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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. */
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