From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
David.Kaplan@amd.com, Andrew.Cooper3@citrix.com,
jpoimboe@kernel.org, gregkh@linuxfoundation.org,
nik.borisov@suse.com
Subject: Re: [PATCH v2 10/11] x86/alternatives: Simplify ALTERNATIVE_n()
Date: Sat, 9 Sep 2023 11:42:27 +0200 [thread overview]
Message-ID: <20230909094227.GA16786@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20230909092554.GC2771@noisy.programming.kicks-ass.net>
On Sat, Sep 09, 2023 at 11:25:54AM +0200, Peter Zijlstra wrote:
> This becomes more of a problem with your example above where the
> respective lengths are 0, 5, 16. In that case, when you patch 5, you'll
> leave 11 single nops in there.
>
> So what that code you deleted does is look for all alternatives that
> start at the same point and computes the max replacementlen, because
> that is the amount of bytes in the source text that has been reserved
> for this alternative.
>
> That is not optional.
Note that the original alternatives did this with the alt_max_*() macro
at build time.
next prev parent reply other threads:[~2023-09-09 9:42 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-14 11:44 [PATCH v2 00/11] Fix up SRSO stuff Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 01/11] x86/cpu: Fixup __x86_return_thunk Peter Zijlstra
2023-08-16 7:55 ` [tip: x86/urgent] x86/cpu: Fix __x86_return_thunk symbol type tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 02/11] x86/cpu: Fix up srso_safe_ret() and __x86_return_thunk() Peter Zijlstra
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 03/11] objtool/x86: Fix SRSO mess Peter Zijlstra
2023-08-14 12:54 ` Andrew.Cooper3
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-16 11:59 ` Peter Zijlstra
2023-08-16 20:31 ` Josh Poimboeuf
2023-08-16 22:08 ` [PATCH] objtool/x86: Fixup frame-pointer vs rethunk Peter Zijlstra
2023-08-16 22:22 ` Josh Poimboeuf
2023-08-17 8:39 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 04/11] x86/alternative: Make custom return thunk unconditional Peter Zijlstra
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 05/11] x86/cpu: Clean up SRSO return thunk mess Peter Zijlstra
2023-08-14 13:02 ` Borislav Petkov
2023-08-14 17:48 ` Borislav Petkov
2023-08-15 21:29 ` Nathan Chancellor
2023-08-15 22:43 ` Peter Zijlstra
2023-08-16 7:38 ` Borislav Petkov
2023-08-16 14:52 ` Nathan Chancellor
2023-08-16 15:08 ` Borislav Petkov
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-16 18:58 ` Nathan Chancellor
2023-08-16 19:24 ` Borislav Petkov
2023-08-16 19:30 ` Nathan Chancellor
2023-08-16 19:42 ` Borislav Petkov
2023-08-16 19:57 ` Borislav Petkov
2023-08-16 21:20 ` tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 06/11] x86/cpu: Rename original retbleed methods Peter Zijlstra
2023-08-14 19:41 ` Josh Poimboeuf
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-16 21:20 ` tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 07/11] x86/cpu: Rename srso_(.*)_alias to srso_alias_\1 Peter Zijlstra
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-16 21:20 ` tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 08/11] x86/cpu: Cleanup the untrain mess Peter Zijlstra
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-16 21:20 ` tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 09/11] x86/cpu/kvm: Provide UNTRAIN_RET_VM Peter Zijlstra
2023-08-16 7:55 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2023-08-16 21:20 ` tip-bot2 for Peter Zijlstra
2023-08-14 11:44 ` [PATCH v2 10/11] x86/alternatives: Simplify ALTERNATIVE_n() Peter Zijlstra
2023-08-15 20:49 ` Nikolay Borisov
2023-08-15 22:44 ` Peter Zijlstra
2023-09-07 8:31 ` Borislav Petkov
2023-09-07 11:09 ` Peter Zijlstra
2023-09-07 11:11 ` Peter Zijlstra
2023-09-07 11:16 ` Peter Zijlstra
2023-09-07 15:06 ` Borislav Petkov
2023-09-07 15:30 ` Borislav Petkov
2023-09-09 7:50 ` Borislav Petkov
2023-09-09 9:25 ` Peter Zijlstra
2023-09-09 9:42 ` Peter Zijlstra [this message]
2023-09-10 14:42 ` Borislav Petkov
2023-09-12 9:27 ` Peter Zijlstra
2023-09-12 9:44 ` Peter Zijlstra
2023-09-13 4:37 ` Borislav Petkov
2023-09-13 8:46 ` Peter Zijlstra
2023-09-13 14:38 ` Borislav Petkov
2023-09-13 16:14 ` Peter Zijlstra
2023-09-15 7:46 ` Peter Zijlstra
2023-09-15 7:51 ` Peter Zijlstra
2023-09-15 12:05 ` Borislav Petkov
2023-09-13 4:24 ` Borislav Petkov
2023-08-14 11:44 ` [PATCH v2 11/11] x86/cpu: Use fancy alternatives to get rid of entry_untrain_ret() Peter Zijlstra
2023-08-14 16:44 ` [PATCH v2 00/11] Fix up SRSO stuff Borislav Petkov
2023-08-14 19:51 ` Josh Poimboeuf
2023-08-14 19:57 ` Borislav Petkov
2023-08-14 20:01 ` Josh Poimboeuf
2023-08-14 20:09 ` Borislav Petkov
2023-08-15 14:26 ` [PATCH] x86/srso: Explain the untraining sequences a bit more Borislav Petkov
2023-08-15 15:41 ` Nikolay Borisov
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