Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (6527efba) · Commits · e / devices / android_kernel_oneplus_sm8150

Makefile

+2 −1

Original line number	Diff line number	Diff line
		@@ -1008,7 +1008,8 @@ prepare0: archprepare FORCE
		prepare: prepare0 prepare-objtool

		ifdef CONFIG_STACK_VALIDATION
		has_libelf := $(shell echo "int main() {}" \| $(HOSTCC) -xc -o /dev/null -lelf - &> /dev/null && echo 1 \|\| echo 0)
		has_libelf := $(call try-run,\
		echo "int main() {}" \| $(HOSTCC) -xc -o /dev/null -lelf -,1,0)
		ifeq ($(has_libelf),1)
		objtool_target := tools/objtool FORCE
		else

tools/objtool/Documentation/stack-validation.txt

+29 −9

Original line number	Diff line number	Diff line
		@@ -299,17 +299,37 @@ they mean, and suggestions for how to fix them.
		Errors in .c files
		------------------

		If you're getting an objtool error in a compiled .c file, chances are
		the file uses an asm() statement which has a "call" instruction. An
		asm() statement with a call instruction must declare the use of the
		stack pointer in its output operand. For example, on x86_64:
		1. c_file.o: warning: objtool: funcA() falls through to next function funcB()

		This means that funcA() doesn't end with a return instruction or an
		unconditional jump, and that objtool has determined that the function
		can fall through into the next function. There could be different
		reasons for this:

		1) funcA()'s last instruction is a call to a "noreturn" function like
		panic(). In this case the noreturn function needs to be added to
		objtool's hard-coded global_noreturns array. Feel free to bug the
		objtool maintainer, or you can submit a patch.

		2) funcA() uses the unreachable() annotation in a section of code
		that is actually reachable.

		3) If funcA() calls an inline function, the object code for funcA()
		might be corrupt due to a gcc bug. For more details, see:
		https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646

		2. If you're getting any other objtool error in a compiled .c file, it
		may be because the file uses an asm() statement which has a "call"
		instruction. An asm() statement with a call instruction must declare
		the use of the stack pointer in its output operand. For example, on
		x86_64:

		register void *__sp asm("rsp");
		asm volatile("call func" : "+r" (__sp));

		Otherwise the stack frame may not get created before the call.

		Another possible cause for errors in C code is if the Makefile removes
		3. Another possible cause for errors in C code is if the Makefile removes
		-fno-omit-frame-pointer or adds -fomit-frame-pointer to the gcc options.

		Also see the above section for .S file errors for more information what

tools/objtool/builtin-check.c

+72 −25

Original line number	Diff line number	Diff line
		@@ -54,6 +54,7 @@ struct instruction {
		struct symbol *call_dest;
		struct instruction *jump_dest;
		struct list_head alts;
		struct symbol *func;
		};

		struct alternative {
		@@ -66,6 +67,7 @@ struct objtool_file {
		struct list_head insn_list;
		DECLARE_HASHTABLE(insn_hash, 16);
		struct section rodata, whitelist;
		bool ignore_unreachables, c_file;
		};

		const char *objname;
		@@ -228,7 +230,7 @@ static int __dead_end_function(struct objtool_file file, struct symbol func,
		}
		}

		if (insn->type == INSN_JUMP_DYNAMIC)
		if (insn->type == INSN_JUMP_DYNAMIC && list_empty(&insn->alts))
		/* sibling call */
		return 0;
		}
		@@ -248,6 +250,7 @@ static int dead_end_function(struct objtool_file file, struct symbol func)
		static int decode_instructions(struct objtool_file *file)
		{
		struct section *sec;
		struct symbol *func;
		unsigned long offset;
		struct instruction *insn;
		int ret;
		@@ -281,6 +284,21 @@ static int decode_instructions(struct objtool_file *file)
		hash_add(file->insn_hash, &insn->hash, insn->offset);
		list_add_tail(&insn->list, &file->insn_list);
		}

		list_for_each_entry(func, &sec->symbol_list, list) {
		if (func->type != STT_FUNC)
		continue;

		if (!find_insn(file, sec, func->offset)) {
		WARN("%s(): can't find starting instruction",
		func->name);
		return -1;
		}

		func_for_each_insn(file, func, insn)
		if (!insn->func)
		insn->func = func;
		}
		}

		return 0;
		@@ -664,13 +682,40 @@ static int add_func_switch_tables(struct objtool_file *file,
		text_rela->addend);

		/*
		* TODO: Document where this is needed, or get rid of it.
		*
		* rare case: jmpq *[addr](%rip)
		*
		* This check is for a rare gcc quirk, currently only seen in
		* three driver functions in the kernel, only with certain
		* obscure non-distro configs.
		*
		* As part of an optimization, gcc makes a copy of an existing
		* switch jump table, modifies it, and then hard-codes the jump
		* (albeit with an indirect jump) to use a single entry in the
		* table. The rest of the jump table and some of its jump
		* targets remain as dead code.
		*
		* In such a case we can just crudely ignore all unreachable
		* instruction warnings for the entire object file. Ideally we
		* would just ignore them for the function, but that would
		* require redesigning the code quite a bit. And honestly
		* that's just not worth doing: unreachable instruction
		* warnings are of questionable value anyway, and this is such
		* a rare issue.
		*
		* kbuild reports:
		* - https://lkml.kernel.org/r/201603231906.LWcVUpxm%25fengguang.wu@intel.com
		* - https://lkml.kernel.org/r/201603271114.K9i45biy%25fengguang.wu@intel.com
		* - https://lkml.kernel.org/r/201603291058.zuJ6ben1%25fengguang.wu@intel.com
		*
		* gcc bug:
		* - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70604
		*/
		if (!rodata_rela)
		if (!rodata_rela) {
		rodata_rela = find_rela_by_dest(file->rodata,
		text_rela->addend + 4);
		if (rodata_rela)
		file->ignore_unreachables = true;
		}

		if (!rodata_rela)
		continue;
		@@ -732,9 +777,6 @@ static int decode_sections(struct objtool_file *file)
		{
		int ret;

		file->whitelist = find_section_by_name(file->elf, "__func_stack_frame_non_standard");
		file->rodata = find_section_by_name(file->elf, ".rodata");

		ret = decode_instructions(file);
		if (ret)
		return ret;
		@@ -799,6 +841,7 @@ static int validate_branch(struct objtool_file *file,
		struct alternative *alt;
		struct instruction *insn;
		struct section *sec;
		struct symbol *func = NULL;
		unsigned char state;
		int ret;

		@@ -813,6 +856,16 @@ static int validate_branch(struct objtool_file *file,
		}

		while (1) {
		if (file->c_file && insn->func) {
		if (func && func != insn->func) {
		WARN("%s() falls through to next function %s()",
		func->name, insn->func->name);
		return 1;
		}

		func = insn->func;
		}

		if (insn->visited) {
		if (frame_state(insn->state) != frame_state(state)) {
		WARN_FUNC("frame pointer state mismatch",
		@@ -823,13 +876,6 @@ static int validate_branch(struct objtool_file *file,
		return 0;
		}

		/*
		* Catch a rare case where a noreturn function falls through to
		* the next function.
		*/
		if (is_fentry_call(insn) && (state & STATE_FENTRY))
		return 0;

		insn->visited = true;
		insn->state = state;

		@@ -1035,12 +1081,8 @@ static int validate_functions(struct objtool_file *file)
		continue;

		insn = find_insn(file, sec, func->offset);
		if (!insn) {
		WARN("%s(): can't find starting instruction",
		func->name);
		warnings++;
		if (!insn)
		continue;
		}

		ret = validate_branch(file, insn, 0);
		warnings += ret;
		@@ -1056,14 +1098,15 @@ static int validate_functions(struct objtool_file *file)
		if (insn->visited)
		continue;

		if (!ignore_unreachable_insn(func, insn) &&
		!warnings) {
		insn->visited = true;

		if (file->ignore_unreachables \|\| warnings \|\|
		ignore_unreachable_insn(func, insn))
		continue;

		WARN_FUNC("function has unreachable instruction", insn->sec, insn->offset);
		warnings++;
		}

		insn->visited = true;
		}
		}
		}

		@@ -1133,6 +1176,10 @@ int cmd_check(int argc, const char **argv)

		INIT_LIST_HEAD(&file.insn_list);
		hash_init(file.insn_hash);
		file.whitelist = find_section_by_name(file.elf, "__func_stack_frame_non_standard");
		file.rodata = find_section_by_name(file.elf, ".rodata");
		file.ignore_unreachables = false;
		file.c_file = find_section_by_name(file.elf, ".comment");

		ret = decode_sections(&file);
		if (ret < 0)