linux-kernel - [PATCH AUTOSEL 5.2 76/85] x86/uaccess: Remove ELF function annotation from copy_user_handle

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Message-Id: <20190726133936.11177-76-sashal@kernel.org>
Date:   Fri, 26 Jul 2019 09:39:26 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.2 76/85] x86/uaccess: Remove ELF function annotation from copy_user_handle_tail()

From: Josh Poimboeuf <jpoimboe@...hat.com>

[ Upstream commit 3a6ab4bcc52263dd5b1d2fd2e4ce95a38c798b4d ]

After an objtool improvement, it's complaining about the CLAC in
copy_user_handle_tail():

  arch/x86/lib/copy_user_64.o: warning: objtool: .altinstr_replacement+0x12: redundant UACCESS disable
  arch/x86/lib/copy_user_64.o: warning: objtool:   copy_user_handle_tail()+0x6: (alt)
  arch/x86/lib/copy_user_64.o: warning: objtool:   copy_user_handle_tail()+0x2: (alt)
  arch/x86/lib/copy_user_64.o: warning: objtool:   copy_user_handle_tail()+0x0: <=== (func)

copy_user_handle_tail() is incorrectly marked as a callable function, so
objtool is rightfully concerned about the CLAC with no corresponding
STAC.

Remove the ELF function annotation.  The copy_user_handle_tail() code
path is already verified by objtool because it's jumped to by other
callable asm code (which does the corresponding STAC).

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/6b6e436774678b4b9873811ff023bd29935bee5b.1563413318.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/lib/copy_user_64.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index 378a1f70ae7d..4fe1601dbc5d 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -239,7 +239,7 @@ copy_user_handle_tail:
 	ret
 
 	_ASM_EXTABLE_UA(1b, 2b)
-ENDPROC(copy_user_handle_tail)
+END(copy_user_handle_tail)
 
 /*
  * copy_user_nocache - Uncached memory copy with exception handling
-- 
2.20.1