compile: Use also inferior munmap

Currently inferior memory is allocated by inferior mmap() but it is never
deallocated; despite the injected objfile incl. its symbols is freed.  This was
intentional so that one can do for example:
inferior:
	char *str = "foo";
GDB:
	(gdb) compile code str = "bar";

I believe later patches will be needed to introduce full control over keeping
vs. discarding the injected module as being discussed in:
	compile: objfiles lifetime UI
	https://sourceware.org/ml/gdb/2015-04/msg00051.html
	Message-ID: <20150429135735.GA16974@host1.jankratochvil.net>
	https://sourceware.org/ml/gdb/2015-05/msg00007.html

As decided by Phil it is better not to leak inferior pages as users can
workaround the issue above for example by:
	(gdb) compile code str = strdup ("bar");

I have checked that in fact gdb/doc/ (written by Phil) already expects the
injected code will be unmapped so that does not need to be changed:
	compile code int ff = 5; p = &ff;
	In this example, @code{p} would point to @code{ff} when the
	@code{compile} command is executing the source code provided to it.
	However, as variables in the (example) program persist with their
	assigned values, the variable @code{p} would point to an invalid
	location when the command exists.

gdb/ChangeLog
2015-04-28  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* arch-utils.c (default_infcall_munmap): New.
	* arch-utils.h (default_infcall_munmap): New declaration.
	* compile/compile-object-load.c (struct munmap_list, munmap_list_add)
	(munmap_list_free, munmap_listp_free_cleanup): New.
	(struct setup_sections_data): Add field munmap_list_headp.
	(setup_sections): Call munmap_list_add.
	(compile_object_load): New variable munmap_list_head, initialize
	setup_sections_data.munmap_list_headp, return munmap_list_head.
	* compile/compile-object-load.h (struct munmap_list): New declaration.
	(struct compile_module): Add field munmap_list_head.
	(munmap_list_free): New declaration.
	* compile/compile-object-run.c (struct do_module_cleanup): Add field
	munmap_list_head.
	(do_module_cleanup): Call munmap_list_free.
	(compile_object_run): Pass munmap_list_head to do_module_cleanup.
	* gdbarch.c: Regenerate.
	* gdbarch.h: Regenerate.
	* gdbarch.sh (infcall_munmap): New.
	* linux-tdep.c (linux_infcall_munmap): New.
	(linux_init_abi): Install it.

gdb/testsuite/ChangeLog
2015-04-28  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.compile/compile.exp (keep jit in memory): Rename to ...
	(do not keep jit in memory): ... this.
	(expect 5): Change it to ...
	(expect no 5): ... this.

1 files changed, 30 insertions, 0 deletions

diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index df42097..8ce2f34 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -2348,6 +2348,35 @@ linux_infcall_mmap (CORE_ADDR size, unsigned prot)
   return retval;
 }
 
+/* See gdbarch.sh 'infcall_munmap'.  */
+
+static void
+linux_infcall_munmap (CORE_ADDR addr, CORE_ADDR size)
+{
+  struct objfile *objf;
+  struct value *munmap_val = find_function_in_inferior ("munmap", &objf);
+  struct value *retval_val;
+  struct gdbarch *gdbarch = get_objfile_arch (objf);
+  LONGEST retval;
+  enum
+    {
+      ARG_ADDR, ARG_LENGTH, ARG_LAST
+    };
+  struct value *arg[ARG_LAST];
+
+  arg[ARG_ADDR] = value_from_pointer (builtin_type (gdbarch)->builtin_data_ptr,
+				      addr);
+  /* Assuming sizeof (unsigned long) == sizeof (size_t).  */
+  arg[ARG_LENGTH] = value_from_ulongest
+		    (builtin_type (gdbarch)->builtin_unsigned_long, size);
+  retval_val = call_function_by_hand (munmap_val, ARG_LAST, arg);
+  retval = value_as_long (retval_val);
+  if (retval != 0)
+    warning (_("Failed inferior munmap call at %s for %s bytes, "
+	       "errno is changed."),
+	     hex_string (addr), pulongest (size));
+}
+
 /* See linux-tdep.h.  */
 
 CORE_ADDR
@@ -2409,6 +2438,7 @@ linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 				    linux_gdb_signal_to_target);
   set_gdbarch_vsyscall_range (gdbarch, linux_vsyscall_range);
   set_gdbarch_infcall_mmap (gdbarch, linux_infcall_mmap);
+  set_gdbarch_infcall_munmap (gdbarch, linux_infcall_munmap);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */