linux-kernel - [PATCH] x86/sev: Mark snp

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Message-Id: <20220824152420.20547-1-bp@alien8.de>
Date:   Wed, 24 Aug 2022 17:24:20 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     Michael Matz <matz@...e.de>, linux-toolchains@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86/sev: Mark snp_abort() noreturn

From: Borislav Petkov <bp@...e.de>

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.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/include/asm/sev.h | 2 +-
 arch/x86/kernel/sev.c      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 4a23e52fe0ee..ebc271bb6d8e 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 4f84c3f11af5..a428c62330d3 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);
 }
-- 
2.35.1