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x86/doublefault: Remove memmove() call
Use of memmove() in #DF is problematic considered tracing and other instrumentation. Remove the memmove() call and simply write out what needs doing; this even clarifies the code, win-win! The code copies from the espfix64 stack to the normal task stack, there is no possible way for that to overlap. Survives selftests/x86, specifically sigreturn_64. Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200505134058.863038566@linutronix.de
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1 changed files with 6 additions and 1 deletions
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@ -299,6 +299,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
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regs->ip == (unsigned long)native_irq_return_iret)
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{
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struct pt_regs *gpregs = (struct pt_regs *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
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unsigned long *p = (unsigned long *)regs->sp;
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/*
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* regs->sp points to the failing IRET frame on the
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@ -306,7 +307,11 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
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* in gpregs->ss through gpregs->ip.
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*
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*/
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memmove(&gpregs->ip, (void *)regs->sp, 5*8);
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gpregs->ip = p[0];
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gpregs->cs = p[1];
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gpregs->flags = p[2];
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gpregs->sp = p[3];
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gpregs->ss = p[4];
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gpregs->orig_ax = 0; /* Missing (lost) #GP error code */
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/*
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