x86/smp: Fix mwait_play_dead() and acpi_processor_ffh_play_dead() noreturn behavior [partial 2]

JIRA: https://issues.redhat.com/browse/RHEL-85302

Conflicts:
	tools/objtool/noreturns.h
	- RHEL doesn't have noreturns.h, so update global_no_returns[]
	  in tools/objtool/check.c for acpi_processor_ffh_play_dead.
	  This completes the partial backport started by cs-9's
	  d0c965e.

commit 4e32645
Author: Josh Poimboeuf <jpoimboe@kernel.org>
Date:   Sun Mar 2 16:48:51 2025 -0800

    x86/smp: Fix mwait_play_dead() and acpi_processor_ffh_play_dead() noreturn behavior

    Fix some related issues (done in a single patch to avoid introducing
    intermediate bisect warnings):

      1) The SMP version of mwait_play_dead() doesn't return, but its
         !SMP counterpart does.  Make its calling behavior consistent by
         resolving the !SMP version to a BUG().  It should never be called
         anyway, this just enforces that at runtime and enables its callers
         to be marked as __noreturn.

      2) While the SMP definition of mwait_play_dead() is annotated as
         __noreturn, the declaration isn't.  Nor is it listed in
         tools/objtool/noreturns.h.  Fix that.

      3) Similar to #1, the SMP version of acpi_processor_ffh_play_dead()
         doesn't return but its !SMP counterpart does.  Make the !SMP
         version a BUG().  It should never be called.

      4) acpi_processor_ffh_play_dead() doesn't return, but is lacking any
         __noreturn annotations.  Fix that.

    This fixes the following objtool warnings:

      vmlinux.o: warning: objtool: acpi_processor_ffh_play_dead+0x67: mwait_play_dead() is missing a __noreturn annotation
      vmlinux.o: warning: objtool: acpi_idle_play_dead+0x3c: acpi_processor_ffh_play_dead() is missing a __noreturn annotation

    Fixes: a7dd183 ("x86/smp: Allow calling mwait_play_dead with an arbitrary hint")
    Fixes: 541ddf3 ("ACPI/processor_idle: Add FFH state handling")
    Reported-by: Paul E. McKenney <paulmck@kernel.org>
    Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Tested-by: Paul E. McKenney <paulmck@kernel.org>
    Link: https://lore.kernel.org/r/e885c6fa9e96a61471b33e48c2162d28b15b14c5.1740962711.git.jpoimboe@kernel.org

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>

Author: joe-lawrence

tools/objtool/check.c

@@ -188,6 +188,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 		"__stack_chk_fail",
 		"__tdx_hypercall_failed",
 		"__ubsan_handle_builtin_unreachable",
+		"acpi_processor_ffh_play_dead",
 		"arch_call_rest_init",
 		"cpu_bringup_and_idle",
 		"cpu_startup_entry",