[PATCH] Workaround for FreeBSD 4.2 bug
Mark Kettenis
kettenis@wins.uva.nl
Sat Jul 21 13:20:00 GMT 2001
This should work around a bug in the FreeBSD 4.2 kernel as reported by
Stu Grossman. I rewrote his patch a bit, and used only three lines of
code plus a comment from his origional patch so I assimed we don't
need an assignment for this bit.
Checked in.
Index: ChangeLog
from Mark Kettenis <kettenis@gnu.org>
* i386bsd-nat.c: Do not include <sys/sysctl.h>.
(_initialize_i386bsd_nat) [KERN_PS_STRINGS]: Move FreeBSD-specific
code to ...
* i386fbsd-nat.c: ... here. New file.
* config/i386/fbsd.mh (NATDEPFILES): Add i386-fbsd.o.
* config/i386/nm-fbsd.h (CHILD_RESUME): Define.
* Makefile.in (ALLDEPFILES): Add i386fbsd-nat.c.
(i386fbsd-nat.o): Add dependencies.
Index: i386bsd-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/i386bsd-nat.c,v
retrieving revision 1.8
diff -u -p -r1.8 i386bsd-nat.c
--- i386bsd-nat.c 2001/07/13 18:27:21 1.8
+++ i386bsd-nat.c 2001/07/21 20:15:10
@@ -323,8 +323,6 @@ kernel_u_size (void)
/* See i386bsd-tdep.c. */
extern int i386bsd_sigcontext_pc_offset;
-#include <sys/sysctl.h>
-
void
_initialize_i386bsd_nat (void)
{
@@ -337,27 +335,4 @@ _initialize_i386bsd_nat (void)
/* Override the default value for the offset of the program counter
in the sigcontext structure. */
i386bsd_sigcontext_pc_offset = offsetof (struct sigcontext, sc_pc);
-
- /* FreeBSD provides a kern.ps_strings sysctl that we can use to
- locate the sigtramp. That way we can still recognize a sigtramp
- if it's location is changed in a new kernel. Of course this is
- still based on the assumption that the sigtramp is placed
- directly under the location where the program arguments and
- environment can be found. */
-#ifdef KERN_PS_STRINGS
- {
- int mib[2];
- int ps_strings;
- size_t len;
-
- mib[0] = CTL_KERN;
- mib[1] = KERN_PS_STRINGS;
- len = sizeof (ps_strings);
- if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) == 0)
- {
- i386bsd_sigtramp_start = ps_strings - 128;
- i386bsd_sigtramp_end = ps_strings;
- }
- }
-#endif
}
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.102
diff -u -p -r1.102 Makefile.in
--- Makefile.in 2001/07/19 18:09:11 1.102
+++ Makefile.in 2001/07/21 20:15:11
@@ -1151,7 +1151,7 @@ ALLDEPFILES = 29k-share/udi/udip2soc.c 2
hp-psymtab-read.c hp-symtab-read.c \
i386-tdep.c i386b-nat.c i386mach-nat.c i386v-nat.c i386-linux-nat.c \
i386aix-nat.c i386m3-nat.c i386v4-nat.c i386ly-tdep.c \
- i386bsd-nat.c i386bsd-tdep.c \
+ i386bsd-nat.c i386bsd-tdep.c i386fbsd-nat.c \
i387-tdep.c \
i386-linux-tdep.c i386-nat.c \
i960-tdep.c \
@@ -1536,6 +1536,8 @@ i386bsd-tdep.o: i386bsd-tdep.c $(defs_h)
$(regcache_h)
i386bsd-nat.o: i386bsd-nat.c $(defs_h) $(inferior_h) $(regcache_h)
+
+i386fbsd-nat.o: i386fbsd-nat.c $(defs_h) $(inferior_h) $(regcache_h)
i386ly-nat.o: i386ly-nat.c $(defs_h) $(frame_h) $(inferior_h) target.h
Index: config/i386/nm-fbsd.h
===================================================================
RCS file: /cvs/src/src/gdb/config/i386/nm-fbsd.h,v
retrieving revision 1.4
diff -u -p -r1.4 nm-fbsd.h
--- config/i386/nm-fbsd.h 2001/03/31 18:09:03 1.4
+++ config/i386/nm-fbsd.h 2001/07/21 20:15:11
@@ -53,6 +53,9 @@ extern unsigned long i386bsd_dr_get_stat
/* Override copies of {fetch,store}_inferior_registers in `infptrace.c'. */
#define FETCH_INFERIOR_REGISTERS
+/* Override child_resume in `infptrace.c' to work around a kernel bug. */
+#define CHILD_RESUME
+
/* We can attach and detach. */
#define ATTACH_DETACH
Index: config/i386/fbsd.mh
===================================================================
RCS file: /cvs/src/src/gdb/config/i386/fbsd.mh,v
retrieving revision 1.7
diff -u -p -r1.7 fbsd.mh
--- config/i386/fbsd.mh 2001/04/12 18:44:40 1.7
+++ config/i386/fbsd.mh 2001/07/21 20:15:11
@@ -1,6 +1,6 @@
# Host: Intel 386 running FreeBSD
XDEPFILES=
# NOTE: Do not spread NATDEPFILES over several lines - it hurts BSD make.
-NATDEPFILES= fork-child.o infptrace.o inftarg.o solib.o solib-svr4.o solib-legacy.o corelow.o core-aout.o core-regset.o i387-nat.o i386bsd-nat.o i386-nat.o
+NATDEPFILES= fork-child.o infptrace.o inftarg.o solib.o solib-svr4.o solib-legacy.o corelow.o core-aout.o core-regset.o i386-nat.o i387-nat.o i386bsd-nat.o i386fbsd-nat.o
XM_FILE= xm-fbsd.h
NAT_FILE= nm-fbsd.h
--- /dev/null Thu Feb 19 16:30:24 1998
+++ i386fbsd-nat.c Sat Jul 21 14:33:58 2001
@@ -0,0 +1,102 @@
+/* Native-dependent code for FreeBSD/i386.
+ Copyright 2001 Free Software Foundation, Inc.
+
+ This file is part of GDB.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include "defs.h"
+#include "inferior.h"
+#include "regcache.h"
+
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/sysctl.h>
+
+/* Prevent warning from -Wmissing-prototypes. */
+void _initialize_i386fbsd_nat (void);
+
+/* Resume execution of the inferior process.
+ If STEP is nonzero, single-step it.
+ If SIGNAL is nonzero, give it that signal. */
+
+void
+child_resume (ptid_t ptid, int step, enum target_signal signal)
+{
+ pid_t pid = ptid_get_pid (ptid);
+ int request = PT_STEP;
+
+ if (pid == -1)
+ /* Resume all threads. This only gets used in the non-threaded
+ case, where "resume all threads" and "resume inferior_ptid" are
+ the same. */
+ pid = ptid_get_pid (inferior_ptid);
+
+ if (!step)
+ {
+ unsigned int eflags;
+
+ /* Workaround for a bug in FreeBSD. Make sure that the trace
+ flag is off when doing a continue. There is a code path
+ through the kernel which leaves the flag set when it should
+ have been cleared. If a process has a signal pending (such
+ as SIGALRM) and we do a PT_STEP, the process never really has
+ a chance to run because the kernel needs to notify the
+ debugger that a signal is being sent. Therefore, the process
+ never goes through the kernel's trap() function which would
+ normally clear it. */
+
+ eflags = read_register (PS_REGNUM);
+ if (eflags & 0x0100)
+ write_register (PS_REGNUM, eflags & ~0x0100);
+
+ request = PT_CONTINUE;
+ }
+
+ /* An addres of (caddr_t) 1 tells ptrace to continue from where it
+ was. (If GDB wanted it to start some other way, we have already
+ written a new PC value to the child.) */
+ if (ptrace (request, pid, (caddr_t) 1,
+ target_signal_to_host (signal)) == -1)
+ perror_with_name ("ptrace");
+}
+
+void
+_initialize_i386fbsd_nat (void)
+{
+ /* FreeBSD provides a kern.ps_strings sysctl that we can use to
+ locate the sigtramp. That way we can still recognize a sigtramp
+ if it's location is changed in a new kernel. Of course this is
+ still based on the assumption that the sigtramp is placed
+ directly under the location where the program arguments and
+ environment can be found. */
+#ifdef KERN_PS_STRINGS
+ {
+ int mib[2];
+ int ps_strings;
+ size_t len;
+
+ mib[0] = CTL_KERN;
+ mib[1] = KERN_PS_STRINGS;
+ len = sizeof (ps_strings);
+ if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) == 0)
+ {
+ i386bsd_sigtramp_start = ps_strings - 128;
+ i386bsd_sigtramp_end = ps_strings;
+ }
+ }
+#endif
+}
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