Date: Wed, 24 Jul 2013 21:32:50 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Yuri <yuri@rawbw.com> Cc: FreeBSD Hackers <hackers@FreeBSD.org> Subject: Re: DTrace copyin with struct doesn't work? Message-ID: <51F01DD2.6060308@FreeBSD.org> In-Reply-To: <51F01940.2020402@rawbw.com> References: <51F01940.2020402@rawbw.com>
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on 24/07/2013 21:13 Yuri said the following:
> This simple .d script fails:
>
> ---script begin---
> #!/usr/sbin/dtrace -s
>
> struct my_args {
> int ii;
> };
>
> fbt::sys_select:entry
> {
> printf("sys_select %i", ((struct my_args*)copyin(arg1, sizeof (struct
> my_args)))->ii);
> }
> ---script end---
>
> dtrace: error on enabled probe ID 1 (ID 33598: fbt:kernel:sys_select:entry):
> invalid address (0xffffff82ff0799d8) in action #1 at DIF offset 40
> dtrace: error on enabled probe ID 1 (ID 33598: fbt:kernel:sys_select:entry):
> invalid address (0xffffff82fefb19d8) in action #1 at DIF offset 40
>
> Function sys_select is defined in kern/sys_generic.c:
> int
> sys_select(struct thread *td, struct select_args *uap)
>From sys_select code it is clear that uap points to something that is already
copied in. Unlike some fields within select_args.
> arg1 in DTrace script should correspond to uap argument of sys_select, and
> dereferencing should always produce an int.
--
Andriy Gapon
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