linux-kernel - [PATCH v4 0/2] Support kexec/kdump for clang built kernel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190725200625.174838-3-ndesaulniers@google.com>
Date:   Thu, 25 Jul 2019 13:06:19 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de
Cc:     peterz@...radead.org, clang-built-linux@...glegroups.com,
        linux-kernel@...r.kernel.org, yamada.masahiro@...ionext.com,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH v4 0/2] Support kexec/kdump for clang built kernel

1. Reuse the implementation of memcpy and memset instead of relying on
__builtin_memcpy and __builtin_memset as it causes infinite recursion
in Clang (at any opt level) or GCC at -O2.
2. Don't reset KBUILD_CFLAGS, rather filter CONFIG_FUNCTION_TRACER,
CONFIG_STACKPROTECTOR, and CONFIG_STACKPROTECTOR_STRONG flags via
`CFLAGS_REMOVE_<file>.o'

A good test of this series (besides boot testing a kexec kernel):
* There should be no undefined symbols in arch/x86/purgatory/purgatory.ro:
$ nm arch/x86/purgatory/purgatory.ro
  particularly `warn`, `bcmp`, `__stack_chk_fail`, `memcpy` or `memset`.
* `-pg`, `-fstack-protector`, `-fstack-protector-strong` should not be
  added to the command line for the c source files under arch/x86/purgatory/
  when compiling with CONFIG_FUNCTION_TRACER=y, CONFIG_STACKPROTECTOR=y,
  and CONFIG_STACKPROTECTOR_STRONG=y.

V4 of: https://lkml.org/lkml/2019/7/23/864

Nick Desaulniers (2):
  x86/purgatory: do not use __builtin_memcpy and __builtin_memset
  x86/purgatory: use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS

 arch/x86/boot/string.c         |  7 +++++++
 arch/x86/purgatory/Makefile    | 29 ++++++++++++++++++++++++-----
 arch/x86/purgatory/purgatory.c |  6 ++++++
 arch/x86/purgatory/string.c    | 23 -----------------------
 4 files changed, 37 insertions(+), 28 deletions(-)
 delete mode 100644 arch/x86/purgatory/string.c

-- 
2.22.0.709.g102302147b-goog