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#!/bin/bash
# SPDX-License-Identifier: GPL-2.0-only

# objdiff - a small script for validating that a commit or series of commits
# didn't change object code.
#
# Copyright 2014, Jason Cooper <jason@lakedaemon.net>
#

# usage example:
#
# $ git checkout COMMIT_A
# $ <your fancy build command here>
# $ ./scripts/objdiff record path/to/*.o
#
# $ git checkout COMMIT_B
# $ <your fancy build command here>
# $ ./scripts/objdiff record path/to/*.o
#
# $ ./scripts/objdiff diff COMMIT_A COMMIT_B
# $

# And to clean up (everything is in .tmp_objdiff/*)
# $ ./scripts/objdiff clean all
#
# Note: 'make mrproper' will also remove .tmp_objdiff

SRCTREE=$(cd $(git rev-parse --show-toplevel 2>/dev/null); pwd)

if [ -z "$SRCTREE" ]; then
	echo >&2 "ERROR: Not a git repository."
	exit 1
fi

TMPD=$SRCTREE/.tmp_objdiff

usage() {
	echo >&2 "Usage: $0 <command> <args>"
	echo >&2 "  record    <list of object files or directories>"
	echo >&2 "  diff      <commitA> <commitB>"
	echo >&2 "  clean     all | <commit>"
	exit 1
}

get_output_dir() {
	dir=${1%/*}

	if [ "$dir" = "$1" ]; then
		dir=.
	fi

	dir=$(cd $dir; pwd)

	echo $TMPD/$CMT${dir#$SRCTREE}
}

do_objdump() {
	dir=$(get_output_dir $1)
	base=${1##*/}
	stripped=$dir/${base%.o}.stripped
	dis=$dir/${base%.o}.dis

	[ ! -d "$dir" ] && mkdir -p $dir

	# remove addresses for a cleaner diff
	# http://dummdida.tumblr.com/post/60924060451/binary-diff-between-libc-from-scientificlinux-and
	$STRIP -g $1 -R __bug_table -R .note -R .comment -o $stripped
	$OBJDUMP -D $stripped | sed -e "s/^[[:space:]]\+[0-9a-f]\+//" -e "s:^$stripped:$1:" > $dis
}

dorecord() {
	[ $# -eq 0 ] && usage

	FILES="$*"

	CMT="`git rev-parse --short HEAD`"

	STRIP="${CROSS_COMPILE}strip"
	OBJDUMP="${CROSS_COMPILE}objdump"

	for d in $FILES; do
		if [ -d "$d" ]; then
			for f in $(find $d -name '*.o')
			do
				do_objdump $f
			done
		else
			do_objdump $d
		fi
	done
}

dodiff() {
	[ $# -ne 2 ] && [ $# -ne 0 ] && usage

	if [ $# -eq 0 ]; then
		SRC="`git rev-parse --short HEAD^`"
		DST="`git rev-parse --short HEAD`"
	else
		SRC="`git rev-parse --short $1`"
		DST="`git rev-parse --short $2`"
	fi

	DIFF="`which colordiff`"

	if [ ${#DIFF} -eq 0 ] || [ ! -x "$DIFF" ]; then
		DIFF="`which diff`"
	fi

	SRCD="$TMPD/$SRC"
	DSTD="$TMPD/$DST"

	if [ ! -d "$SRCD" ]; then
		echo >&2 "ERROR: $SRCD doesn't exist"
		exit 1
	fi

	if [ ! -d "$DSTD" ]; then
		echo >&2 "ERROR: $DSTD doesn't exist"
		exit 1
	fi

	$DIFF -Nurd $SRCD $DSTD
}

doclean() {
	[ $# -eq 0 ] && usage
	[ $# -gt 1 ] && usage

	if [ "x$1" = "xall" ]; then
		rm -rf $TMPD/*
	else
		CMT="`git rev-parse --short $1`"

		if [ -d "$TMPD/$CMT" ]; then
			rm -rf $TMPD/$CMT
		else
			echo >&2 "$CMT not found"
		fi
	fi
}

[ $# -eq 0 ] &&	usage

case "$1" in
	record)
		shift
		dorecord $*
		;;
	diff)
		shift
		dodiff $*
		;;
	clean)
		shift
		doclean $*
		;;
	*)
		echo >&2 "Unrecognized command '$1'"
		exit 1
		;;
esac
'struct bpf_spin_lock' is allowed per map element. It drastically simplifies implementation yet allows bpf program to use any number of bpf_spin_locks. - when bpf_spin_lock is taken the calls (either bpf2bpf or helpers) are not allowed. - bpf program must bpf_spin_unlock() before return. - bpf program can access 'struct bpf_spin_lock' only via bpf_spin_lock()/bpf_spin_unlock() helpers. - load/store into 'struct bpf_spin_lock lock;' field is not allowed. - to use bpf_spin_lock() helper the BTF description of map value must be a struct and have 'struct bpf_spin_lock anyname;' field at the top level. Nested lock inside another struct is not allowed. - syscall map_lookup doesn't copy bpf_spin_lock field to user space. - syscall map_update and program map_update do not update bpf_spin_lock field. - bpf_spin_lock cannot be on the stack or inside networking packet. bpf_spin_lock can only be inside HASH or ARRAY map value. - bpf_spin_lock is available to root only and to all program types. - bpf_spin_lock is not allowed in inner maps of map-in-map. - ld_abs is not allowed inside spin_lock-ed region. - tracing progs and socket filter progs cannot use bpf_spin_lock due to insufficient preemption checks Implementation details: - cgroup-bpf class of programs can nest with xdp/tc programs. Hence bpf_spin_lock is equivalent to spin_lock_irqsave. Other solutions to avoid nested bpf_spin_lock are possible. Like making sure that all networking progs run with softirq disabled. spin_lock_irqsave is the simplest and doesn't add overhead to the programs that don't use it. - arch_spinlock_t is used when its implemented as queued_spin_lock - archs can force their own arch_spinlock_t - on architectures where queued_spin_lock is not available and sizeof(arch_spinlock_t) != sizeof(__u32) trivial lock is used. - presence of bpf_spin_lock inside map value could have been indicated via extra flag during map_create, but specifying it via BTF is cleaner. It provides introspection for map key/value and reduces user mistakes. Next steps: - allow bpf_spin_lock in other map types (like cgroup local storage) - introduce BPF_F_LOCK flag for bpf_map_update() syscall and helper to request kernel to grab bpf_spin_lock before rewriting the value. That will serialize access to map elements. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>