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Marc Zyngier a3f6a89c83 scripts: fix gfp-translate after ___GFP_*_BITS conversion to an enum

Richard reports that since 772dd03427 ("mm: enumerate all gfp flags"),
gfp-translate is broken, as the bit numbers are implicit, leaving the
shell script unable to extract them.  Even more, some bits are now at a
variable location, making it double extra hard to parse using a simple
shell script.

Use a brute-force approach to the problem by generating a small C stub
that will use the enum to dump the interesting bits.

As an added bonus, we are now able to identify invalid bits for a given
configuration.  As an added drawback, we cannot parse include files that
predate this change anymore.  Tough luck.

Link: https://lkml.kernel.org/r/20240823163850.3791201-1-maz@kernel.org
Fixes: 772dd03427 ("mm: enumerate all gfp flags")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reported-by: Richard Weinberger <richard@nod.at>
Cc: Petr Tesařík <petr@tesarici.cz>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2024-09-01 17:59:01 -07:00

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#!/bin/bash

SPDX-License-Identifier: GPL-2.0-only

Translate the bits making up a GFP mask

(c) 2009, Mel Gorman mel@csn.ul.ie

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.c || exit 1

echo Source: $SOURCE echo Parsing: $GFPMASK

( cat <<EOF #include <stdint.h> #include <stdio.h>

// Try to fool compiler.h into not including extra stuff #define ASSEMBLY 1

#include <generated/autoconf.h> #include <linux/gfp_types.h>

static const char *masks[] = { EOF

sed -nEe 's/^[[:space:]]+(___GFP_.*)_BIT,.*$/\1/p' $SOURCE/include/linux/gfp_types.h |
while read b; do
    cat <<EOF

#if defined($b) && ($b > 0) [${b}_BIT] = "$b", #endif EOF done

cat <<EOF

};

int main(int argc, char *argv[]) { unsigned long long mask = $GFPMASK;

for (int i = 0; i < sizeof(mask) * 8; i++) {
	unsigned long long bit = 1ULL << i;
	if (mask & bit)
		printf("\t%-25s0x%llx\n",
		       (i < ___GFP_LAST_BIT && masks[i]) ?
				masks[i] : "*** INVALID ***",
		       bit);
}

return 0;

} EOF ) > $TMPFILE

${CC:-gcc} -Wall -o ${TMPFILE}.bin -I $SOURCE/include $TMPFILE && ${TMPFILE}.bin

rm -f $TMPFILE ${TMPFILE}.bin

exit 0

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