linux-kernel - [tip: x86/urgent] x86/sev: Mark snp

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Message-ID: <166143608669.401.14403984449767044288.tip-bot2@tip-bot2>
Date:   Thu, 25 Aug 2022 14:01:26 -0000
From:   "tip-bot2 for Borislav Petkov" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Michael Matz <matz@...e.de>, Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/sev: Mark snp_abort() noreturn

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     c93c296fff6b369a7115916145047c8a3db6e27f
Gitweb:        https://git.kernel.org/tip/c93c296fff6b369a7115916145047c8a3db6e27f
Author:        Borislav Petkov <bp@...e.de>
AuthorDate:    Wed, 24 Aug 2022 17:13:26 +02:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Thu, 25 Aug 2022 15:54:03 +02:00

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@...e.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Peter Zijlstra <peterz@...radead.org>
Link: https://lore.kernel.org/r/20220824152420.20547-1-bp@alien8.de
---
 arch/x86/include/asm/sev.h |  2 +-
 arch/x86/kernel/sev.c      |  2 +-
 tools/objtool/check.c      | 34 ++++++++++++++++++----------------
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 4a23e52..ebc271b 100644
--- 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 4f84c3f..a428c62 100644
--- 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 0cec74d..ad51689 100644
--- 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)