From: Peter Zijlstra <peterz@infradead.org>
To: Alexander Lobakin <alobakin@pm.me>
Cc: Borislav Petkov <bp@alien8.de>,
x86@kernel.org, jpoimboe@redhat.com, andrew.cooper3@citrix.com,
linux-kernel@vger.kernel.org, alexei.starovoitov@gmail.com,
ndesaulniers@google.com
Subject: Re: [PATCH 4/9] x86/alternative: Implement .retpoline_sites support
Date: Tue, 19 Oct 2021 12:02:18 +0200 [thread overview]
Message-ID: <YW6XqiOkWG/avY29@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YW6SqH1R7stXk2GG@hirez.programming.kicks-ass.net>
On Tue, Oct 19, 2021 at 11:40:56AM +0200, Peter Zijlstra wrote:
> On Mon, Oct 18, 2021 at 11:06:35PM +0000, Alexander Lobakin wrote:
> > WARN in patch_retpoline:408: addr pcibios_scan_specific_bus+0x196/0x200, op 0xe8, reg 0xb88ca
> > WARN in patch_retpoline:408: addr xen_pv_teardown_msi_irqs+0x8d/0x120, op 0xe8, reg 0xb88ca
> > WARN in patch_retpoline:408: addr __mptcp_sockopt_sync+0x7e/0x200, op 0xe8, reg 0xb88ca
> > [...]
> > (thousands of them, but op == 0xe8 && reg == 0xb88ca are always the same)
> >
> > I know this reg calculation is about to be replaced, but anyway ;)
>
> Well, I was sorta hoping to keep that with something like:
>
> https://lkml.kernel.org/r/YWgA+vbWCdGLZhq5@hirez.programming.kicks-ass.net
>
> Anyway, let me try and reproduce.
Using: make O=defconfig CC=clang-13 -j80 -s
( is actually defconfig+kvm_guest.config,
and clang-13 from debian/testing )
on https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=objtool/core
It seems to 'just' work:
spectre_v2=retpoline,amd:
gets me two very sad and lonely replacements:
[] SMP alternatives: retpoline at: 0xffffffff82e764b4 (ffffffff82e764b4) len: 5 to: __x86_indirect_thunk_rbx+0x0/0x20
[] SMP alternatives: ffffffff82e764b4: orig: e8 07 d3 18 ff
[] SMP alternatives: ffffffff82e764b4: repl: 0f ae e8 ff d3
[] SMP alternatives: retpoline at: 0xffffffff82e76f39 (ffffffff82e76f39) len: 5 to: __x86_indirect_thunk_rdi+0x0/0x20
[] SMP alternatives: ffffffff82e76f39: orig: e8 02 c9 18 ff
[] SMP alternatives: ffffffff82e76f39: repl: 0f ae e8 ff d7
The rest is R11 and therefore doesn't actaully fit.
For spectre_v2=off everything gets replaced, and that also seems happy.
[] SMP alternatives: retpoline at: pm_check_save_msr+0x24/0x30 (ffffffff81d2ef24) len: 5 to: __x86_indirect_thunk_r11+0x0/0x20
[] SMP alternatives: ffffffff82603eb0: [3:5) optimized NOPs: 41 ff d3 66 90
[] SMP alternatives: ffffffff81d2ef24: orig: e8 97 49 2d 00
[] SMP alternatives: ffffffff81d2ef24: repl: 41 ff d3 66 90
next prev parent reply other threads:[~2021-10-19 10:02 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-13 12:22 [PATCH 0/9] x86: Rewrite the retpoline rewrite logic Peter Zijlstra
2021-10-13 12:22 ` [PATCH 1/9] objtool,x86: Replace alternatives with .retpoline_sites Peter Zijlstra
2021-10-13 13:29 ` Borislav Petkov
2021-10-13 20:11 ` Josh Poimboeuf
2021-10-14 15:43 ` Peter Zijlstra
2021-10-13 12:22 ` [PATCH 2/9] x86/retpoline: Remove unused replacement symbols Peter Zijlstra
2021-10-13 12:22 ` [PATCH 3/9] x86/asm: Fix register order Peter Zijlstra
2021-10-13 20:15 ` Josh Poimboeuf
2021-10-13 12:22 ` [PATCH 4/9] x86/alternative: Implement .retpoline_sites support Peter Zijlstra
2021-10-13 14:38 ` Andrew Cooper
2021-10-13 15:12 ` Peter Zijlstra
2021-10-13 17:11 ` Andrew Cooper
2021-10-14 10:05 ` Peter Zijlstra
2021-10-13 20:39 ` Josh Poimboeuf
2021-10-13 21:20 ` Peter Zijlstra
2021-10-13 21:49 ` Josh Poimboeuf
2021-10-13 21:52 ` Josh Poimboeuf
2021-10-13 22:10 ` Peter Zijlstra
2021-10-13 22:47 ` Andrew Cooper
2021-10-13 20:52 ` Josh Poimboeuf
2021-10-13 21:00 ` Peter Zijlstra
2021-10-19 11:37 ` Peter Zijlstra
2021-10-19 16:46 ` Josh Poimboeuf
2021-10-19 16:49 ` Josh Poimboeuf
2021-10-20 8:25 ` Peter Zijlstra
2021-10-20 8:30 ` Peter Zijlstra
2021-10-13 21:11 ` Josh Poimboeuf
2021-10-13 21:43 ` Peter Zijlstra
2021-10-13 22:05 ` Josh Poimboeuf
2021-10-13 22:14 ` Peter Zijlstra
2021-10-15 14:24 ` Borislav Petkov
2021-10-15 16:56 ` Peter Zijlstra
2021-10-18 23:06 ` Alexander Lobakin
2021-10-19 0:25 ` Alexander Lobakin
2021-10-19 9:47 ` Alexander Lobakin
2021-10-19 10:16 ` Peter Zijlstra
2021-10-19 15:37 ` Sami Tolvanen
2021-10-19 18:00 ` Alexander Lobakin
2021-10-19 9:40 ` Peter Zijlstra
2021-10-19 10:02 ` Peter Zijlstra [this message]
2021-10-13 12:22 ` [PATCH 5/9] x86/alternative: Handle Jcc __x86_indirect_thunk_\reg Peter Zijlstra
2021-10-13 20:11 ` Nick Desaulniers
2021-10-13 21:08 ` Peter Zijlstra
2021-10-13 12:22 ` [PATCH 6/9] x86/alternative: Try inline spectre_v2=retpoline,amd Peter Zijlstra
2021-10-13 12:22 ` [PATCH 7/9] x86/alternative: Add debug prints to apply_retpolines() Peter Zijlstra
2021-10-13 12:22 ` [PATCH 8/9] x86,bugs: Unconditionally allow spectre_v2=retpoline,amd Peter Zijlstra
2021-10-13 12:22 ` [PATCH 9/9] bpf,x86: Respect X86_FEATURE_RETPOLINE* Peter Zijlstra
2021-10-13 21:06 ` Josh Poimboeuf
2021-10-13 21:54 ` Peter Zijlstra
2021-10-14 9:46 ` Peter Zijlstra
2021-10-14 9:48 ` Peter Zijlstra
2021-10-20 7:34 ` Peter Zijlstra
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