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Subject[tip: x86/boot] x86/boot: Discard .eh_frame sections
The following commit has been merged into the x86/boot branch of tip:

Commit-ID: 163159aad74d3763b350861b879b41e8f64121fc
Gitweb: https://git.kernel.org/tip/163159aad74d3763b350861b879b41e8f64121fc
Author: Ilie Halip <ilie.halip@gmail.com>
AuthorDate: Tue, 26 Nov 2019 16:45:44 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Fri, 13 Dec 2019 11:45:59 +01:00

x86/boot: Discard .eh_frame sections

When using GCC as compiler and LLVM's lld as linker, linking setup.elf
fails:

LD arch/x86/boot/setup.elf
ld.lld: error: init sections too big!

This happens because GCC generates .eh_frame sections for most of the
files in that directory, then ld.lld places the merged section before
__end_init, triggering an assert in the linker script.

Fix this by discarding the .eh_frame sections, as suggested by Boris.
The kernel proper linker script discards them too.

[ bp: Going back in history, 64-bit kernel proper has been discarding
.eh_frame since 2002:

commit acca80acefe20420e69561cf55be64f16c34ea97
Author: Andi Kleen <ak@muc.de>
Date: Tue Oct 29 23:54:35 2002 -0800

[PATCH] x86-64 updates for 2.5.44

...

- Remove the .eh_frame on linking. This saves several hundred KB in the
bzImage
]

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com
Cc: Andy Lutomirski <luto@kernel.org>
Cc: clang-built-linux@googlegroups.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lore.kernel.org/lkml/20191118175223.GM6363@zn.tnic/
Link: https://github.com/ClangBuiltLinux/linux/issues/760
Link: https://lkml.kernel.org/r/20191126144545.19354-1-ilie.halip@gmail.com
---
arch/x86/boot/setup.ld | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/setup.ld b/arch/x86/boot/setup.ld
index 0149e41..3da1c37 100644
--- a/arch/x86/boot/setup.ld
+++ b/arch/x86/boot/setup.ld
@@ -51,7 +51,10 @@ SECTIONS
. = ALIGN(16);
_end = .;

- /DISCARD/ : { *(.note*) }
+ /DISCARD/ : {
+ *(.eh_frame)
+ *(.note*)
+ }

/*
* The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
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