8250826: jhsdb does not work with coredump which comes from Substrate VM

Reviewed-by: cjplummer, sspitsyn

Author: YaSuenag

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

@@ -67,6 +67,7 @@ typedef struct map_info {
    off_t            offset;   // file offset of this mapping
    uintptr_t        vaddr;    // starting virtual address
    size_t           memsz;    // size of the mapping
+   uint32_t         flags;    // acces flags
    struct map_info* next;
 } map_info;
 

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

@@ -351,7 +351,7 @@ static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) {
          case PT_LOAD: {
             if (core_php->p_filesz != 0) {
                if (add_map_info(ph, ph->core->core_fd, core_php->p_offset,
-                  core_php->p_vaddr, core_php->p_filesz) == NULL) goto err;
+                  core_php->p_vaddr, core_php->p_filesz, core_php->p_flags) == NULL) goto err;
             }
             break;
          }
@@ -390,10 +390,21 @@ static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* li
 
       if (existing_map == NULL){
         if (add_map_info(ph, lib_fd, lib_php->p_offset,
-                          target_vaddr, lib_php->p_memsz) == NULL) {
+                         target_vaddr, lib_php->p_memsz, lib_php->p_flags) == NULL) {
           goto err;
         }
+      } else if (lib_php->p_flags != existing_map->flags) {
+        // Access flags for this memory region are different between the library
+        // and coredump. It might be caused by mprotect() call at runtime.
+        // We should respect the coredump.
+        continue;
       } else {
+        // Read only segments in ELF should not be any different from PT_LOAD segments
+        // in the coredump.
+        // Also the first page of the ELF header might be included
+        // in the coredump (See JDK-7133122).
+        // Thus we need to replace the PT_LOAD segment with the library version.
+        //
         // Coredump stores value of p_memsz elf field
         // rounded up to page boundary.
 
@@ -460,7 +471,7 @@ static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) {
     case PT_LOAD: {
       // add only non-writable segments of non-zero filesz
       if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) {
-        if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err;
+        if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz, exec_php->p_flags) == NULL) goto err;
       }
       break;
     }

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

@@ -113,6 +113,7 @@ typedef struct map_info {
    uint64_t         offset;   // file offset of this mapping
    uint64_t         vaddr;    // starting virtual address
    size_t           memsz;    // size of the mapping
+   uint32_t         flags;    // access flags
    struct map_info* next;
 } map_info;
 

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

@@ -248,7 +248,7 @@ static bool read_core_segments(struct ps_prochandle* ph) {
         print_debug("failed to read LC_SEGMENT_64 i = %d!\n", i);
         goto err;
       }
-      if (add_map_info(ph, fd, segcmd.fileoff, segcmd.vmaddr, segcmd.vmsize) == NULL) {
+      if (add_map_info(ph, fd, segcmd.fileoff, segcmd.vmaddr, segcmd.vmsize, segcmd.flags) == NULL) {
         print_debug("Failed to add map_info at i = %d\n", i);
         goto err;
       }
@@ -788,7 +788,7 @@ static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) {
          case PT_LOAD: {
             if (core_php->p_filesz != 0) {
                if (add_map_info(ph, ph->core->core_fd, core_php->p_offset,
-                  core_php->p_vaddr, core_php->p_filesz) == NULL) goto err;
+                  core_php->p_vaddr, core_php->p_filesz, core_php->p_flags) == NULL) goto err;
             }
             break;
          }
@@ -827,7 +827,7 @@ static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* li
 
       if (existing_map == NULL){
         if (add_map_info(ph, lib_fd, lib_php->p_offset,
-                          target_vaddr, lib_php->p_filesz) == NULL) {
+                          target_vaddr, lib_php->p_filesz, lib_php->p_flags) == NULL) {
           goto err;
         }
       } else {
@@ -893,7 +893,7 @@ static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) {
          case PT_LOAD: {
             // add only non-writable segments of non-zero filesz
             if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) {
-               if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err;
+               if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz, exec_php->p_flags) == NULL) goto err;
             }
             break;
          }

src/jdk.hotspot.agent/share/native/libsaproc/ps_core_common.c

@@ -41,6 +41,13 @@
 #include "sun_jvm_hotspot_debugger_amd64_AMD64ThreadContext.h"
 #endif
 
+// Define a segment permission flag allowing read if there is a read flag. Otherwise use 0.
+#ifdef PF_R
+#define MAP_R_FLAG PF_R
+#else
+#define MAP_R_FLAG 0
+#endif
+
 #ifdef LINUX
 // I have no idea why this function is called ps_pread() on macos but ps_pdread on linux.
 #define ps_pread ps_pdread
@@ -113,7 +120,7 @@ void core_release(struct ps_prochandle* ph) {
   }
 }
 
-static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t memsz) {
+static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t memsz, uint32_t flags) {
   map_info* map;
   if ( (map = (map_info*) calloc(1, sizeof(map_info))) == NULL) {
     print_debug("can't allocate memory for map_info\n");
@@ -125,14 +132,15 @@ static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t
   map->offset = offset;
   map->vaddr  = vaddr;
   map->memsz  = memsz;
+  map->flags  = flags;
   return map;
 }
 
 // add map info with given fd, offset, vaddr and memsz
 map_info* add_map_info(struct ps_prochandle* ph, int fd, off_t offset,
-                       uintptr_t vaddr, size_t memsz) {
+                       uintptr_t vaddr, size_t memsz, uint32_t flags) {
   map_info* map;
-  if ((map = allocate_init_map(fd, offset, vaddr, memsz)) == NULL) {
+  if ((map = allocate_init_map(fd, offset, vaddr, memsz, flags)) == NULL) {
     return NULL;
   }
 
@@ -149,7 +157,7 @@ static map_info* add_class_share_map_info(struct ps_prochandle* ph, off_t offset
                              uintptr_t vaddr, size_t memsz) {
   map_info* map;
   if ((map = allocate_init_map(ph->core->classes_jsa_fd,
-                               offset, vaddr, memsz)) == NULL) {
+                               offset, vaddr, memsz, MAP_R_FLAG)) == NULL) {
     return NULL;
   }
 

src/jdk.hotspot.agent/share/native/libsaproc/ps_core_common.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 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
@@ -27,7 +27,7 @@
 
 map_info* core_lookup(struct ps_prochandle *ph, uintptr_t addr);
 map_info* add_map_info(struct ps_prochandle* ph, int fd, off_t offset,
-                       uintptr_t vaddr, size_t memsz);
+                       uintptr_t vaddr, size_t memsz, uint32_t flags);
 void core_release(struct ps_prochandle* ph);
 bool read_string(struct ps_prochandle* ph, uintptr_t addr, char* buf, size_t size);
 bool init_classsharing_workaround(struct ps_prochandle* ph);