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From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, jgross@suse.com, mbenes@suze.cz,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/9] objtool: Rework rebuild_reloc logic
Date: Thu, 18 Mar 2021 18:04:25 +0100	[thread overview]
Message-ID: <YFOIGYblhHTqp/fa@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210318163640.5u6rucdk66aodun7@treble>

On Thu, Mar 18, 2021 at 11:36:40AM -0500, Josh Poimboeuf wrote:
> > I was thinking you could get a section changed without touching
> > relocations, but while that is theoretically possible, it is exceedingly
> > unlikely (and objtool doesn't do that).
> 
> Hm?  This is a *relocation* section, not a normal one.  So by
> definition, it only changes when its relocations change.

The way I read this code:

 	list_for_each_entry(sec, &elf->sections, list) {
 		if (sec->changed) {
+			if (sec->reloc &&
+			    elf_rebuild_reloc_section(elf, sec->reloc)) {
+				WARN_ELF("elf_rebuild_reloc_section");
+				return -1;
+			}

is that we iterate the regular sections (which could be dirtied because
we changed some data), and if that section has a relocation section, we
rebuild that for good measure (even though it might not have altered
relocations).

Or am I just totally confused ?

  reply	other threads:[~2021-03-18 17:05 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12 17:16 [PATCH 0/9] x86,objtool: Optimize !RETPOLINE Peter Zijlstra
2021-03-12 17:16 ` [PATCH 1/9] x86/retpoline: Simplify retpolines Peter Zijlstra
2021-03-12 17:16 ` [PATCH 2/9] objtool: Correctly handle retpoline thunk calls Peter Zijlstra
2021-03-16 21:19   ` Josh Poimboeuf
2021-03-12 17:16 ` [PATCH 3/9] objtool: Per arch retpoline naming Peter Zijlstra
2021-03-12 17:16 ` [PATCH 4/9] objtool: Fix static_call list generation Peter Zijlstra
2021-03-17  3:18   ` Josh Poimboeuf
2021-03-12 17:16 ` [PATCH 5/9] objtool: Rework rebuild_reloc logic Peter Zijlstra
2021-03-17  3:34   ` Josh Poimboeuf
2021-03-17  8:12     ` Peter Zijlstra
2021-03-18  0:49       ` Josh Poimboeuf
2021-03-18 12:57         ` Peter Zijlstra
2021-03-18 16:36           ` Josh Poimboeuf
2021-03-18 17:04             ` Peter Zijlstra [this message]
2021-03-18 17:38               ` Josh Poimboeuf
2021-03-19  0:19                 ` Josh Poimboeuf
2021-03-19  9:22                 ` Peter Zijlstra
2021-03-19 15:15                   ` Josh Poimboeuf
2021-03-12 17:16 ` [PATCH 6/9] objtool: Add elf_create_undef_symbol() Peter Zijlstra
2021-03-17 13:52   ` Miroslav Benes
2021-03-17 14:13     ` Peter Zijlstra
2021-03-17 14:39       ` Miroslav Benes
2021-03-17 15:08         ` Sami Tolvanen
2021-03-18  0:46       ` Josh Poimboeuf
2021-03-18  7:56         ` Peter Zijlstra
2021-03-12 17:16 ` [PATCH 7/9] objtool: Allow archs to rewrite retpolines Peter Zijlstra
2021-03-12 17:16 ` [PATCH 8/9] objtool: Skip magical retpoline .altinstr_replacement Peter Zijlstra
2021-03-12 17:16 ` [PATCH 9/9] objtool,x86: Rewrite retpoline thunk calls Peter Zijlstra

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