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x86/traps: Mark fixup_bad_iret() noinstr
This is called from deep entry ASM in a situation where instrumentation will cause more harm than providing useful information. Switch from memmove() to memcpy() because memmove() can't be called from noinstr code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134903.346741553@linutronix.de
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1 changed files with 9 additions and 7 deletions
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@ -578,7 +578,7 @@ struct bad_iret_stack {
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struct pt_regs regs;
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};
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asmlinkage __visible notrace
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asmlinkage __visible noinstr
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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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@ -589,19 +589,21 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
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* just below the IRET frame) and we want to pretend that the
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* exception came from the IRET target.
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*/
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struct bad_iret_stack *new_stack =
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(struct bad_iret_stack *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
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struct bad_iret_stack tmp, *new_stack =
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(struct bad_iret_stack *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
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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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/* Copy the IRET target to the temporary storage. */
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memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8);
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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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memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip));
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/* Update the entry stack */
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memcpy(new_stack, &tmp, sizeof(tmp));
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BUG_ON(!user_mode(&new_stack->regs));
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return new_stack;
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}
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NOKPROBE_SYMBOL(fixup_bad_iret);
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#endif
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static bool is_sysenter_singlestep(struct pt_regs *regs)
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