From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Kees Cook <keescook@chromium.org>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>,
linux-mips@vger.kernel.org, Fangrui Song <maskray@google.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Paul Burton <paulburton@kernel.org>, Borislav Petkov <bp@suse.de>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH v3] MIPS: Truncate link address into 32bit for 32bit kernel
Date: Sat, 11 Apr 2020 00:40:42 +0100 (BST) [thread overview]
Message-ID: <alpine.LFD.2.21.2004110032550.851719@eddie.linux-mips.org> (raw)
In-Reply-To: <202004101334.A641706F0@keescook>
On Fri, 10 Apr 2020, Kees Cook wrote:
> > diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
> > index d6e97df51cfb..0178f7085317 100644
> > --- a/arch/mips/kernel/Makefile
> > +++ b/arch/mips/kernel/Makefile
> > @@ -112,4 +112,13 @@ obj-$(CONFIG_MIPS_CPC) += mips-cpc.o
> > obj-$(CONFIG_CPU_PM) += pm.o
> > obj-$(CONFIG_MIPS_CPS_PM) += pm-cps.o
> >
> > -CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS)
> > +# When linking a 32-bit executable the LLVM linker cannot cope with a
> > +# 32-bit load address that has been sign-extended to 64 bits. Simply
> > +# remove the upper 32 bits then, as it is safe to do so with other
> > +# linkers.
> > +ifdef CONFIG_64BIT
> > + load-ld = $(VMLINUX_LOAD_ADDRESS)
> > +else
> > + load-ld = $(shell $(objtree)/arch/mips/tools/truncate32 $(VMLINUX_LOAD_ADDRESS))
>
> This is major overkill. Just use the Makefile's builtin text
> manipulation:
>
> load-ld = $(subst 0xffffffff,0x,$(VMLINUX_LOAD_ADDRESS))
This looks like the best approach to me, thank you for the hint! And we
only ever want to strip 0xffffffff anyway. (I forgot about this function
of `make', doh!)
Maciej
prev parent reply other threads:[~2020-04-10 23:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-05 8:24 [PATCH] MIPS: malta: Set load address for 32bit kernel correctly Jiaxun Yang
2020-04-05 16:47 ` Maciej W. Rozycki
2020-04-05 16:53 ` Jiaxun Yang
2020-04-05 17:23 ` Maciej W. Rozycki
2020-04-06 10:57 ` YunQiang Su
2020-04-06 11:10 ` Jiaxun Yang
2020-04-06 16:43 ` Fangrui Song
2020-04-07 8:06 ` [PATCH v2] MIPS: Truncate load-y into 32bit for 32bit kernel Jiaxun Yang
2020-04-07 17:21 ` Nick Desaulniers
2020-04-07 18:00 ` Fangrui Song
2020-04-07 18:10 ` Maciej W. Rozycki
2020-04-10 9:06 ` [PATCH v3] MIPS: Truncate link address " Jiaxun Yang
2020-04-10 20:45 ` Kees Cook
2020-04-10 23:40 ` Maciej W. Rozycki [this message]
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