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authorLinus Torvalds <torvalds@linux-foundation.org>2020-08-04 13:26:06 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-04 13:26:06 -0700
commit3e4a12a1bafafecaf1631f02099e82b424967718 (patch)
tree0ce456b6a8ca6e2b4b51972513a77de7dba4b58d /scripts/gcc-plugins
parent19a93823cf63d44d04c7571152087f12cb2199e6 (diff)
parent496b24ec6d47f2d304a0c5836ba4b1bb5d30bab8 (diff)
downloadlinux-stericsson-3e4a12a1bafafecaf1631f02099e82b424967718.tar.gz
Merge tag 'gcc-plugins-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugin updates from Kees Cook: "Primarily improvements to STACKLEAK from Alexander Popov, along with some additional cleanups. - Update URLs for HTTPS scheme where available (Alexander A. Klimov) - Improve STACKLEAK code generation on x86 (Alexander Popov)" * tag 'gcc-plugins-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: gcc-plugins: Replace HTTP links with HTTPS ones gcc-plugins/stackleak: Add 'verbose' plugin parameter gcc-plugins/stackleak: Use asm instrumentation to avoid useless register saving ARM: vdso: Don't use gcc plugins for building vgettimeofday.c gcc-plugins/stackleak: Don't instrument itself
Diffstat (limited to 'scripts/gcc-plugins')
-rw-r--r--scripts/gcc-plugins/cyc_complexity_plugin.c2
-rw-r--r--scripts/gcc-plugins/sancov_plugin.c2
-rw-r--r--scripts/gcc-plugins/stackleak_plugin.c248
-rw-r--r--scripts/gcc-plugins/structleak_plugin.c2
4 files changed, 220 insertions, 34 deletions
diff --git a/scripts/gcc-plugins/cyc_complexity_plugin.c b/scripts/gcc-plugins/cyc_complexity_plugin.c
index 1909ec617431..73124c2b3edd 100644
--- a/scripts/gcc-plugins/cyc_complexity_plugin.c
+++ b/scripts/gcc-plugins/cyc_complexity_plugin.c
@@ -5,7 +5,7 @@
* Homepage:
* https://github.com/ephox-gcc-plugins/cyclomatic_complexity
*
- * http://en.wikipedia.org/wiki/Cyclomatic_complexity
+ * https://en.wikipedia.org/wiki/Cyclomatic_complexity
* The complexity M is then defined as:
* M = E - N + 2P
* where
diff --git a/scripts/gcc-plugins/sancov_plugin.c b/scripts/gcc-plugins/sancov_plugin.c
index 0f98634c20a0..caff4a6c7e9a 100644
--- a/scripts/gcc-plugins/sancov_plugin.c
+++ b/scripts/gcc-plugins/sancov_plugin.c
@@ -11,7 +11,7 @@
*
* 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://lwn.net/Articles/674854/
* https://github.com/google/syzkaller
* https://lwn.net/Articles/677764/
*
diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c
index cc75eeba0be1..48e141e07956 100644
--- a/scripts/gcc-plugins/stackleak_plugin.c
+++ b/scripts/gcc-plugins/stackleak_plugin.c
@@ -20,7 +20,7 @@
*
* Debugging:
* - use fprintf() to stderr, debug_generic_expr(), debug_gimple_stmt(),
- * print_rtl() and print_simple_rtl();
+ * print_rtl_single() and debug_rtx();
* - add "-fdump-tree-all -fdump-rtl-all" to the plugin CFLAGS in
* Makefile.gcc-plugins to see the verbose dumps of the gcc passes;
* - use gcc -E to understand the preprocessing shenanigans;
@@ -32,7 +32,10 @@
__visible int plugin_is_GPL_compatible;
static int track_frame_size = -1;
+static bool build_for_x86 = false;
static const char track_function[] = "stackleak_track_stack";
+static bool disable = false;
+static bool verbose = false;
/*
* Mark these global variables (roots) for gcc garbage collector since
@@ -43,32 +46,32 @@ static GTY(()) tree track_function_decl;
static struct plugin_info stackleak_plugin_info = {
.version = "201707101337",
.help = "track-min-size=nn\ttrack stack for functions with a stack frame size >= nn bytes\n"
+ "arch=target_arch\tspecify target build arch\n"
"disable\t\tdo not activate the plugin\n"
+ "verbose\t\tprint info about the instrumentation\n"
};
-static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after)
+static void add_stack_tracking_gcall(gimple_stmt_iterator *gsi, bool after)
{
gimple stmt;
- gcall *stackleak_track_stack;
+ gcall *gimple_call;
cgraph_node_ptr node;
basic_block bb;
- /* Insert call to void stackleak_track_stack(void) */
+ /* Insert calling stackleak_track_stack() */
stmt = gimple_build_call(track_function_decl, 0);
- stackleak_track_stack = as_a_gcall(stmt);
- if (after) {
- gsi_insert_after(gsi, stackleak_track_stack,
- GSI_CONTINUE_LINKING);
- } else {
- gsi_insert_before(gsi, stackleak_track_stack, GSI_SAME_STMT);
- }
+ gimple_call = as_a_gcall(stmt);
+ if (after)
+ gsi_insert_after(gsi, gimple_call, GSI_CONTINUE_LINKING);
+ else
+ gsi_insert_before(gsi, gimple_call, GSI_SAME_STMT);
/* Update the cgraph */
- bb = gimple_bb(stackleak_track_stack);
+ bb = gimple_bb(gimple_call);
node = cgraph_get_create_node(track_function_decl);
gcc_assert(node);
cgraph_create_edge(cgraph_get_node(current_function_decl), node,
- stackleak_track_stack, bb->count,
+ gimple_call, bb->count,
compute_call_stmt_bb_frequency(current_function_decl, bb));
}
@@ -85,6 +88,83 @@ static bool is_alloca(gimple stmt)
return false;
}
+static tree get_current_stack_pointer_decl(void)
+{
+ varpool_node_ptr node;
+
+ FOR_EACH_VARIABLE(node) {
+ tree var = NODE_DECL(node);
+ tree name = DECL_NAME(var);
+
+ if (DECL_NAME_LENGTH(var) != sizeof("current_stack_pointer") - 1)
+ continue;
+
+ if (strcmp(IDENTIFIER_POINTER(name), "current_stack_pointer"))
+ continue;
+
+ return var;
+ }
+
+ if (verbose) {
+ fprintf(stderr, "stackleak: missing current_stack_pointer in %s()\n",
+ DECL_NAME_POINTER(current_function_decl));
+ }
+ return NULL_TREE;
+}
+
+static void add_stack_tracking_gasm(gimple_stmt_iterator *gsi, bool after)
+{
+ gasm *asm_call = NULL;
+ tree sp_decl, input;
+ vec<tree, va_gc> *inputs = NULL;
+
+ /* 'no_caller_saved_registers' is currently supported only for x86 */
+ gcc_assert(build_for_x86);
+
+ /*
+ * Insert calling stackleak_track_stack() in asm:
+ * asm volatile("call stackleak_track_stack"
+ * :: "r" (current_stack_pointer))
+ * Use ASM_CALL_CONSTRAINT trick from arch/x86/include/asm/asm.h.
+ * This constraint is taken into account during gcc shrink-wrapping
+ * optimization. It is needed to be sure that stackleak_track_stack()
+ * call is inserted after the prologue of the containing function,
+ * when the stack frame is prepared.
+ */
+ sp_decl = get_current_stack_pointer_decl();
+ if (sp_decl == NULL_TREE) {
+ add_stack_tracking_gcall(gsi, after);
+ return;
+ }
+ input = build_tree_list(NULL_TREE, build_const_char_string(2, "r"));
+ input = chainon(NULL_TREE, build_tree_list(input, sp_decl));
+ vec_safe_push(inputs, input);
+ asm_call = gimple_build_asm_vec("call stackleak_track_stack",
+ inputs, NULL, NULL, NULL);
+ gimple_asm_set_volatile(asm_call, true);
+ if (after)
+ gsi_insert_after(gsi, asm_call, GSI_CONTINUE_LINKING);
+ else
+ gsi_insert_before(gsi, asm_call, GSI_SAME_STMT);
+ update_stmt(asm_call);
+}
+
+static void add_stack_tracking(gimple_stmt_iterator *gsi, bool after)
+{
+ /*
+ * The 'no_caller_saved_registers' attribute is used for
+ * stackleak_track_stack(). If the compiler supports this attribute for
+ * the target arch, we can add calling stackleak_track_stack() in asm.
+ * That improves performance: we avoid useless operations with the
+ * caller-saved registers in the functions from which we will remove
+ * stackleak_track_stack() call during the stackleak_cleanup pass.
+ */
+ if (lookup_attribute_spec(get_identifier("no_caller_saved_registers")))
+ add_stack_tracking_gasm(gsi, after);
+ else
+ add_stack_tracking_gcall(gsi, after);
+}
+
/*
* Work with the GIMPLE representation of the code. Insert the
* stackleak_track_stack() call after alloca() and into the beginning
@@ -94,7 +174,7 @@ static unsigned int stackleak_instrument_execute(void)
{
basic_block bb, entry_bb;
bool prologue_instrumented = false, is_leaf = true;
- gimple_stmt_iterator gsi;
+ gimple_stmt_iterator gsi = { 0 };
/*
* ENTRY_BLOCK_PTR is a basic block which represents possible entry
@@ -122,8 +202,13 @@ static unsigned int stackleak_instrument_execute(void)
if (!is_alloca(stmt))
continue;
+ if (verbose) {
+ fprintf(stderr, "stackleak: be careful, alloca() in %s()\n",
+ DECL_NAME_POINTER(current_function_decl));
+ }
+
/* Insert stackleak_track_stack() call after alloca() */
- stackleak_add_track_stack(&gsi, true);
+ add_stack_tracking(&gsi, true);
if (bb == entry_bb)
prologue_instrumented = true;
}
@@ -168,7 +253,7 @@ static unsigned int stackleak_instrument_execute(void)
bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun));
}
gsi = gsi_after_labels(bb);
- stackleak_add_track_stack(&gsi, false);
+ add_stack_tracking(&gsi, false);
return 0;
}
@@ -182,21 +267,10 @@ static bool large_stack_frame(void)
#endif
}
-/*
- * Work with the RTL representation of the code.
- * Remove the unneeded stackleak_track_stack() calls from the functions
- * which don't call alloca() and don't have a large enough stack frame size.
- */
-static unsigned int stackleak_cleanup_execute(void)
+static void remove_stack_tracking_gcall(void)
{
rtx_insn *insn, *next;
- if (cfun->calls_alloca)
- return 0;
-
- if (large_stack_frame())
- return 0;
-
/*
* Find stackleak_track_stack() calls. Loop through the chain of insns,
* which is an RTL representation of the code for a function.
@@ -257,6 +331,102 @@ static unsigned int stackleak_cleanup_execute(void)
}
#endif
}
+}
+
+static bool remove_stack_tracking_gasm(void)
+{
+ bool removed = false;
+ rtx_insn *insn, *next;
+
+ /* 'no_caller_saved_registers' is currently supported only for x86 */
+ gcc_assert(build_for_x86);
+
+ /*
+ * Find stackleak_track_stack() asm calls. Loop through the chain of
+ * insns, which is an RTL representation of the code for a function.
+ *
+ * The example of a matching insn:
+ * (insn 11 5 12 2 (parallel [ (asm_operands/v
+ * ("call stackleak_track_stack") ("") 0
+ * [ (reg/v:DI 7 sp [ current_stack_pointer ]) ]
+ * [ (asm_input:DI ("r")) ] [])
+ * (clobber (reg:CC 17 flags)) ]) -1 (nil))
+ */
+ for (insn = get_insns(); insn; insn = next) {
+ rtx body;
+
+ next = NEXT_INSN(insn);
+
+ /* Check the expression code of the insn */
+ if (!NONJUMP_INSN_P(insn))
+ continue;
+
+ /*
+ * Check the expression code of the insn body, which is an RTL
+ * Expression (RTX) describing the side effect performed by
+ * that insn.
+ */
+ body = PATTERN(insn);
+
+ if (GET_CODE(body) != PARALLEL)
+ continue;
+
+ body = XVECEXP(body, 0, 0);
+
+ if (GET_CODE(body) != ASM_OPERANDS)
+ continue;
+
+ if (strcmp(ASM_OPERANDS_TEMPLATE(body),
+ "call stackleak_track_stack")) {
+ continue;
+ }
+
+ delete_insn_and_edges(insn);
+ gcc_assert(!removed);
+ removed = true;
+ }
+
+ return removed;
+}
+
+/*
+ * Work with the RTL representation of the code.
+ * Remove the unneeded stackleak_track_stack() calls from the functions
+ * which don't call alloca() and don't have a large enough stack frame size.
+ */
+static unsigned int stackleak_cleanup_execute(void)
+{
+ const char *fn = DECL_NAME_POINTER(current_function_decl);
+ bool removed = false;
+
+ /*
+ * Leave stack tracking in functions that call alloca().
+ * Additional case:
+ * gcc before version 7 called allocate_dynamic_stack_space() from
+ * expand_stack_vars() for runtime alignment of constant-sized stack
+ * variables. That caused cfun->calls_alloca to be set for functions
+ * that in fact don't use alloca().
+ * For more info see gcc commit 7072df0aae0c59ae437e.
+ * Let's leave such functions instrumented as well.
+ */
+ if (cfun->calls_alloca) {
+ if (verbose)
+ fprintf(stderr, "stackleak: instrument %s(): calls_alloca\n", fn);
+ return 0;
+ }
+
+ /* Leave stack tracking in functions with large stack frame */
+ if (large_stack_frame()) {
+ if (verbose)
+ fprintf(stderr, "stackleak: instrument %s()\n", fn);
+ return 0;
+ }
+
+ if (lookup_attribute_spec(get_identifier("no_caller_saved_registers")))
+ removed = remove_stack_tracking_gasm();
+
+ if (!removed)
+ remove_stack_tracking_gcall();
return 0;
}
@@ -376,9 +546,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
/* Parse the plugin arguments */
for (i = 0; i < argc; i++) {
- if (!strcmp(argv[i].key, "disable"))
- return 0;
-
if (!strcmp(argv[i].key, "track-min-size")) {
if (!argv[i].value) {
error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
@@ -392,6 +559,19 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
plugin_name, argv[i].key, argv[i].value);
return 1;
}
+ } else if (!strcmp(argv[i].key, "arch")) {
+ if (!argv[i].value) {
+ error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
+ plugin_name, argv[i].key);
+ return 1;
+ }
+
+ if (!strcmp(argv[i].value, "x86"))
+ build_for_x86 = true;
+ } else if (!strcmp(argv[i].key, "disable")) {
+ disable = true;
+ } else if (!strcmp(argv[i].key, "verbose")) {
+ verbose = true;
} else {
error(G_("unknown option '-fplugin-arg-%s-%s'"),
plugin_name, argv[i].key);
@@ -399,6 +579,12 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
}
}
+ if (disable) {
+ if (verbose)
+ fprintf(stderr, "stackleak: disabled for this translation unit\n");
+ return 0;
+ }
+
/* Give the information about the plugin */
register_callback(plugin_name, PLUGIN_INFO, NULL,
&stackleak_plugin_info);
diff --git a/scripts/gcc-plugins/structleak_plugin.c b/scripts/gcc-plugins/structleak_plugin.c
index e89be8f5c859..b9ef2e162107 100644
--- a/scripts/gcc-plugins/structleak_plugin.c
+++ b/scripts/gcc-plugins/structleak_plugin.c
@@ -11,7 +11,7 @@
* otherwise leak kernel stack to userland if they aren't properly initialized
* by later code
*
- * Homepage: http://pax.grsecurity.net/
+ * Homepage: https://pax.grsecurity.net/
*
* Options:
* -fplugin-arg-structleak_plugin-disable