From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
peterz@infradead.org, jthierry@redhat.com, tglx@linutronix.de
Subject: Re: [PATCH 5/7] x86/speculation: Annotate intra-function calls
Date: Fri, 3 Apr 2020 10:14:49 -0700 (PDT) [thread overview]
Message-ID: <2c615bae-6002-80b7-493d-b24ec48f69c9@oracle.com> (raw)
In-Reply-To: <20200403161607.jxz6duaz7dud22wf@treble>
On 4/3/20 6:16 PM, Josh Poimboeuf wrote:
> On Fri, Apr 03, 2020 at 11:05:38AM -0500, Josh Poimboeuf wrote:
>> On Thu, Apr 02, 2020 at 10:22:18AM +0200, Alexandre Chartre wrote:
>>> .macro RETPOLINE_JMP reg:req
>>> - call .Ldo_rop_\@
>>> + INTRA_FUNCTION_CALL .Ldo_rop_\@
>>> .Lspec_trap_\@:
>>> pause
>>> lfence
>>> @@ -102,7 +116,7 @@
>>> .Ldo_retpoline_jmp_\@:
>>> RETPOLINE_JMP \reg
>>> .Ldo_call_\@:
>>> - call .Ldo_retpoline_jmp_\@
>>> + INTRA_FUNCTION_CALL .Ldo_retpoline_jmp_\@
>>> .endm
>>
>> There's a catch: this is part of an alternative. Which means if
>> X86_FEATURE_RETPOLINE isn't set at runtime, then the retpoline won't be
>> there and the ORC data will be wrong.
>>
>> In fact objtool should probably be made smart enough to warn about this
>> situation, when an alternative changes the stack state.
>>
>> The only way I can think of to fix this is to have ORC alternatives :-/
So that means that any alternative that does a stack manipulation isn't
currently supported?
alex.
> Or they could be converted to use static branches instead of
> alternatives.
>
next prev parent reply other threads:[~2020-04-03 17:13 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-02 8:22 [PATCH 0/7] objtool changes to remove most ANNOTATE_NOSPEC_ALTERNATIVE Alexandre Chartre
2020-04-02 8:22 ` [PATCH 1/7] objtool: is_fentry_call() crashes if call has no destination Alexandre Chartre
2020-04-02 8:22 ` [PATCH 2/7] objtool: Allow branches within the same alternative Alexandre Chartre
2020-04-02 12:03 ` Julien Thierry
2020-04-02 12:38 ` Alexandre Chartre
2020-04-02 8:22 ` [PATCH 3/7] objtool: Add support for intra-function calls Alexandre Chartre
2020-04-02 12:53 ` Julien Thierry
2020-04-02 13:24 ` Alexandre Chartre
2020-04-02 13:38 ` Julien Thierry
2020-04-02 14:56 ` Alexandre Chartre
2020-04-02 15:04 ` Peter Zijlstra
2020-04-02 15:54 ` Josh Poimboeuf
2020-04-03 7:06 ` Alexandre Chartre
2020-04-02 15:49 ` Josh Poimboeuf
2020-04-02 17:27 ` Josh Poimboeuf
2020-04-03 8:01 ` Julien Thierry
2020-04-03 12:41 ` Peter Zijlstra
2020-04-03 12:49 ` Julien Thierry
2020-04-03 14:37 ` Peter Zijlstra
2020-04-03 14:44 ` Josh Poimboeuf
2020-04-02 8:22 ` [PATCH 4/7] objtool: Add support for return trampoline call Alexandre Chartre
2020-04-02 13:26 ` Julien Thierry
2020-04-02 14:46 ` Alexandre Chartre
2020-04-02 15:31 ` Julien Thierry
2020-04-02 15:40 ` Peter Zijlstra
2020-04-03 8:11 ` Julien Thierry
2020-04-03 15:17 ` Josh Poimboeuf
2020-04-03 15:22 ` Josh Poimboeuf
2020-04-03 15:32 ` Josh Poimboeuf
2020-04-03 15:46 ` Peter Zijlstra
2020-04-03 15:55 ` Josh Poimboeuf
2020-04-04 13:32 ` Peter Zijlstra
2020-04-04 14:22 ` Josh Poimboeuf
2020-04-04 15:51 ` Peter Zijlstra
2020-04-06 8:19 ` Alexandre Chartre
2020-04-06 9:31 ` Peter Zijlstra
2020-04-06 11:03 ` Alexandre Chartre
2020-04-06 14:16 ` Josh Poimboeuf
2020-04-02 15:27 ` Peter Zijlstra
2020-04-03 7:19 ` Alexandre Chartre
2020-04-06 14:34 ` Alexandre Chartre
2020-04-06 14:55 ` Alexandre Chartre
2020-04-02 8:22 ` [PATCH 5/7] x86/speculation: Annotate intra-function calls Alexandre Chartre
2020-04-03 16:05 ` Josh Poimboeuf
2020-04-03 16:16 ` Josh Poimboeuf
2020-04-03 17:14 ` Alexandre Chartre [this message]
2020-04-03 17:18 ` Peter Zijlstra
2020-04-03 17:24 ` Josh Poimboeuf
2020-04-03 18:20 ` Peter Zijlstra
2020-04-02 8:22 ` [PATCH 6/7] x86/speculation: Annotate retpoline return instructions Alexandre Chartre
2020-04-02 8:22 ` [PATCH 7/7] x86/speculation: Remove most ANNOTATE_NOSPEC_ALTERNATIVE Alexandre Chartre
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