Hi all,
The attached patch fixes the PR 82635. I tested it on all active
branches including the gcc-6 branch where we make extensive use of this
MD_FALLBACK_FRAME_STATE_FOR macro. Namely in the libjava test suite.
(Found no other suitable tests which do make use of this macro).
No regressions.
If there are no objections, I'm going to commit the patch below to all
active branches in the next days.
Thanks,
Andreas
2017-11-02 Andreas Tobler <andre...@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.
Index: libgcc/config/i386/freebsd-unwind.h
===================================================================
--- libgcc/config/i386/freebsd-unwind.h (revision 254350)
+++ libgcc/config/i386/freebsd-unwind.h (working copy)
@@ -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. */
