Fix C++ and PLTs (PR 17201, PR17199 ?)

4 files changed, 228 insertions, 0 deletions

diff --git a/gdb/linespec.c b/gdb/linespec.c
index ccedec8..e203fbe 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3651,10 +3651,26 @@ struct collect_minsyms
   /* The list_mode setting from the initial call.  */
   int list_mode;
 
+  /* If WANT_TRAMPOLINE is set, ignore mst_text @plt symbols, thus
+     collecting only the corresponding mst_solib_trampoline
+     symbol.  */
+  int want_trampoline;
+
   /* The resulting symbols.  */
   VEC (bound_minimal_symbol_d) *msyms;
 };
 
+static int
+name_is_plt (const char *name)
+{
+  size_t len = strlen (name);
+
+  if (len > 4 && strcmp (name + len - 4, "@plt") == 0)
+    return 1;
+
+  return 0;
+}
+
 /* A helper function to classify a minimal_symbol_type according to
    priority.  */
 
@@ -3701,6 +3717,11 @@ add_minsym (struct minimal_symbol *minsym, void *d)
   struct collect_minsyms *info = (struct collect_minsyms *) d;
   bound_minimal_symbol_d mo;
 
+  if (info->want_trampoline
+      && MSYMBOL_TYPE (minsym) == mst_text
+      && name_is_plt (MSYMBOL_LINKAGE_NAME (minsym)))
+    return;
+
   mo.minsym = minsym;
   mo.objfile = info->objfile;
 
@@ -3767,6 +3788,7 @@ search_minsyms_for_name (struct collect_info *info, const char *name,
   local.funfirstline = info->state->funfirstline;
   local.list_mode = info->state->list_mode;
   local.symtab = symtab;
+  local.want_trampoline = !name_is_plt (name);
 
   cleanup = make_cleanup (VEC_cleanup (bound_minimal_symbol_d), &local.msyms);
 
diff --git a/gdb/testsuite/gdb.base/break-trampoline-solib.c b/gdb/testsuite/gdb.base/break-trampoline-solib.c
new file mode 100644
index 0000000..9f52d0b
--- /dev/null
+++ b/gdb/testsuite/gdb.base/break-trampoline-solib.c
@@ -0,0 +1,20 @@
+/* Copyright 2016 Free Software Foundation, Inc.
+
+   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, see <http://www.gnu.org/licenses/>.  */
+
+int
+foo (void)
+{
+  return 0; /* in dso */
+}
diff --git a/gdb/testsuite/gdb.base/break-trampoline.c b/gdb/testsuite/gdb.base/break-trampoline.c
new file mode 100644
index 0000000..c81db33
--- /dev/null
+++ b/gdb/testsuite/gdb.base/break-trampoline.c
@@ -0,0 +1,24 @@
+/* Copyright 2016 Free Software Foundation, Inc.
+
+   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, see <http://www.gnu.org/licenses/>.  */
+
+/* Shared library entry point.  */
+extern int foo (void);
+
+int
+main (void)
+{
+  foo ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/break-trampoline.exp b/gdb/testsuite/gdb.base/break-trampoline.exp
new file mode 100644
index 0000000..e2907dc
--- /dev/null
+++ b/gdb/testsuite/gdb.base/break-trampoline.exp
@@ -0,0 +1,162 @@
+# Copyright 2016 Free Software Foundation, Inc.
+
+# 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, see <http://www.gnu.org/licenses/>.
+
+# Exercise various corner cases around plt symbols:
+#
+# - Make sure that setting a breakpoint on "foo" in a shared library
+#   does not end up with a location set in foo@plt if the shared
+#   library is loaded.  Instead the foo@plt location is replaced by
+#   the "foo" function in the shared library.
+#
+if { [skip_shlib_tests] } {
+    return 0
+}
+
+standard_testfile break-trampoline.c break-trampoline-solib.c
+set exec_src ${srcdir}/${subdir}/${srcfile}
+set lib_src ${srcdir}/${subdir}/${srcfile2}
+
+# Test both C and C++.
+
+proc do_test {lang} {
+    global exec_src lib_src binfile gdb_prompt
+    global hex decimal
+
+    set lib [standard_output_file break-trampoline-solib-$lang.so]
+    set lib_opts [list debug $lang]
+
+    set binfile [standard_output_file break-trampoline-$lang]
+    set exec_opts [list debug $lang shlib=${lib}]
+
+    if [get_compiler_info] {
+	return -1
+    }
+
+    if { [gdb_compile_shlib ${lib_src} ${lib} $lib_opts] != ""
+	 || [gdb_compile ${exec_src} ${binfile} executable $exec_opts] != ""} {
+	untested "Could not compile $lib or $binfile."
+	return -1
+    }
+
+    set any "\[^\r\n\]*"
+    set ws "\[ \t\]*"
+
+    if {$lang == "c++"} {
+	set foo_plt "foo()@plt"
+	set foo_sym "foo()"
+    } else {
+	set foo_plt "foo@plt"
+	set foo_sym "foo"
+    }
+    set foo_plt_re [string_to_regexp $foo_plt]
+    set foo_sym_re [string_to_regexp $foo_sym]
+
+    with_test_prefix "set break before run" {
+	clean_restart ${binfile}
+	gdb_load_shlib ${lib}
+
+	gdb_test "break foo" "Breakpoint 1 at $hex"
+
+	set test "info breakpoints before run"
+	gdb_test_multiple "info breakpoints" $test {
+	    -re "breakpoint${any}<${foo_plt_re}>\r\n$gdb_prompt $" {
+		pass $test
+	    }
+	}
+
+	gdb_run_cmd
+	set test "run to foo"
+	gdb_test_multiple "" $test {
+	    -re "foo \\(\\) at ${any}${lib_src}:${decimal}\r\n.*$gdb_prompt $" {
+		pass $test
+	    }
+	}
+
+	set test "info breakpoints, foo resolved"
+	gdb_test_multiple "info breakpoints" $test {
+	    -re "${foo_plt_re}.*$gdb_prompt $" {
+		fail "$test (PR 17201)"
+	    }
+	    -re "breakpoint${ws}${any}y${any}in ${foo_sym_re} at ${any}${lib_src}:${decimal}\r\n.*hit 1 time.*$gdb_prompt $" {
+		pass $test
+	    }
+	}
+    }
+
+    # Test that setting a breakpoint on the plt symbol directly does
+    # not end up resolved to the text symbol in the dso.
+    with_test_prefix "set breat at plt before run" {
+	clean_restart ${binfile}
+	gdb_load_shlib ${lib}
+
+	gdb_test "break ${foo_plt}" "Breakpoint 1 at $hex"
+
+	set test "info breakpoints before run"
+	gdb_test_multiple "info breakpoints" $test {
+	    -re "breakpoint${any}<$foo_plt_re>\r\n$gdb_prompt $" {
+		pass $test
+	    }
+	}
+
+	set test "run to foo@plt"
+	gdb_run_cmd
+	gdb_test_multiple "" $test {
+	    -re "in ${foo_plt_re}.*$gdb_prompt $" {
+		pass $test
+	    }
+	}
+
+	set test "info breakpoints after run"
+	gdb_test_multiple "info breakpoints" $test {
+	    -re "breakpoint${any}<${foo_plt_re}>\r\n.*hit 1 time.*$gdb_prompt $" {
+		pass $test
+	    }
+	}
+    }
+
+    with_test_prefix "set break after run" {
+	clean_restart ${binfile}
+	gdb_load_shlib ${lib}
+
+	if ![runto_main] {
+	    return 0
+	}
+
+	# Set up breakpoints.
+	set test "break foo"
+	gdb_test_multiple "break foo" $test {
+	    -re "2 locations.*$gdb_prompt $" {
+		fail "$test (PR 17201)"
+	    }
+	    -re "Breakpoint 2 at $hex: file .*$lib_src, line.*$gdb_prompt $" {
+		pass $test
+	    }
+	}
+
+	set test "info breakpoints"
+	gdb_test_multiple "info breakpoints" $test {
+	    -re "${foo_plt_re}.*$gdb_prompt $" {
+		fail "$test (PR 17201)"
+	    }
+	    -re "breakpoint${any} in ${foo_sym_re} at ${any}$lib_src:${any}\r\n$gdb_prompt $" {
+		pass $test
+	    }
+	}
+    }
+}
+
+foreach_with_prefix language {c c++} {
+    do_test $language
+}