From: Arvind Sankar <nivedita@alum.mit.edu>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-efi@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Arvind Sankar <nivedita@alum.mit.edu>
Subject: Re: [PATCH v2 2/3] x86/boot/compressed: force hidden visibility for all symbol references
Date: Wed, 27 May 2020 10:36:50 -0400 [thread overview]
Message-ID: <20200527143650.GA3103408@rani.riverdale.lan> (raw)
In-Reply-To: <20200523120021.34996-3-ardb@kernel.org>
On Sat, May 23, 2020 at 02:00:20PM +0200, Ard Biesheuvel wrote:
> Eliminate all GOT entries in the decompressor binary, by forcing hidden
> visibility for all symbol references, which informs the compiler that
> such references will be resolved at link time without the need for
> allocating GOT entries.
>
> To ensure that no GOT entries will creep back in, add an assertion to
> the decompressor linker script that will fire if the .got section has
> a non-zero size.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> arch/x86/boot/compressed/Makefile | 1 +
> arch/x86/boot/compressed/hidden.h | 19 +++++++++++++++++++
> arch/x86/boot/compressed/vmlinux.lds.S | 1 +
> 3 files changed, 21 insertions(+)
>
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index 5f7c262bcc99..aa9ed814e5fa 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -40,6 +40,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
> KBUILD_CFLAGS += -Wno-pointer-sign
> KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
> KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
> +KBUILD_CFLAGS += -include hidden.h
>
Ard, from the other thread [1] in case you missed it -- the plain
hidden.h fails to build in-tree. We need something like
KBUILD_CFLAGS += -include $(srctree)/$(src)/hidden.h
instead.
[1] https://lore.kernel.org/lkml/20200526153104.GC2190602@rani.riverdale.lan/
next prev parent reply other threads:[~2020-05-27 14:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-23 12:00 [PATCH v2 0/3] x86/boot: get rid of GOT entries and associated fixup code Ard Biesheuvel
2020-05-23 12:00 ` [PATCH v2 1/3] x86/boot/compressed: move .got.plt entries out of the .got section Ard Biesheuvel
2020-05-24 15:08 ` Ingo Molnar
2020-05-24 15:11 ` Ard Biesheuvel
2020-05-24 15:14 ` Ingo Molnar
2020-05-23 12:00 ` [PATCH v2 2/3] x86/boot/compressed: force hidden visibility for all symbol references Ard Biesheuvel
2020-05-24 15:12 ` Ingo Molnar
2020-05-24 15:15 ` Ard Biesheuvel
2020-05-27 14:36 ` Arvind Sankar [this message]
2020-05-27 18:29 ` Brian Gerst
2020-05-27 18:30 ` Ard Biesheuvel
2020-05-28 7:46 ` Ard Biesheuvel
2020-05-23 12:00 ` [PATCH v2 3/3] x86/boot/compressed: get rid of GOT fixup code Ard Biesheuvel
2020-05-23 15:17 ` Arvind Sankar
2020-05-24 8:42 ` Ard Biesheuvel
2020-05-23 15:16 ` [PATCH v2 0/3] x86/boot: get rid of GOT entries and associated " Arvind Sankar
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