1 files changed, 138 insertions, 36 deletions

diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index baf187bee98..4be60364a40 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -22,11 +22,15 @@
 #undef is_fake_mcount
 #undef fn_is_fake_mcount
 #undef MIPS_is_fake_mcount
+#undef mcount_adjust
 #undef sift_rel_mcount
+#undef nop_mcount
 #undef find_secsym_ndx
 #undef __has_rel_mcount
 #undef has_rel_mcount
 #undef tot_relsize
+#undef get_mcountsym
+#undef get_sym_str_and_relp
 #undef do_func
 #undef Elf_Addr
 #undef Elf_Ehdr
@@ -49,14 +53,18 @@
 #ifdef RECORD_MCOUNT_64
 # define append_func            append64
 # define sift_rel_mcount        sift64_rel_mcount
+# define nop_mcount             nop_mcount_64
 # define find_secsym_ndx        find64_secsym_ndx
 # define __has_rel_mcount       __has64_rel_mcount
 # define has_rel_mcount         has64_rel_mcount
 # define tot_relsize            tot64_relsize
+# define get_sym_str_and_relp   get_sym_str_and_relp_64
 # define do_func                do64
+# define get_mcountsym          get_mcountsym_64
 # 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 mcount_adjust          mcount_adjust_64
 # define Elf_Addr               Elf64_Addr
 # define Elf_Ehdr               Elf64_Ehdr
 # define Elf_Shdr               Elf64_Shdr
@@ -77,14 +85,18 @@
 #else
 # define append_func            append32
 # define sift_rel_mcount        sift32_rel_mcount
+# define nop_mcount             nop_mcount_32
 # define find_secsym_ndx        find32_secsym_ndx
 # define __has_rel_mcount       __has32_rel_mcount
 # define has_rel_mcount         has32_rel_mcount
 # define tot_relsize            tot32_relsize
+# define get_sym_str_and_relp   get_sym_str_and_relp_32
 # define do_func                do32
+# define get_mcountsym          get_mcountsym_32
 # 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 mcount_adjust          mcount_adjust_32
 # define Elf_Addr               Elf32_Addr
 # define Elf_Ehdr               Elf32_Ehdr
 # define Elf_Shdr               Elf32_Shdr
@@ -123,6 +135,8 @@ static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
 }
 static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
 
+static int mcount_adjust = 0;
+
 /*
  * 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
@@ -234,6 +248,49 @@ static void append_func(Elf_Ehdr *const ehdr,
         uwrite(fd_map, ehdr, sizeof(*ehdr));
 }
 
+static unsigned get_mcountsym(Elf_Sym const *const sym0,
+                              Elf_Rel const *relp,
+                              char const *const str0)
+{
+        unsigned mcountsym = 0;
+
+        Elf_Sym const *const symp =
+                &sym0[Elf_r_sym(relp)];
+        char const *symname = &str0[w(symp->st_name)];
+        char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
+
+        if (symname[0] == '.')
+                ++symname;  /* ppc64 hack */
+        if (strcmp(mcount, symname) == 0 ||
+            (altmcount && strcmp(altmcount, symname) == 0))
+                mcountsym = Elf_r_sym(relp);
+
+        return mcountsym;
+}
+
+static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
+                                 Elf_Ehdr const *const ehdr,
+                                 Elf_Sym const **sym0,
+                                 char const **str0,
+                                 Elf_Rel const **relp)
+{
+        Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+                + (void *)ehdr);
+        unsigned const symsec_sh_link = w(relhdr->sh_link);
+        Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
+        Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
+        Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
+                + (void *)ehdr);
+
+        *sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
+                                  + (void *)ehdr);
+
+        *str0 = (char const *)(_w(strsec->sh_offset)
+                               + (void *)ehdr);
+
+        *relp = rel0;
+}
+
 /*
  * Look at the relocations in order to find the calls to mcount.
  * Accumulate the section offsets that are found, and their relocation info,
@@ -250,47 +307,27 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
 {
         uint_t *const mloc0 = mlocp;
         Elf_Rel *mrelp = *mrelpp;
-        Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
-                + (void *)ehdr);
-        unsigned const symsec_sh_link = w(relhdr->sh_link);
-        Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
-        Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
-                + (void *)ehdr);
-
-        Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
-        char const *const str0 = (char const *)(_w(strsec->sh_offset)
-                + (void *)ehdr);
-
-        Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
-                + (void *)ehdr);
+        Elf_Sym const *sym0;
+        char const *str0;
+        Elf_Rel const *relp;
         unsigned rel_entsize = _w(relhdr->sh_entsize);
         unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
-        Elf_Rel const *relp = rel0;
-
         unsigned mcountsym = 0;
         unsigned t;
 
+        get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
+
         for (t = nrel; t; --t) {
-                if (!mcountsym) {
-                        Elf_Sym const *const symp =
-                                &sym0[Elf_r_sym(relp)];
-                        char const *symname = &str0[w(symp->st_name)];
-                        char const *mcount = '_' == gpfx ? "_mcount" : "mcount";
-
-                        if ('.' == symname[0])
-                                ++symname;  /* ppc64 hack */
-                        if (0 == strcmp(mcount, symname) ||
-                            (altmcount && 0 == strcmp(altmcount, symname)))
-                                mcountsym = Elf_r_sym(relp);
-                }
+                if (!mcountsym)
+                        mcountsym = get_mcountsym(sym0, relp, str0);
 
                 if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
-                        uint_t const addend = _w(_w(relp->r_offset) - recval);
-
+                        uint_t const addend =
+                                _w(_w(relp->r_offset) - recval + mcount_adjust);
                         mrelp->r_offset = _w(offbase
                                 + ((void *)mlocp - (void *)mloc0));
                         Elf_r_info(mrelp, recsym, reltype);
-                        if (sizeof(Elf_Rela) == rel_entsize) {
+                        if (rel_entsize == sizeof(Elf_Rela)) {
                                 ((Elf_Rela *)mrelp)->r_addend = addend;
                                 *mlocp++ = 0;
                         } else
@@ -304,6 +341,63 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
         return mlocp;
 }
 
+/*
+ * Read the relocation table again, but this time its called on sections
+ * that are not going to be traced. The mcount calls here will be converted
+ * into nops.
+ */
+static void nop_mcount(Elf_Shdr const *const relhdr,
+                       Elf_Ehdr const *const ehdr,
+                       const char *const txtname)
+{
+        Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+                + (void *)ehdr);
+        Elf_Sym const *sym0;
+        char const *str0;
+        Elf_Rel const *relp;
+        Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
+        unsigned rel_entsize = _w(relhdr->sh_entsize);
+        unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
+        unsigned mcountsym = 0;
+        unsigned t;
+        int once = 0;
+
+        get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
+
+        for (t = nrel; t; --t) {
+                int ret = -1;
+
+                if (!mcountsym)
+                        mcountsym = get_mcountsym(sym0, relp, str0);
+
+                if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
+                        if (make_nop)
+                                ret = make_nop((void *)ehdr, shdr->sh_offset + relp->r_offset);
+                        if (warn_on_notrace_sect && !once) {
+                                printf("Section %s has mcount callers being ignored\n",
+                                       txtname);
+                                once = 1;
+                                /* just warn? */
+                                if (!make_nop)
+                                        return;
+                        }
+                }
+
+                /*
+                 * If we successfully removed the mcount, mark the relocation
+                 * as a nop (don't do anything with it).
+                 */
+                if (!ret) {
+                        Elf_Rel rel;
+                        rel = *(Elf_Rel *)relp;
+                        Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
+                        ulseek(fd_map, (void *)relp - (void *)ehdr, SEEK_SET);
+                        uwrite(fd_map, &rel, sizeof(rel));
+                }
+                relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
+        }
+}
+
 
 /*
  * Find a symbol in the given section, to be used as the base for relocating
@@ -354,13 +448,13 @@ __has_rel_mcount(Elf_Shdr const *const relhdr,  /* is SHT_REL or SHT_RELA */
         Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
         char const *const txtname = &shstrtab[w(txthdr->sh_name)];
 
-        if (0 == strcmp("__mcount_loc", txtname)) {
+        if (strcmp("__mcount_loc", txtname) == 0) {
                 fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
                         fname);
                 succeed_file();
         }
-        if (SHT_PROGBITS != w(txthdr->sh_type) ||
-            !is_mcounted_section_name(txtname))
+        if (w(txthdr->sh_type) != SHT_PROGBITS ||
+            !(w(txthdr->sh_flags) & SHF_EXECINSTR))
                 return NULL;
         return txtname;
 }
@@ -370,7 +464,7 @@ static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
                                   char const *const shstrtab,
                                   char const *const fname)
 {
-        if (SHT_REL  != w(relhdr->sh_type) && SHT_RELA != w(relhdr->sh_type))
+        if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
                 return NULL;
         return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
 }
@@ -383,9 +477,11 @@ static unsigned tot_relsize(Elf_Shdr const *const shdr0,
 {
         unsigned totrelsz = 0;
         Elf_Shdr const *shdrp = shdr0;
+        char const *txtname;
 
         for (; nhdr; --nhdr, ++shdrp) {
-                if (has_rel_mcount(shdrp, shdr0, shstrtab, fname))
+                txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
+                if (txtname && is_mcounted_section_name(txtname))
                         totrelsz += _w(shdrp->sh_size);
         }
         return totrelsz;
@@ -421,7 +517,7 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
         for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
                 char const *const txtname = has_rel_mcount(relhdr, shdr0,
                         shstrtab, fname);
-                if (txtname) {
+                if (txtname && is_mcounted_section_name(txtname)) {
                         uint_t recval = 0;
                         unsigned const recsym = find_secsym_ndx(
                                 w(relhdr->sh_info), txtname, &recval,
@@ -432,6 +528,12 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
                         mlocp = sift_rel_mcount(mlocp,
                                 (void *)mlocp - (void *)mloc0, &mrelp,
                                 relhdr, ehdr, recsym, recval, reltype);
+                } else if (txtname && (warn_on_notrace_sect || make_nop)) {
+                        /*
+                         * This section is ignored by ftrace, but still
+                         * has mcount calls. Convert them to nops now.
+                         */
+                        nop_mcount(relhdr, ehdr, txtname);
                 }
         }
         if (mloc0 != mlocp) {