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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Arnd Bergmann <arnd@arndb.de>, Jann Horn <jannh@google.com>,
	Randy Dunlap <rdunlap@infradead.org>
Subject: [PATCH 06/22] x86/head/64: Annotate start_cpu0() as non-callable
Date: Sun, 14 Jul 2019 19:37:01 -0500	[thread overview]
Message-ID: <b6568e859d8af1d2b5c9efed40cfb45f0b3ebb90.1563150885.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1563150885.git.jpoimboe@redhat.com>

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@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 */
-- 
2.20.1


  parent reply	other threads:[~2019-07-15  0:37 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-15  0:36 [PATCH 00/22] x86, objtool: several fixes/improvements Josh Poimboeuf
2019-07-15  0:36 ` [PATCH 01/22] x86/paravirt: Fix callee-saved function ELF sizes Josh Poimboeuf
2019-07-15  4:58   ` Juergen Gross
2019-07-15 12:43     ` Josh Poimboeuf
2019-07-15  0:36 ` [PATCH 02/22] x86/kvm: Fix fastop function ELF metadata Josh Poimboeuf
2019-07-15  9:05   ` Paolo Bonzini
2019-07-15  0:36 ` [PATCH 03/22] x86/kvm: Fix frame pointer usage in vmx_vmenter() Josh Poimboeuf
2019-07-15  9:04   ` Paolo Bonzini
2019-07-15 12:37     ` Josh Poimboeuf
2019-07-15 13:03       ` Paolo Bonzini
2019-07-15 13:35         ` Josh Poimboeuf
2019-07-15 18:17           ` Paolo Bonzini
2019-07-15  0:36 ` [PATCH 04/22] x86/kvm: Don't call kvm_spurious_fault() from .fixup Josh Poimboeuf
2019-07-15  9:07   ` Paolo Bonzini
2019-07-15 12:40     ` Josh Poimboeuf
2019-07-15 13:05       ` Paolo Bonzini
2019-07-15 13:25         ` Josh Poimboeuf
2019-07-15 18:16           ` Paolo Bonzini
2019-07-15  0:37 ` [PATCH 05/22] x86/entry: Fix thunk function ELF sizes Josh Poimboeuf
2019-07-15  0:37 ` Josh Poimboeuf [this message]
2019-07-15  0:37 ` [PATCH 07/22] x86/uaccess: Remove ELF function annotation from copy_user_handle_tail() Josh Poimboeuf
2019-07-16 18:16   ` Nick Desaulniers
2019-07-16 18:51     ` Peter Zijlstra
2019-07-15  0:37 ` [PATCH 08/22] x86/uaccess: Don't leak AC flag into fentry from mcsafe_handle_tail() Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 09/22] x86/uaccess: Remove redundant CLACs in getuser/putuser error paths Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 10/22] bpf: Disable GCC -fgcse optimization for ___bpf_prog_run() Josh Poimboeuf
2019-07-16 18:15   ` Nick Desaulniers
2019-07-16 23:02     ` Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 11/22] objtool: Add mcsafe_handle_tail() to the uaccess safe list Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 12/22] objtool: Track original function across branches Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 13/22] objtool: Refactor function alias logic Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 14/22] objtool: Warn on zero-length functions Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 15/22] objtool: Change dead_end_function() to return boolean Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 16/22] objtool: Do frame pointer check before dead end check Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 17/22] objtool: Refactor sibling call detection logic Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 18/22] objtool: Refactor jump table code Josh Poimboeuf
2019-07-15  9:38   ` Peter Zijlstra
2019-07-15  0:37 ` [PATCH 19/22] objtool: Support repeated uses of the same C jump table Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 20/22] objtool: Fix seg fault on bad switch table entry Josh Poimboeuf
2019-07-15 17:24   ` Nick Desaulniers
2019-07-15 17:29     ` Josh Poimboeuf
2019-07-18 23:02       ` Nick Desaulniers
2019-07-15  0:37 ` [PATCH 21/22] objtool: convert insn type to enum Josh Poimboeuf
2019-07-15  0:37 ` [PATCH 22/22] objtool: Support conditional retpolines Josh Poimboeuf
2019-07-15  9:52 ` [PATCH 00/22] x86, objtool: several fixes/improvements Peter Zijlstra
2019-07-15 19:38 ` Josh Poimboeuf
2019-07-15 21:45   ` Nick Desaulniers
2019-07-16 23:17     ` Josh Poimboeuf
2019-07-18 22:26       ` Nick Desaulniers
2019-09-27 20:24         ` Nick Desaulniers

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