[PATCH v6 2/4] x86/syscalls: Specific usage of verify_pre_usermode_state

H. Peter Anvin hpa at zytor.com
Tue Apr 4 11:11:03 PDT 2017


On 04/04/17 10:47, Thomas Garnier wrote:
> Implement specific usage of verify_pre_usermode_state for user-mode
> returns for x86.
> 
> Signed-off-by: Thomas Garnier <thgarnie at google.com>
>  
> +	/*
> +	 * If address limit is not based on user-mode, jump to slow path for
> +	 * additional security checks.
> +	 */
> +	movq	$TASK_SIZE_MAX, %rcx
> +	cmp	%rcx, TASK_addr_limit(%r11)
> +	jnz	1f
> +
>  	LOCKDEP_SYS_EXIT

Nitpick: use jne not jnz when comparing for equality.  Same instruction
but more readable.

	-hpa





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