1 files changed, 74 insertions, 89 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index f0d8796b984a..d4d82bb9b551 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -216,10 +216,15 @@ static bool is_rust_noreturn(const struct symbol *func)
 	       str_ends_with(func->name, "_4core9panicking14panic_explicit")				||
 	       str_ends_with(func->name, "_4core9panicking14panic_nounwind")				||
 	       str_ends_with(func->name, "_4core9panicking18panic_bounds_check")			||
+	       str_ends_with(func->name, "_4core9panicking18panic_nounwind_fmt")			||
 	       str_ends_with(func->name, "_4core9panicking19assert_failed_inner")			||
+	       str_ends_with(func->name, "_4core9panicking30panic_null_pointer_dereference")		||
 	       str_ends_with(func->name, "_4core9panicking36panic_misaligned_pointer_dereference")	||
+	       str_ends_with(func->name, "_7___rustc17rust_begin_unwind")				||
+	       strstr(func->name, "_4core9panicking13assert_failed")					||
 	       strstr(func->name, "_4core9panicking11panic_const24panic_const_")			||
-	       (strstr(func->name, "_4core5slice5index24slice_") &&
+	       (strstr(func->name, "_4core5slice5index") &&
+		strstr(func->name, "slice_") &&
 		str_ends_with(func->name, "_fail"));
 }
 
@@ -638,47 +643,8 @@ static int add_dead_ends(struct objtool_file *file)
 	uint64_t offset;
 
 	/*
-	 * Check for manually annotated dead ends.
-	 */
-	rsec = find_section_by_name(file->elf, ".rela.discard.unreachable");
-	if (!rsec)
-		goto reachable;
-
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type == STT_SECTION) {
-			offset = reloc_addend(reloc);
-		} else if (reloc->sym->local_label) {
-			offset = reloc->sym->offset;
-		} else {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, offset);
-		if (insn)
-			insn = prev_insn_same_sec(file, insn);
-		else if (offset == reloc->sym->sec->sh.sh_size) {
-			insn = find_last_insn(file, reloc->sym->sec);
-			if (!insn) {
-				WARN("can't find unreachable insn at %s+0x%" PRIx64,
-				     reloc->sym->sec->name, offset);
-				return -1;
-			}
-		} else {
-			WARN("can't find unreachable insn at %s+0x%" PRIx64,
-			     reloc->sym->sec->name, offset);
-			return -1;
-		}
-
-		insn->dead_end = true;
-	}
-
-reachable:
-	/*
-	 * These manually annotated reachable checks are needed for GCC 4.4,
-	 * where the Linux unreachable() macro isn't supported.  In that case
-	 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
-	 * not a dead end.
+	 * UD2 defaults to being a dead-end, allow them to be annotated for
+	 * non-fatal, eg WARN.
 	 */
 	rsec = find_section_by_name(file->elf, ".rela.discard.reachable");
 	if (!rsec)
@@ -1280,12 +1246,15 @@ static const char *uaccess_safe_builtin[] = {
 	"__ubsan_handle_load_invalid_value",
 	/* STACKLEAK */
 	"stackleak_track_stack",
+	/* TRACE_BRANCH_PROFILING */
+	"ftrace_likely_update",
+	/* STACKPROTECTOR */
+	"__stack_chk_fail",
 	/* misc */
 	"csum_partial_copy_generic",
 	"copy_mc_fragile",
 	"copy_mc_fragile_handle_tail",
 	"copy_mc_enhanced_fast_string",
-	"ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
 	"rep_stos_alternative",
 	"rep_movs_alternative",
 	"__copy_user_nocache",
@@ -1604,6 +1573,8 @@ static int add_jump_destinations(struct objtool_file *file)
 	unsigned long dest_off;
 
 	for_each_insn(file, insn) {
+		struct symbol *func = insn_func(insn);
+
 		if (insn->jump_dest) {
 			/*
 			 * handle_group_alt() may have previously set
@@ -1627,7 +1598,7 @@ static int add_jump_destinations(struct objtool_file *file)
 		} else if (reloc->sym->return_thunk) {
 			add_return_call(file, insn, true);
 			continue;
-		} else if (insn_func(insn)) {
+		} else if (func) {
 			/*
 			 * External sibling call or internal sibling call with
 			 * STT_FUNC reloc.
@@ -1660,6 +1631,15 @@ static int add_jump_destinations(struct objtool_file *file)
 				continue;
 			}
 
+			/*
+			 * GCOV/KCOV dead code can jump to the end of the
+			 * function/section.
+			 */
+			if (file->ignore_unreachables && func &&
+			    dest_sec == insn->sec &&
+			    dest_off == func->offset + func->len)
+				continue;
+
 			WARN_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
 				  dest_sec->name, dest_off);
 			return -1;
@@ -1684,8 +1664,7 @@ static int add_jump_destinations(struct objtool_file *file)
 		/*
 		 * Cross-function jump.
 		 */
-		if (insn_func(insn) && insn_func(jump_dest) &&
-		    insn_func(insn) != insn_func(jump_dest)) {
+		if (func && insn_func(jump_dest) && func != insn_func(jump_dest)) {
 
 			/*
 			 * For GCC 8+, create parent/child links for any cold
@@ -1702,10 +1681,10 @@ static int add_jump_destinations(struct objtool_file *file)
 			 * case where the parent function's only reference to a
 			 * subfunction is through a jump table.
 			 */
-			if (!strstr(insn_func(insn)->name, ".cold") &&
+			if (!strstr(func->name, ".cold") &&
 			    strstr(insn_func(jump_dest)->name, ".cold")) {
-				insn_func(insn)->cfunc = insn_func(jump_dest);
-				insn_func(jump_dest)->pfunc = insn_func(insn);
+				func->cfunc = insn_func(jump_dest);
+				insn_func(jump_dest)->pfunc = func;
 			}
 		}
 
@@ -2099,6 +2078,14 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 		    reloc_addend(reloc) == pfunc->offset)
 			break;
 
+		/*
+		 * Clang sometimes leaves dangling unused jump table entries
+		 * which point to the end of the function.  Ignore them.
+		 */
+		if (reloc->sym->sec == pfunc->sec &&
+		    reloc_addend(reloc) == pfunc->offset + pfunc->len)
+			goto next;
+
 		dest_insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
 		if (!dest_insn)
 			break;
@@ -2116,6 +2103,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 		alt->insn = dest_insn;
 		alt->next = insn->alts;
 		insn->alts = alt;
+next:
 		prev_offset = reloc_offset(reloc);
 	}
 
@@ -2627,13 +2615,14 @@ static void mark_rodata(struct objtool_file *file)
 	 *
 	 * - .rodata: can contain GCC switch tables
 	 * - .rodata.<func>: same, if -fdata-sections is being used
-	 * - .rodata..c_jump_table: contains C annotated jump tables
+	 * - .data.rel.ro.c_jump_table: contains C annotated jump tables
 	 *
 	 * .rodata.str1.* sections are ignored; they don't contain jump tables.
 	 */
 	for_each_sec(file, sec) {
-		if (!strncmp(sec->name, ".rodata", 7) &&
-		    !strstr(sec->name, ".str1.")) {
+		if ((!strncmp(sec->name, ".rodata", 7) &&
+		     !strstr(sec->name, ".str1.")) ||
+		    !strncmp(sec->name, ".data.rel.ro", 12)) {
 			sec->rodata = true;
 			found = true;
 		}
@@ -3366,7 +3355,7 @@ static int handle_insn_ops(struct instruction *insn,
 		if (update_cfi_state(insn, next_insn, &state->cfi, op))
 			return 1;
 
-		if (!insn->alt_group)
+		if (!opts.uaccess || !insn->alt_group)
 			continue;
 
 		if (op->dest.type == OP_DEST_PUSHF) {
@@ -3661,6 +3650,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 			    !strncmp(func->name, "__pfx_", 6))
 				return 0;
 
+			if (file->ignore_unreachables)
+				return 0;
+
 			WARN("%s() falls through to next function %s()",
 			     func->name, insn_func(insn)->name);
 			return 1;
@@ -3830,6 +3822,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 			return 0;
 
 		case INSN_STAC:
+			if (!opts.uaccess)
+				break;
+
 			if (state.uaccess) {
 				WARN_INSN(insn, "recursive UACCESS enable");
 				return 1;
@@ -3839,6 +3834,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 			break;
 
 		case INSN_CLAC:
+			if (!opts.uaccess)
+				break;
+
 			if (!state.uaccess && func) {
 				WARN_INSN(insn, "redundant UACCESS disable");
 				return 1;
@@ -3880,6 +3878,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 		if (!next_insn) {
 			if (state.cfi.cfa.base == CFI_UNDEFINED)
 				return 0;
+			if (file->ignore_unreachables)
+				return 0;
+
 			WARN("%s: unexpected end of section", sec->name);
 			return 1;
 		}
@@ -4018,6 +4019,11 @@ static int validate_unret(struct objtool_file *file, struct instruction *insn)
 			WARN_INSN(insn, "RET before UNTRAIN");
 			return 1;
 
+		case INSN_CONTEXT_SWITCH:
+			if (insn_func(insn))
+				break;
+			return 0;
+
 		case INSN_NOP:
 			if (insn->retpoline_safe)
 				return 0;
@@ -4027,6 +4033,9 @@ static int validate_unret(struct objtool_file *file, struct instruction *insn)
 			break;
 		}
 
+		if (insn->dead_end)
+			return 0;
+
 		if (!next) {
 			WARN_INSN(insn, "teh end!");
 			return -1;
@@ -4181,7 +4190,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
 	 * It may also insert a UD2 after calling a __noreturn function.
 	 */
 	prev_insn = prev_insn_same_sec(file, insn);
-	if (prev_insn->dead_end &&
+	if (prev_insn && prev_insn->dead_end &&
 	    (insn->type == INSN_BUG ||
 	     (insn->type == INSN_JUMP_UNCONDITIONAL &&
 	      insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
@@ -4303,7 +4312,8 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
 	if (!insn || insn->ignore || insn->visited)
 		return 0;
 
-	state->uaccess = sym->uaccess_safe;
+	if (opts.uaccess)
+		state->uaccess = sym->uaccess_safe;
 
 	ret = validate_branch(file, insn_func(insn), insn, *state);
 	if (ret)
@@ -4603,35 +4613,6 @@ static int validate_sls(struct objtool_file *file)
 	return warnings;
 }
 
-static bool ignore_noreturn_call(struct instruction *insn)
-{
-	struct symbol *call_dest = insn_call_dest(insn);
-
-	/*
-	 * FIXME: hack, we need a real noreturn solution
-	 *
-	 * Problem is, exc_double_fault() may or may not return, depending on
-	 * whether CONFIG_X86_ESPFIX64 is set.  But objtool has no visibility
-	 * to the kernel config.
-	 *
-	 * Other potential ways to fix it:
-	 *
-	 *   - have compiler communicate __noreturn functions somehow
-	 *   - remove CONFIG_X86_ESPFIX64
-	 *   - read the .config file
-	 *   - add a cmdline option
-	 *   - create a generic objtool annotation format (vs a bunch of custom
-	 *     formats) and annotate it
-	 */
-	if (!strcmp(call_dest->name, "exc_double_fault")) {
-		/* prevent further unreachable warnings for the caller */
-		insn->sym->warned = 1;
-		return true;
-	}
-
-	return false;
-}
-
 static int validate_reachable_instructions(struct objtool_file *file)
 {
 	struct instruction *insn, *prev_insn;
@@ -4648,7 +4629,7 @@ static int validate_reachable_instructions(struct objtool_file *file)
 		prev_insn = prev_insn_same_sec(file, insn);
 		if (prev_insn && prev_insn->dead_end) {
 			call_dest = insn_call_dest(prev_insn);
-			if (call_dest && !ignore_noreturn_call(prev_insn)) {
+			if (call_dest) {
 				WARN_INSN(insn, "%s() is missing a __noreturn annotation",
 					  call_dest->name);
 				warnings++;
@@ -4671,6 +4652,8 @@ static int disas_funcs(const char *funcs)
 	char *cmd;
 
 	cross_compile = getenv("CROSS_COMPILE");
+	if (!cross_compile)
+		cross_compile = "";
 
 	objdump_str = "%sobjdump -wdr %s | gawk -M -v _funcs='%s' '"
 			"BEGIN { split(_funcs, funcs); }"
@@ -4777,8 +4760,10 @@ int check(struct objtool_file *file)
 	init_cfi_state(&force_undefined_cfi);
 	force_undefined_cfi.force_undefined = true;
 
-	if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
+	if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3))) {
+		ret = -1;
 		goto out;
+	}
 
 	cfi_hash_add(&init_cfi);
 	cfi_hash_add(&func_cfi);
@@ -4795,7 +4780,7 @@ int check(struct objtool_file *file)
 	if (opts.retpoline) {
 		ret = validate_retpoline(file);
 		if (ret < 0)
-			return ret;
+			goto out;
 		warnings += ret;
 	}
 
@@ -4831,7 +4816,7 @@ int check(struct objtool_file *file)
 		 */
 		ret = validate_unrets(file);
 		if (ret < 0)
-			return ret;
+			goto out;
 		warnings += ret;
 	}
 
@@ -4894,7 +4879,7 @@ int check(struct objtool_file *file)
 	if (opts.prefix) {
 		ret = add_prefix_symbols(file);
 		if (ret < 0)
-			return ret;
+			goto out;
 		warnings += ret;
 	}