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Check for required alignment by testing CPU types.
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Use the same test that extract.h does for processors whose load (and,
for CISC processors, memory-to-register arithmetic) instructions support
unaligned operands.

This gets rid of the last place where we used LBL_ALIGN, so get rid of
it.  (We weren't setting it with CMake in any case.)
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@guyharris
guyharris committed Aug 4, 2018
1 parent fbd4c58 commit 90afc76
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Showing 6 changed files with 16 additions and 205 deletions.
100 changes: 0 additions & 100 deletions aclocal.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -752,106 +752,6 @@ AC_DEFUN(AC_LBL_HAVE_RUN_PATH,
AC_MSG_RESULT($ac_cv_lbl_have_run_path)
])

dnl
dnl Checks to see if unaligned memory accesses fail
dnl
dnl usage:
dnl
dnl AC_LBL_UNALIGNED_ACCESS
dnl
dnl results:
dnl
dnl LBL_ALIGN (DEFINED)
dnl
AC_DEFUN(AC_LBL_UNALIGNED_ACCESS,
[AC_MSG_CHECKING(if unaligned accesses fail)
AC_CACHE_VAL(ac_cv_lbl_unaligned_fail,
[case "$host_cpu" in
#
# These are CPU types where:
#
# the CPU faults on an unaligned access, but at least some
# OSes that support that CPU catch the fault and simulate
# the unaligned access (e.g., Alpha/{Digital,Tru64} UNIX) -
# the simulation is slow, so we don't want to use it;
#
# the CPU, I infer (from the old
#
# XXX: should also check that they don't do weird things (like on arm)
#
# comment) doesn't fault on unaligned accesses, but doesn't
# do a normal unaligned fetch, either (e.g., presumably, ARM);
#
# for whatever reason, the test program doesn't work
# (this has been claimed to be the case for several of those
# CPUs - I don't know what the problem is; the problem
# was reported as "the test program dumps core" for SuperH,
# but that's what the test program is *supposed* to do -
# it dumps core before it writes anything, so the test
# for an empty output file should find an empty output
# file and conclude that unaligned accesses don't work).
#
# This run-time test won't work if you're cross-compiling, so
# in order to support cross-compiling for a particular CPU,
# we have to wire in the list of CPU types anyway, as far as
# I know, so perhaps we should just have a set of CPUs on
# which we know it doesn't work, a set of CPUs on which we
# know it does work, and have the script just fail on other
# cpu types and update it when such a failure occurs.
#
alpha*|arm*|bfin*|hp*|mips*|sh*|sparc*|ia64|nv1)
ac_cv_lbl_unaligned_fail=yes
;;
*)
cat >conftest.c <<EOF
# include <sys/types.h>
# include <sys/wait.h>
# include <stdio.h>
unsigned char a[[5]] = { 1, 2, 3, 4, 5 };
main() {
unsigned int i;
pid_t pid;
int status;
/* avoid "core dumped" message */
pid = fork();
if (pid < 0)
exit(2);
if (pid > 0) {
/* parent */
pid = waitpid(pid, &status, 0);
if (pid < 0)
exit(3);
exit(!WIFEXITED(status));
}
/* child */
i = *(unsigned int *)&a[[1]];
printf("%d\n", i);
exit(0);
}
EOF
${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS \
conftest.c $LIBS >/dev/null 2>&1
if test ! -x conftest ; then
dnl failed to compile for some reason
ac_cv_lbl_unaligned_fail=yes
else
./conftest >conftest.out
if test ! -s conftest.out ; then
ac_cv_lbl_unaligned_fail=yes
else
ac_cv_lbl_unaligned_fail=no
fi
fi
rm -f -r conftest* core core.conftest
;;
esac])
AC_MSG_RESULT($ac_cv_lbl_unaligned_fail)
if test $ac_cv_lbl_unaligned_fail = yes ; then
AC_DEFINE(LBL_ALIGN,1,[if unaligned access fails])
fi])

dnl
dnl If the file .devel exists:
dnl Add some warning flags if the compiler supports them
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3 changes: 0 additions & 3 deletions cmakeconfig.h.in
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Original file line number Diff line number Diff line change
Expand Up @@ -265,9 +265,6 @@
/* IPv6 */
#cmakedefine INET6 1

/* if unaligned access fails */
#cmakedefine LBL_ALIGN 1

/* path for device for USB sniffing */
#cmakedefine LINUX_USB_MON_DEV "@LINUX_USB_MON_DEV@"

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3 changes: 0 additions & 3 deletions config.h.in
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Original file line number Diff line number Diff line change
Expand Up @@ -268,9 +268,6 @@
/* IPv6 */
#undef INET6

/* if unaligned access fails */
#undef LBL_ALIGN

/* path for device for USB sniffing */
#undef LINUX_USB_MON_DEV

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95 changes: 0 additions & 95 deletions configure
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Original file line number Diff line number Diff line change
Expand Up @@ -9948,101 +9948,6 @@ _ACEOF
fi


{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if unaligned accesses fail" >&5
$as_echo_n "checking if unaligned accesses fail... " >&6; }
if ${ac_cv_lbl_unaligned_fail+:} false; then :
$as_echo_n "(cached) " >&6
else
case "$host_cpu" in

#
# These are CPU types where:
#
# the CPU faults on an unaligned access, but at least some
# OSes that support that CPU catch the fault and simulate
# the unaligned access (e.g., Alpha/{Digital,Tru64} UNIX) -
# the simulation is slow, so we don't want to use it;
#
# the CPU, I infer (from the old
#
# XXX: should also check that they don't do weird things (like on arm)
#
# comment) doesn't fault on unaligned accesses, but doesn't
# do a normal unaligned fetch, either (e.g., presumably, ARM);
#
# for whatever reason, the test program doesn't work
# (this has been claimed to be the case for several of those
# CPUs - I don't know what the problem is; the problem
# was reported as "the test program dumps core" for SuperH,
# but that's what the test program is *supposed* to do -
# it dumps core before it writes anything, so the test
# for an empty output file should find an empty output
# file and conclude that unaligned accesses don't work).
#
# This run-time test won't work if you're cross-compiling, so
# in order to support cross-compiling for a particular CPU,
# we have to wire in the list of CPU types anyway, as far as
# I know, so perhaps we should just have a set of CPUs on
# which we know it doesn't work, a set of CPUs on which we
# know it does work, and have the script just fail on other
# cpu types and update it when such a failure occurs.
#
alpha*|arm*|bfin*|hp*|mips*|sh*|sparc*|ia64|nv1)
ac_cv_lbl_unaligned_fail=yes
;;

*)
cat >conftest.c <<EOF
# include <sys/types.h>
# include <sys/wait.h>
# include <stdio.h>
unsigned char a[5] = { 1, 2, 3, 4, 5 };
main() {
unsigned int i;
pid_t pid;
int status;
/* avoid "core dumped" message */
pid = fork();
if (pid < 0)
exit(2);
if (pid > 0) {
/* parent */
pid = waitpid(pid, &status, 0);
if (pid < 0)
exit(3);
exit(!WIFEXITED(status));
}
/* child */
i = *(unsigned int *)&a[1];
printf("%d\n", i);
exit(0);
}
EOF
${CC-cc} -o conftest $CFLAGS $CPPFLAGS $LDFLAGS \
conftest.c $LIBS >/dev/null 2>&1
if test ! -x conftest ; then
ac_cv_lbl_unaligned_fail=yes
else
./conftest >conftest.out
if test ! -s conftest.out ; then
ac_cv_lbl_unaligned_fail=yes
else
ac_cv_lbl_unaligned_fail=no
fi
fi
rm -f -r conftest* core core.conftest
;;
esac
fi

{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lbl_unaligned_fail" >&5
$as_echo "$ac_cv_lbl_unaligned_fail" >&6; }
if test $ac_cv_lbl_unaligned_fail = yes ; then

$as_echo "#define LBL_ALIGN 1" >>confdefs.h

fi




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2 changes: 0 additions & 2 deletions configure.ac
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Original file line number Diff line number Diff line change
Expand Up @@ -1846,8 +1846,6 @@ AC_CHECK_MEMBERS([dl_hp_ppa_info_t.dl_module_id_1],,,
#include <sys/dlpi_ext.h>
])

AC_LBL_UNALIGNED_ACCESS

AC_SUBST(V_CCOPT)
AC_SUBST(V_DEFS)
AC_SUBST(V_FINDALLDEVS)
Expand Down
18 changes: 16 additions & 2 deletions dlpisubs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -113,6 +113,20 @@ pcap_stats_dlpi(pcap_t *p, struct pcap_stat *ps)
return (0);
}

/*
* Does the processor for which we're compiling this support aligned loads?
*/
#if (defined(__i386__) || defined(_M_IX86) || defined(__X86__) || defined(__x86_64__) || defined(_M_X64)) || \
(defined(__arm__) || defined(_M_ARM) || defined(__aarch64__)) || \
(defined(__m68k__) && (!defined(__mc68000__) && !defined(__mc68010__))) || \
(defined(__ppc__) || defined(__ppc64__) || defined(_M_PPC) || defined(_ARCH_PPC) || defined(_ARCH_PPC64)) || \
(defined(__s390__) || defined(__s390x__) || defined(__zarch__))
/* Yes, it does. */
#else
/* No, it doesn't. */
#define REQUIRE_ALIGNMENT
#endif

/*
* Loop through the packets and call the callback for each packet.
* Return the number of packets read.
Expand All @@ -127,7 +141,7 @@ pcap_process_pkts(pcap_t *p, pcap_handler callback, u_char *user,
struct pcap_pkthdr pkthdr;
#ifdef HAVE_SYS_BUFMOD_H
struct sb_hdr *sbp;
#ifdef LBL_ALIGN
#ifdef REQUIRE_ALIGNMENT
struct sb_hdr sbhdr;
#endif
#endif
Expand Down Expand Up @@ -157,7 +171,7 @@ pcap_process_pkts(pcap_t *p, pcap_handler callback, u_char *user,
return (n);
}
}
#ifdef LBL_ALIGN
#ifdef REQUIRE_ALIGNMENT
if ((long)bufp & 3) {
sbp = &sbhdr;
memcpy(sbp, bufp, sizeof(*sbp));
Expand Down

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