| Message ID | 20220610233513.1798771-16-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KCFI support | expand |
On Fri, Jun 10, 2022 at 04:35:08PM -0700, Sami Tolvanen wrote: > The __cfi_ preambles contain int3 padding and a mov instruction that > embeds the KCFI type identifier in the following format: > > ; type preamble > __cfi_function: > int3 > int3 > mov <id>, %eax > int3 > int3 > function: > ... > > While the preamble symbols are STT_FUNC and contain valid > instructions, they are never executed and always fall through. Skip > the warning for them. > > .kcfi_traps sections point to CFI traps in text sections. Also skip > the warning about them referencing !ENDBR instructions. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 864bb9dd3584..337b92c3b755 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3207,6 +3207,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, next_insn = next_insn_to_validate(file, insn); if (func && insn->func && func != insn->func->pfunc) { + /* Ignore KCFI type preambles, which always fall through */ + if (!strncmp(func->name, "__cfi_", 6)) + return 0; + WARN("%s() falls through to next function %s()", func->name, insn->func->name); return 1; @@ -3827,7 +3831,8 @@ static int validate_ibt(struct objtool_file *file) !strcmp(sec->name, "__ex_table") || !strcmp(sec->name, "__jump_table") || !strcmp(sec->name, "__mcount_loc") || - !strcmp(sec->name, "__tracepoints")) + !strcmp(sec->name, "__tracepoints") || + !strcmp(sec->name, ".kcfi_traps")) continue; list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
The __cfi_ preambles contain int3 padding and a mov instruction that embeds the KCFI type identifier in the following format: ; type preamble __cfi_function: int3 int3 mov <id>, %eax int3 int3 function: ... While the preamble symbols are STT_FUNC and contain valid instructions, they are never executed and always fall through. Skip the warning for them. .kcfi_traps sections point to CFI traps in text sections. Also skip the warning about them referencing !ENDBR instructions. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- tools/objtool/check.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)