Commit cce622ab authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'objtool-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull objtool fix from Ingo Molnar:
 "Fix a segfault that occurs when built with Clang"

* tag 'objtool-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix seg fault with Clang non-section symbols
parents 6be5f582 44f6a7c0

tools/objtool/check.c

+9 −2
Original line number Diff line number Diff line
@@ -467,13 +467,20 @@ static int create_static_call_sections(struct objtool_file *file) 


		/* populate reloc for 'addr' */

		reloc = malloc(sizeof(*reloc));



		if (!reloc) {

			perror("malloc");

			return -1;

		}

		memset(reloc, 0, sizeof(*reloc));

		reloc->sym = insn->sec->sym;

		reloc->addend = insn->offset;



		insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc);

		if (!reloc->sym) {

			WARN_FUNC("static call tramp: missing containing symbol",

				  insn->sec, insn->offset);

			return -1;

		}



		reloc->type = R_X86_64_PC32;

		reloc->offset = idx * sizeof(struct static_call_site);

		reloc->sec = reloc_sec;

tools/objtool/elf.c

+26 −0
Original line number Diff line number Diff line
@@ -262,6 +262,32 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns 
	return find_reloc_by_dest_range(elf, sec, offset, 1);

}



void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,

			      struct reloc *reloc)

{

	if (sec->sym) {

		reloc->sym = sec->sym;

		reloc->addend = offset;

		return;

	}



	/*

	 * The Clang assembler strips section symbols, so we have to reference

	 * the function symbol instead:

	 */

	reloc->sym = find_symbol_containing(sec, offset);

	if (!reloc->sym) {

		/*

		 * Hack alert.  This happens when we need to reference the NOP

		 * pad insn immediately after the function.

		 */

		reloc->sym = find_symbol_containing(sec, offset - 1);

	}



	if (reloc->sym)

		reloc->addend = offset - reloc->sym->offset;

}



static int read_sections(struct elf *elf)

{

	Elf_Scn *s = NULL;

tools/objtool/elf.h

+2 −0
Original line number Diff line number Diff line
@@ -140,6 +140,8 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns 
struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,

				     unsigned long offset, unsigned int len);

struct symbol *find_func_containing(struct section *sec, unsigned long offset);

void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,

			      struct reloc *reloc);

int elf_rebuild_reloc_section(struct elf *elf, struct section *sec);



#define for_each_sec(file, sec)						\

tools/objtool/orc_gen.c

+5 −24
Original line number Diff line number Diff line
@@ -105,32 +105,13 @@ static int create_orc_entry(struct elf *elf, struct section *u_sec, struct secti 
	}

	memset(reloc, 0, sizeof(*reloc));



	if (insn_sec->sym) {

		reloc->sym = insn_sec->sym;

		reloc->addend = insn_off;

	} else {

		/*

		 * The Clang assembler doesn't produce section symbols, so we

		 * have to reference the function symbol instead:

		 */

		reloc->sym = find_symbol_containing(insn_sec, insn_off);

		if (!reloc->sym) {

			/*

			 * Hack alert.  This happens when we need to reference

			 * the NOP pad insn immediately after the function.

			 */

			reloc->sym = find_symbol_containing(insn_sec,

							   insn_off - 1);

		}

	insn_to_reloc_sym_addend(insn_sec, insn_off, reloc);

	if (!reloc->sym) {

			WARN("missing symbol for insn at offset 0x%lx\n",

		WARN("missing symbol for insn at offset 0x%lx",

		     insn_off);

		return -1;

	}



		reloc->addend = insn_off - reloc->sym->offset;

	}



	reloc->type = R_X86_64_PC32;

	reloc->offset = idx * sizeof(int);

	reloc->sec = ip_relocsec;