linux-kernel - [PATCH v2 0/2] Stop generating .eh

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Date:   Mon, 24 Feb 2020 18:21:27 -0500
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Borislav Petkov <bp@...en8.de>,
        Nathan Chancellor <natechancellor@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Michael Matz <matz@...e.de>, Fangrui Song <maskray@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v2 0/2] Stop generating .eh_frame sections

In three places in the x86 kernel we are currently generating .eh_frame
sections only to discard them later via linker script. This is in the
boot code (setup.elf), the realmode trampoline (realmode.elf) and the
compressed kernel.

Implement Fangrui and Nick's suggestion [1] to fix KBUILD_CFLAGS by
adding -fno-asynchronous-unwind-tables to avoid generating .eh_frame
sections in the first place, rather than discarding it in the linker
script.

Changes from v1:

Rebase on top of tip:x86/boot and include reverting the addition of
	.eh_frame discard in compressed/vmlinux.lds.S.
Fix up a comment that refers to .eh_frame, pointed out by Nick.

Arvind Sankar (2):
  arch/x86: Use -fno-asynchronous-unwind-tables to suppress .eh_frame sections
  arch/x86: Drop unneeded linker script discard of .eh_frame

 arch/x86/boot/Makefile                 | 1 +
 arch/x86/boot/compressed/Makefile      | 1 +
 arch/x86/boot/compressed/vmlinux.lds.S | 5 -----
 arch/x86/boot/setup.ld                 | 1 -
 arch/x86/include/asm/dwarf2.h          | 4 ++--
 arch/x86/kernel/vmlinux.lds.S          | 7 ++-----
 arch/x86/realmode/rm/Makefile          | 1 +
 arch/x86/realmode/rm/realmode.lds.S    | 1 -
 drivers/firmware/efi/libstub/Makefile  | 3 ++-
 9 files changed, 9 insertions(+), 15 deletions(-)

-- 
2.24.1