From: Linus Torvalds <torvalds@linux-foundation.org>
To: Borislav Petkov <bp@suse.de>
Cc: Arnd Bergmann <arnd@arndb.de>,
Arvind Sankar <nivedita@alum.mit.edu>,
Kalle Valo <kvalo@codeaurora.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Kees Cook <keescook@chromium.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: gcc-10: kernel stack is corrupted and fails to boot
Date: Wed, 13 May 2020 17:11:21 -0700 [thread overview]
Message-ID: <CAHk-=wjZXFe08MiNRevJFGDvX0O6kcQTiK8GFBS7hwUAzB+LQw@mail.gmail.com> (raw)
In-Reply-To: <20200513233616.GD6733@zn.tnic>
On Wed, May 13, 2020 at 4:36 PM Borislav Petkov <bp@suse.de> wrote:
>
>
> Looking at them, they do have an mb() too so how about this then
> instead?
>
> #define prevent_tail_call_optimization() mb()
Yeah, I think a full mb() is likely safe, because that's pretty much
always going to be a real instruction with real semantics, and no
amount of link-time optimizations can move it around a call
instruction.
I could imagine some completely UP in-order CPU that doesn't need to
serialize with anything at all, and even "mb()" might be empty. I
think you can compile old ARM kernels for that. But realistically I
think we can ignore them at least for now - I'm not sure the link-time
optimization will even do things like that tailcall conversion, and
I'm not convinced that old pre-ARMv7 systems will be relevant by the
time (if) it ever does.
Linus
next prev parent reply other threads:[~2020-05-14 0:11 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-09 12:06 [PATCH net-next 1/2] ath10k: fix gcc-10 zero-length-bounds warnings Arnd Bergmann
2020-05-09 12:06 ` [PATCH net-next 2/2] ath10k: fix ath10k_pci struct layout Arnd Bergmann
2020-05-11 12:05 ` Kalle Valo
2020-05-11 12:17 ` Kalle Valo
2020-05-11 12:39 ` Arnd Bergmann
2020-05-13 6:50 ` gcc-10: kernel stack is corrupted and fails to boot Kalle Valo
2020-05-13 8:49 ` Arnd Bergmann
2020-05-13 12:45 ` Kalle Valo
2020-05-13 13:45 ` Arnd Bergmann
2020-05-13 15:31 ` Kalle Valo
2020-05-13 16:00 ` Arnd Bergmann
2020-05-13 16:07 ` David Laight
2020-05-14 9:13 ` Harald Arnesen
2020-05-13 15:48 ` Arvind Sankar
2020-05-13 21:28 ` Arnd Bergmann
2020-05-13 21:41 ` Borislav Petkov
2020-05-13 21:49 ` Arnd Bergmann
2020-05-13 22:20 ` Borislav Petkov
2020-05-13 22:51 ` Arvind Sankar
2020-05-13 23:13 ` Linus Torvalds
2020-05-13 23:36 ` Borislav Petkov
2020-05-14 0:11 ` Linus Torvalds [this message]
2020-05-14 0:51 ` Nick Desaulniers
2020-05-14 2:20 ` Linus Torvalds
2020-05-14 3:50 ` Andy Lutomirski
[not found] ` <CAHk-=wgiGxRgJGS-zyer1C_x2MQUVo6iZn0=aJyuFTqJWk-mpA@mail.gmail.com>
2020-05-14 5:22 ` Arvind Sankar
2020-05-14 8:40 ` Arnd Bergmann
2020-05-14 13:27 ` [PATCH] x86: Fix early boot crash on gcc-10, third try Borislav Petkov
2020-05-14 14:45 ` Kalle Valo
2020-05-14 15:50 ` gcc-10: kernel stack is corrupted and fails to boot Arvind Sankar
2020-05-14 8:11 ` David Laight
2020-05-13 23:07 ` Linus Torvalds
2020-05-09 15:48 ` [PATCH net-next 1/2] ath10k: fix gcc-10 zero-length-bounds warnings Gustavo A. R. Silva
2020-05-11 12:02 ` Kalle Valo
2020-05-11 12:46 ` Arnd Bergmann
2020-05-11 13:09 ` Kalle Valo
2020-05-11 13:47 ` Arnd Bergmann
2020-05-12 7:33 ` Kalle Valo
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