From: "Woodhouse, David" <dwmw@amazon.co.uk>
To: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>
Cc: <x86@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, <stable@vger.kernel.org>,
"Ghitulete, Razvan-alin" <rga@amazon.com>
Subject: Re: [PATCH] x86/mce: Make machine check speculation protected
Date: Fri, 19 Jan 2018 09:46:26 +0100 [thread overview]
Message-ID: <1516351586.5087.9.camel@amazon.co.uk> (raw)
In-Reply-To: <alpine.DEB.2.20.1801181626290.1847@nanos>
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On Thu, 2018-01-18 at 16:28 +0100, Thomas Gleixner wrote:
> The machine check idtentry uses an indirect branch directly from the low
> level code. This evades the speculation protection.
>
> Replace it by a direct call into C code and issue the indirect call there
> so the compiler can apply the proper speculation protection.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable for at least 4.9.
> ---
> arch/x86/entry/entry_64.S | 2 +-
> arch/x86/include/asm/traps.h | 1 +
> arch/x86/kernel/cpu/mcheck/mce.c | 5 +++++
> 3 files changed, 7 insertions(+), 1 deletion(-)
>
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -1264,7 +1264,7 @@ idtentry async_page_fault do_async_page_
> #endif
>
> #ifdef CONFIG_X86_MCE
> -idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vector(%rip)
> +idtentry machine_check do_mce has_error_code=0 paranoid=1
> #endif
>
> /*
> --- a/arch/x86/include/asm/traps.h
> +++ b/arch/x86/include/asm/traps.h
> @@ -88,6 +88,7 @@ dotraplinkage void do_simd_coprocessor_e
> #ifdef CONFIG_X86_32
> dotraplinkage void do_iret_error(struct pt_regs *, long);
> #endif
> +dotraplinkage void do_mce(struct pt_regs *, long);
>
> static inline int get_si_code(unsigned long condition)
> {
> --- a/arch/x86/kernel/cpu/mcheck/mce.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce.c
> @@ -1785,6 +1785,11 @@ static void unexpected_machine_check(str
> void (*machine_check_vector)(struct pt_regs *, long error_code) =
> unexpected_machine_check;
>
> +dotraplinkage void do_mce(struct pt_regs *regs, long error_code)
> +{
> + machine_check_vector(regs, error_code);
> +}
> +
> /*
> * Called for each booted CPU to set up machine checks.
> * Must be called with preempt off:
>
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next prev parent reply other threads:[~2018-01-19 8:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-18 15:28 [PATCH] x86/mce: Make machine check speculation protected Thomas Gleixner
2018-01-18 15:46 ` Peter Zijlstra
2018-01-18 15:53 ` Borislav Petkov
2018-01-18 15:55 ` David Woodhouse
2018-01-19 8:46 ` Woodhouse, David [this message]
2018-01-19 15:46 ` [tip:x86/pti] " tip-bot for Thomas Gleixner
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