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Message-Id: <20180523195421.180248-17-thgarnie@google.com>
Date: Wed, 23 May 2018 12:54:10 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Herbert Xu <herbert@...dor.apana.org.au>,
"David S . Miller" <davem@...emloft.net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H . Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Thomas Garnier <thgarnie@...gle.com>,
Philippe Ombredanne <pombredanne@...b.com>,
Kate Stewart <kstewart@...uxfoundation.org>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Yonghong Song <yhs@...com>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Kees Cook <keescook@...omium.org>,
Tom Lendacky <thomas.lendacky@....com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Andy Lutomirski <luto@...nel.org>,
Dominik Brodowski <linux@...inikbrodowski.net>,
Borislav Petkov <bp@...en8.de>,
Borislav Petkov <bp@...e.de>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
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Cc: x86@...nel.org,
linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
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Subject: [PATCH v3 16/27] compiler: Option to add PROVIDE_HIDDEN replacement for weak symbols
Provide an option to have a PROVIDE_HIDDEN (linker script) entry for
each weak symbol. This option solve an error in x86_64 where the linker
optimizes pie generate code to be non-pie because --emit-relocs was used
instead of -pie (to reduce dynamic relocations).
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
init/Kconfig | 7 +++++++
scripts/link-vmlinux.sh | 14 ++++++++++++++
2 files changed, 21 insertions(+)
diff --git a/init/Kconfig b/init/Kconfig
index 0fc3a58d9f2f..2866cca86b4a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1954,6 +1954,13 @@ config ASN1
inform it as to what tags are to be expected in a stream and what
functions to call on what tags.
+config WEAK_PROVIDE_HIDDEN
+ bool
+ help
+ Generate linker script PROVIDE_HIDDEN entries for all weak symbols. It
+ allows to prevent non-pie code being replaced by the linker if the
+ emit-relocs option is used instead of pie (useful for x86_64 pie).
+
source "kernel/Kconfig.locks"
config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 4bf811c09f59..f5d31119b9d7 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -142,6 +142,17 @@ kallsyms()
${CC} ${aflags} -c -o ${2} ${afile}
}
+gen_weak_provide_hidden()
+{
+ if [ -n "${CONFIG_WEAK_PROVIDE_HIDDEN}" ]; then
+ local pattern="s/^\s\+ w \(\w\+\)$/PROVIDE_HIDDEN(\1 = .);/gp"
+ echo -e "SECTIONS {\n. = _end;" > .tmp_vmlinux_hiddenld
+ ${NM} ${1} | sed -n "${pattern}" >> .tmp_vmlinux_hiddenld
+ echo "}" >> .tmp_vmlinux_hiddenld
+ LDFLAGS_vmlinux="${LDFLAGS_vmlinux} -T .tmp_vmlinux_hiddenld"
+ fi
+}
+
# Create map file with all symbols from ${1}
# See mksymap for additional details
mksysmap()
@@ -226,6 +237,9 @@ modpost_link vmlinux.o
# modpost vmlinux.o to check for section mismatches
${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
+# Generate weak linker script
+gen_weak_provide_hidden vmlinux.o
+
kallsymso=""
kallsyms_vmlinux=""
if [ -n "${CONFIG_KALLSYMS}" ]; then
--
2.17.0.441.gb46fe60e1d-goog
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