixmap.h>
+#include <asm/ptrace.h>
 
 /*
  * KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return.
@@ -27,4 +28,48 @@
 
 #define MAX_NOTE_BYTES 1024
 
+/* CPU does not save ss and esp on stack if execution is already
+ * running in kernel mode at the time of NMI occurrence. This code
+ * fixes it.
+ */
+static inline void crash_fixup_ss_esp(struct pt_regs *newregs,
+                                        struct pt_regs *oldregs)
+{
+        memcpy(newregs, oldregs, sizeof(*newregs));
+        newregs->esp = (unsigned long)&(oldregs->esp);
+        __asm__ __volatile__(
+                        "xorl %%eax, %%eax\n\t"
+                        "movw %%ss, %%ax\n\t"
+                        :"=a"(newregs->xss));
+}
+
+/*
+ * This function is responsible for capturing register states if coming
+ * via panic otherwise just fix up the ss and esp if coming via kernel
+ * mode exception.
+ */
+static inline void crash_setup_regs(struct pt_regs *newregs,
+                                       struct pt_regs *oldregs)
+{
+       if (oldregs)
+               crash_fixup_ss_esp(newregs, oldregs);
+       else {
+               __asm__ __volatile__("movl %%ebx,%0" : "=m"(newregs->ebx));
+               __asm__ __volatile__("movl %%ecx,%0" : "=m"(newregs->ecx));
+               __asm__ __volatile__("movl %%edx,%0" : "=m"(newregs->edx));
+               __asm__ __volatile__("movl %%esi,%0" : "=m"(newregs->esi));
+               __asm__ __volatile__("movl %%edi,%0" : "=m"(newregs->edi));
+               __asm__ __volatile__("movl %%ebp,%0" : "=m"(newregs->ebp));
+               __asm__ __volatile__("movl %%eax,%0" : "=m"(newregs->eax));
+               __asm__ __volatile__("movl %%esp,%0" : "=m"(newregs->esp));
+               __asm__ __volatile__("movw %%ss, %%ax;" :"=a"(newregs->xss));
+               __asm__ __volatile__("movw %%cs, %%ax;" :"=a"(newregs->xcs));
+               __asm__ __volatile__("movw %%ds, %%ax;" :"=a"(newregs->xds));
+               __asm__ __volatile__("movw %%es, %%ax;" :"=a"(newregs->xes));
+               __asm__ __volatile__("pushfl; popl %0" :"=m"(newregs->eflags));
+
+               newregs->eip = (unsigned long)current_text_addr();
+       }
+}
+
 #endif /* _I386_KEXEC_H */