From: Linus Torvalds <torvalds@linux-foundation.org>
To: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Kees Cook <keescook@chromium.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-hardening@vger.kernel.org
Subject: Re: mainline build failure of powerpc allmodconfig for prom_init_check
Date: Sun, 17 Jul 2022 07:44:22 -0700 [thread overview]
Message-ID: <CAHk-=whc3Uvhrmrr27xp5=oOhSDjXc5s1ZxC3B7xMYV6oj4WRQ@mail.gmail.com> (raw)
In-Reply-To: <CADVatmO9XzFnX+N0TuOtr0FYyxKr1oe5RAhCEJjmnvjteT5QNw@mail.gmail.com>
On Sun, Jul 17, 2022 at 2:13 AM Sudip Mukherjee
<sudipm.mukherjee@gmail.com> wrote:
>
> I was trying to check it. With gcc-11 the assembly code generated is
> not using memset, but using __memset.
> But with gcc-12, I can see the assembly code is using memset. One
> example from the assembly:
You could try making the 'args' array in 'struct prom_args' be marked
'volatile'.
Ie something like this:
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -115,6 +115,6 @@ struct prom_args {
__be32 service;
__be32 nargs;
__be32 nret;
- __be32 args[10];
+ volatile __be32 args[10];
};
because I think it's just the compilers turning the small loop over
those fields into a "memset()".
Linus
next prev parent reply other threads:[~2022-07-17 14:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-14 8:55 mainline build failure of powerpc allmodconfig for prom_init_check Sudip Mukherjee (Codethink)
2022-07-17 9:12 ` Sudip Mukherjee
2022-07-17 14:44 ` Linus Torvalds [this message]
2022-07-17 19:54 ` Segher Boessenkool
2022-07-18 3:52 ` Michael Ellerman
2022-07-18 14:56 ` Segher Boessenkool
2022-07-17 20:25 ` Sudip Mukherjee
2022-07-17 20:29 ` Linus Torvalds
2022-07-17 20:38 ` Sudip Mukherjee
2022-07-17 20:56 ` Linus Torvalds
2022-07-17 20:56 ` Segher Boessenkool
2022-07-17 21:11 ` Linus Torvalds
2022-07-17 21:45 ` Segher Boessenkool
2022-07-18 1:38 ` Linus Torvalds
2022-07-18 4:41 ` Michael Ellerman
2022-07-18 7:51 ` David Laight
2022-07-18 13:44 ` [PATCH] powerpc/64s: Disable stack variable initialisation for prom_init Michael Ellerman
2022-07-18 15:03 ` Sudip Mukherjee
2022-07-18 18:34 ` Linus Torvalds
2022-07-18 19:06 ` mainline build failure of powerpc allmodconfig for prom_init_check Linus Torvalds
2022-07-18 22:08 ` Segher Boessenkool
2022-07-18 22:55 ` Linus Torvalds
2022-07-19 13:35 ` Michael Ellerman
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