+/*
+ * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
+ * _mcount symbol is needed for dynamic function tracer, with it, to disable
+ * tracing(ftrace_make_nop), the instruction in the position is replaced with
+ * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
+ * instruction back. So, here, we set the 2nd one as fake and filter it.
+ *
+ * c: 3c030000 lui v1,0x0 <--> b label
+ * c: R_MIPS_HI16 _mcount
+ * c: R_MIPS_NONE *ABS*
+ * c: R_MIPS_NONE *ABS*
+ * 10: 64630000 daddiu v1,v1,0
+ * 10: R_MIPS_LO16 _mcount
+ * 10: R_MIPS_NONE *ABS*
+ * 10: R_MIPS_NONE *ABS*
+ * 14: 03e0082d move at,ra
+ * 18: 0060f809 jalr v1
+ * label:
+ */
+#define MIPS_FAKEMCOUNT_OFFSET 4
+
+static int MIPS_is_fake_mcount(Elf_Rel const *rp)
+{
+ static Elf_Addr old_r_offset;
+ Elf_Addr current_r_offset = _w(rp->r_offset);
+ int is_fake;
+
+ is_fake = old_r_offset &&
+ (current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
+ old_r_offset = current_r_offset;
+
+ return is_fake;
+}