Skip to main content

Browse the archive

Revision be0f272bfc83797f70d44faca86954df62e2bbc0 authored by Ard Biesheuvel on 20 November 2017, 17:41:30 UTC, committed by Will Deacon on 01 December 2017, 13:04:59 UTC 
arm64: ftrace: emit ftrace-mod.o contents through code
 
When building the arm64 kernel with both CONFIG_ARM64_MODULE_PLTS and
CONFIG_DYNAMIC_FTRACE enabled, the ftrace-mod.o object file is built
with the kernel and contains a trampoline that is linked into each
module, so that modules can be loaded far away from the kernel and
still reach the ftrace entry point in the core kernel with an ordinary
relative branch, as is emitted by the compiler instrumentation code
dynamic ftrace relies on.

In order to be able to build out of tree modules, this object file
needs to be included into the linux-headers or linux-devel packages,
which is undesirable, as it makes arm64 a special case (although a
precedent does exist for 32-bit PPC).

Given that the trampoline essentially consists of a PLT entry, let's
not bother with a source or object file for it, and simply patch it
in whenever the trampoline is being populated, using the existing
PLT support routines.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
1 parent 7e8b9c1
Raw File
mkcompile_h 
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0

TARGET=$1
ARCH=$2
SMP=$3
PREEMPT=$4
CC=$5

vecho() { [ "${quiet}" = "silent_" ] || echo "$@" ; }

# If compile.h exists already and we don't own autoconf.h
# (i.e. we're not the same user who did make *config), don't
# modify compile.h
# So "sudo make install" won't change the "compiled by <user>"
# do "compiled by root"

if [ -r $TARGET -a ! -O include/generated/autoconf.h ]; then
  vecho "  SKIPPED $TARGET"
  exit 0
fi

# Do not expand names
set -f

# Fix the language to get consistent output
LC_ALL=C
export LC_ALL

if [ -z "$KBUILD_BUILD_VERSION" ]; then
	VERSION=$(cat .version 2>/dev/null || echo 1)
else
	VERSION=$KBUILD_BUILD_VERSION
fi

if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then
	TIMESTAMP=`date`
else
	TIMESTAMP=$KBUILD_BUILD_TIMESTAMP
fi
if test -z "$KBUILD_BUILD_USER"; then
	LINUX_COMPILE_BY=$(whoami | sed 's/\\/\\\\/')
else
	LINUX_COMPILE_BY=$KBUILD_BUILD_USER
fi
if test -z "$KBUILD_BUILD_HOST"; then
	LINUX_COMPILE_HOST=`hostname`
else
	LINUX_COMPILE_HOST=$KBUILD_BUILD_HOST
fi

UTS_VERSION="#$VERSION"
CONFIG_FLAGS=""
if [ -n "$SMP" ] ; then CONFIG_FLAGS="SMP"; fi
if [ -n "$PREEMPT" ] ; then CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT"; fi
UTS_VERSION="$UTS_VERSION $CONFIG_FLAGS $TIMESTAMP"

# Truncate to maximum length

UTS_LEN=64
UTS_TRUNCATE="cut -b -$UTS_LEN"

# Generate a temporary compile.h

( echo /\* This file is auto generated, version $VERSION \*/
  if [ -n "$CONFIG_FLAGS" ] ; then echo "/* $CONFIG_FLAGS */"; fi

  echo \#define UTS_MACHINE \"$ARCH\"

  echo \#define UTS_VERSION \"`echo $UTS_VERSION | $UTS_TRUNCATE`\"

  echo \#define LINUX_COMPILE_BY \"`echo $LINUX_COMPILE_BY | $UTS_TRUNCATE`\"
  echo \#define LINUX_COMPILE_HOST \"`echo $LINUX_COMPILE_HOST | $UTS_TRUNCATE`\"

  echo \#define LINUX_COMPILER \"`$CC -v 2>&1 | grep ' version ' | sed 's/[[:space:]]*$//'`\"
) > .tmpcompile

# Only replace the real compile.h if the new one is different,
# in order to preserve the timestamp and avoid unnecessary
# recompilations.
# We don't consider the file changed if only the date/time changed.
# A kernel config change will increase the generation number, thus
# causing compile.h to be updated (including date/time) due to the
# changed comment in the
# first line.

if [ -r $TARGET ] && \
      grep -v 'UTS_VERSION' $TARGET > .tmpver.1 && \
      grep -v 'UTS_VERSION' .tmpcompile > .tmpver.2 && \
      cmp -s .tmpver.1 .tmpver.2; then
   rm -f .tmpcompile
else
   vecho "  UPD     $TARGET"
   mv -f .tmpcompile $TARGET
fi
rm -f .tmpver.1 .tmpver.2
back to top