i#7046 Add Linux support to dr_create_memory_dump.

api/docs/release.dox

@@ -163,6 +163,7 @@ changes:
    signature between AArch64 and RISC-V.
  - Changed the drcachesim -LL_miss_file option by adding a process ID field to the output.
    This helps in better analyzing cache misses in multi-process environments.
+ - Added X64 Linux only support to dr_create_memory_dump.
 
 Further non-compatibility-affecting changes include:
  - Added DWARF-5 support to the drsyms library by linking in 4 static libraries

core/CMakeLists.txt

@@ -390,6 +390,7 @@ if (UNIX)
       set(OS_SRCS ${OS_SRCS} unix/loader_android.c)
     else ()
       set(OS_SRCS ${OS_SRCS} unix/loader_linux.c)
+      set(OS_SRCS ${OS_SRCS} unix/coredump.c)
     endif ()
     set(OS_SRCS ${OS_SRCS} unix/memquery_linux.c)
     set(OS_SRCS ${OS_SRCS} unix/memquery.c)

core/lib/dr_tools.h

@@ -341,6 +341,12 @@ typedef enum {
      * \note Windows only.
      */
     DR_MEMORY_DUMP_LDMP = 0x0001,
+    /**
+     * Memory dump in Executable and Linkable Format.
+     *
+     * \note X64 Linux only.
+     */
+    DR_MEMORY_DUMP_ELF = 0x0002,
 } dr_memory_dump_flags_t;
 
 /** Indicates the type of memory dump for dr_create_memory_dump(). */

core/lib/instrument.c

@@ -2497,6 +2497,9 @@ dr_create_memory_dump(dr_memory_dump_spec_t *spec)
 #ifdef WINDOWS
     if (TEST(DR_MEMORY_DUMP_LDMP, spec->flags))
         return os_dump_core_live(spec->label, spec->ldmp_path, spec->ldmp_path_size);
+#elif defined(LINUX) && defined(X64)
+    if (TEST(DR_MEMORY_DUMP_ELF, spec->flags))
+        return os_dump_core_live();
 #endif
     return false;
 }

core/unix/coredump.c

@@ -0,0 +1,360 @@
+/* **********************************************************
+ * Copyright (c) 2024 Google, Inc.  All rights reserved.
+ * **********************************************************/
+
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL VMWARE, INC. OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+#include <elf.h>
+#include <sys/mman.h>
+#include "../globals.h"
+
+#include <stdio.h>
+
+#include "../os_shared.h"
+#include "../hashtable.h"
+#include "memquery.h"
+#include "elf_defines.h"
+
+#define MAX_SECTION_HEADERS 200
+#define MAX_SECTION_NAME_BUFFER_SIZE 8192
+#define SECTION_HEADER_TABLE ".shstrtab"
+#define VVAR_SECTION "[vvar]"
+
+DECLARE_CXTSWPROT_VAR(static mutex_t dump_core_lock, INIT_LOCK_FREE(dump_core_lock));
+
+typedef struct _section_header_info_t {
+    app_pc vm_start;
+    app_pc vm_end;
+    uint prot;
+    ELF_ADDR name_offset;
+} section_header_info_t;
+
+/*
+ * Writes an ELF header to the file. Returns true if the ELF header is written to the core
+ * dump file, false otherwise.
+ */
+static bool
+write_elf_header(DR_PARAM_IN file_t elf_file, DR_PARAM_IN ELF_ADDR entry_point,
+                 DR_PARAM_IN ELF_OFF section_header_table_offset,
+                 DR_PARAM_IN ELF_OFF flags, DR_PARAM_IN ELF_OFF program_header_count,
+                 DR_PARAM_IN ELF_OFF section_header_count,
+                 DR_PARAM_IN ELF_OFF section_string_table_index)
+{
+    ELF_HEADER_TYPE ehdr;
+    ehdr.e_ident[0] = ELFMAG0;
+    ehdr.e_ident[1] = ELFMAG1;
+    ehdr.e_ident[2] = ELFMAG2;
+    ehdr.e_ident[3] = ELFMAG3;
+    ehdr.e_ident[EI_CLASS] = ELFCLASS64;
+    ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
+    ehdr.e_ident[EI_VERSION] = EV_CURRENT;
+    ehdr.e_ident[EI_OSABI] = ELFOSABI_LINUX;
+    ehdr.e_ident[EI_ABIVERSION] = 0;
+    ehdr.e_type = ET_CORE;
+    ehdr.e_machine = IF_AARCHXX_ELSE(EM_AARCH64, EM_X86_64);
+    ehdr.e_version = EV_CURRENT;
+    /* This is the memory address of the entry point from where the process starts
+     * executing. */
+    ehdr.e_entry = entry_point;
+    /* Points to the start of the program header table. */
+    ehdr.e_phoff = sizeof(ehdr);
+    /* Points to the start of the section header table. */
+    ehdr.e_shoff = section_header_table_offset;
+    ehdr.e_flags = 0;
+    /* Contains the size of this header */
+    ehdr.e_ehsize = sizeof(ehdr);
+    /* Contains the size of a program header table entry. As explained below, this will
+     * typically be 0x20 (32 bit) or 0x38 (64 bit). */
+    ehdr.e_phentsize = sizeof(ELF_PROGRAM_HEADER_TYPE);
+    /* Contains the number of entries in the program header table. */
+    ehdr.e_phnum = program_header_count;
+    ehdr.e_shentsize = sizeof(ELF_SECTION_HEADER_TYPE);
+    /* Contains the number of entries in the section header table. */
+    ehdr.e_shnum = section_header_count;
+    /* Contains index of the section header table entry that contains the section names.
+     */
+    ehdr.e_shstrndx = section_string_table_index;
+
+    return os_write(elf_file, (void *)&ehdr, sizeof(ehdr)) == sizeof(ehdr);
+}
+
+/*
+ * Writes a program header to the file. Returns true if the program header is written to
+ * the core dump file, false otherwise.
+ */
+static bool
+write_program_header(DR_PARAM_IN file_t elf_file, DR_PARAM_IN ELF_WORD type,
+                     DR_PARAM_IN ELF_WORD flags, DR_PARAM_IN ELF_OFF offset,
+                     DR_PARAM_IN ELF_ADDR virtual_address,
+                     DR_PARAM_IN ELF_ADDR physical_address,
+                     DR_PARAM_IN ELF_WORD file_size, DR_PARAM_IN ELF_WORD memory_size,
+                     DR_PARAM_IN ELF_WORD alignment)
+{
+    ELF_PROGRAM_HEADER_TYPE phdr;
+    phdr.p_type = type;              /* Segment type. */
+    phdr.p_flags = flags;            /* Segment flags. */
+    phdr.p_offset = offset;          /* Segment file offset. */
+    phdr.p_vaddr = virtual_address;  /* Segment virtual address. */
+    phdr.p_paddr = physical_address; /* Segment physical address. */
+    phdr.p_filesz = file_size;       /* Segment size in file. */
+    phdr.p_memsz = memory_size;      /* Segment size in memory. */
+    phdr.p_align = alignment;        /* Segment alignment. */
+
+    return os_write(elf_file, (void *)&phdr, sizeof(phdr)) == sizeof(phdr);
+}
+
+/*
+ * Write a section header to the file. Returns true if the section header is written to
+ * the core dump file, false otherwise.
+ */
+static bool
+write_section_header(DR_PARAM_IN file_t elf_file,
+                     DR_PARAM_IN ELF_WORD string_table_offset, DR_PARAM_IN ELF_WORD type,
+                     DR_PARAM_IN ELF_WORD flags, DR_PARAM_IN ELF_ADDR virtual_address,
+                     DR_PARAM_IN ELF_OFF offset, DR_PARAM_IN ELF_WORD section_size,
+                     DR_PARAM_IN ELF_WORD link, DR_PARAM_IN ELF_WORD info,
+                     DR_PARAM_IN ELF_WORD alignment, DR_PARAM_IN ELF_WORD entry_size)
+{
+    ELF_SECTION_HEADER_TYPE shdr;
+    shdr.sh_name = string_table_offset; /* Section name (string tbl index). */
+    shdr.sh_type = type;                /* Section type. */
+    shdr.sh_flags = flags;              /* Section flags. */
+    shdr.sh_addr = virtual_address;     /* Section virtual addr at execution. */
+    shdr.sh_offset = offset;            /* Section file offset. */
+    shdr.sh_size = section_size;        /* Section size in bytes. */
+    shdr.sh_link = link;                /* Link to another section. */
+    shdr.sh_info = info;                /* Additional section information. */
+    shdr.sh_addralign = alignment;      /* Section alignment. */
+    shdr.sh_entsize = entry_size;       /* Entry size if section holds table. */
+
+    return os_write(elf_file, (void *)&shdr, sizeof(shdr)) == sizeof(shdr);
+}
+
+/*
+ * Writes a memory dump file in ELF format. Returns true if a core dump file is written,
+ * false otherwise.
+ */
+static bool
+os_dump_core_internal(void)
+{
+    strhash_table_t *string_htable =
+        strhash_hash_create(GLOBAL_DCONTEXT, /*bits=*/8, /*load_factor_percent=*/80,
+                            /*table_flags=*/0, NULL _IF_DEBUG("mmap-string-table"));
+
+    // Insert a null string at the beginning for sections with no comment.
+    char string_table[MAX_SECTION_NAME_BUFFER_SIZE];
+    // Reserve the first byte for sections without a name.
+    string_table[0] = '\0';
+    ELF_ADDR string_table_offset = 1;
+    ELF_OFF section_count = 0;
+    ELF_OFF section_data_size = 0;
+    // Reserve a section for the section name string table.
+    section_header_info_t section_header_info[MAX_SECTION_HEADERS + 1];
+
+    memquery_iter_t iter;
+    if (!memquery_iterator_start(&iter, NULL, /*may_alloc=*/false)) {
+        SYSLOG_INTERNAL_ERROR("Too many section headers.");
+        return false;
+    }
+    while (memquery_iterator_next(&iter)) {
+        // Skip non-readable section.
+        if (iter.prot == MEMPROT_NONE || strcmp(iter.comment, VVAR_SECTION) == 0) {
+            continue;
+        }
+        ELF_ADDR offset = 0;
+        if (iter.comment != NULL && iter.comment[0] != '\0') {
+            offset = (ELF_ADDR)strhash_hash_lookup(GLOBAL_DCONTEXT, string_htable,
+                                                   iter.comment);
+            if (offset == 0) {
+                strhash_hash_add(GLOBAL_DCONTEXT, string_htable, iter.comment,
+                                 (void *)string_table_offset);
+                const size_t comment_len = d_r_strlen(iter.comment);
+                if (comment_len + string_table_offset > MAX_SECTION_NAME_BUFFER_SIZE) {
+                    SYSLOG_INTERNAL_ERROR("Section name table is too small to store "
+                                          "all the section names.");
+                    return false;
+                }
+                offset = string_table_offset;
+                d_r_strncpy(&string_table[string_table_offset], iter.comment,
+                            comment_len);
+                string_table_offset += comment_len + 1;
+                string_table[string_table_offset - 1] = '\0';
+            }
+        }
+        section_header_info[section_count].vm_start = iter.vm_start;
+        section_header_info[section_count].vm_end = iter.vm_end;
+        section_header_info[section_count].prot = iter.prot;
+        section_header_info[section_count].name_offset = offset;
+        section_data_size += iter.vm_end - iter.vm_start;
+        ++section_count;
+        if (section_count > MAX_SECTION_HEADERS) {
+            SYSLOG_INTERNAL_ERROR("Too many section headers.");
+            return false;
+        }
+    }
+    memquery_iterator_stop(&iter);
+
+    // Add the string table section. Append the section name ".shstrtab" to the
+    // section names table.
+    const size_t section_header_table_len = d_r_strlen(SECTION_HEADER_TABLE) + 1;
+    d_r_strncpy(&string_table[string_table_offset], SECTION_HEADER_TABLE,
+                section_header_table_len);
+    string_table_offset += section_header_table_len;
+    ++section_count;
+    section_data_size += string_table_offset;
+
+    file_t elf_file;
+    char dump_core_file_name[MAXIMUM_PATH];
+    if (!get_unique_logfile(".elf", dump_core_file_name, sizeof(dump_core_file_name),
+                            false, &elf_file) ||
+        elf_file == INVALID_FILE) {
+        SYSLOG_INTERNAL_ERROR("Unable to open the core dump file.");
+        return false;
+    }
+
+    if (!write_elf_header(elf_file, /*entry_point=*/0,
+                          /*section_header_table_offset*/ sizeof(ELF_HEADER_TYPE) +
+                              1 /*program_header_count*/ *
+                                  sizeof(ELF_PROGRAM_HEADER_TYPE) +
+                              section_data_size,
+                          /*flags=*/0,
+                          /*program_header_count=*/1,
+                          /*section_header_count=*/section_count,
+                          /*section_string_table_index=*/section_count - 1)) {
+        os_close(elf_file);
+        return false;
+    }
+    // TODO i#7046: Fill the program header with valid data.
+    if (!write_program_header(elf_file, PT_NULL, PF_X, /*offset=*/0,
+                              /*virtual_address=*/0,
+                              /*physical_address=*/0,
+                              /*file_size=*/0, /*memory_size=*/0, /*alignment=*/0)) {
+        os_close(elf_file);
+        return false;
+    }
+    // Write memory content to the core dump file.
+    for (int section_index = 0; section_index < section_count - 1; ++section_index) {
+        const size_t length = section_header_info[section_index].vm_end -
+            section_header_info[section_index].vm_start;
+        const size_t written = os_write(
+            elf_file, (void *)section_header_info[section_index].vm_start, length);
+        if (written != length) {
+            SYSLOG_INTERNAL_ERROR("Failed to write the requested memory content into "
+                                  "the core dump file.");
+            os_close(elf_file);
+            return false;
+        }
+    }
+    // Write the section names section.
+    if (os_write(elf_file, (void *)string_table, string_table_offset) !=
+        string_table_offset) {
+        SYSLOG_INTERNAL_ERROR("Failed to write section name string table into the "
+                              "core dump file.");
+        os_close(elf_file);
+        return false;
+    }
+    // Write section headers to the core dump file.
+    // TODO i#7046: Handle multiple program headers.
+    ELF_OFF file_offset = sizeof(ELF_HEADER_TYPE) +
+        1 /*program_header_count*/ * sizeof(ELF_PROGRAM_HEADER_TYPE);
+    for (int section_index = 0; section_index < section_count - 1; ++section_index) {
+        ELF_WORD flags = SHF_ALLOC | SHF_MERGE;
+        if (section_header_info[section_index].prot & PROT_WRITE) {
+            flags |= SHF_WRITE;
+        }
+        if (!write_section_header(
+                elf_file, section_header_info[section_index].name_offset, SHT_PROGBITS,
+                flags, (ELF_ADDR)section_header_info[section_index].vm_start, file_offset,
+                section_header_info[section_index].vm_end -
+                    section_header_info[section_index].vm_start,
+                /*link=*/0,
+                /*info=*/0, /*alignment=*/sizeof(ELF_WORD),
+                /*entry_size=*/0)) {
+            os_close(elf_file);
+            return false;
+        }
+        file_offset += section_header_info[section_index].vm_end -
+            section_header_info[section_index].vm_start;
+    }
+    // Write the section names section.
+    if (!write_section_header(
+            elf_file, string_table_offset - strlen(SECTION_HEADER_TABLE), SHT_STRTAB,
+            /*flags=*/0, /*virtual_address=*/0, file_offset,
+            /*section_size=*/string_table_offset, /*link=*/0,
+            /*info=*/0, /*alignment=*/1,
+            /*entry_size=*/0)) {
+        os_close(elf_file);
+        return false;
+    }
+
+    os_close(elf_file);
+    strhash_hash_destroy(GLOBAL_DCONTEXT, string_htable);
+    return true;
+}
+
+/*
+ * Returns true if a core dump file is written, false otherwise.
+ */
+bool
+os_dump_core_live(void)
+{
+    static thread_id_t current_dumping_thread_id VAR_IN_SECTION(NEVER_PROTECTED_SECTION) =
+        0;
+    thread_id_t current_id = d_r_get_thread_id();
+#ifdef DEADLOCK_AVOIDANCE
+    dcontext_t *dcontext = get_thread_private_dcontext();
+    thread_locks_t *old_thread_owned_locks = NULL;
+#endif
+
+    if (current_id == current_dumping_thread_id) {
+        return false; /* avoid infinite loop */
+    }
+
+#ifdef DEADLOCK_AVOIDANCE
+    /* First turn off deadlock avoidance for this thread (needed for live dump
+     * to try to grab all_threads and thread_initexit locks).
+     */
+    if (dcontext != NULL) {
+        old_thread_owned_locks = dcontext->thread_owned_locks;
+        dcontext->thread_owned_locks = NULL;
+    }
+#endif
+    /* Only allow one thread to dumpcore at a time, also protects static
+     * buffers and current_dumping_thread_id.
+     */
+    d_r_mutex_lock(&dump_core_lock);
+    current_dumping_thread_id = current_id;
+    const bool ret = os_dump_core_internal();
+    current_dumping_thread_id = 0;
+    d_r_mutex_unlock(&dump_core_lock);
+
+#ifdef DEADLOCK_AVOIDANCE
+    /* Restore deadlock avoidance for this thread. */
+    if (dcontext != NULL) {
+        dcontext->thread_owned_locks = old_thread_owned_locks;
+    }
+#endif
+    return ret;
+}