9059 Simplify SMAP relocations with krtld
Portions contributed by: John Levon <john.levon@joyent.com>

*** 117,126 ****
--- 117,177 ----
                  instr[i - 1] = SDT_NOP;
  
          return (0);
  }
  
+ 
+ /*
+  * We're relying on the fact that the call we're replacing is
+  * call (e8) plus 4 bytes of address, making a 5 byte instruction
+  */
+ #define NOP_INSTR       0x90
+ #define SMAP_NOPS       5
+ 
+ /*
+  * Currently the only call replaced as a hot inline
+  * is smap_enable() and smap_disable(). If more are needed
+  * we should probably come up with an sdt probe like prefix
+  * and look for those instead of exact call names.
+  */
+ static int
+ smap_reloc_resolve(struct module *mp, char *symname, uint8_t *instr)
+ {
+         uint_t symlen;
+         hotinline_desc_t *hid;
+ 
+         if (strcmp(symname, "smap_enable") == 0 ||
+             strcmp(symname, "smap_disable") == 0) {
+ 
+ #ifdef  KOBJ_DEBUG
+                 if (kobj_debug & D_RELOCATIONS) {
+                         _kobj_printf(ops, "smap_reloc_resolve: %s relocating "
+                             "enable/disable_smap\n", mp->filename);
+                 }
+ #endif
+ 
+                 hid = kobj_alloc(sizeof (hotinline_desc_t), KM_WAIT);
+                 symlen = strlen(symname) + 1;
+                 hid->hid_symname = kobj_alloc(symlen, KM_WAIT);
+                 bcopy(symname, hid->hid_symname, symlen);
+ 
+                 /*
+                  * We backtrack one byte here to consume the call
+                  * instruction itself.
+                  */
+                 hid->hid_instr_offset = (uintptr_t)instr - 1;
+                 hid->hid_next = mp->hi_calls;
+                 mp->hi_calls = hid;
+ 
+                 memset((void *)hid->hid_instr_offset, NOP_INSTR, SMAP_NOPS);
+ 
+                 return (0);
+         }
+ 
+         return (1);
+ }
+ 
  int
  do_relocate(struct module *mp, char *reltbl, int nreloc, int relocsize,
      Addr baseaddr)
  {
          unsigned long stndx;
*** 218,227 ****
--- 269,283 ----
                                   */
                                  if (symref->st_shndx == SHN_UNDEF &&
                                      sdt_reloc_resolve(mp, mp->strings +
                                      symref->st_name, (uint8_t *)off) == 0)
                                          continue;
+ 
+                                 if (symref->st_shndx == SHN_UNDEF &&
+                                     smap_reloc_resolve(mp, mp->strings +
+                                     symref->st_name, (uint8_t *)off) == 0)
+                                         continue;
  
                                  if (symref->st_shndx == SHN_UNDEF &&
                                      tnf_reloc_resolve(mp->strings +
                                      symref->st_name, &symref->st_value,
                                      &addend, off, &probelist, &taglist) != 0) {