[PATCH 2/4] Add symbol-handling callbacks to the jit-reader interface.

Sanjoy Das
2011-07-05T06:27:27Z

Implements the callbacks in `struct gdbjit_symtab_callbacks'. This
will allow the JIT debug info reader to be able to parse the debug
info and actually push the symbols into GDB.

gdb/ChangeLog:

* jit.c: Add symbol handling callbacks for the JIT reader
interface.
---
gdb/ChangeLog | 4 +
gdb/jit.c | 522 +++++++++++++++++++++++++++++++++++++++++++++++++++------
2 files changed, 475 insertions(+), 51 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 3ad44e8..38b83f1 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,9 @@
2011-07-04 Sanjoy Das <sanjoy@playingwithpointers.com>

+ * jit.c: Add symbol handling callbacks for the JIT reader interface.
+
+2011-07-04 Sanjoy Das <sanjoy@playingwithpointers.com>
+
* jit-reader.h: Add (new) JIT reader interface.
* jit.c: Include jit-reader.h in source file
* Makefile.in: Add jit-reader.h to HFILES_NO_SRCDIR.
diff --git a/gdb/jit.c b/gdb/jit.c
index 4ce5814..f8810a8 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -21,8 +21,10 @@

#include "jit.h"
#include "jit-reader.h"
+#include "block.h"
#include "breakpoint.h"
#include "command.h"
+#include "dictionary.h"
#include "gdbcmd.h"
#include "gdbcore.h"
#include "inferior.h"
@@ -31,8 +33,11 @@
#include "symfile.h"
#include "symtab.h"
#include "target.h"
+#include "gdb_dirent.h"
#include "gdb_stat.h"

+#include <dlfcn.h>
+
static const struct objfile_data *jit_objfile_data;

static const char *const jit_break_name = "__jit_debug_register_code";
@@ -45,6 +50,115 @@ static const struct inferior_data *jit_inferior_data = NULL;

static int jit_debug = 0;

+/* The environment variable we poke at to get the file name of the shared object
+ to load. */
+
+static const char *jit_dbg_reader_so_name_env = "JIT_DEBUG_READER";
+
+/* Symbols (and the corresponding types) to be loaded from the shared object
+ supposed to do the debug-info parsing. */
+typedef int (jit_init_reader_fn) (void **);
+static const char *jit_init_reader_sym = "gdbjit_init_reader";
+
+typedef int (jit_read_debug_info_fn) (void *, struct gdbjit_symtab_callbacks *,
+ void *mem, long sz);
+static const char *jit_read_debug_info_sym = "gdbjit_read_debug_info";
+
+typedef int (jit_unwind_frame_fn) (void *, struct gdbjit_unwind_callbacks *);
+static const char *jit_unwind_frame_sym = "gdbjit_unwind_frame";
+
+typedef void (jit_destroy_reader_fn) (void *);
+static const char *jit_destroy_reader_sym = "gdbjit_destroy_reader";
+
+typedef struct gdbjit_frame_id (jit_get_frame_id_fn) (void *, struct
+ gdbjit_unwind_callbacks *);
+static const char *jit_get_frame_id_sym = "gdbjit_get_frame_id";
+
+static const char *jit_so_api_version_sym = "__gdbjit_so_api_version";
+
+struct jit_dbg_reader
+{
+ jit_init_reader_fn *init;
+ jit_read_debug_info_fn *read;
+ jit_unwind_frame_fn *unwind;
+ jit_get_frame_id_fn *get_frame_id;
+ jit_destroy_reader_fn *destroy;
+
+ void *handle, *private_data;
+};
+
+static struct jit_dbg_reader *
+jit_dbg_reader_load (void)
+{
+ /* Check if a reader has been provided. */
+ const char *file_name = getenv (jit_dbg_reader_so_name_env);
+ void *handle = NULL;
+ int (*jit_reader_so_api_version) (void) = NULL;
+ struct jit_dbg_reader *reader = NULL;
+
+ if (file_name == NULL)
+ return NULL;
+
+ handle = dlopen (file_name, RTLD_NOW);
+ if (!handle)
+ goto cleanup;
+
+ reader = XZALLOC (struct jit_dbg_reader);
+ reader->init = dlsym (handle, jit_init_reader_sym);
+ reader->handle = handle;
+
+ if (!reader->init)
+ goto cleanup;
+
+ reader->read = dlsym (handle, jit_read_debug_info_sym);
+ if (!reader->read)
+ goto cleanup;
+
+ reader->unwind = dlsym (handle, jit_unwind_frame_sym);
+ if (!reader->unwind)
+ goto cleanup;
+
+ reader->get_frame_id = dlsym (handle, jit_get_frame_id_sym);
+ if (!reader->get_frame_id)
+ goto cleanup;
+
+ reader->destroy = dlsym (handle, jit_destroy_reader_sym);
+ if (!reader->destroy)
+ goto cleanup;
+
+ jit_reader_so_api_version = dlsym (handle, jit_so_api_version_sym);
+ if (!jit_reader_so_api_version ||
+ jit_reader_so_api_version () != GDB_JIT_INTERFACE_VERSION)
+ {
+ goto cleanup;
+ }
+
+ if (reader->init (&reader->private_data) != GDB_JIT_SUCCESS)
+ goto cleanup;
+
+ return reader;
+
+ cleanup:
+ xfree (reader);
+ if (handle)
+ {
+ dlclose (handle);
+ fprintf (stderr, "Could not load reader object %s\n", file_name);
+ }
+ else /* also report why the shared object could not be loaded */
+ fprintf (stderr, "Could not load reader object %s (%s)\n", file_name,
+ dlerror());
+ return NULL;
+}
+
+static void
+jit_dbg_reader_destroy (struct jit_dbg_reader *reader)
+{
+ if (reader)
+ reader->destroy (reader->private_data);
+ xfree (reader);
+}
+
static void
show_jit_debug (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
@@ -135,6 +249,9 @@ struct jit_inferior_data
{
CORE_ADDR breakpoint_addr; /* &__jit_debug_register_code() */
CORE_ADDR descriptor_addr; /* &__jit_debug_descriptor */
+ struct jit_dbg_reader *reader; /* If a debug info reader was found. */
+ struct objfile *jit_objfile; /* The object file where all the JIT symbols
+ will be added. */
};

/* Return jit_inferior_data for current inferior. Allocate if not already
@@ -233,6 +350,286 @@ jit_read_code_entry (struct gdbarch *gdbarch,
extract_unsigned_integer (&entry_buf[3 * ptr_size], 8, byte_order);
}

+struct gdbjit_block
+{
+ struct gdbjit_block *next, *parent;
+ struct block *real_block;
+
+ /* The first and last code address corresponding to this block */
+ CORE_ADDR begin, end;
+ /* The name of this block (if any). If this is non-NULL, the FUNCTION symbol
+ symbol is set to this value. */
+ const char *name;
+};
+
+struct gdbjit_symtab
+{
+ struct gdbjit_block *blocks;
+ struct linetable *linetable;
+ int nblocks;
+
+ const char *file_name;
+};
+
+struct jit_dbg_reader_data
+{
+ struct objfile **objf;
+};
+
+static int
+jit_target_read_impl (void *target_mem, void *gdb_buf, int len)
+{
+ return target_read_memory ((CORE_ADDR) target_mem, gdb_buf, len);
+}
+
+static struct gdbjit_symtab *
+jit_symtab_open_impl (struct gdbjit_symtab_callbacks *cb, const char *file_name)
+{
+ struct gdbjit_symtab *ret = XZALLOC (struct gdbjit_symtab);
+ ret->file_name = xstrdup (file_name);
+ return ret;
+}
+
+/* Returns true if the block corrensponding to old should be placed before the
+ block corrensponding to new in the final blockvector. */
+static int
+compare_block (struct gdbjit_block *old, struct gdbjit_block *new)
+{
+ if (old == NULL)
+ return 1;
+ if (old->begin < new->begin)
+ return 1;
+ else if (old->begin == new->begin)
+ {
+ if (old->end > new->end)
+ return 1;
+ else
+ return 0;
+ }
+ else
+ return 0;
+}
+
+static struct gdbjit_block *
+jit_new_block_impl (struct gdbjit_symtab_callbacks *cb,
+ struct gdbjit_symtab *symtab,
+ struct gdbjit_block *parent,
+ void *begin, void *end, const char *name)
+{
+ struct gdbjit_block *block = XZALLOC (struct gdbjit_block);
+
+ (void) cb;
+
+ block->next = symtab->blocks;
+ block->begin = (CORE_ADDR) begin;
+ block->end = (CORE_ADDR) end;
+ block->name = name ? xstrdup (name) : NULL;
+ block->parent = parent;
+
+ /* Ensure that the blocks are inserted in the correct (reverse of the order
+ expected by blockvector). */
+ if (compare_block (symtab->blocks, block))
+ {
+ symtab->blocks = block;
+ }
+ else
+ {
+ struct gdbjit_block *i = symtab->blocks;
+
+ for (;; i = i->next)
+ {
+ /* Guranteed to terminate, since compare_block (NULL, _) returns 1 */
+ if (compare_block (i->next, block))
+ {
+ block->next = i->next;
+ i->next = block;
+ break;
+ }
+ }
+ }
+ symtab->nblocks++;
+
+ return block;
+}
+
+static void
+jit_symtab_add_line_mapping_impl (struct gdbjit_symtab_callbacks *cb,
+ struct gdbjit_symtab *stab,
+ int nlines,
+ struct gdbjit_line_mapping *map)
+{
+ int i;
+ /* Must copy */
+ if (!nlines)
+ return;
+
+ stab->linetable = xmalloc (sizeof (struct linetable) + (nlines - 1) *
+ sizeof (struct linetable_entry));
+ stab->linetable->nitems = nlines;
+ for (i = 0; i < nlines; i++)
+ {
+ stab->linetable->item [i].pc = (CORE_ADDR) map[i].pc;
+ stab->linetable->item [i].line = map[i].line;
+ }
+}
+
+static void
+jit_symtab_close_impl (struct gdbjit_symtab_callbacks *cb,
+ struct gdbjit_symtab *stab)
+{
+ struct jit_dbg_reader_data *dat = cb->private;
+ struct symtab *symtab;
+ struct gdbjit_block *blck_iter, *blck_iter_tmp;
+ struct block *block_iter;
+ struct objfile *objfile;
+ int actual_nblocks = FIRST_LOCAL_BLOCK + stab->nblocks, i;
+ CORE_ADDR begin, end;
+
+ if (*dat->objf == NULL)
+ {
+ objfile = allocate_objfile (NULL, 0);
+ *dat->objf = objfile;
+ objfile->gdbarch = target_gdbarch;
+ objfile->msymbols = obstack_alloc (&objfile->objfile_obstack,
+ sizeof (struct minimal_symbol));
+ objfile->msymbols[0].ginfo.name = NULL;
+ objfile->msymbols[0].ginfo.value.address = 0;
+ objfile->name = xstrdup ("JIT");
+ }
+ else
+ objfile = *dat->objf;
+
+ symtab = allocate_symtab (stab->file_name, objfile);
+ symtab->dirname = NULL; /* JIT compilers compile in memory */
+
+ if (stab->linetable) {
+ int size = (stab->linetable->nitems - 1) * sizeof (struct linetable_entry) +
+ sizeof (struct linetable);
+ LINETABLE (symtab) = obstack_alloc (&objfile->objfile_obstack, size);
+ memcpy (LINETABLE (symtab), stab->linetable, size);
+ } else {
+ LINETABLE (symtab) = NULL;
+ }
+
+ symtab->blockvector = obstack_alloc (&objfile->objfile_obstack,
+ (sizeof (struct blockvector)
+ + (actual_nblocks - 1) *
+ sizeof (struct block *)));
+
+ /* (begin, end) will contain the PC range this entire blockvector spans. */
+ symtab->primary = 1;
+ BLOCKVECTOR_MAP (symtab->blockvector) = NULL;
+ begin = stab->blocks->begin;
+ end = stab->blocks->end;
+ BLOCKVECTOR_NBLOCKS (symtab->blockvector) = actual_nblocks;
+
+ for (i = (actual_nblocks - 1), blck_iter = stab->blocks;
+ i >= FIRST_LOCAL_BLOCK; i--)
+ {
+ struct block *bl = allocate_block (&objfile->objfile_obstack);
+ struct symbol *block_name = obstack_alloc (&objfile->objfile_obstack,
+ sizeof (struct symbol));
+
+ BLOCK_DICT (bl) = dict_create_linear (&objfile->objfile_obstack, NULL);
+ BLOCK_START (bl) = (CORE_ADDR) blck_iter->begin;
+ BLOCK_END (bl) = (CORE_ADDR) blck_iter->end;
+ BLOCK_FUNCTION (bl) = block_name;
+
+ memset (block_name, 0, sizeof (struct symbol));
+ SYMBOL_DOMAIN (block_name) = VAR_DOMAIN;
+ SYMBOL_CLASS (block_name) = LOC_BLOCK;
+ block_name->symtab = symtab;
+ SYMBOL_BLOCK_VALUE (block_name) = bl;
+
+ block_name->ginfo.name = obstack_alloc (&objfile->objfile_obstack,
+ 1 + strlen (blck_iter->name));
+ strcpy (block_name->ginfo.name, blck_iter->name);
+ BLOCK_FUNCTION (bl) = block_name;
+
+ BLOCKVECTOR_BLOCK (symtab->blockvector, i) = bl;
+ if (begin < (long) blck_iter->begin)
+ begin = (long) blck_iter->begin;
+ if (end > (long) blck_iter->end)
+ end = (long) blck_iter->end;
+ }
+
+ blck_iter = blck_iter->next;
+
+ /* Now add the special blocks. */
+ block_iter = NULL;
+ for (i = 0; i < FIRST_LOCAL_BLOCK; i++)
+ {
+ struct block *bl = allocate_block (&objfile->objfile_obstack);
+ BLOCK_DICT (bl) = dict_create_linear (&objfile->objfile_obstack, NULL);
+ BLOCK_SUPERBLOCK (bl) = block_iter;
+ block_iter = bl;
+
+ BLOCK_START (bl) = (CORE_ADDR) begin;
+ BLOCK_END (bl) = (CORE_ADDR) end;
+
+ BLOCKVECTOR_BLOCK (symtab->blockvector, i) = bl;
+ }
+
+ /* Fill up the superblock fields. */
+ for (blck_iter = stab->blocks; blck_iter; blck_iter = blck_iter->next)
+ {
+ if (blck_iter->parent != NULL)
+ BLOCK_SUPERBLOCK (blck_iter->real_block) =
+ blck_iter->parent->real_block;
+ }
+
+ /* Free memory. */
+ blck_iter = stab->blocks;
+ for (blck_iter = stab->blocks, blck_iter_tmp = blck_iter->next;
+ blck_iter; blck_iter = blck_iter_tmp)
+ {
+ xfree (blck_iter);
+ }
+}
+
+static int
+jit_try_read_symtab (struct jit_inferior_data *inf_data,
+ CORE_ADDR target_mem, long sz)
+{
+ void *gdb_mem;
+ int status = 0;
+ struct jit_dbg_reader *i;
+ struct jit_dbg_reader_data priv_data;
+ struct gdbjit_symtab_callbacks callbacks =
+ {
+ jit_symtab_open_impl,
+ jit_new_block_impl,
+ jit_symtab_add_line_mapping_impl,
+ jit_target_read_impl,
+ jit_symtab_close_impl,
+
+ &priv_data
+ };
+
+ if (!inf_data->reader)
+ return 0;
+
+ priv_data.objf = &inf_data->jit_objfile;
+
+ gdb_mem = xmalloc (sz);
+ if (target_read_memory (target_mem, gdb_mem, sz))
+ {
+ status = 0;
+ goto cleanup;
+ }
+
+ if (inf_data->reader->read (inf_data->reader->private_data, &callbacks,
+ gdb_mem, sz) == GDB_JIT_SUCCESS)
+ {
+ status = 1;
+ goto cleanup;
+ }
+
+ cleanup:
+ xfree (gdb_mem);
+ return status;
+}
+
/* This function registers code associated with a JIT code entry. It uses the
pointer and size pair in the entry to read the symbol file from the remote
and then calls symbol_file_add_from_local_memory to add it as though it were
@@ -242,14 +639,9 @@ static void
jit_register_code (struct gdbarch *gdbarch,
CORE_ADDR entry_addr, struct jit_code_entry *code_entry)
{
- bfd *nbfd;
- struct section_addr_info *sai;
- struct bfd_section *sec;
struct objfile *objfile;
- struct cleanup *old_cleanups, *my_cleanups;
- int i;
- const struct bfd_arch_info *b;
- CORE_ADDR *entry_addr_ptr;
+ int i, success;
+ struct jit_inferior_data *inf_data = get_jit_inferior_data ();

if (jit_debug)
fprintf_unfiltered (gdb_stdlog,
@@ -258,53 +650,68 @@ jit_register_code (struct gdbarch *gdbarch,
paddress (gdbarch, code_entry->symfile_addr),
pulongest (code_entry->symfile_size));

- nbfd = bfd_open_from_target_memory (code_entry->symfile_addr,
- code_entry->symfile_size, gnutarget);
- old_cleanups = make_cleanup_bfd_close (nbfd);
-
- /* Check the format. NOTE: This initializes important data that GDB uses!
- We would segfault later without this line. */
- if (!bfd_check_format (nbfd, bfd_object))
+ if (jit_try_read_symtab (inf_data, code_entry->symfile_addr,
+ code_entry->symfile_size))
{
- printf_unfiltered (_("\
+ objfile = inf_data->jit_objfile;
+ }
+ else
+ {
+ struct cleanup *old_cleanups;
+ bfd *nbfd;
+ struct section_addr_info *sai;
+ struct bfd_section *sec;
+ const struct bfd_arch_info *b;
+ CORE_ADDR *entry_addr_ptr;
+
+ nbfd = bfd_open_from_target_memory (code_entry->symfile_addr,
+ code_entry->symfile_size, gnutarget);
+ old_cleanups = make_cleanup_bfd_close (nbfd);
+
+ /* Check the format. NOTE: This initializes important data that GDB uses!
+ We would segfault later without this line. */
+ if (!bfd_check_format (nbfd, bfd_object))
+ {
+ printf_unfiltered (_("\
JITed symbol file is not an object file, ignoring it.\n"));
- do_cleanups (old_cleanups);
- return;
+ do_cleanups (old_cleanups);
+ return;
+ }
+
+ /* Check bfd arch. */
+ b = gdbarch_bfd_arch_info (gdbarch);
+ if (b->compatible (b, bfd_get_arch_info (nbfd)) != b)
+ warning (_("JITed object file architecture %s is not compatible "
+ "with target architecture %s."), bfd_get_arch_info
+ (nbfd)->printable_name, b->printable_name);
+
+ /* Read the section address information out of the symbol file. Since the
+ file is generated by the JIT at runtime, it should all of the absolute
+ addresses that we care about. */
+ sai = alloc_section_addr_info (bfd_count_sections (nbfd));
+ make_cleanup_free_section_addr_info (sai);
+ i = 0;
+ for (sec = nbfd->sections; sec != NULL; sec = sec->next)
+ if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0)
+ {
+ /* We assume that these virtual addresses are absolute, and do not
+ treat them as offsets. */
+ sai->other[i].addr = bfd_get_section_vma (nbfd, sec);
+ sai->other[i].name = xstrdup (bfd_get_section_name (nbfd, sec));
+ sai->other[i].sectindex = sec->index;
+ ++i;
+ }
+
+ /* This call takes ownership of sai. */
+ objfile = symbol_file_add_from_bfd (nbfd, 0, sai, OBJF_SHARED, NULL);
+
+ /* Remember a mapping from entry_addr to objfile. */
+ entry_addr_ptr = xmalloc (sizeof (CORE_ADDR));
+ *entry_addr_ptr = entry_addr;
+ set_objfile_data (objfile, jit_objfile_data, entry_addr_ptr);
+
+ discard_cleanups (old_cleanups);
}
-
- /* Check bfd arch. */
- b = gdbarch_bfd_arch_info (gdbarch);
- if (b->compatible (b, bfd_get_arch_info (nbfd)) != b)
- warning (_("JITed object file architecture %s is not compatible "
- "with target architecture %s."), bfd_get_arch_info
- (nbfd)->printable_name, b->printable_name);
-
- /* Read the section address information out of the symbol file. Since the
- file is generated by the JIT at runtime, it should all of the absolute
- addresses that we care about. */
- sai = alloc_section_addr_info (bfd_count_sections (nbfd));
- make_cleanup_free_section_addr_info (sai);
- i = 0;
- for (sec = nbfd->sections; sec != NULL; sec = sec->next)
- if ((bfd_get_section_flags (nbfd, sec) & (SEC_ALLOC|SEC_LOAD)) != 0)
- {
- /* We assume that these virtual addresses are absolute, and do not
- treat them as offsets. */
- sai->other[i].addr = bfd_get_section_vma (nbfd, sec);
- sai->other[i].name = xstrdup (bfd_get_section_name (nbfd, sec));
- sai->other[i].sectindex = sec->index;
- ++i;
- }
-
- /* This call takes ownership of sai. */
- objfile = symbol_file_add_from_bfd (nbfd, 0, sai, OBJF_SHARED, NULL);
-
- /* Remember a mapping from entry_addr to objfile. */
- entry_addr_ptr = xmalloc (sizeof (CORE_ADDR));
- *entry_addr_ptr = entry_addr;
- set_objfile_data (objfile, jit_objfile_data, entry_addr_ptr);
-
- discard_cleanups (old_cleanups);
}

/* This function unregisters JITed code and frees the corresponding
@@ -385,6 +792,8 @@ jit_inferior_init (struct gdbarch *gdbarch)
if (jit_breakpoint_re_set_internal (gdbarch, inf_data) != 0)
return;

+ inf_data->reader = jit_dbg_reader_load ();
+
if (inf_data->descriptor_addr == 0)
{
struct minimal_symbol *desc_symbol;
@@ -464,6 +873,11 @@ jit_reset_inferior_data_and_breakpoints (void)
/* Remove any existing JIT breakpoint(s). */
remove_jit_event_breakpoints ();

+ /* Destroy JIT reader objects. */
+ jit_dbg_reader_destroy (inf_data->reader);
+ if (inf_data->jit_objfile)
+ free_objfile (inf_data->jit_objfile);
+
jit_inferior_init (target_gdbarch);
}

@@ -484,6 +898,12 @@ jit_inferior_exit_hook (struct inferior *inf)
{
struct objfile *objf;
struct objfile *temp;
+ struct jit_inferior_data *inf_data;
+
+ inf_data = inferior_data (inf, jit_inferior_data);
+ jit_dbg_reader_destroy (inf_data->reader);
+ if (inf_data->jit_objfile)
+ free_objfile (inf_data->jit_objfile);

ALL_OBJFILES_SAFE (objf, temp)
if (objfile_data (objf, jit_objfile_data) != NULL)
--
1.7.5.3