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From: Roland McGrath <roland@redhat.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>,
	linux-kernel@vger.kernel.org, mingo@elte.hu,
	mathieu.desnoyers@polymtl.ca, hpa@zytor.com, tglx@linutronix.de,
	rostedt@goodmis.org, andi@firstfloor.org, rth@redhat.com,
	mhiramat@redhat.com, fweisbec@gmail.com, avi@redhat.com,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH 7/9] jump label: sort jump table at build-time
Date: Fri,  9 Apr 2010 14:32:49 -0700 (PDT)	[thread overview]
Message-ID: <20100409213249.BDEF9CD14@magilla.sf.frob.com> (raw)
In-Reply-To: Vivek Goyal's message of  Friday, 9 April 2010 17:24:25 -0400 <20100409212425.GB8219@redhat.com>

I think it just happens to come out harmless.  The relocs.c extraction
stuff doesn't actually care about the exact address to be relocated, it
only needs to know that a relocated value sits at a given place in the
binary.  The sorting rearranges the addresses in the text without
rearranging their corresponding relocs, but it's still the case that at
exactly each of those spots in text there is a relocated address.  The
boot-time "relocation" is just a blind adjustment to all those spots,
without reference to the original relocation details.  So it Just Works.
I'm not at all sure this is how we want things to be.  It's rather
nonobvious and fragile if we change any of the related magic.  But I think
it is entirely reliable in today's code that it will do the right thing.


Thanks,
Roland

  reply	other threads:[~2010-04-09 21:33 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-09 19:49 [PATCH 0/9] jump label v6 Jason Baron
2010-04-09 19:49 ` [PATCH 1/9] jump label: notifier atomic call chain notrace Jason Baron
2010-04-09 19:49 ` [PATCH 2/9] jump label: base patch Jason Baron
2010-04-09 19:49 ` [PATCH 3/9] jump label: x86 support Jason Baron
2010-04-09 19:49 ` [PATCH 4/9] jump label: tracepoint support Jason Baron
2010-04-09 19:49 ` [PATCH 5/9] jump label: add module support Jason Baron
2010-04-09 19:49 ` [PATCH 6/9] jump label: move ftrace_dyn_arch_init to common code Jason Baron
2010-04-09 19:49 ` [PATCH 7/9] jump label: sort jump table at build-time Jason Baron
2010-04-09 21:24   ` Vivek Goyal
2010-04-09 21:32     ` Roland McGrath [this message]
2010-04-09 19:50 ` [PATCH 8/9] jump label: initialize workqueue tracepoints *before* they are registered Jason Baron
2010-04-09 19:50 ` [PATCH 9/9] jump label: jump_label_text_reserved() to reserve our jump points Jason Baron
2010-04-09 21:09   ` Masami Hiramatsu
2010-04-09 20:36 ` [PATCH 0/9] jump label v6 Masami Hiramatsu
2010-04-09 21:37   ` Jason Baron
2010-04-09 21:58     ` Masami Hiramatsu
2010-04-10  6:16 ` David Miller
2010-04-10  6:22   ` H. Peter Anvin
2010-04-13 16:56 ` Mathieu Desnoyers
2010-04-14 19:34   ` Jason Baron

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