The syscall trampolines in FreeBSD libc do not have unwind annotations.
---
src/x86/Gos-freebsd.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/src/x86/Gos-freebsd.c b/src/x86/Gos-freebsd.c
index 247c35f..aafdfc9 100644
--- a/src/x86/Gos-freebsd.c
+++ b/src/x86/Gos-freebsd.c
@@ -91,6 +91,11 @@ XXX
w3 == 0x14688e03 && w4 == 0x0001a1b8 && w5 == 0x80cd5000)
ret = X86_SCF_FREEBSD_SIGFRAME;
}
+
+ /* Check for syscall */
+ if (ret == X86_SCF_NONE && (*a->access_mem) (as, ip - 2, &w0, 0, arg) >= 0 &&
+ (w0 & 0xffff) == 0x80cd)
+ ret = X86_SCF_FREEBSD_SYSCALL;
Debug (16, "returning %d\n", ret);
c->sigcontext_format = ret;
return (ret);
@@ -131,6 +136,10 @@ unw_handle_signal_frame (unw_cursor_t *cursor)
c->dwarf.loc[EFLAGS] = DWARF_LOC (uc_addr + FREEBSD_UC_MCONTEXT_EFLAGS_OFF, 0);
c->dwarf.loc[TRAPNO] = DWARF_LOC (uc_addr + FREEBSD_UC_MCONTEXT_TRAPNO_OFF, 0);
c->dwarf.loc[ST0] = DWARF_NULL_LOC;
+ } else if (c->sigcontext_format == X86_SCF_FREEBSD_SYSCALL) {
+ c->dwarf.loc[EIP] = DWARF_LOC (c->dwarf.cfa, 0);
+ c->dwarf.loc[EAX] = DWARF_NULL_LOC;
+ c->dwarf.cfa += 4;
} else {
Debug (8, "Gstep: not handling frame format %d\n", c->sigcontext_format);
abort();
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