Merge tag 'for-hubcap-v4.9-readahead' of git://github.com/martinbrandenburg/linux

orangefs: integrate readahead cache changes from out-of-tree

The readahead cache has long been present as a compile time option to
OrangeFS. As it had not been tested in some time, it was disabled by
default. Recently, Walt Ligon started work reviving it, which eventually
culminated in the commit below to OrangeFS SVN.

r12519 | walt | 2016-07-13 14:32:42 -0400 (Wed, 13 Jul 2016) | 1 line
reintegrating readahead cache code

This cache is implemented almost entirely in userspace. There are a few
parameters exposed via sysfs, and the cache must be flushed after an
inode is released.

1 files changed, 144 insertions, 0 deletions

diff --git a/scripts/gcc-plugins/sancov_plugin.c b/scripts/gcc-plugins/sancov_plugin.c
new file mode 100644
index 000000000000..aedd6113cb73
--- /dev/null
+++ b/scripts/gcc-plugins/sancov_plugin.c
@@ -0,0 +1,144 @@
+/*
+ * Copyright 2011-2016 by Emese Revfy <re.emese@gmail.com>
+ * Licensed under the GPL v2, or (at your option) v3
+ *
+ * Homepage:
+ * https://github.com/ephox-gcc-plugins/sancov
+ *
+ * This plugin inserts a __sanitizer_cov_trace_pc() call at the start of basic blocks.
+ * It supports all gcc versions with plugin support (from gcc-4.5 on).
+ * It is based on the commit "Add fuzzing coverage support" by Dmitry Vyukov <dvyukov@google.com>.
+ *
+ * You can read about it more here:
+ *  https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296
+ *  http://lwn.net/Articles/674854/
+ *  https://github.com/google/syzkaller
+ *  https://lwn.net/Articles/677764/
+ *
+ * Usage:
+ * make run
+ */
+
+#include "gcc-common.h"
+
+int plugin_is_GPL_compatible;
+
+tree sancov_fndecl;
+
+static struct plugin_info sancov_plugin_info = {
+	.version	= "20160402",
+	.help		= "sancov plugin\n",
+};
+
+static unsigned int sancov_execute(void)
+{
+	basic_block bb;
+
+	/* Remove this line when this plugin and kcov will be in the kernel.
+	if (!strcmp(DECL_NAME_POINTER(current_function_decl), DECL_NAME_POINTER(sancov_fndecl)))
+		return 0;
+	*/
+
+	FOR_EACH_BB_FN(bb, cfun) {
+		const_gimple stmt;
+		gcall *gcall;
+		gimple_stmt_iterator gsi = gsi_after_labels(bb);
+
+		if (gsi_end_p(gsi))
+			continue;
+
+		stmt = gsi_stmt(gsi);
+		gcall = as_a_gcall(gimple_build_call(sancov_fndecl, 0));
+		gimple_set_location(gcall, gimple_location(stmt));
+		gsi_insert_before(&gsi, gcall, GSI_SAME_STMT);
+	}
+	return 0;
+}
+
+#define PASS_NAME sancov
+
+#define NO_GATE
+#define TODO_FLAGS_FINISH TODO_dump_func | TODO_verify_stmts | TODO_update_ssa_no_phi | TODO_verify_flow
+
+#include "gcc-generate-gimple-pass.h"
+
+static void sancov_start_unit(void __unused *gcc_data, void __unused *user_data)
+{
+	tree leaf_attr, nothrow_attr;
+	tree BT_FN_VOID = build_function_type_list(void_type_node, NULL_TREE);
+
+	sancov_fndecl = build_fn_decl("__sanitizer_cov_trace_pc", BT_FN_VOID);
+
+	DECL_ASSEMBLER_NAME(sancov_fndecl);
+	TREE_PUBLIC(sancov_fndecl) = 1;
+	DECL_EXTERNAL(sancov_fndecl) = 1;
+	DECL_ARTIFICIAL(sancov_fndecl) = 1;
+	DECL_PRESERVE_P(sancov_fndecl) = 1;
+	DECL_UNINLINABLE(sancov_fndecl) = 1;
+	TREE_USED(sancov_fndecl) = 1;
+
+	nothrow_attr = tree_cons(get_identifier("nothrow"), NULL, NULL);
+	decl_attributes(&sancov_fndecl, nothrow_attr, 0);
+	gcc_assert(TREE_NOTHROW(sancov_fndecl));
+#if BUILDING_GCC_VERSION > 4005
+	leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL);
+	decl_attributes(&sancov_fndecl, leaf_attr, 0);
+#endif
+}
+
+int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
+{
+	int i;
+	struct register_pass_info sancov_plugin_pass_info;
+	const char * const plugin_name = plugin_info->base_name;
+	const int argc = plugin_info->argc;
+	const struct plugin_argument * const argv = plugin_info->argv;
+	bool enable = true;
+
+	static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = {
+		{
+			.base = &sancov_fndecl,
+			.nelt = 1,
+			.stride = sizeof(sancov_fndecl),
+			.cb = &gt_ggc_mx_tree_node,
+			.pchw = &gt_pch_nx_tree_node
+		},
+		LAST_GGC_ROOT_TAB
+	};
+
+	/* BBs can be split afterwards?? */
+	sancov_plugin_pass_info.pass				= make_sancov_pass();
+#if BUILDING_GCC_VERSION >= 4009
+	sancov_plugin_pass_info.reference_pass_name		= "asan";
+#else
+	sancov_plugin_pass_info.reference_pass_name		= "nrv";
+#endif
+	sancov_plugin_pass_info.ref_pass_instance_number	= 0;
+	sancov_plugin_pass_info.pos_op				= PASS_POS_INSERT_BEFORE;
+
+	if (!plugin_default_version_check(version, &gcc_version)) {
+		error(G_("incompatible gcc/plugin versions"));
+		return 1;
+	}
+
+	for (i = 0; i < argc; ++i) {
+		if (!strcmp(argv[i].key, "no-sancov")) {
+			enable = false;
+			continue;
+		}
+		error(G_("unkown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
+	}
+
+	register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info);
+
+	if (!enable)
+		return 0;
+
+#if BUILDING_GCC_VERSION < 6000
+	register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL);
+	register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)&gt_ggc_r_gt_sancov);
+	register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_plugin_pass_info);
+#endif
+
+	return 0;
+}