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* [PATCH] [GOLD] Add plugin API for processing plugin-added input files
@ 2017-08-25  5:49 Stephen Crane
  2017-09-14 22:16 ` Stephen Crane
  0 siblings, 1 reply; 15+ messages in thread
From: Stephen Crane @ 2017-08-25  5:49 UTC (permalink / raw)
  To: binutils

I have a gold plugin that needs to call the
unique_segment_for_sections interface for sections in an input file
created by a plugin. Specifically, I want to assign a section created
during LTO to a unique output segment with special flags. Here is a
patch that allows this use case by adding a callback that gives the
plugin the opportunity to get an input handle for plugin-created input
files. Could this be added to the gold plugin API? Is there a better
way to do this?

Thanks,
Stephen Crane



Gold plugins may wish to further process an input file added by a plugin. For
example, the plugin may need to assign a unique segment for sections in a
plugin-generated input file. This patch adds a plugin callback that is called
when reading symbols from a new input file added after the all_symbols_read
event (i.e. an input file added by a plugin).
---
 gold/plugin.cc       | 63 +++++++++++++++++++++++++++++++++++++++-------------
 gold/plugin.h        | 19 ++++++++++++++++
 include/plugin-api.h | 26 +++++++++++++++++++++-
 3 files changed, 92 insertions(+), 16 deletions(-)

diff --git a/gold/plugin.cc b/gold/plugin.cc
index c051805cec..fcd913b34e 100644
--- a/gold/plugin.cc
+++ b/gold/plugin.cc
@@ -167,6 +167,9 @@ static enum ld_plugin_status
 get_input_section_size(const struct ld_plugin_section section,
                        uint64_t* secsize);

+static enum ld_plugin_status
+register_new_input(ld_plugin_new_input_handler handler);
+
 };

 #endif // ENABLE_PLUGINS
@@ -211,7 +214,7 @@ Plugin::load()
   sscanf(ver, "%d.%d", &major, &minor);

   // Allocate and populate a transfer vector.
-  const int tv_fixed_size = 29;
+  const int tv_fixed_size = 30;

   int tv_size = this->args_.size() + tv_fixed_size;
   ld_plugin_tv* tv = new ld_plugin_tv[tv_size];
@@ -345,6 +348,10 @@ Plugin::load()
   tv[i].tv_tag = LDPT_GET_INPUT_SECTION_SIZE;
   tv[i].tv_u.tv_get_input_section_size = get_input_section_size;

+  ++i;
+  tv[i].tv_tag = LDPT_REGISTER_NEW_INPUT_HOOK;
+  tv[i].tv_u.tv_register_new_input = register_new_input;
+
   ++i;
   tv[i].tv_tag = LDPT_NULL;
   tv[i].tv_u.tv_val = 0;
@@ -383,6 +390,15 @@ Plugin::all_symbols_read()
     (*this->all_symbols_read_handler_)();
 }

+// Call the new_input handler.
+
+inline void
+Plugin::new_input(struct ld_plugin_input_file* plugin_input_file)
+{
+  if (this->new_input_handler_ != NULL)
+    (*this->new_input_handler_)(plugin_input_file);
+}
+
 // Call the cleanup handler.

 inline void
@@ -476,8 +492,6 @@ Plugin_manager::claim_file(Input_file* input_file,
off_t offset,

   gold_assert(lock_initialized);
   Hold_lock hl(*this->lock_);
-  if (this->in_replacement_phase_)
-    return NULL;

   unsigned int handle = this->objects_.size();
   this->input_file_ = input_file;
@@ -494,19 +508,28 @@ Plugin_manager::claim_file(Input_file*
input_file, off_t offset,
        this->current_ != this->plugins_.end();
        ++this->current_)
     {
-      if ((*this->current_)->claim_file(&this->plugin_input_file_))
+      // If we aren't yet in replacement phase, allow plugins to claim input
+      // files, otherwise notify the plugin of the new input file, if needed.
+      if (!this->in_replacement_phase_)
         {
-      this->any_claimed_ = true;
-      this->in_claim_file_handler_ = false;
-
-          if (this->objects_.size() > handle
-              && this->objects_[handle]->pluginobj() != NULL)
-            return this->objects_[handle]->pluginobj();
-
-          // If the plugin claimed the file but did not call the
-          // add_symbols callback, we need to create the Pluginobj now.
-          Pluginobj* obj = this->make_plugin_object(handle);
-          return obj;
+          if ((*this->current_)->claim_file(&this->plugin_input_file_))
+            {
+              this->any_claimed_ = true;
+              this->in_claim_file_handler_ = false;
+
+              if (this->objects_.size() > handle
+                  && this->objects_[handle]->pluginobj() != NULL)
+                return this->objects_[handle]->pluginobj();
+
+              // If the plugin claimed the file but did not call the
+              // add_symbols callback, we need to create the Pluginobj now.
+              Pluginobj* obj = this->make_plugin_object(handle);
+              return obj;
+            }
+        }
+      else
+        {
+          (*this->current_)->new_input(&this->plugin_input_file_);
         }
     }

@@ -1903,6 +1926,16 @@ unique_segment_for_sections(const char* segment_name,
   return LDPS_OK;
 }

+// Register a new_input handler.
+
+static enum ld_plugin_status
+register_new_input(ld_plugin_new_input_handler handler)
+{
+  gold_assert(parameters->options().has_plugins());
+  parameters->options().plugins()->set_new_input_handler(handler);
+  return LDPS_OK;
+}
+
 #endif // ENABLE_PLUGINS

 // Allocate a Pluginobj object of the appropriate size and endianness.
diff --git a/gold/plugin.h b/gold/plugin.h
index 7658668502..d591d26821 100644
--- a/gold/plugin.h
+++ b/gold/plugin.h
@@ -60,6 +60,7 @@ class Plugin
       claim_file_handler_(NULL),
       all_symbols_read_handler_(NULL),
       cleanup_handler_(NULL),
+      new_input_handler_(NULL),
       cleanup_done_(false)
   { }

@@ -78,6 +79,10 @@ class Plugin
   void
   all_symbols_read();

+  // Call the new_input handler.
+  void
+  new_input(struct ld_plugin_input_file* plugin_input_file);
+
   // Call the cleanup handler.
   void
   cleanup();
@@ -97,6 +102,11 @@ class Plugin
   set_cleanup_handler(ld_plugin_cleanup_handler handler)
   { this->cleanup_handler_ = handler; }

+  // Register a new_input handler.
+  void
+  set_new_input_handler(ld_plugin_new_input_handler handler)
+  { this->new_input_handler_ = handler; }
+
   // Add an argument
   void
   add_option(const char* arg)
@@ -118,6 +128,7 @@ class Plugin
   ld_plugin_claim_file_handler claim_file_handler_;
   ld_plugin_all_symbols_read_handler all_symbols_read_handler_;
   ld_plugin_cleanup_handler cleanup_handler_;
+  ld_plugin_new_input_handler new_input_handler_;
   // TRUE if the cleanup handlers have been called.
   bool cleanup_done_;
 };
@@ -218,6 +229,14 @@ class Plugin_manager
     (*this->current_)->set_all_symbols_read_handler(handler);
   }

+  // Register a new_input handler.
+  void
+  set_new_input_handler(ld_plugin_new_input_handler handler)
+  {
+    gold_assert(this->current_ != plugins_.end());
+    (*this->current_)->set_new_input_handler(handler);
+  }
+
   // Register a claim-file handler.
   void
   set_cleanup_handler(ld_plugin_cleanup_handler handler)
diff --git a/include/plugin-api.h b/include/plugin-api.h
index 3a3e8b456d..0fbd6fed9e 100644
--- a/include/plugin-api.h
+++ b/include/plugin-api.h
@@ -365,6 +365,28 @@ enum ld_plugin_status
 (*ld_plugin_get_input_section_size) (const struct ld_plugin_section section,
                                      uint64_t *secsize);

+typedef
+enum ld_plugin_status
+(*ld_plugin_new_input_handler) (const struct ld_plugin_input_file *file);
+
+/* The linker's interface for registering the "new_input" handler. This handler
+   will be notified when a new input file has been added after the
+   all_symbols_read event, allowing the plugin to, for example, set a unique
+   segment for sections in plugin-generated input files. */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_register_new_input) (ld_plugin_new_input_handler handler);
+
+/* The linker's interface for getting an input file handle for a new input file
+   added by a plugin.  */
+
+typedef
+enum ld_plugin_status
+(*ld_plugin_get_input_handle) (const char *pathname,
+                               void **handle);
+
+
 enum ld_plugin_level
 {
   LDPL_INFO,
@@ -407,7 +429,8 @@ enum ld_plugin_tag
   LDPT_UNIQUE_SEGMENT_FOR_SECTIONS = 27,
   LDPT_GET_SYMBOLS_V3 = 28,
   LDPT_GET_INPUT_SECTION_ALIGNMENT = 29,
-  LDPT_GET_INPUT_SECTION_SIZE = 30
+  LDPT_GET_INPUT_SECTION_SIZE = 30,
+  LDPT_REGISTER_NEW_INPUT_HOOK = 31
 };

 /* The plugin transfer vector.  */
@@ -441,6 +464,7 @@ struct ld_plugin_tv
     ld_plugin_unique_segment_for_sections tv_unique_segment_for_sections;
     ld_plugin_get_input_section_alignment tv_get_input_section_alignment;
     ld_plugin_get_input_section_size tv_get_input_section_size;
+    ld_plugin_register_new_input tv_register_new_input;
   } tv_u;
 };

-- 
2.14.1

^ permalink raw reply	[flat|nested] 15+ messages in thread
* Re: [PATCH 2/2] [GOLD] Add plugin API for processing plugin-added input files
@ 2017-09-26  1:46 Stephen Crane
  2017-10-11  7:09 ` Sriraman Tallam via binutils
  0 siblings, 1 reply; 15+ messages in thread
From: Stephen Crane @ 2017-09-26  1:46 UTC (permalink / raw)
  To: Cary Coutant; +Cc: Binutils, Sriraman Tallam

Here is a gold test for the new API. I've included just the test in
this patch, hopefully that's ok. I wasn't sure if it was better to
have a separate shell script for the new test or combine it with
plugin_final_layout.sh since they are testing for the same result. If
you have any opinions on that, I'm happy to change it.

New test exercises the new input hook by generating a new file using the basic
test plugin and then reordering its sections and assigning sections to unique
segments in a second plugin.

gold/ChangeLog:
2017-09-25  Stephen Crane  <sjc@immunant.com.com>

    * testsuite/plugin_new_section_layout.c: New plugin to test
    new_input plugin API.
    * testsuite/plugin_layout_new_file.sh: New test shell script based
    on plugin_final_layout.sh.
    * testsuite/Makefile.am (plugin_layout_new_file): New test case.
    * testsuite/Makefile.in: Regenerate.

---
 gold/testsuite/Makefile.am                 |  19 +++
 gold/testsuite/Makefile.in                 |  27 ++++-
 gold/testsuite/plugin_layout_new_file.sh   |  91 +++++++++++++++
 gold/testsuite/plugin_new_section_layout.c | 181 +++++++++++++++++++++++++++++
 5 files changed, 324 insertions(+), 3 deletions(-)
 create mode 100755 gold/testsuite/plugin_layout_new_file.sh
 create mode 100644 gold/testsuite/plugin_new_section_layout.c

diff --git a/gold/testsuite/Makefile.am b/gold/testsuite/Makefile.am
index 26ee77abcc..e2de96c69b 100644
--- a/gold/testsuite/Makefile.am
+++ b/gold/testsuite/Makefile.am
@@ -2390,6 +2390,25 @@ plugin_section_alignment.so:
plugin_section_alignment.o gcctestdir/ld
 plugin_section_alignment.o: plugin_section_alignment.cc
  $(CXXCOMPILE) -O0 -c -fpic -o $@ $<

+check_SCRIPTS += plugin_layout_new_file.sh
+check_DATA += plugin_layout_new_file.stdout
plugin_layout_new_file_readelf.stdout
+MOSTLYCLEANFILES += plugin_layout_new_file
+plugin_layout_new_file.o: plugin_final_layout.cc
+ $(CXXCOMPILE) -O0 -c -ffunction-sections  -fdata-sections -g -o $@ $<
+plugin_layout_new_file.o.syms: plugin_layout_new_file.o
+ $(TEST_READELF) -sW $< >$@ 2>/dev/null
+plugin_layout_new_file: plugin_layout_new_file.o.syms plugin_test.so
plugin_new_section_layout.so gcctestdir/ld
+ $(CXXLINK) -Bgcctestdir/ -Wl,--plugin,"./plugin_test.so"
-Wl,--plugin,"./plugin_new_section_layout.so"
plugin_layout_new_file.o.syms
+plugin_layout_new_file.stdout: plugin_layout_new_file
+ $(TEST_NM) -n --synthetic plugin_layout_new_file >
plugin_layout_new_file.stdout
+plugin_layout_new_file_readelf.stdout: plugin_layout_new_file
+ $(TEST_READELF) -Wl plugin_layout_new_file >
plugin_layout_new_file_readelf.stdout
+
+plugin_new_section_layout.so: plugin_new_section_layout.o gcctestdir/ld
+ $(LINK) -Bgcctestdir/ -shared plugin_new_section_layout.o
+plugin_new_section_layout.o: plugin_new_section_layout.c
+ $(COMPILE) -O0 -c -fpic -o $@ $<
+
 endif PLUGINS

 check_PROGRAMS += exclude_libs_test
diff --git a/gold/testsuite/Makefile.in b/gold/testsuite/Makefile.in
index eae68b56cb..9bab136100 100644
--- a/gold/testsuite/Makefile.in
+++ b/gold/testsuite/Makefile.in
@@ -570,12 +570,16 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2)
$(am__EXEEXT_3) \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@@TLS_TRUE@am__append_51 =
plugin_test_tls.err
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@am__append_52 = unused.c \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_final_layout \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_layout_with_alignment
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_layout_with_alignment \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_layout_new_file
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@am__append_53 =
plugin_final_layout.sh \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_layout_with_alignment.sh
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_layout_with_alignment.sh \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_layout_new_file.sh
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@am__append_54 =
plugin_final_layout.stdout \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@
plugin_final_layout_readelf.stdout \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@
plugin_layout_with_alignment.stdout
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@
plugin_layout_with_alignment.stdout \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_layout_new_file.stdout \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@
plugin_layout_new_file_readelf.stdout
 @GCC_TRUE@@NATIVE_LINKER_TRUE@am__append_55 = exclude_libs_test \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@ local_labels_test \
 @GCC_TRUE@@NATIVE_LINKER_TRUE@ discard_locals_test
@@ -5220,6 +5224,8 @@ plugin_final_layout.sh.log: plugin_final_layout.sh
  @p='plugin_final_layout.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst"
$(am__check_post)
 plugin_layout_with_alignment.sh.log: plugin_layout_with_alignment.sh
  @p='plugin_layout_with_alignment.sh'; $(am__check_pre)
$(LOG_COMPILE) "$$tst" $(am__check_post)
+plugin_layout_new_file.sh.log: plugin_layout_new_file.sh
+ @p='plugin_layout_new_file.sh'; $(am__check_pre) $(LOG_COMPILE)
"$$tst" $(am__check_post)
 exclude_libs_test.sh.log: exclude_libs_test.sh
  @p='exclude_libs_test.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst"
$(am__check_post)
 discard_locals_test.sh.log: discard_locals_test.sh
@@ -6978,6 +6984,21 @@ uninstall-am:
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(CXXLINK) -Bgcctestdir/
-shared plugin_section_alignment.o
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_section_alignment.o:
plugin_section_alignment.cc
 @GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(CXXCOMPILE) -O0 -c
-fpic -o $@ $<
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_layout_new_file.o:
plugin_final_layout.cc
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(CXXCOMPILE) -O0 -c
-ffunction-sections  -fdata-sections -g -o $@ $<
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_layout_new_file.o.syms:
plugin_layout_new_file.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(TEST_READELF) -sW $<
>$@ 2>/dev/null
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_layout_new_file:
plugin_layout_new_file.o.syms plugin_test.so
plugin_new_section_layout.so gcctestdir/ld
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(CXXLINK) -Bgcctestdir/
-Wl,--plugin,"./plugin_test.so"
-Wl,--plugin,"./plugin_new_section_layout.so"
plugin_layout_new_file.o.syms
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_layout_new_file.stdout:
plugin_layout_new_file
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(TEST_NM) -n
--synthetic plugin_layout_new_file > plugin_layout_new_file.stdout
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_layout_new_file_readelf.stdout:
plugin_layout_new_file
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(TEST_READELF) -Wl
plugin_layout_new_file > plugin_layout_new_file_readelf.stdout
+
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_new_section_layout.so:
plugin_new_section_layout.o gcctestdir/ld
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(LINK) -Bgcctestdir/
-shared plugin_new_section_layout.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_new_section_layout.o:
plugin_new_section_layout.c
+@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(COMPILE) -O0 -c -fpic -o $@ $<
 @GCC_TRUE@@NATIVE_LINKER_TRUE@exclude_libs_test.syms: exclude_libs_test
 @GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) -sW $< >$@ 2>/dev/null
 @GCC_TRUE@@NATIVE_LINKER_TRUE@libexclude_libs_test_1.a: exclude_libs_test_1.o
diff --git a/gold/testsuite/plugin_layout_new_file.sh
b/gold/testsuite/plugin_layout_new_file.sh
new file mode 100755
index 0000000000..09885e67f0
--- /dev/null
+++ b/gold/testsuite/plugin_layout_new_file.sh
@@ -0,0 +1,91 @@
+#!/bin/sh
+
+# plugin_new_section_layout.sh -- test
+
+# Copyright (C) 2011-2017 Free Software Foundation, Inc.
+# Written by Sriraman Tallam <tmsriram@google.com>.
+
+# This file is part of gold.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+# The goal of this program is to verify if plugin section reordering and
+# assignment works for plugin-created object files.  File final_layout.cc is in
+# this test.
+
+
+set -e
+
+check()
+{
+    awk "
+BEGIN { saw1 = 0; saw2 = 0; err = 0; }
+/.*$2\$/ { saw1 = 1; }
+/.*$3\$/ {
+     saw2 = 1;
+     if (!saw1)
+       {
+   printf \"layout of $2 and $3 is not right\\n\";
+   err = 1;
+   exit 1;
+       }
+    }
+END {
+      if (!saw1 && !err)
+        {
+   printf \"did not see $2\\n\";
+   exit 1;
+ }
+      if (!saw2 && !err)
+ {
+   printf \"did not see $3\\n\";
+   exit 1;
+ }
+    }" $1
+}
+
+# With readelf -l, an ELF Section to Segment mapping is printed as :
+##############################################
+#  Section to Segment mapping:
+#  Segment Sections...
+#  ...
+#     0x     .text.plugin_created_unique
+#  ...
+##############################################
+# Check of .text.plugin_created_unique is the only section in the segment.
+check_unique_segment()
+{
+    awk "
+BEGIN { saw_section = 0; saw_unique = 0; }
+/$2/ { saw_section = 1; }
+/[ ]*0[0-9][ ]*$2[ ]*\$/ { saw_unique = 1; }
+END {
+      if (!saw_section)
+ {
+   printf \"Section $2 not seen in output\\n\";
+   exit 1;
+ }
+      else if (!saw_unique)
+ {
+   printf \"Unique segment not seen for: $2\\n\";
+   exit 1;
+ }
+    }" $1
+}
+
+check plugin_layout_new_file.stdout "_Z3foov" "_Z3barv"
+check plugin_layout_new_file.stdout "_Z3barv" "_Z3bazv"
+check_unique_segment plugin_layout_new_file_readelf.stdout
".text.plugin_created_unique"
diff --git a/gold/testsuite/plugin_new_section_layout.c
b/gold/testsuite/plugin_new_section_layout.c
new file mode 100644
index 0000000000..f27ad4c530
--- /dev/null
+++ b/gold/testsuite/plugin_new_section_layout.c
@@ -0,0 +1,181 @@
+/* plugin_new_section_layout.c -- Simple plugin to reorder function sections in
+   plugin-generated objects
+
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   Written by Stephen Crane <sjc@immunant.com>.
+
+   This file is part of gold.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+   MA 02110-1301, USA.  */
+
+/* This plugin tests the new_input API of the linker plugin interface that
+ * allows plugins to modify section layout and assign sections to segments for
+ * sections in plugin-generated object files. It assumes that another plugin is
+ * also in use which will add new files. In practice a plugin is likely to
+ * generate new input files itself in all_symbols_read and want to
+ * reorder/assign sections for these files in the new_input_hook callback. */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include "plugin-api.h"
+#include "elf/common.h"
+
+static ld_plugin_get_input_section_count get_input_section_count = NULL;
+static ld_plugin_get_input_section_type get_input_section_type = NULL;
+static ld_plugin_get_input_section_name get_input_section_name = NULL;
+static ld_plugin_update_section_order update_section_order = NULL;
+static ld_plugin_allow_section_ordering allow_section_ordering = NULL;
+static ld_plugin_allow_unique_segment_for_sections
+    allow_unique_segment_for_sections = NULL;
+static ld_plugin_unique_segment_for_sections
unique_segment_for_sections = NULL;
+
+enum ld_plugin_status onload(struct ld_plugin_tv *tv);
+enum ld_plugin_status new_input_hook(const struct ld_plugin_input_file *file);
+
+/* Plugin entry point.  */
+enum ld_plugin_status
+onload(struct ld_plugin_tv *tv)
+{
+  struct ld_plugin_tv *entry;
+  for (entry = tv; entry->tv_tag != LDPT_NULL; ++entry)
+    {
+      switch (entry->tv_tag)
+        {
+        case LDPT_GET_INPUT_SECTION_COUNT:
+          get_input_section_count = *entry->tv_u.tv_get_input_section_count;
+          break;
+        case LDPT_GET_INPUT_SECTION_TYPE:
+          get_input_section_type = *entry->tv_u.tv_get_input_section_type;
+          break;
+        case LDPT_GET_INPUT_SECTION_NAME:
+          get_input_section_name = *entry->tv_u.tv_get_input_section_name;
+          break;
+ case LDPT_UPDATE_SECTION_ORDER:
+   update_section_order = *entry->tv_u.tv_update_section_order;
+   break;
+ case LDPT_ALLOW_SECTION_ORDERING:
+   allow_section_ordering = *entry->tv_u.tv_allow_section_ordering;
+   break;
+ case LDPT_ALLOW_UNIQUE_SEGMENT_FOR_SECTIONS:
+   allow_unique_segment_for_sections
+       = *entry->tv_u.tv_allow_unique_segment_for_sections;
+   break;
+ case LDPT_UNIQUE_SEGMENT_FOR_SECTIONS:
+   unique_segment_for_sections
+       = *entry->tv_u.tv_unique_segment_for_sections;
+   break;
+        case LDPT_REGISTER_NEW_INPUT_HOOK:
+          assert((*entry->tv_u.tv_register_new_input) (new_input_hook)
+ == LDPS_OK);
+          break;
+        default:
+          break;
+        }
+    }
+
+  if (get_input_section_count == NULL
+      || get_input_section_type == NULL
+      || get_input_section_name == NULL
+      || update_section_order == NULL
+      || allow_section_ordering == NULL
+      || allow_unique_segment_for_sections == NULL
+      || unique_segment_for_sections == NULL)
+    {
+      fprintf(stderr, "Some interfaces are missing\n");
+      return LDPS_ERR;
+    }
+
+  /* Inform the linker to prepare for section reordering.  */
+  (*allow_section_ordering)();
+  /* Inform the linker to prepare to map some sections to unique
+     segments.  */
+  (*allow_unique_segment_for_sections)();
+
+  return LDPS_OK;
+}
+
+inline static int is_prefix_of(const char *prefix, const char *str)
+{
+  return strncmp(prefix, str, strlen (prefix)) == 0;
+}
+
+/* This function is called by the linker when new files are added by a plugin.
+   We can now tell the linker the desired function order since we have a file
+   handle for the newly added file.  */
+
+enum ld_plugin_status
+new_input_hook(const struct ld_plugin_input_file *file)
+{
+  struct ld_plugin_section section_list[3];
+  int num_entries = 0;
+  unsigned int count;
+
+  if (get_input_section_count(file->handle, &count) != LDPS_OK)
+    return LDPS_ERR;
+
+  for (unsigned i = 0; i < count; ++i)
+  {
+    struct ld_plugin_section section;
+    unsigned int type = 0;
+    char *name = NULL;
+    int position = 3;
+
+    section.handle = file->handle;
+    section.shndx = i;
+
+    if (get_input_section_type(section, &type) != LDPS_OK)
+      return LDPL_FATAL;
+    if (type != SHT_PROGBITS)
+      continue;
+
+    if (get_input_section_name(section, &name))
+      return LDPL_FATAL;
+
+    /* As in plugin_section_order.c, order is foo() followed by bar()
+       followed by baz() */
+    if (is_prefix_of(".text.", name))
+    {
+      if (strstr(name, "_Z3foov") != NULL)
+        position = 0;
+      else if (strstr(name, "_Z3barv") != NULL)
+        position = 1;
+      else if (strstr(name, "_Z3bazv") != NULL)
+        position = 2;
+      else
+        position = 3;
+    }
+    if (position < 3)
+    {
+      section_list[position] = section;
+      num_entries++;
+    }
+  }
+
+  if (num_entries != 3)
+    return LDPL_FATAL;
+
+  update_section_order(section_list, num_entries);
+  unique_segment_for_sections (".text.plugin_created_unique", 0, 0x1000,
+                               section_list, num_entries);
+
+  return LDPS_OK;
+}
-- 
2.14.1

^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2017-12-12 18:51 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-08-25  5:49 [PATCH] [GOLD] Add plugin API for processing plugin-added input files Stephen Crane
2017-09-14 22:16 ` Stephen Crane
2017-09-20 21:51   ` Cary Coutant
2017-09-26  1:46 [PATCH 2/2] " Stephen Crane
2017-10-11  7:09 ` Sriraman Tallam via binutils
2017-10-14  1:00   ` Stephen Crane
2017-10-14  5:47     ` Sriraman Tallam via binutils
2017-10-20  0:51       ` Cary Coutant
2017-10-20 21:49         ` [PATCH] " Stephen Crane
2017-11-08  0:39           ` Stephen Crane
2017-11-08 22:37             ` Cary Coutant
2017-11-10  1:24               ` Stephen Crane
2017-11-10  5:06                 ` Cary Coutant
2017-11-10 16:29                   ` Sriraman Tallam via binutils
2017-11-10 22:11                   ` Sriraman Tallam via binutils
2017-12-11 22:10                   ` Sriraman Tallam via binutils
2017-12-11 22:16                     ` Stephen Crane
2017-12-11 22:33                       ` Sriraman Tallam via binutils
2017-12-11 23:03                       ` Sriraman Tallam via binutils
2017-12-12 18:51                         ` Stephen Crane

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