Commit c6f5dc28 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

objtool: Union instruction::{call_dest,jump_table} 



The instruction call_dest and jump_table members can never be used at
the same time, their usage depends on type.

 struct instruction {
 	struct list_head           list;                 /*     0    16 */
 	struct hlist_node          hash;                 /*    16    16 */
 	struct list_head           call_node;            /*    32    16 */
 	struct section *           sec;                  /*    48     8 */
 	long unsigned int          offset;               /*    56     8 */
 	/* --- cacheline 1 boundary (64 bytes) --- */
 	long unsigned int          immediate;            /*    64     8 */
 	unsigned int               len;                  /*    72     4 */
 	u8                         type;                 /*    76     1 */

 	/* Bitfield combined with previous fields */

 	u16                        dead_end:1;           /*    76: 8  2 */
 	u16                        ignore:1;             /*    76: 9  2 */
 	u16                        ignore_alts:1;        /*    76:10  2 */
 	u16                        hint:1;               /*    76:11  2 */
 	u16                        save:1;               /*    76:12  2 */
 	u16                        restore:1;            /*    76:13  2 */
 	u16                        retpoline_safe:1;     /*    76:14  2 */
 	u16                        noendbr:1;            /*    76:15  2 */
 	u16                        entry:1;              /*    78: 0  2 */
 	u16                        visited:4;            /*    78: 1  2 */
 	u16                        no_reloc:1;           /*    78: 5  2 */

 	/* XXX 2 bits hole, try to pack */
 	/* Bitfield combined with next fields */

 	s8                         instr;                /*    79     1 */
 	struct alt_group *         alt_group;            /*    80     8 */
-	struct symbol *            call_dest;            /*    88     8 */
-	struct instruction *       jump_dest;            /*    96     8 */
-	struct instruction *       first_jump_src;       /*   104     8 */
-	struct reloc *             jump_table;           /*   112     8 */
-	struct alternative *       alts;                 /*   120     8 */
+	struct instruction *       jump_dest;            /*    88     8 */
+	struct instruction *       first_jump_src;       /*    96     8 */
+	union {
+		struct symbol *    _call_dest;           /*   104     8 */
+		struct reloc *     _jump_table;          /*   104     8 */
+	};                                               /*   104     8 */
+	struct alternative *       alts;                 /*   112     8 */
+	struct symbol *            sym;                  /*   120     8 */
 	/* --- cacheline 2 boundary (128 bytes) --- */
-	struct symbol *            sym;                  /*   128     8 */
-	struct stack_op *          stack_ops;            /*   136     8 */
-	struct cfi_state *         cfi;                  /*   144     8 */
+	struct stack_op *          stack_ops;            /*   128     8 */
+	struct cfi_state *         cfi;                  /*   136     8 */

-	/* size: 152, cachelines: 3, members: 29 */
-	/* sum members: 150 */
+	/* size: 144, cachelines: 3, members: 28 */
+	/* sum members: 142 */
 	/* sum bitfield members: 14 bits, bit holes: 1, sum bit holes: 2 bits */
-	/* last cacheline: 24 bytes */
+	/* last cacheline: 16 bytes */
 };

pre:	5:39.35 real,   215.58 user,    123.69 sys,     23448736 mem
post:	5:38.18 real,   213.25 user,    124.90 sys,     23449040 mem

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build only
Tested-by: Thomas Weißschuh <linux@weissschuh.net> # compile and run
Link: https://lore.kernel.org/r/20230208172245.640914454@infradead.org
parent 0932dbe1

tools/objtool/check.c

+46 −27
Original line number Diff line number Diff line
@@ -114,16 +114,34 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file, 
	for (insn = next_insn_same_sec(file, insn); insn;		\

	     insn = next_insn_same_sec(file, insn))



static inline struct symbol *insn_call_dest(struct instruction *insn)

{

	if (insn->type == INSN_JUMP_DYNAMIC ||

	    insn->type == INSN_CALL_DYNAMIC)

		return NULL;



	return insn->_call_dest;

}



static inline struct reloc *insn_jump_table(struct instruction *insn)

{

	if (insn->type == INSN_JUMP_DYNAMIC ||

	    insn->type == INSN_CALL_DYNAMIC)

		return insn->_jump_table;



	return NULL;

}



static bool is_jump_table_jump(struct instruction *insn)

{

	struct alt_group *alt_group = insn->alt_group;



	if (insn->jump_table)

	if (insn_jump_table(insn))

		return true;



	/* Retpoline alternative for a jump table? */

	return alt_group && alt_group->orig_group &&

	       alt_group->orig_group->first_insn->jump_table;

	       insn_jump_table(alt_group->orig_group->first_insn);

}



static bool is_sibling_call(struct instruction *insn)
@@ -137,8 +155,8 @@ static bool is_sibling_call(struct instruction *insn) 
			return !is_jump_table_jump(insn);

	}



	/* add_jump_destinations() sets insn->call_dest for sibling calls. */

	return (is_static_jump(insn) && insn->call_dest);

	/* add_jump_destinations() sets insn_call_dest(insn) for sibling calls. */

	return (is_static_jump(insn) && insn_call_dest(insn));

}



/*
@@ -274,8 +292,8 @@ static void init_insn_state(struct objtool_file *file, struct insn_state *state, 


	/*

	 * We need the full vmlinux for noinstr validation, otherwise we can

	 * not correctly determine insn->call_dest->sec (external symbols do

	 * not have a section).

	 * not correctly determine insn_call_dest(insn)->sec (external symbols

	 * do not have a section).

	 */

	if (opts.link && opts.noinstr && sec)

		state->noinstr = sec->noinstr;
@@ -678,7 +696,7 @@ static int create_static_call_sections(struct objtool_file *file) 
			return -1;



		/* find key symbol */

		key_name = strdup(insn->call_dest->name);

		key_name = strdup(insn_call_dest(insn)->name);

		if (!key_name) {

			perror("strdup");

			return -1;
@@ -709,7 +727,7 @@ static int create_static_call_sections(struct objtool_file *file) 
			 * trampoline address.  This is fixed up in

			 * static_call_add_module().

			 */

			key_sym = insn->call_dest;

			key_sym = insn_call_dest(insn);

		}

		free(key_name);
@@ -1340,7 +1358,7 @@ static void annotate_call_site(struct objtool_file *file, 
			       struct instruction *insn, bool sibling)

{

	struct reloc *reloc = insn_reloc(file, insn);

	struct symbol *sym = insn->call_dest;

	struct symbol *sym = insn_call_dest(insn);



	if (!sym)

		sym = reloc->sym;
@@ -1425,7 +1443,7 @@ static void annotate_call_site(struct objtool_file *file, 
static void add_call_dest(struct objtool_file *file, struct instruction *insn,

			  struct symbol *dest, bool sibling)

{

	insn->call_dest = dest;

	insn->_call_dest = dest;

	if (!dest)

		return;
@@ -1683,12 +1701,12 @@ static int add_call_destinations(struct objtool_file *file) 
			if (insn->ignore)

				continue;



			if (!insn->call_dest) {

			if (!insn_call_dest(insn)) {

				WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);

				return -1;

			}



			if (insn_func(insn) && insn->call_dest->type != STT_FUNC) {

			if (insn_func(insn) && insn_call_dest(insn)->type != STT_FUNC) {

				WARN_FUNC("unsupported call to non-function",

					  insn->sec, insn->offset);

				return -1;
@@ -2125,7 +2143,7 @@ static void mark_func_jump_tables(struct objtool_file *file, 
		reloc = find_jump_table(file, func, insn);

		if (reloc) {

			reloc->jump_table_start = true;

			insn->jump_table = reloc;

			insn->_jump_table = reloc;

		}

	}

}
@@ -2137,10 +2155,10 @@ static int add_func_jump_tables(struct objtool_file *file, 
	int ret;



	func_for_each_insn(file, func, insn) {

		if (!insn->jump_table)

		if (!insn_jump_table(insn))

			continue;



		ret = add_jump_table(file, insn, insn->jump_table);

		ret = add_jump_table(file, insn, insn_jump_table(insn));

		if (ret)

			return ret;

	}
@@ -2612,8 +2630,8 @@ static int decode_sections(struct objtool_file *file) 
static bool is_fentry_call(struct instruction *insn)

{

	if (insn->type == INSN_CALL &&

	    insn->call_dest &&

	    insn->call_dest->fentry)

	    insn_call_dest(insn) &&

	    insn_call_dest(insn)->fentry)

		return true;



	return false;
@@ -3320,8 +3338,8 @@ static inline const char *call_dest_name(struct instruction *insn) 
	struct reloc *rel;

	int idx;



	if (insn->call_dest)

		return insn->call_dest->name;

	if (insn_call_dest(insn))

		return insn_call_dest(insn)->name;



	rel = insn_reloc(NULL, insn);

	if (rel && !strcmp(rel->sym->name, "pv_ops")) {
@@ -3403,13 +3421,13 @@ static int validate_call(struct objtool_file *file, 
			 struct insn_state *state)

{

	if (state->noinstr && state->instr <= 0 &&

	    !noinstr_call_dest(file, insn, insn->call_dest)) {

	    !noinstr_call_dest(file, insn, insn_call_dest(insn))) {

		WARN_FUNC("call to %s() leaves .noinstr.text section",

				insn->sec, insn->offset, call_dest_name(insn));

		return 1;

	}



	if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {

	if (state->uaccess && !func_uaccess_safe(insn_call_dest(insn))) {

		WARN_FUNC("call to %s() with UACCESS enabled",

				insn->sec, insn->offset, call_dest_name(insn));

		return 1;
@@ -3847,11 +3865,11 @@ static int validate_entry(struct objtool_file *file, struct instruction *insn) 


			/* fallthrough */

		case INSN_CALL:

			dest = find_insn(file, insn->call_dest->sec,

					 insn->call_dest->offset);

			dest = find_insn(file, insn_call_dest(insn)->sec,

					 insn_call_dest(insn)->offset);

			if (!dest) {

				WARN("Unresolved function after linking!?: %s",

				     insn->call_dest->name);

				     insn_call_dest(insn)->name);

				return -1;

			}
@@ -3952,13 +3970,13 @@ static int validate_retpoline(struct objtool_file *file) 
static bool is_kasan_insn(struct instruction *insn)

{

	return (insn->type == INSN_CALL &&

		!strcmp(insn->call_dest->name, "__asan_handle_no_return"));

		!strcmp(insn_call_dest(insn)->name, "__asan_handle_no_return"));

}



static bool is_ubsan_insn(struct instruction *insn)

{

	return (insn->type == INSN_CALL &&

		!strcmp(insn->call_dest->name,

		!strcmp(insn_call_dest(insn)->name,

			"__ubsan_handle_builtin_unreachable"));

}
@@ -4036,7 +4054,8 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
	 * It may also insert a UD2 after calling a __noreturn function.

	 */

	prev_insn = list_prev_entry(insn, list);

	if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&

	if ((prev_insn->dead_end ||

	     dead_end_function(file, insn_call_dest(prev_insn))) &&

	    (insn->type == INSN_BUG ||

	     (insn->type == INSN_JUMP_UNCONDITIONAL &&

	      insn->jump_dest && insn->jump_dest->type == INSN_BUG)))

tools/objtool/include/objtool/check.h

+4 −2
Original line number Diff line number Diff line
@@ -62,10 +62,12 @@ struct instruction { 
	s8 instr;



	struct alt_group *alt_group;

	struct symbol *call_dest;

	struct instruction *jump_dest;

	struct instruction *first_jump_src;

	struct reloc *jump_table;

	union {

		struct symbol *_call_dest;

		struct reloc *_jump_table;

	};

	struct alternative *alts;

	struct symbol *sym;

	struct stack_op *stack_ops;