From: Nick Desaulniers <ndesaulniers@google.com>
To: gregkh@linuxfoundation.org
Cc: clang-built-linux@googlegroups.com,
Nick Desaulniers <ndesaulniers@google.com>,
stable@vger.kernel.org,
Nathan Chancellor <natechancellor@gmail.com>,
Alan Modra <amodra@gmail.com>,
Jordan Rupprect <rupprecht@google.com>,
Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org
Subject: [PATCH v3] lkdtm: support llvm-objcopy
Date: Wed, 15 May 2019 11:24:41 -0700 [thread overview]
Message-ID: <20190515182441.30990-1-ndesaulniers@google.com> (raw)
In-Reply-To: <20190515181909.GA11401@archlinux-i9>
With CONFIG_LKDTM=y and make OBJCOPY=llvm-objcopy, llvm-objcopy errors:
llvm-objcopy: error: --set-section-flags=.text conflicts with
--rename-section=.text=.rodata
Rather than support setting flags then renaming sections vs renaming
then setting flags, it's simpler to just change both at the same time
via --rename-section. Adding the load flag is required for GNU objcopy
to mark .rodata Type as PROGBITS after the rename.
This can be verified with:
$ readelf -S drivers/misc/lkdtm/rodata_objcopy.o
...
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
...
[ 1] .rodata PROGBITS 0000000000000000 00000040
0000000000000004 0000000000000000 A 0 0 4
...
Which shows that .text is now renamed .rodata, the alloc flag A is set,
the type is PROGBITS, and the section is not flagged as writeable W.
Cc: stable@vger.kernel.org
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=24554
Link: https://github.com/ClangBuiltLinux/linux/issues/448
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Suggested-by: Alan Modra <amodra@gmail.com>
Suggested-by: Jordan Rupprect <rupprecht@google.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
Changes from v2 -> v3:
* correct Nathan's email address and collect his reviewed by.
Changes from v1 -> v2:
* add load flag, as per Kees and Alan.
* update commit message to mention reason for load flag.
* add Kees' and Alan's suggested by.
* carry Kees' Ack.
* cc stable.
drivers/misc/lkdtm/Makefile | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index 951c984de61a..fb10eafe9bde 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -15,8 +15,7 @@ KCOV_INSTRUMENT_rodata.o := n
OBJCOPYFLAGS :=
OBJCOPYFLAGS_rodata_objcopy.o := \
- --set-section-flags .text=alloc,readonly \
- --rename-section .text=.rodata
+ --rename-section .text=.rodata,alloc,readonly,load
targets += rodata.o rodata_objcopy.o
$(obj)/rodata_objcopy.o: $(obj)/rodata.o FORCE
$(call if_changed,objcopy)
--
2.21.0.1020.gf2820cf01a-goog
prev parent reply other threads:[~2019-05-15 18:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-13 22:21 [PATCH] lkdtm: support llvm-objcopy Nick Desaulniers
2019-05-13 22:26 ` Nick Desaulniers
2019-05-13 23:04 ` Kees Cook
2019-05-13 23:29 ` Nathan Chancellor
2019-05-13 23:38 ` Jordan Rupprecht
2019-05-13 23:47 ` Nathan Chancellor
2019-05-13 23:50 ` Nick Desaulniers
2019-05-14 18:10 ` Kees Cook
2019-05-14 20:24 ` Nick Desaulniers
2019-05-15 16:42 ` Kees Cook
2019-05-15 17:37 ` Nick Desaulniers
2019-05-15 18:12 ` [PATCH v2] " Nick Desaulniers
2019-05-15 18:19 ` Nathan Chancellor
2019-05-15 18:24 ` Nick Desaulniers [this message]
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