linux-kernel - [tip:core/urgent] x86/head/64: Annotate start

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Message-ID: <tip-61a73f5cd1a5794626d216cc56e20a1b195c5d0c@git.kernel.org>
Date:   Thu, 18 Jul 2019 12:11:14 -0700
From:   tip-bot for Josh Poimboeuf <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, jpoimboe@...hat.com, tglx@...utronix.de,
        mingo@...nel.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org
Subject: [tip:core/urgent] x86/head/64: Annotate start_cpu0() as
 non-callable

Commit-ID:  61a73f5cd1a5794626d216cc56e20a1b195c5d0c
Gitweb:     https://git.kernel.org/tip/61a73f5cd1a5794626d216cc56e20a1b195c5d0c
Author:     Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Wed, 17 Jul 2019 20:36:41 -0500
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 18 Jul 2019 21:01:04 +0200

x86/head/64: Annotate start_cpu0() as non-callable

After an objtool improvement, it complains about the fact that
start_cpu0() jumps to code which has an LRET instruction.

  arch/x86/kernel/head_64.o: warning: objtool: .head.text+0xe4: unsupported instruction in callable function

Technically, start_cpu0() is callable, but it acts nothing like a
callable function.  Prevent objtool from treating it like one by
removing its ELF function annotation.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/6b1b4505fcb90571a55fa1b52d71fb458ca24454.1563413318.git.jpoimboe@redhat.com

---
 arch/x86/kernel/head_64.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index bcd206c8ac90..66b4a7757397 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -253,10 +253,10 @@ END(secondary_startup_64)
  * start_secondary() via .Ljump_to_C_code.
  */
 ENTRY(start_cpu0)
-	movq	initial_stack(%rip), %rsp
 	UNWIND_HINT_EMPTY
+	movq	initial_stack(%rip), %rsp
 	jmp	.Ljump_to_C_code
-ENDPROC(start_cpu0)
+END(start_cpu0)
 #endif
 
 	/* Both SMP bootup and ACPI suspend change these variables */