- // UNW_X86_64_CFA does not return the CFA DWARF expects
- // (it is a synonym for UNW_X86_64_RSP) so copy the cursor,
- // unwind it once in order to find the parent SP:
+ /* See 6.4 of DWARF4 (http://dwarfstd.org/doc/DWARF4.pdf#page=140):
+ *
+ * > Typically, the CFA is defined to be the value of the stack
+ * > pointer at the call site in the previous frame (which may be
+ * > different from its value on entry to the current frame).
+ *
+ * We need to unwind the frame in order to get the SP of the parent
+ * frame.
+ *
+ * Warning: the CFA returned by libunwind (UNW_X86_64_RSP, etc.)
+ * is the SP of the *current* frame. */