linux-kernel - Re: [PATCH 06/17] x86, mpx: trace attempts to find bounds tables

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Message-ID: <55156445.3000609@sr71.net>
Date:	Fri, 27 Mar 2015 07:08:05 -0700
From:	Dave Hansen <dave@...1.net>
To:	Borislav Petkov <bp@...en8.de>
CC:	linux-kernel@...r.kernel.org, x86@...nel.org, tglx@...utronix.de,
	dave.hansen@...ux.intel.com
Subject: Re: [PATCH 06/17] x86, mpx: trace attempts to find bounds tables

On 03/27/2015 05:32 AM, Borislav Petkov wrote:
>> > This event traces any time we go looking to unmap a bounds table
>> > for a given virtual address range.  This is useful to ensure
>> > that the kernel actually "tried" to free a bounds table versus
>> > times it succeeded.
>> > 
>> > It might try and fail if it realized that a table was shared
>> > with an adjacent VMA which is not being unmapped.
> Would it make sense to extend this tracepoint to also dump the error
> values returned from unmap_edge_bts() and unmap_single_bt() inside
> mpx_unmap_tables()?

Both of the paths below this point (the "real" unmap and the zap) also
have tracepoints.  It might also get confusing to see -ENOENT in the
success case.  Also, in practice, you can see the siginfo get generated
and tell that something bad happened.

I think I'd rather leave it as-is.


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