8250750: JDK-8247515 fix for OSX pc_to_symbol() lookup fails with some symbols

Reviewed-by: sspitsyn, kevinw

src/jdk.hotspot.agent/macosx/native/libsaproc/libproc_impl.c

@@ -208,12 +208,12 @@ void Prelease(struct ps_prochandle* ph) {
   free(ph);
 }
 
-lib_info* add_lib_info(struct ps_prochandle* ph, const char* libname, uintptr_t base, size_t memsz) {
-  return add_lib_info_fd(ph, libname, -1, base, memsz);
+lib_info* add_lib_info(struct ps_prochandle* ph, const char* libname, uintptr_t base) {
+  return add_lib_info_fd(ph, libname, -1, base);
 }
 
-lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd, uintptr_t base, size_t memsz) {
-   lib_info* newlib;
+lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd, uintptr_t base) {
+  lib_info* newlib;
   print_debug("add_lib_info_fd %s\n", libname);
 
   if ( (newlib = (lib_info*) calloc(1, sizeof(struct lib_info))) == NULL) {
@@ -229,7 +229,6 @@ lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd,
   strcpy(newlib->name, libname);
 
   newlib->base = base;
-  newlib->memsz = memsz;
 
   if (fd == -1) {
     if ( (newlib->fd = pathmap_open(newlib->name)) < 0) {
@@ -259,11 +258,11 @@ lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd,
   }
 #endif // __APPLE__
 
-  newlib->symtab = build_symtab(newlib->fd);
+  newlib->symtab = build_symtab(newlib->fd, &newlib->memsz);
   if (newlib->symtab == NULL) {
     print_debug("symbol table build failed for %s\n", newlib->name);
   } else {
-    print_debug("built symbol table for 0x%lx %s\n", newlib, newlib->name);
+    print_debug("built symbol table for 0x%lx memsz=0x%lx %s\n", newlib, newlib->memsz, newlib->name);
   }
 
   // even if symbol table building fails, we add the lib_info.

src/jdk.hotspot.agent/macosx/native/libsaproc/libproc_impl.h

@@ -36,6 +36,7 @@
 #include <mach-o/loader.h>
 #include <mach-o/nlist.h>
 #include <mach-o/fat.h>
+#include <mach-o/stab.h>
 
 #ifndef register_t
 #define register_t uint64_t
@@ -171,11 +172,10 @@ typedef bool (*thread_info_callback)(struct ps_prochandle* ph, pthread_t pid, lw
 bool read_thread_info(struct ps_prochandle* ph, thread_info_callback cb);
 
 // adds a new shared object to lib list, returns NULL on failure
-lib_info* add_lib_info(struct ps_prochandle* ph, const char* libname, uintptr_t base, size_t memsz);
+lib_info* add_lib_info(struct ps_prochandle* ph, const char* libname, uintptr_t base);
 
 // adds a new shared object to lib list, supply open lib file descriptor as well
-lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd,
-                          uintptr_t base, size_t memsz);
+lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd, uintptr_t base);
 
 sa_thread_info* add_thread_info(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id);
 // a test for ELF signature without using libelf

src/jdk.hotspot.agent/macosx/native/libsaproc/ps_core.c

@@ -507,7 +507,7 @@ static bool read_shared_lib_info(struct ps_prochandle* ph) {
           } else {
             break; // Ignore non-relative paths, which are system libs. See JDK-8249779.
           }
-          add_lib_info(ph, name, iter->vaddr, iter->memsz);
+          add_lib_info(ph, name, iter->vaddr);
           break;
         }
       }

src/jdk.hotspot.agent/macosx/native/libsaproc/symtab.c

@@ -93,11 +93,12 @@ void build_search_table(symtab_t *symtab) {
 }
 
 // read symbol table from given fd.
-struct symtab* build_symtab(int fd) {
+struct symtab* build_symtab(int fd, size_t *p_max_offset) {
   symtab_t* symtab = NULL;
   int i, j;
   mach_header_64 header;
   off_t image_start;
+  size_t max_offset = 0;
 
   print_debug("build_symtab\n");
   if (!get_arch_off(fd, CPU_TYPE_X86_64, &image_start)) {
@@ -187,6 +188,11 @@ struct symtab* build_symtab(int fd) {
     if (stridx == 0 || offset == 0) {
       continue; // Skip this entry. It's not a reference to code or data
     }
+    if (lentry.n_type == N_OSO) {
+      // This is an object file name/path. These entries have something other than
+      // an offset in lentry.n_value, so we need to ignore them.
+      continue;
+    }
     symtab->symbols[i].offset = offset;
     symtab->symbols[i].name = symtab->strs + stridx;
     symtab->symbols[i].size = strlen(symtab->symbols[i].name);
@@ -195,6 +201,11 @@ struct symtab* build_symtab(int fd) {
       continue; // Skip this entry. It points to an empty string.
     }
 
+    // Track the maximum offset we've seen. This is used to determine the address range
+    // that the library covers.
+    if (offset > max_offset) {
+      max_offset = (offset + 4096) & ~0xfff; // Round up to next page boundary
+    }
     print_debug("symbol read: %d %d n_type=0x%x n_sect=0x%x n_desc=0x%x n_strx=0x%lx offset=0x%lx %s\n",
                 j, i, lentry.n_type, lentry.n_sect, lentry.n_desc, stridx, offset, symtab->symbols[i].name);
     i++;
@@ -212,6 +223,7 @@ struct symtab* build_symtab(int fd) {
 
   // build a hashtable for fast query
   build_search_table(symtab);
+  *p_max_offset = max_offset;
   return symtab;
 quit:
   if (symtab) destroy_symtab(symtab);

src/jdk.hotspot.agent/macosx/native/libsaproc/symtab.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -32,7 +32,7 @@
 struct symtab;
 
 // build symbol table for a given ELF or MachO file escriptor
-struct symtab* build_symtab(int fd);
+struct symtab* build_symtab(int fd, size_t *p_max_offset);
 
 // destroy the symbol table
 void destroy_symtab(struct symtab* symtab);