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objtool: Disable CFI warnings 

JIRA: https://issues.redhat.com/browse/RHEL-255

Conflicts:
	tools/objtool/check.c
	- cs-9 already has upstream 9440155ccb94 ("ftrace: Add
	  HAVE_DYNAMIC_FTRACE_NO_PATCHABLE"), which introduced
	  __patchable_function_entries

commit 3c68a92d17add767109441f4040391b9e8a14a98
Author: Sami Tolvanen <samitolvanen@google.com>
Date:   Thu Sep 8 14:54:59 2022 -0700

    objtool: Disable CFI warnings

    The __cfi_ preambles contain a mov instruction that embeds the KCFI
    type identifier in the following format:

      ; type preamble
      __cfi_function:
        mov <id>, %eax
      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>
    Reviewed-by: Kees Cook <keescook@chromium.org>
    Tested-by: Kees Cook <keescook@chromium.org>
    Tested-by: Nathan Chancellor <nathan@kernel.org>
    Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
    Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Kees Cook <keescook@chromium.org>
    Link: https://lore.kernel.org/r/20220908215504.3686827-18-samitolvanen@google.com

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
This commit is contained in:
Joe Lawrence 2023-05-01 17:45:22 -04:00
parent 6054303c9e
commit a3048abbe6
1 changed files with 5 additions and 0 deletions
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5
tools/objtool/check.c
View File

@ -3317,6 +3317,10 @@ 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;
@ -4115,6 +4119,7 @@ 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, ".kcfi_traps") ||
strstr(sec->name, "__patchable_function_entries"))
continue;