linux-kernel - Re: [patch part-II V2 04/13] x86/entry/64: Trace irqflags unconditionally as ON when returning to user space

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Message-ID: <40696243-992c-915d-09b5-b088f7331a18@oracle.com>
Date:   Tue, 10 Mar 2020 11:25:55 +0100
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: Re: [patch part-II V2 04/13] x86/entry/64: Trace irqflags
 unconditionally as ON when returning to user space


On 3/8/20 11:24 PM, Thomas Gleixner wrote:
> User space cannot longer disable interrupts so trace return to user space
> unconditionally as IRQS_ON.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
> V2: Cover 32bit as well
> ---
>   arch/x86/entry/entry_32.S |    2 +-
>   arch/x86/entry/entry_64.S |    4 ++--
>   2 files changed, 3 insertions(+), 3 deletions(-)
> 

Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>

alex.

> --- a/arch/x86/entry/entry_32.S
> +++ b/arch/x86/entry/entry_32.S
> @@ -1088,7 +1088,7 @@ SYM_FUNC_START(entry_INT80_32)
>   	STACKLEAK_ERASE
>   
>   restore_all:
> -	TRACE_IRQS_IRET
> +	TRACE_IRQS_ON
>   	SWITCH_TO_ENTRY_STACK
>   	CHECK_AND_APPLY_ESPFIX
>   
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -174,7 +174,7 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_h
>   	movq	%rsp, %rsi
>   	call	do_syscall_64		/* returns with IRQs disabled */
>   
> -	TRACE_IRQS_IRETQ		/* we're about to change IF */
> +	TRACE_IRQS_ON			/* return enables interrupts */
>   
>   	/*
>   	 * Try to use SYSRET instead of IRET if we're returning to
> @@ -619,7 +619,7 @@ SYM_CODE_START_LOCAL(common_interrupt)
>   .Lretint_user:
>   	mov	%rsp,%rdi
>   	call	prepare_exit_to_usermode
> -	TRACE_IRQS_IRETQ
> +	TRACE_IRQS_ON
>   
>   SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL)
>   #ifdef CONFIG_DEBUG_ENTRY
>