#!/bin/bash

# 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>
#
# Licensed under the terms of the GNU GPL version 2

# 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##*/}
	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
	$OBJDUMP -D $1 | sed "s/^[[:space:]]\+[0-9a-f]\+//" > $dis
}

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

	FILES="$*"

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

	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
entify parts that consist solely of unused elements.

flex_array_shrink() returns the number of pages freed.

Signed-off-by: David Rientjes &lt;rientjes@google.com&gt;
Cc: Dave Hansen &lt;dave@linux.vnet.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>flex_array: add flex_array_clear function</title>
<updated>2009-09-22T14:17:47Z</updated>
<author>
<name>David Rientjes</name>
<email>rientjes@google.com</email>
</author>
<published>2009-09-22T00:04:30Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=e6de3988aa52debb25a427d085061f3bf1181d54'/>
<id>urn:sha1:e6de3988aa52debb25a427d085061f3bf1181d54</id>
<content type='text'>
Add a new function to the flex_array API:

	int flex_array_clear(struct flex_array *fa,
				unsigned int element_nr)

This function will zero the element at element_nr in the flex_array.

Although this is equivalent to using flex_array_put() and passing a
pointer to zero'd memory, flex_array_clear() does not require such a
pointer to memory that would most likely need to be allocated on the
caller's stack which could be significantly large depending on
element_size.

Signed-off-by: David Rientjes &lt;rientjes@google.com&gt;
Cc: Dave Hansen &lt;dave@linux.vnet.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>flex_array: convert element_nr formals to unsigned</title>
<updated>2009-08-27T03:06:52Z</updated>
<author>
<name>David Rientjes</name>
<email>rientjes@google.com</email>
</author>
<published>2009-08-26T21:29:22Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=b62e408c05228f40e69bb38a48db8961cac6cd23'/>
<id>urn:sha1:b62e408c05228f40e69bb38a48db8961cac6cd23</id>
<content type='text'>
It's problematic to allow signed element_nr's or total's to be passed as
part of the flex array API.

flex_array_alloc() allows total_nr_elements to be set to a negative
quantity, which is obviously erroneous.

flex_array_get() and flex_array_put() allows negative array indices in
dereferencing an array part, which could address memory mapped before
struct flex_array.

The fix is to convert all existing element_nr formals to be qualified as
unsigned.  Existing checks to compare it to total_nr_elements or the max
array size based on element_size need not be changed.

Signed-off-by: David Rientjes &lt;rientjes@google.com&gt;
Cc: Dave Hansen &lt;dave@linux.vnet.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>flex_array: declare parts member to have incomplete type</title>
<updated>2009-08-27T03:06:52Z</updated>
<author>
<name>David Rientjes</name>
<email>rientjes@google.com</email>
</author>
<published>2009-08-26T21:29:21Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=8e7ee27095aee87b5db1b0061e2ceea5878a1bbd'/>
<id>urn:sha1:8e7ee27095aee87b5db1b0061e2ceea5878a1bbd</id>
<content type='text'>
The `parts' member of struct flex_array should evaluate to an incomplete
type so that sizeof() cannot be used and C99 does not require the
zero-length specification.

Signed-off-by: David Rientjes &lt;rientjes@google.com&gt;
Acked-by: Dave Hansen &lt;dave@linux.vnet.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>lib: flexible array implementation</title>
<updated>2009-07-30T02:10:36Z</updated>
<author>
<name>Dave Hansen</name>
<email>dave@linux.vnet.ibm.com</email>
</author>
<published>2009-07-29T22:04:18Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=534acc057b5a08ec33fa57cdd2f5a09ef124e7f2'/>
<id>urn:sha1:534acc057b5a08ec33fa57cdd2f5a09ef124e7f2</id>
<content type='text'>
Once a structure goes over PAGE_SIZE*2, we see occasional allocation
failures.  Some people have chosen to switch over to things like vmalloc()
that will let them keep array-like access to such a large structures.
But, vmalloc() has plenty of downsides.

Here's an alternative.  I think it's what Andrew was suggesting here:

	http://lkml.org/lkml/2009/7/2/518

I call it a flexible array.  It does all of its work in PAGE_SIZE bits, so
never does an order&gt;0 allocation.  The base level has
PAGE_SIZE-2*sizeof(int) bytes of storage for pointers to the second level.
 So, with a 32-bit arch, you get about 4MB (4183112 bytes) of total
storage when the objects pack nicely into a page.  It is half that on
64-bit because the pointers are twice the size.  There's a table detailing
this in the code.

There are kerneldocs for the functions, but here's an
overview:

flex_array_alloc() - dynamically allocate a base structure
flex_array_free() - free the array and all of the
		    second-level pages
flex_array_free_parts() - free the second-level pages, but
			  not the base (for static bases)
flex_array_put() - copy into the array at the given index
flex_array_get() - copy out of the array at the given index
flex_array_prealloc() - preallocate the second-level pages
			between the given indexes to
			guarantee no allocs will occur at
			put() time.

We could also potentially just pass the "element_size" into each of the
API functions instead of storing it internally.  That would get us one
more base pointer on 32-bit.

I've been testing this by running it in userspace.  The header and patch
that I've been using are here, as well as the little script I'm using to
generate the size table which goes in the kerneldocs.

	http://sr71.net/~dave/linux/flexarray/

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Dave Hansen &lt;dave@linux.vnet.ibm.com&gt;
Reviewed-by: KAMEZAWA Hiroyuki &lt;kamezawa.hiroyu@jp.fujitsu.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>