From: Frederic Weisbecker <frederic@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>
Subject: Re: [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check()
Date: Wed, 26 Feb 2020 02:13:50 +0100 [thread overview]
Message-ID: <20200226011349.GH9599@lenoir> (raw)
In-Reply-To: <20200225220216.315548935@linutronix.de>
On Tue, Feb 25, 2020 at 10:36:38PM +0100, Thomas Gleixner wrote:
> From: Andy Lutomirski <luto@kernel.org>
>
> do_machine_check() can be raised in almost any context including the most
> fragile ones. Prevent kprobes and tracing.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> arch/x86/include/asm/traps.h | 3 ---
> arch/x86/kernel/cpu/mce/core.c | 12 ++++++++++--
> 2 files changed, 10 insertions(+), 5 deletions(-)
>
> --- a/arch/x86/include/asm/traps.h
> +++ b/arch/x86/include/asm/traps.h
> @@ -88,9 +88,6 @@ dotraplinkage void do_page_fault(struct
> dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *regs, long error_code);
> dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code);
> dotraplinkage void do_alignment_check(struct pt_regs *regs, long error_code);
> -#ifdef CONFIG_X86_MCE
> -dotraplinkage void do_machine_check(struct pt_regs *regs, long error_code);
> -#endif
> dotraplinkage void do_simd_coprocessor_error(struct pt_regs *regs, long error_code);
> #ifdef CONFIG_X86_32
> dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code);
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -1213,8 +1213,14 @@ static void __mc_scan_banks(struct mce *
> * On Intel systems this is entered on all CPUs in parallel through
> * MCE broadcast. However some CPUs might be broken beyond repair,
> * so be always careful when synchronizing with others.
> + *
> + * Tracing and kprobes are disabled: if we interrupted a kernel context
> + * with IF=1, we need to minimize stack usage. There are also recursion
> + * issues: if the machine check was due to a failure of the memory
> + * backing the user stack, tracing that reads the user stack will cause
> + * potentially infinite recursion.
> */
> -void do_machine_check(struct pt_regs *regs, long error_code)
> +void notrace do_machine_check(struct pt_regs *regs, long error_code)
> {
> DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
> DECLARE_BITMAP(toclear, MAX_NR_BANKS);
> @@ -1360,6 +1366,7 @@ void do_machine_check(struct pt_regs *re
> ist_exit(regs);
> }
> EXPORT_SYMBOL_GPL(do_machine_check);
> +NOKPROBE_SYMBOL(do_machine_check);
That won't protect all the function called by do_machine_check(), right?
There are lots of them.
next prev parent reply other threads:[~2020-02-26 1:13 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-25 21:36 [patch 00/10] x86/entry: Consolidation - Part I Thomas Gleixner
2020-02-25 21:36 ` [patch 01/10] x86/entry/32: Add missing ASM_CLAC to general_protection entry Thomas Gleixner
2020-02-26 1:00 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check() Thomas Gleixner
2020-02-26 1:13 ` Frederic Weisbecker [this message]
2020-02-26 5:29 ` Andy Lutomirski
2020-02-26 13:28 ` Peter Zijlstra
2020-02-26 15:10 ` Andy Lutomirski
2020-02-26 16:08 ` Peter Zijlstra
2020-02-26 17:28 ` Andy Lutomirski
2020-02-26 18:42 ` Borislav Petkov
2020-02-26 18:59 ` Peter Zijlstra
2020-02-26 19:09 ` Andy Lutomirski
2020-02-26 20:59 ` Steven Rostedt
2020-02-26 11:18 ` Borislav Petkov
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Andy Lutomirski
2020-02-25 21:36 ` [patch 03/10] x86/entry/32: Force MCE through do_mce() Thomas Gleixner
2020-02-26 1:11 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 04/10] x86/traps: Remove pointless irq enable from do_spurious_interrupt_bug() Thomas Gleixner
2020-02-26 1:19 ` Frederic Weisbecker
2020-02-25 21:36 ` [patch 05/10] x86/traps: Document do_spurious_interrupt_bug() Thomas Gleixner
2020-02-26 17:08 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 06/10] x86/traps: Remove redundant declaration of do_double_fault() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 07/10] x86/irq: Remove useless return value from do_IRQ() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 08/10] x86/entry/32: Remove the 0/-1 distinction from exception entries Thomas Gleixner
2020-02-26 5:34 ` Andy Lutomirski
2020-02-26 18:42 ` Thomas Gleixner
2020-02-26 18:57 ` Andy Lutomirski
2020-02-26 19:15 ` Thomas Gleixner
2020-02-27 14:24 ` [patch V2 " Thomas Gleixner
2020-02-29 11:49 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 09/10] x86/entry/entry_32: Route int3 through common_exception Thomas Gleixner
2020-02-26 17:35 ` Frederic Weisbecker
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 10/10] x86/traps: Stop using ist_enter/exit() in do_int3() Thomas Gleixner
2020-02-27 14:15 ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-27 14:33 ` tip-bot2 for Andy Lutomirski
2020-02-26 5:26 ` [patch 00/10] x86/entry: Consolidation - Part I Andy Lutomirski
2020-02-26 5:35 ` Andy Lutomirski
2020-02-27 11:01 ` Alexandre Chartre
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