#!/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
 value='linux-3.13.y'>linux-3.13.y</option>
<option value='linux-3.14.y'>linux-3.14.y</option>
<option value='linux-3.15.y'>linux-3.15.y</option>
<option value='linux-3.16.y'>linux-3.16.y</option>
<option value='linux-3.17.y'>linux-3.17.y</option>
<option value='linux-3.18.y'>linux-3.18.y</option>
<option value='linux-3.19.y'>linux-3.19.y</option>
<option value='linux-3.2.y'>linux-3.2.y</option>
<option value='linux-3.3.y'>linux-3.3.y</option>
<option value='linux-3.4.y'>linux-3.4.y</option>
<option value='linux-3.5.y'>linux-3.5.y</option>
<option value='linux-3.6.y'>linux-3.6.y</option>
<option value='linux-3.7.y'>linux-3.7.y</option>
<option value='linux-3.8.y'>linux-3.8.y</option>
<option value='linux-3.9.y'>linux-3.9.y</option>
<option value='linux-4.0.y'>linux-4.0.y</option>
<option value='linux-4.1.y'>linux-4.1.y</option>
<option value='linux-4.10.y'>linux-4.10.y</option>
<option value='linux-4.11.y'>linux-4.11.y</option>
<option value='linux-4.12.y'>linux-4.12.y</option>
<option value='linux-4.13.y'>linux-4.13.y</option>
<option value='linux-4.14.y'>linux-4.14.y</option>
<option value='linux-4.15.y'>linux-4.15.y</option>
<option value='linux-4.16.y'>linux-4.16.y</option>
<option value='linux-4.17.y'>linux-4.17.y</option>
<option value='linux-4.18.y'>linux-4.18.y</option>
<option value='linux-4.19.y'>linux-4.19.y</option>
<option value='linux-4.2.y'>linux-4.2.y</option>
<option value='linux-4.20.y'>linux-4.20.y</option>
<option value='linux-4.3.y'>linux-4.3.y</option>
<option value='linux-4.4.y'>linux-4.4.y</option>
<option value='linux-4.5.y'>linux-4.5.y</option>
<option value='linux-4.6.y'>linux-4.6.y</option>
<option value='linux-4.7.y'>linux-4.7.y</option>
<option value='linux-4.8.y'>linux-4.8.y</option>
<option value='linux-4.9.y'>linux-4.9.y</option>
<option value='linux-5.0.y'>linux-5.0.y</option>
<option value='linux-5.1.y'>linux-5.1.y</option>
<option value='linux-5.10.y'>linux-5.10.y</option>
<option value='linux-5.11.y'>linux-5.11.y</option>
<option value='linux-5.12.y'>linux-5.12.y</option>
<option value='linux-5.13.y'>linux-5.13.y</option>
<option value='linux-5.14.y'>linux-5.14.y</option>
<option value='linux-5.15.y'>linux-5.15.y</option>
<option value='linux-5.16.y'>linux-5.16.y</option>
<option value='linux-5.17.y'>linux-5.17.y</option>
<option value='linux-5.18.y'>linux-5.18.y</option>
<option value='linux-5.19.y'>linux-5.19.y</option>
<option value='linux-5.2.y'>linux-5.2.y</option>
<option value='linux-5.3.y'>linux-5.3.y</option>
<option value='linux-5.4.y'>linux-5.4.y</option>
<option value='linux-5.5.y'>linux-5.5.y</option>
<option value='linux-5.6.y'>linux-5.6.y</option>
<option value='linux-5.7.y'>linux-5.7.y</option>
<option value='linux-5.8.y'>linux-5.8.y</option>
<option value='linux-5.9.y'>linux-5.9.y</option>
<option value='linux-6.0.y'>linux-6.0.y</option>
<option value='linux-6.1.y'>linux-6.1.y</option>
<option value='linux-6.10.y'>linux-6.10.y</option>
<option value='linux-6.11.y'>linux-6.11.y</option>
<option value='linux-6.12.y'>linux-6.12.y</option>
<option value='linux-6.13.y'>linux-6.13.y</option>
<option value='linux-6.14.y'>linux-6.14.y</option>
<option value='linux-6.15.y'>linux-6.15.y</option>
<option value='linux-6.16.y'>linux-6.16.y</option>
<option value='linux-6.17.y'>linux-6.17.y</option>
<option value='linux-6.18.y'>linux-6.18.y</option>
<option value='linux-6.19.y'>linux-6.19.y</option>
<option value='linux-6.2.y'>linux-6.2.y</option>
<option value='linux-6.3.y'>linux-6.3.y</option>
<option value='linux-6.4.y'>linux-6.4.y</option>
<option value='linux-6.5.y'>linux-6.5.y</option>
<option value='linux-6.6.y'>linux-6.6.y</option>
<option value='linux-6.7.y'>linux-6.7.y</option>
<option value='linux-6.8.y'>linux-6.8.y</option>
<option value='linux-6.9.y'>linux-6.9.y</option>
<option value='linux-rolling-lts'>linux-rolling-lts</option>
<option value='linux-rolling-stable'>linux-rolling-stable</option>
<option value='master'>master</option>
</select> <input type='submit' value='switch'/></form></td></tr>
<tr><td class='sub'>Hosts the 0x221E linux distro kernel.</td><td class='sub right'>Ubuntu</td></tr></table>
<table class='tabs'><tr><td>
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<div class='path'>path: <a href='/distro/kernel/log/?id=b28913e897edfeedc4e33b03b28068b27d002e6c&amp;showmsg=1'>root</a>/<a href='/distro/kernel/log/rust?id=b28913e897edfeedc4e33b03b28068b27d002e6c&amp;showmsg=1'>rust</a>/<a href='/distro/kernel/log/rust/kernel?id=b28913e897edfeedc4e33b03b28068b27d002e6c&amp;showmsg=1'>kernel</a>/<a href='/distro/kernel/log/rust/kernel/ptr?id=b28913e897edfeedc4e33b03b28068b27d002e6c&amp;showmsg=1'>ptr</a>/<a href='/distro/kernel/log/rust/kernel/ptr/projection.rs?id=b28913e897edfeedc4e33b03b28068b27d002e6c&amp;showmsg=1'>projection.rs</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/distro/kernel/log/rust/kernel/ptr/projection.rs?id=b28913e897edfeedc4e33b03b28068b27d002e6c'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2026-03-07 23:06:17 +0100'>2026-03-07</span></td><td class='logsubject'><a href='/distro/kernel/commit/rust/kernel/ptr/projection.rs?id=f41941aab3acd33f13d65a2ae496329bc8ae4de0'>rust: ptr: add projection infrastructure</a></td><td>Gary Guo</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
Add a generic infrastructure for performing field and index projections on
raw pointers. This will form the basis of performing I/O projections.

Pointers manipulations are intentionally using the safe wrapping variants
instead of the unsafe variants, as the latter requires pointers to be
inside an allocation which is not necessarily true for I/O pointers.

This projection macro protects against rogue `Deref` implementation, which
can causes the projected pointer to be outside the bounds of starting
pointer. This is extremely unlikely and Rust has a lint to catch this, but
is unsoundness regardless. The protection works by inducing type inference
ambiguity when `Deref` is implemented.

This projection macro also stops projecting into unaligned fields (i.e.
fields of `#[repr(packed)]` structs), as misaligned pointers require
special handling. This is implemented by attempting to create reference to
projected field inside a `if false` block. Despite being unreachable, Rust
still checks that they're not unaligned fields.

The projection macro supports both fallible and infallible index
projections. These are described in detail inside the documentation.

Signed-off-by: Gary Guo &lt;gary@garyguo.net&gt;
Reviewed-by: Benno Lossin &lt;lossin@kernel.org&gt;
Acked-by: Miguel Ojeda &lt;ojeda@kernel.org&gt;
Link: https://patch.msgid.link/20260302164239.284084-3-gary@kernel.org
[ * Add intro-doc links where possible,
  * Fix typos and slightly improve wording, e.g. "as documentation
    describes" -&gt; "as the documentation of [`Self::proj`] describes",
  * Add an empty line between regular and safety comments, before
    examples, and between logically independent comments,
  * Capitalize various safety comments.

    - Danilo ]
Signed-off-by: Danilo Krummrich &lt;dakr@kernel.org&gt;


</td></tr>