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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
gfp-translate 
#!/bin/bash
# Translate the bits making up a GFP mask
# (c) 2009, Mel Gorman <mel@csn.ul.ie>
# Licensed under the terms of the GNU GPL License version 2
SOURCE=
GFPMASK=none

# Helper function to report failures and exit
die() {
	echo ERROR: $@
	if [ "$TMPFILE" != "" ]; then
		rm -f $TMPFILE
	fi
	exit -1
}

usage() {
	echo "usage: gfp-translate [-h] [ --source DIRECTORY ] gfpmask"
	exit 0
}

# Parse command-line arguments
while [ $# -gt 0 ]; do
	case $1 in
		--source)
			SOURCE=$2
			shift 2
			;;
		-h)
			usage
			;;
		--help)
			usage
			;;
		*)
			GFPMASK=$1
			shift
			;;
	esac
done

# Guess the kernel source directory if it's not set. Preference is in order of
# o current directory
# o /usr/src/linux
if [ "$SOURCE" = "" ]; then
	if [ -r "/usr/src/linux/Makefile" ]; then
		SOURCE=/usr/src/linux
	fi
	if [ -r "`pwd`/Makefile" ]; then
		SOURCE=`pwd`
	fi
fi

# Confirm that a source directory exists
if [ ! -r "$SOURCE/Makefile" ]; then
	die "Could not locate kernel source directory or it is invalid"
fi

# Confirm that a GFP mask has been specified
if [ "$GFPMASK" = "none" ]; then
	usage
fi

# Extract GFP flags from the kernel source
TMPFILE=`mktemp -t gfptranslate-XXXXXX` || exit 1
grep -q ___GFP $SOURCE/include/linux/gfp.h
if [ $? -eq 0 ]; then
	grep "^#define ___GFP" $SOURCE/include/linux/gfp.h | sed -e 's/u$//' | grep -v GFP_BITS > $TMPFILE
else
	grep "^#define __GFP" $SOURCE/include/linux/gfp.h | sed -e 's/(__force gfp_t)//' | sed -e 's/u)/)/' | grep -v GFP_BITS | sed -e 's/)\//) \//' > $TMPFILE
fi

# Parse the flags
IFS="
"
echo Source: $SOURCE
echo Parsing: $GFPMASK
for LINE in `cat $TMPFILE`; do
	MASK=`echo $LINE | awk '{print $3}'`
	if [ $(($GFPMASK&$MASK)) -ne 0 ]; then
		echo $LINE
	fi
done

rm -f $TMPFILE
exit 0
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