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Re: using utrace for instruction tracing
This is what I found when I googled ARCH_HAS_SINGLE_STEP x86 utrace
http://lkml.org/lkml/2007/2/21/264
Date Wed, 21 Feb 2007 13:18:11 -0500
From Jeff Dike <>
Subject Re: [PATCH] UML utrace support, step 1
......
> +#define ARCH_HAS_SINGLE_STEP (1)
Note you'll eventually want to define the block-step macro and functions
depending on subarch. (ia64 supports it, and x86 one day will.)
I guess I didn't read the comment carefully enough. I think this mail
is from a guy implementing utrace for x86 and is saying that block
stepping isn't supported.
Jim Keniston wrote:
On Wed, 2007-09-05 at 15:46 -0700, Dave Nomura wrote:
I notice that the utrace documentation says that single-stepping is only
supported if ARCH_HAS_SINGLE_STEP/ARCH_HAS_BLOCK_STEP is supported. My
googling found a note you sent the says it is supported on ia64 and ppc,
but not on x86 yet. Any idea if there are any work underway to support
this on x86?
Frank: Is this a unacceptable, or can we live with no user instruction
tracing on x86 until support is added? I'm not very familiar with how
PI ITRACE does single step tracing on x86, for kernel/user code tracing
but I know it is significantly different than the PPC.
I'm not sure what you're looking at, but utrace definitely supports
single-stepping on x86 -- and at least ppc64, x86_64, and s390 as well,
since uprobes runs on all those and uses single-stepping.
Jim
--
Dave Nomura
LTC Linux Power Toolchain