1 files changed, 81 insertions, 5 deletions

diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 7f39d0943d2d..58e933a20544 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -19,20 +19,28 @@
  * Licensed under the GNU General Public License, version 2 (GPLv2).
  */
 #undef append_func
+#undef is_fake_mcount
+#undef fn_is_fake_mcount
+#undef MIPS_is_fake_mcount
 #undef sift_rel_mcount
 #undef find_secsym_ndx
 #undef __has_rel_mcount
 #undef has_rel_mcount
 #undef tot_relsize
 #undef do_func
+#undef Elf_Addr
 #undef Elf_Ehdr
 #undef Elf_Shdr
 #undef Elf_Rel
 #undef Elf_Rela
 #undef Elf_Sym
 #undef ELF_R_SYM
+#undef Elf_r_sym
 #undef ELF_R_INFO
+#undef Elf_r_info
 #undef ELF_ST_BIND
+#undef fn_ELF_R_SYM
+#undef fn_ELF_R_INFO
 #undef uint_t
 #undef _w
 #undef _align
@@ -46,14 +54,22 @@
 # define has_rel_mcount         has64_rel_mcount
 # define tot_relsize            tot64_relsize
 # define do_func                do64
+# define is_fake_mcount         is_fake_mcount64
+# define fn_is_fake_mcount      fn_is_fake_mcount64
+# define MIPS_is_fake_mcount    MIPS64_is_fake_mcount
+# define Elf_Addr               Elf64_Addr
 # define Elf_Ehdr               Elf64_Ehdr
 # define Elf_Shdr               Elf64_Shdr
 # define Elf_Rel                Elf64_Rel
 # define Elf_Rela               Elf64_Rela
 # define Elf_Sym                Elf64_Sym
 # define ELF_R_SYM              ELF64_R_SYM
+# define Elf_r_sym              Elf64_r_sym
 # define ELF_R_INFO             ELF64_R_INFO
+# define Elf_r_info             Elf64_r_info
 # define ELF_ST_BIND            ELF64_ST_BIND
+# define fn_ELF_R_SYM           fn_ELF64_R_SYM
+# define fn_ELF_R_INFO          fn_ELF64_R_INFO
 # define uint_t                 uint64_t
 # define _w                     w8
 # define _align                 7u
@@ -66,20 +82,81 @@
 # define has_rel_mcount         has32_rel_mcount
 # define tot_relsize            tot32_relsize
 # define do_func                do32
+# define is_fake_mcount         is_fake_mcount32
+# define fn_is_fake_mcount      fn_is_fake_mcount32
+# define MIPS_is_fake_mcount    MIPS32_is_fake_mcount
+# define Elf_Addr               Elf32_Addr
 # define Elf_Ehdr               Elf32_Ehdr
 # define Elf_Shdr               Elf32_Shdr
 # define Elf_Rel                Elf32_Rel
 # define Elf_Rela               Elf32_Rela
 # define Elf_Sym                Elf32_Sym
 # define ELF_R_SYM              ELF32_R_SYM
+# define Elf_r_sym              Elf32_r_sym
 # define ELF_R_INFO             ELF32_R_INFO
+# define Elf_r_info             Elf32_r_info
 # define ELF_ST_BIND            ELF32_ST_BIND
+# define fn_ELF_R_SYM           fn_ELF32_R_SYM
+# define fn_ELF_R_INFO          fn_ELF32_R_INFO
 # define uint_t                 uint32_t
 # define _w                     w
 # define _align                 3u
 # define _size                  4
 #endif
 
+/* Functions and pointers that do_file() may override for specific e_machine. */
+static int fn_is_fake_mcount(Elf_Rel const *rp)
+{
+        return 0;
+}
+static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;
+
+static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
+{
+        return ELF_R_SYM(_w(rp->r_info));
+}
+static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
+
+static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
+{
+        rp->r_info = ELF_R_INFO(sym, type);
+}
+static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
+
+/*
+ * 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;
+}
+
 /* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
 static void append_func(Elf_Ehdr *const ehdr,
                         Elf_Shdr *const shstr,
@@ -157,7 +234,6 @@ static void append_func(Elf_Ehdr *const ehdr,
         uwrite(fd_map, ehdr, sizeof(*ehdr));
 }
 
-
 /*
  * Look at the relocations in order to find the calls to mcount.
  * Accumulate the section offsets that are found, and their relocation info,
@@ -197,22 +273,22 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
         for (t = nrel; t; --t) {
                 if (!mcountsym) {
                         Elf_Sym const *const symp =
-                                &sym0[ELF_R_SYM(_w(relp->r_info))];
+                                &sym0[Elf_r_sym(relp)];
                         char const *symname = &str0[w(symp->st_name)];
 
                         if ('.' == symname[0])
                                 ++symname;  /* ppc64 hack */
                         if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),
                                         symname))
-                                mcountsym = ELF_R_SYM(_w(relp->r_info));
+                                mcountsym = Elf_r_sym(relp);
                 }
 
-                if (mcountsym == ELF_R_SYM(_w(relp->r_info))) {
+                if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
                         uint_t const addend = _w(_w(relp->r_offset) - recval);
 
                         mrelp->r_offset = _w(offbase
                                 + ((void *)mlocp - (void *)mloc0));
-                        mrelp->r_info = _w(ELF_R_INFO(recsym, reltype));
+                        Elf_r_info(mrelp, recsym, reltype);
                         if (sizeof(Elf_Rela) == rel_entsize) {
                                 ((Elf_Rela *)mrelp)->r_addend = addend;
                                 *mlocp++ = 0;