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@@ -233,32 +233,40 @@ DO_ERROR(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op)
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DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun)
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DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
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DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
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-#ifdef CONFIG_X86_32
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DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
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-#endif
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DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check)
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#ifdef CONFIG_X86_64
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/* Runs on IST stack */
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-dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
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-{
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- enum ctx_state prev_state;
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-
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- prev_state = exception_enter();
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- if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
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- X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
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- preempt_conditional_sti(regs);
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- do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
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- preempt_conditional_cli(regs);
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- }
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- exception_exit(prev_state);
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-}
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-
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dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
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{
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static const char str[] = "double fault";
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struct task_struct *tsk = current;
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+#ifdef CONFIG_X86_ESPFIX64
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+ extern unsigned char native_irq_return_iret[];
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+
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+ /*
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+ * If IRET takes a non-IST fault on the espfix64 stack, then we
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+ * end up promoting it to a doublefault. In that case, modify
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+ * the stack to make it look like we just entered the #GP
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+ * handler from user space, similar to bad_iret.
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+ */
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+ if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY &&
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+ regs->cs == __KERNEL_CS &&
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+ regs->ip == (unsigned long)native_irq_return_iret)
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+ {
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+ struct pt_regs *normal_regs = task_pt_regs(current);
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+
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+ /* Fake a #GP(0) from userspace. */
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+ memmove(&normal_regs->ip, (void *)regs->sp, 5*8);
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+ normal_regs->orig_ax = 0; /* Missing (lost) #GP error code */
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+ regs->ip = (unsigned long)general_protection;
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+ regs->sp = (unsigned long)&normal_regs->orig_ax;
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+ return;
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+ }
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+#endif
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+
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exception_enter();
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/* Return not checked because double check cannot be ignored */
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notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
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@@ -399,6 +407,35 @@ asmlinkage __visible struct pt_regs *sync_regs(struct pt_regs *eregs)
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return regs;
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}
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NOKPROBE_SYMBOL(sync_regs);
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+
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+struct bad_iret_stack {
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+ void *error_entry_ret;
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+ struct pt_regs regs;
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+};
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+
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+asmlinkage __visible
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+struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
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+{
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+ /*
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+ * This is called from entry_64.S early in handling a fault
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+ * caused by a bad iret to user mode. To handle the fault
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+ * correctly, we want move our stack frame to task_pt_regs
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+ * and we want to pretend that the exception came from the
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+ * iret target.
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+ */
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+ struct bad_iret_stack *new_stack =
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+ container_of(task_pt_regs(current),
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+ struct bad_iret_stack, regs);
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+
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+ /* Copy the IRET target to the new stack. */
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+ memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8);
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+
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+ /* Copy the remainder of the stack from the current stack. */
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+ memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip));
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+
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+ BUG_ON(!user_mode_vm(&new_stack->regs));
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+ return new_stack;
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+}
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#endif
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/*
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@@ -778,7 +815,7 @@ void __init trap_init(void)
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set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
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set_intr_gate(X86_TRAP_TS, invalid_TSS);
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set_intr_gate(X86_TRAP_NP, segment_not_present);
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- set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
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+ set_intr_gate(X86_TRAP_SS, stack_segment);
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set_intr_gate(X86_TRAP_GP, general_protection);
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set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
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set_intr_gate(X86_TRAP_MF, coprocessor_error);
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Linus Torvalds