x86/sev: Mark snp_abort() noreturn

Mark both the function prototype and definition as noreturn in order to
prevent the compiler from doing transformations which confuse objtool
like so:

  vmlinux.o: warning: objtool: sme_enable+0x71: unreachable instruction

This triggers with gcc-12.

Add it and sev_es_terminate() to the objtool noreturn tracking array
too. Sort it while at it.

Suggested-by: Michael Matz <matz@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220824152420.20547-1-bp@alien8.de

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 4a23e52fe0ee1632eb64fb1ed6ab183c5b7bb81f..ebc271bb6d8ed1d74e07194604b25244646ffc0a 100644 (file)
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -195,7 +195,7 @@ void snp_set_memory_shared(unsigned long vaddr, unsigned int npages);
 void snp_set_memory_private(unsigned long vaddr, unsigned int npages);
 void snp_set_wakeup_secondary_cpu(void);
 bool snp_init(struct boot_params *bp);
-void snp_abort(void);
+void __init __noreturn snp_abort(void);
 int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err);
 #else
 static inline void sev_es_ist_enter(struct pt_regs *regs) { }

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 4f84c3f11af5b60cfe1a9d6d68b1823d4b74c532..a428c62330d371a6742ada0a2e9e578dd3f1def6 100644 (file)
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2112,7 +2112,7 @@ bool __init snp_init(struct boot_params *bp)
        return true;
 }
 
-void __init snp_abort(void)
+void __init __noreturn snp_abort(void)
 {
        sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
 }

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0cec74da7ffea42da25d5423207995e1a0579ad0..ad51689dfb41556b5e1a3da5872dc9e570711e5d 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -162,32 +162,34 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 
        /*
         * Unfortunately these have to be hard coded because the noreturn
-        * attribute isn't provided in ELF data.
+        * attribute isn't provided in ELF data. Keep 'em sorted.
         */
        static const char * const global_noreturns[] = {
+               "__invalid_creds",
+               "__module_put_and_kthread_exit",
+               "__reiserfs_panic",
                "__stack_chk_fail",
-               "panic",
+               "__ubsan_handle_builtin_unreachable",
+               "cpu_bringup_and_idle",
+               "cpu_startup_entry",
                "do_exit",
+               "do_group_exit",
                "do_task_dead",
-               "kthread_exit",
-               "make_task_dead",
-               "__module_put_and_kthread_exit",
+               "ex_handler_msr_mce",
+               "fortify_panic",
                "kthread_complete_and_exit",
-               "__reiserfs_panic",
+               "kthread_exit",
+               "kunit_try_catch_throw",
                "lbug_with_loc",
-               "fortify_panic",
-               "usercopy_abort",
                "machine_real_restart",
+               "make_task_dead",
+               "panic",
                "rewind_stack_and_make_dead",
-               "kunit_try_catch_throw",
-               "xen_start_kernel",
-               "cpu_bringup_and_idle",
-               "do_group_exit",
+               "sev_es_terminate",
+               "snp_abort",
                "stop_this_cpu",
-               "__invalid_creds",
-               "cpu_startup_entry",
-               "__ubsan_handle_builtin_unreachable",
-               "ex_handler_msr_mce",
+               "usercopy_abort",
+               "xen_start_kernel",
        };
 
        if (!func)