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Commit e72e58fa authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull objtool fixes from Ingo Molnar:
 "A handful of objtool fixes related to unreachable code, plus a build
  fix for out of tree modules"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Enclose contents of unreachable() macro in a block
  objtool: Prevent GCC from merging annotate_unreachable()
  objtool: Improve detection of BUG() and other dead ends
  objtool: Fix CONFIG_STACK_VALIDATION=y warning for out-of-tree modules
parents 74e3f63c 4e4636cf

Makefile

+12 −12
Original line number Diff line number Diff line
@@ -910,6 +910,18 @@ mod_sign_cmd = true 
endif

export mod_sign_cmd



ifdef CONFIG_STACK_VALIDATION

  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

    $(warning "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev, libelf-devel or elfutils-libelf-devel")

    SKIP_STACK_VALIDATION := 1

    export SKIP_STACK_VALIDATION

  endif

endif





ifeq ($(KBUILD_EXTMOD),)

core-y		+= kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/
@@ -1037,18 +1049,6 @@ prepare0: archprepare gcc-plugins 
# All the preparing..

prepare: prepare0 prepare-objtool



ifdef CONFIG_STACK_VALIDATION

  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

    $(warning "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev, libelf-devel or elfutils-libelf-devel")

    SKIP_STACK_VALIDATION := 1

    export SKIP_STACK_VALIDATION

  endif

endif



PHONY += prepare-objtool

prepare-objtool: $(objtool_target)

arch/x86/kernel/vmlinux.lds.S

+1 −0
Original line number Diff line number Diff line
@@ -346,6 +346,7 @@ SECTIONS 
	/DISCARD/ : {

		*(.eh_frame)

		*(__func_stack_frame_non_standard)

		*(__unreachable)

	}

}

include/linux/compiler-gcc.h

+13 −1
Original line number Diff line number Diff line
@@ -197,6 +197,17 @@ 
#endif

#endif



#ifdef CONFIG_STACK_VALIDATION

#define annotate_unreachable() ({					\

	asm("%c0:\t\n"							\

	    ".pushsection __unreachable, \"a\"\t\n"			\

	    ".long %c0b\t\n"						\

	    ".popsection\t\n" : : "i" (__LINE__));			\

})

#else

#define annotate_unreachable()

#endif



/*

 * Mark a position in code as unreachable.  This can be used to

 * suppress control flow warnings after asm blocks that transfer
@@ -206,7 +217,8 @@ 
 * this in the preprocessor, but we can live with this because they're

 * unreleased.  Really, we need to have autoconf for the kernel.

 */

#define unreachable() __builtin_unreachable()

#define unreachable() \

	do { annotate_unreachable(); __builtin_unreachable(); } while (0)



/* Mark a function definition as prohibited from being cloned. */

#define __noclone	__attribute__((__noclone__, __optimize__("no-tracer")))

tools/objtool/arch.h

+2 −3
Original line number Diff line number Diff line
@@ -31,9 +31,8 @@ 
#define INSN_CALL_DYNAMIC	8

#define INSN_RETURN		9

#define INSN_CONTEXT_SWITCH	10

#define INSN_BUG		11

#define INSN_NOP		12

#define INSN_OTHER		13

#define INSN_NOP		11

#define INSN_OTHER		12

#define INSN_LAST		INSN_OTHER



int arch_decode_instruction(struct elf *elf, struct section *sec,

tools/objtool/arch/x86/decode.c

+0 −3
Original line number Diff line number Diff line
@@ -118,9 +118,6 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, 
			 op2 == 0x35)

			/* sysenter, sysret */

			*type = INSN_CONTEXT_SWITCH;

		else if (op2 == 0x0b || op2 == 0xb9)

			/* ud2 */

			*type = INSN_BUG;

		else if (op2 == 0x0d || op2 == 0x1f)

			/* nopl/nopw */

			*type = INSN_NOP;