Re: [tip:x86/apic] x86/idt: Move IST stack based traps to table init

[Andrei Vagin]

Hi Thomas,

We run CRIU tests for linux-next and today they detected an issue. I've
bisected this problem and it looks like a problem is in this patch.

[root@fc24 criu]# python ./test/zdtm.py run -t zdtm/static/env00
=== Run 1/1 ================ zdtm/static/env00

========================== Run zdtm/static/env00 in h ==========================
Start test
./env00 --pidfile=env00.pid --outfile=env00.out --envname=ENV_00_TEST
Run criu dump
=[log]=> dump/zdtm/static/env00/36/1/dump.log
------------------------ grep Error ------------------------
(00.004013) Dump private signals of 36
(00.004022) Dump shared signals of 36
(00.004036) Parasite syscall_ip at 0x400000
(00.004097) ** delivering signal 11 si_code=128
(00.004103) Error (compel/src/lib/infect.c:528): Unexpected 36 task interruption, aborting
(00.004118) Error (criu/cr-dump.c:1371): Can't infect (pid: 36) with parasite
(00.004208) Unlock network
(00.004218) Unfreezing tasks into 1
(00.004223) 	Unseizing 36 into 1
(00.004244) Error (criu/cr-dump.c:1807): Dumping FAILED.
------------------------ ERROR OVER ------------------------
################### Test zdtm/static/env00 FAIL at CRIU dump ###################
Send the 9 signal to  36
Wait for zdtm/static/env00(36) to die for 0.100000
##################################### FAIL #####################################

Here is a line in a code where we get this unexpected error:
https://github.com/xemul/criu/blob/criu-dev/compel/src/lib/infect.c#L735

At this moment criu tries to execute the memfd_create syscall in a
context of another task with help of ptrace.

Here is a link to a test job:
https://travis-ci.org/avagin/linux/builds/270623449

Thanks,
Andrei

On Tue, Aug 29, 2017 at 04:18:51AM -0700, tip-bot for Jacob Shin wrote:
> Commit-ID:  90f6225fba0c732f3f5f9f5e265bdefa021ff12d
> Gitweb:     http://git.kernel.org/tip/90f6225fba0c732f3f5f9f5e265bdefa021ff12d
> Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> AuthorDate: Mon, 28 Aug 2017 08:47:52 +0200
> Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Tue, 29 Aug 2017 12:07:27 +0200
> 
> x86/idt: Move IST stack based traps to table init
> 
> Initialize the IST based traps via a table.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Brian Gerst <brgerst@xxxxxxxxx>
> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Link: http://lkml.kernel.org/r/20170828064959.091328949@xxxxxxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/desc.h |  2 ++
>  arch/x86/kernel/idt.c       | 22 ++++++++++++++++++++++
>  arch/x86/kernel/traps.c     |  9 +--------
>  3 files changed, 25 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
> index 930acd5..e624527 100644
> --- a/arch/x86/include/asm/desc.h
> +++ b/arch/x86/include/asm/desc.h
> @@ -509,9 +509,11 @@ extern void idt_setup_early_traps(void);
>  
>  #ifdef CONFIG_X86_64
>  extern void idt_setup_early_pf(void);
> +extern void idt_setup_ist_traps(void);
>  extern void idt_setup_debugidt_traps(void);
>  #else
>  static inline void idt_setup_early_pf(void) { }
> +static inline void idt_setup_ist_traps(void) { }
>  static inline void idt_setup_debugidt_traps(void) { }
>  #endif
>  
> diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
> index f5281b8..a6326fd 100644
> --- a/arch/x86/kernel/idt.c
> +++ b/arch/x86/kernel/idt.c
> @@ -92,6 +92,20 @@ struct desc_ptr idt_descr __ro_after_init = {
>  gate_desc debug_idt_table[IDT_ENTRIES] __page_aligned_bss;
>  
>  /*
> + * The exceptions which use Interrupt stacks. They are setup after
> + * cpu_init() when the TSS has been initialized.
> + */
> +static const __initdata struct idt_data ist_idts[] = {
> +	ISTG(X86_TRAP_DB,	debug,		DEBUG_STACK),
> +	ISTG(X86_TRAP_NMI,	nmi,		NMI_STACK),
> +	ISTG(X86_TRAP_BP,	int3,		DEBUG_STACK),
> +	ISTG(X86_TRAP_DF,	double_fault,	DOUBLEFAULT_STACK),
> +#ifdef CONFIG_X86_MCE
> +	ISTG(X86_TRAP_MC,	&machine_check,	MCE_STACK),
> +#endif
> +};
> +
> +/*
>   * Override for the debug_idt. Same as the default, but with interrupt
>   * stack set to DEFAULT_STACK (0). Required for NMI trap handling.
>   */
> @@ -158,6 +172,14 @@ void __init idt_setup_early_pf(void)
>  }
>  
>  /**
> + * idt_setup_ist_traps - Initialize the idt table with traps using IST
> + */
> +void __init idt_setup_ist_traps(void)
> +{
> +	idt_setup_from_table(idt_table, ist_idts, ARRAY_SIZE(ist_idts));
> +}
> +
> +/**
>   * idt_setup_debugidt_traps - Initialize the debug idt table with debug traps
>   */
>  void __init idt_setup_debugidt_traps(void)
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 1492bf5..293f5bd 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -979,14 +979,7 @@ void __init trap_init(void)
>  	 */
>  	cpu_init();
>  
> -	/*
> -	 * X86_TRAP_DB and X86_TRAP_BP have been set
> -	 * in early_trap_init(). However, ITS works only after
> -	 * cpu_init() loads TSS. See comments in early_trap_init().
> -	 */
> -	set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
> -	/* int3 can be called from all */
> -	set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
> +	idt_setup_ist_traps();
>  
>  	x86_init.irqs.trap_init();
>