diff options
Diffstat (limited to 'scripts/gcc-plugins/stackleak_plugin.c')
| -rw-r--r-- | scripts/gcc-plugins/stackleak_plugin.c | 205 |
1 files changed, 177 insertions, 28 deletions
diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index cc75eeba0be1..a18b0d4af456 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; @@ -32,6 +32,7 @@ __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"; /* @@ -43,32 +44,31 @@ 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" }; -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 +85,79 @@ 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; + } + + 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 +167,7 @@ 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 @@ -123,7 +196,7 @@ static unsigned int stackleak_instrument_execute(void) continue; /* 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 +241,7 @@ 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 +255,10 @@ 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 +319,84 @@ 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) +{ + bool removed = false; + + if (cfun->calls_alloca) + return 0; + + if (large_stack_frame()) + 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; } @@ -392,6 +532,15 @@ __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 { error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); |