Rework signal frame probing for FreeBSD/x86

[thirdparty/binutils-gdb.git] / gdb / i386fbsd-nat.c

diff --git a/gdb/i386fbsd-nat.c b/gdb/i386fbsd-nat.c
index f4951d1912c97e4594e3455f05576df46b0bba7e..ad439e3d44e384729699e8aa1117c072ac75d418 100644 (file)
--- a/gdb/i386fbsd-nat.c
+++ b/gdb/i386fbsd-nat.c
@@ -25,6 +25,7 @@
 #include <sys/types.h>
 #include <sys/ptrace.h>
 #include <sys/sysctl.h>
+#include <sys/user.h>
 
 #include "fbsd-nat.h"
 #include "i386-tdep.h"
@@ -148,25 +149,28 @@ _initialize_i386fbsd_nat (void)
   /* Support debugging kernel virtual memory images.  */
   bsd_kvm_add_target (i386fbsd_supply_pcb);
 
-  /* FreeBSD provides a kern.ps_strings sysctl that we can use to
-     locate the sigtramp.  That way we can still recognize a sigtramp
-     if its 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
+#ifdef KERN_PROC_SIGTRAMP
+  /* Normally signal frames are detected via i386fbsd_sigtramp_p.
+     However, FreeBSD 9.2 through 10.1 do not include the page holding
+     the signal code in core dumps.  These releases do provide a
+     kern.proc.sigtramp.<pid> sysctl that returns the location of the
+     signal trampoline for a running process.  We fetch the location
+     of the current (gdb) process and use this to identify signal
+     frames in core dumps from these releases.  */
   {
-    int mib[2];
-    u_long ps_strings;
+    int mib[4];
+    struct kinfo_sigtramp kst;
     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)
+    mib[1] = KERN_PROC;
+    mib[2] = KERN_PROC_SIGTRAMP;
+    mib[3] = getpid ();
+    len = sizeof (kst);
+    if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
       {
-       i386fbsd_sigtramp_start_addr = ps_strings - 128;
-       i386fbsd_sigtramp_end_addr = ps_strings;
+       i386fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
+       i386fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;
       }
   }
 #endif