Commit 18a14575 authored Oct 28, 2020 by Sami Tolvanen Committed by Kees Cook Feb 23, 2021

objtool: Fix __mcount_loc generation with Clang's assembler



When objtool generates relocations for the __mcount_loc section, it
tries to reference __fentry__ calls by their section symbol offset.
However, this fails with Clang's integrated assembler as it may not
generate section symbols for every section. This patch looks up a
function symbol instead if the section symbol is missing, similarly
to commit e81e0724 ("objtool: Support Clang non-section symbols
in ORC generation").

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

parent 99d00215

tools/objtool/check.c

+15 −2

Original line number	Diff line number	Diff line
		@@ -573,8 +573,21 @@ static int create_mcount_loc_sections(struct objtool_file *file)
		}
		memset(reloc, 0, sizeof(*reloc));

		if (insn->sec->sym) {
		reloc->sym = insn->sec->sym;
		reloc->addend = insn->offset;
		} else {
		reloc->sym = find_symbol_containing(insn->sec, insn->offset);

		if (!reloc->sym) {
		WARN("missing symbol for insn at offset 0x%lx\n",
		insn->offset);
		return -1;
		}

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

		reloc->type = R_X86_64_64;
		reloc->offset = idx * sizeof(unsigned long);
		reloc->sec = reloc_sec;