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linux/scripts/syscalltbl.sh
Josh Poimboeuf 9142be9e64 x86/syscall: Mark exit[_group] syscall handlers __noreturn
The direct-call syscall dispatch function doesn't know that the exit()
and exit_group() syscall handlers don't return, so the call sites aren't
optimized accordingly.

Fix that by marking the exit syscall declarations __noreturn.

Fixes the following warnings:

  vmlinux.o: warning: objtool: x64_sys_call+0x2804: __x64_sys_exit() is missing a __noreturn annotation
  vmlinux.o: warning: objtool: ia32_sys_call+0x29b6: __ia32_sys_exit_group() is missing a __noreturn annotation

Fixes: 1e3ad78334 ("x86/syscall: Don't force use of indirect calls for system calls")
Closes: https://lkml.kernel.org/lkml/6dba9b32-db2c-4e6d-9500-7a08852f17a3@paulmck-laptop
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/r/5d8882bc077d8eadcc7fd1740b56dfb781f12288.1719381528.git.jpoimboe@kernel.org
2024-06-28 15:23:38 +02:00

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#!/bin/sh
# SPDX-License-Identifier: GPL-2.0-only
#
# Generate a syscall table header.
#
# Each line of the syscall table should have the following format:
#
# NR ABI NAME [NATIVE] [COMPAT]
#
# NR syscall number
# ABI ABI name
# NAME syscall name
# NATIVE native entry point (optional)
# COMPAT compat entry point (optional)
set -e
usage() {
echo >&2 "usage: $0 [--abis ABIS] INFILE OUTFILE" >&2
echo >&2
echo >&2 " INFILE input syscall table"
echo >&2 " OUTFILE output header file"
echo >&2
echo >&2 "options:"
echo >&2 " --abis ABIS ABI(s) to handle (By default, all lines are handled)"
exit 1
}
# default unless specified by options
abis=
while [ $# -gt 0 ]
do
case $1 in
--abis)
abis=$(echo "($2)" | tr ',' '|')
shift 2;;
-*)
echo "$1: unknown option" >&2
usage;;
*)
break;;
esac
done
if [ $# -ne 2 ]; then
usage
fi
infile="$1"
outfile="$2"
nxt=0
grep -E "^[0-9]+[[:space:]]+$abis" "$infile" | {
while read nr abi name native compat noreturn; do
if [ $nxt -gt $nr ]; then
echo "error: $infile: syscall table is not sorted or duplicates the same syscall number" >&2
exit 1
fi
while [ $nxt -lt $nr ]; do
echo "__SYSCALL($nxt, sys_ni_syscall)"
nxt=$((nxt + 1))
done
if [ "$compat" = "-" ]; then
unset compat
fi
if [ -n "$noreturn" ]; then
if [ "$noreturn" != "noreturn" ]; then
echo "error: $infile: invalid string \"$noreturn\" in 'noreturn' column"
exit 1
fi
if [ -n "$compat" ]; then
echo "__SYSCALL_COMPAT_NORETURN($nr, $native, $compat)"
else
echo "__SYSCALL_NORETURN($nr, $native)"
fi
elif [ -n "$compat" ]; then
echo "__SYSCALL_WITH_COMPAT($nr, $native, $compat)"
elif [ -n "$native" ]; then
echo "__SYSCALL($nr, $native)"
else
echo "__SYSCALL($nr, sys_ni_syscall)"
fi
nxt=$((nr + 1))
done
} > "$outfile"