PR10000: emit _stp_relocate* calculations correctly for kernel/module global $data

* translate.cxx (dump_unwindsyms): Also emit STT_OBJECT symbols,
  therefore .data etc. sections into stap-symbols.h.

* tapsets.cxx (iterate_over_modules): Omit a dwfl_getmodules()
  RC-checking assertion that blocked meaningful $context var
  error messages.
  (dwflpp::emit_address): Bypass dwfl_module_relocate_address()
  for kernel symbols as it has been unreliable; subtract sess.sym_stext
  manually.

* testsuite/buildok/seventeen.stp: Extend test with module $global.

3 files changed, 32 insertions, 9 deletions

diff --git a/tapsets.cxx b/tapsets.cxx
index c36a1aa0..82c61525 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -1040,7 +1040,10 @@ struct dwflpp
         off = dwfl_getmodules (dwfl, callback, data, off);
       }
     while (off > 0);
-    dwfl_assert("dwfl_getmodules", off == 0);
+    // Don't complain if we exited dwfl_getmodules early.
+    // This could be a $target variable error that will be
+    // reported soon anyway.
+    // dwfl_assert("dwfl_getmodules", off == 0);
 
     // PR6864 XXX: For dwarfless case (if .../vmlinux is missing), then the
     // "kernel" module is not reported in the loop above.  However, we
@@ -1699,15 +1702,25 @@ struct dwflpp
     // relocatable module probing code will need to have.
     Dwfl_Module *mod = dwfl_addrmodule (dwfl, address);
     dwfl_assert ("dwfl_addrmodule", mod);
+    const char *modname = dwfl_module_info (mod, NULL, NULL, NULL,
+                                                NULL, NULL, NULL, NULL);
     int n = dwfl_module_relocations (mod);
     dwfl_assert ("dwfl_module_relocations", n >= 0);
-    int i = dwfl_module_relocate_address (mod, &address);
+    Dwarf_Addr reloc_address = address;
+    int i = dwfl_module_relocate_address (mod, &reloc_address);
     dwfl_assert ("dwfl_module_relocate_address", i >= 0);
-    const char *modname = dwfl_module_info (mod, NULL, NULL, NULL,
-                                                NULL, NULL, NULL, NULL);
     dwfl_assert ("dwfl_module_info", modname);
     const char *secname = dwfl_module_relocation_info (mod, i, NULL);
 
+    if (sess.verbose > 2)
+      {
+        clog << "emit dwarf addr 0x" << hex << address << dec
+             << " => module " << modname  
+             << " section " << (secname ?: "null")
+             << " relocaddr 0x" << hex << reloc_address << dec
+             << endl;
+      }
+
     if (n > 0 && !(n == 1 && secname == NULL))
      {
 	dwfl_assert ("dwfl_module_relocation_info", secname);
@@ -1717,7 +1730,7 @@ struct dwflpp
             // module, for a kernel module (or other ET_REL module object).
             obstack_printf (pool, "({ static unsigned long addr = 0; ");
             obstack_printf (pool, "if (addr==0) addr = _stp_module_relocate (\"%s\",\"%s\",%#" PRIx64 "); ",
-                            modname, secname, address);
+                            modname, secname, reloc_address);
             obstack_printf (pool, "addr; })");
           }
         else if (n == 1 && module_name == TOK_KERNEL && secname[0] == '\0')
@@ -1728,7 +1741,7 @@ struct dwflpp
             secname = "_stext";
             obstack_printf (pool, "({ static unsigned long addr = 0; ");
             obstack_printf (pool, "if (addr==0) addr = _stp_module_relocate (\"%s\",\"%s\",%#" PRIx64 "); ",
-                            modname, secname, address);
+                            modname, secname, address); // PR10000 NB: not reloc_address
             obstack_printf (pool, "addr; })");
           }
 	else
diff --git a/testsuite/buildok/seventeen.stp b/testsuite/buildok/seventeen.stp
index 126db1fb..4e0b07c4 100755
--- a/testsuite/buildok/seventeen.stp
+++ b/testsuite/buildok/seventeen.stp
@@ -11,3 +11,12 @@ probe kernel.function("pipe_write")
 	printf("0x%x\n", $write_fifo_fops->llseek)
 %)
 }
+
+# PR10000: We're looking for *some* module function that has a nearby global variable in scope
+# XXX: See PR4096
+probe module("nfs").function("nfs_create_client") !, module("nfs").function("nfs_init_client") !,
+	kernel.function("nfs_fsync_dir") {
+	println(kernel_string($nfs_program->name))
+}
+
+probe timer.s(5) { exit() }
diff --git a/translate.cxx b/translate.cxx
index 0b81d9bb..47fffd1e 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -4564,7 +4564,7 @@ dump_unwindsyms (Dwfl_Module *m,
               // base address outself. (see also below).
               extra_offset = sym.st_value - base;
               if (c->session.verbose > 2)
-                clog << "Found kernel _stext 0x" << hex << extra_offset << dec << endl;
+                clog << "Found kernel _stext extra offset 0x" << hex << extra_offset << dec << endl;
             }
 
           // We only need the function symbols to identify kernel-mode
@@ -4572,8 +4572,9 @@ dump_unwindsyms (Dwfl_Module *m,
           // These fake absolute addresses occur in some older i386
           // kernels to indicate they are vDSO symbols, not real
           // functions in the kernel.
-          if (GELF_ST_TYPE (sym.st_info) == STT_FUNC &&
-              ! (sym.st_shndx == SHN_UNDEF || sym.st_shndx == SHN_ABS))
+          if ((GELF_ST_TYPE (sym.st_info) == STT_FUNC ||
+               GELF_ST_TYPE (sym.st_info) == STT_OBJECT) // PR10000: also need .data
+               && !(sym.st_shndx == SHN_UNDEF || sym.st_shndx == SHN_ABS))
             {
               Dwarf_Addr sym_addr = sym.st_value;
               const char *secname = NULL;