Add a patch that we just pulled into gcc7-devel via upstream that

addresses a real-world issue around threading and unwinding as
files/patch-freebsd-unwind.h .

This will become obsolete with the next release of GCC 7, GCC 7.3.

Bump PORTREVISION since this is a functional change.

1 files changed, 90 insertions, 0 deletions

diff --git a/lang/gcc7/files/patch-freebsd-unwind.h b/lang/gcc7/files/patch-freebsd-unwind.h
new file mode 100644
index 000000000000..dfc68fc0191c
--- /dev/null
+++ b/lang/gcc7/files/patch-freebsd-unwind.h
@@ -0,0 +1,90 @@
+2017-11-05  Andreas Tobler  <andreast@gcc.gnu.org>
+
+	Backport from mainline
+	2017-11-04  Andreas Tobler  <andreast@gcc.gnu.org>
+
+	PR libgcc/82635
+	* config/i386/freebsd-unwind.h (MD_FALLBACK_FRAME_STATE_FOR): Use a
+	sysctl to determine whether we're in a trampoline.
+	Keep the pattern matching method for systems without
+	KERN_PROC_SIGTRAMP sysctl.
+
+--- UTC
+--- libgcc/config/i386/freebsd-unwind.h	2017/11/05 17:24:37	254430
++++ libgcc/config/i386/freebsd-unwind.h	2017/11/05 19:30:41	254431
+@@ -28,7 +28,10 @@
+ 
+ #include <sys/types.h>
+ #include <signal.h>
++#include <unistd.h>
++#include <sys/sysctl.h>
+ #include <sys/ucontext.h>
++#include <sys/user.h>
+ #include <machine/sigframe.h>
+ 
+ #define REG_NAME(reg)	sf_uc.uc_mcontext.mc_## reg
+@@ -36,6 +39,38 @@
+ #ifdef __x86_64__
+ #define MD_FALLBACK_FRAME_STATE_FOR x86_64_freebsd_fallback_frame_state
+ 
++#ifdef KERN_PROC_SIGTRAMP
++/* FreeBSD past 9.3 provides a kern.proc.sigtramp.<pid> sysctl that
++   returns the location of the signal trampoline. Use this to find
++   out whether we're in a trampoline.
++*/
++static int
++x86_64_outside_sigtramp_range (unsigned char *pc)
++{
++  static int sigtramp_range_determined = 0;
++  static unsigned char *sigtramp_start, *sigtramp_end;
++
++  if (sigtramp_range_determined == 0)
++    {
++      struct kinfo_sigtramp kst = {0};
++      size_t len = sizeof (kst);
++      int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_SIGTRAMP, getpid() };
++
++      sigtramp_range_determined = 1;
++      if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
++      {
++        sigtramp_range_determined = 2;
++        sigtramp_start = kst.ksigtramp_start;
++        sigtramp_end   = kst.ksigtramp_end;
++      }
++    }
++  if (sigtramp_range_determined < 2)  /* sysctl failed if < 2 */
++    return 1;
++
++  return (pc < sigtramp_start || pc >= sigtramp_end);
++}
++#endif
++
+ static _Unwind_Reason_Code
+ x86_64_freebsd_fallback_frame_state
+ (struct _Unwind_Context *context, _Unwind_FrameState *fs)
+@@ -43,6 +78,7 @@
+   struct sigframe *sf;
+   long new_cfa;
+ 
++#ifndef KERN_PROC_SIGTRAMP
+   /* Prior to FreeBSD 9, the signal trampoline was located immediately
+      before the ps_strings.  To support non-executable stacks on AMD64,
+      the sigtramp was moved to a shared page for FreeBSD 9.  Unfortunately
+@@ -62,12 +98,15 @@
+         && *(unsigned int *)(context->ra +  8) == 0x01a1c0c7
+         && *(unsigned int *)(context->ra + 12) == 0x050f0000 ))
+     return _URC_END_OF_STACK;
++#else
++  if (x86_64_outside_sigtramp_range(context->ra))
++    return _URC_END_OF_STACK;
++#endif
+ 
+   sf = (struct sigframe *) context->cfa;
+   new_cfa = sf->REG_NAME(rsp);
+   fs->regs.cfa_how = CFA_REG_OFFSET;
+-  /* Register 7 is rsp  */
+-  fs->regs.cfa_reg = 7;
++  fs->regs.cfa_reg =  __LIBGCC_STACK_POINTER_REGNUM__;
+   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
+ 
+   /* The SVR4 register numbering macros aren't usable in libgcc.  */