linux-kernel - [tip: x86/misc] x86/lib: Make get/put_user() exception handling a visible symbol

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Date:   Fri, 02 Jun 2023 08:59:12 -0000
From:   "tip-bot2 for Nadav Amit" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Nadav Amit <namit@...are.com>,
        "Borislav Petkov (AMD)" <bp@...en8.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/misc] x86/lib: Make get/put_user() exception handling a
 visible symbol

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

Commit-ID:     5516c89d58283413134f8d26960c6303d5d5bd89
Gitweb:        https://git.kernel.org/tip/5516c89d58283413134f8d26960c6303d5d5bd89
Author:        Nadav Amit <namit@...are.com>
AuthorDate:    Thu, 25 May 2023 11:42:44 -07:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Fri, 02 Jun 2023 10:51:46 +02:00

x86/lib: Make get/put_user() exception handling a visible symbol

The .L-prefixed exception handling symbols of get_user() and put_user()
do get discarded from the symbol table of the final kernel image.

This confuses tools which parse that symbol table and try to map the
chunk of code to a symbol. And, in general, from toolchain perspective,
it is a good practice to have all code belong to a symbol, and the
correct one at that.

  ( Currently, objdump displays that exception handling chunk as part
    of the previous symbol which is a "fallback" of sorts and not
    correct. )

While at it, rename them to something more descriptive.

  [ bp: Rewrite commit message, rename symbols. ]

Signed-off-by: Nadav Amit <namit@...are.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20230525184244.2311-1-namit@vmware.com
---
 arch/x86/lib/getuser.S | 32 ++++++++++++++++----------------
 arch/x86/lib/putuser.S | 24 ++++++++++++------------
 2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S
index b64a2bd..9c63713 100644
--- a/arch/x86/lib/getuser.S
+++ b/arch/x86/lib/getuser.S
@@ -143,43 +143,43 @@ SYM_FUNC_END(__get_user_nocheck_8)
 EXPORT_SYMBOL(__get_user_nocheck_8)
 
 
-SYM_CODE_START_LOCAL(.Lbad_get_user_clac)
+SYM_CODE_START_LOCAL(__get_user_handle_exception)
 	ASM_CLAC
 .Lbad_get_user:
 	xor %edx,%edx
 	mov $(-EFAULT),%_ASM_AX
 	RET
-SYM_CODE_END(.Lbad_get_user_clac)
+SYM_CODE_END(__get_user_handle_exception)
 
 #ifdef CONFIG_X86_32
-SYM_CODE_START_LOCAL(.Lbad_get_user_8_clac)
+SYM_CODE_START_LOCAL(__get_user_8_handle_exception)
 	ASM_CLAC
 bad_get_user_8:
 	xor %edx,%edx
 	xor %ecx,%ecx
 	mov $(-EFAULT),%_ASM_AX
 	RET
-SYM_CODE_END(.Lbad_get_user_8_clac)
+SYM_CODE_END(__get_user_8_handle_exception)
 #endif
 
 /* get_user */
-	_ASM_EXTABLE(1b, .Lbad_get_user_clac)
-	_ASM_EXTABLE(2b, .Lbad_get_user_clac)
-	_ASM_EXTABLE(3b, .Lbad_get_user_clac)
+	_ASM_EXTABLE(1b, __get_user_handle_exception)
+	_ASM_EXTABLE(2b, __get_user_handle_exception)
+	_ASM_EXTABLE(3b, __get_user_handle_exception)
 #ifdef CONFIG_X86_64
-	_ASM_EXTABLE(4b, .Lbad_get_user_clac)
+	_ASM_EXTABLE(4b, __get_user_handle_exception)
 #else
-	_ASM_EXTABLE(4b, .Lbad_get_user_8_clac)
-	_ASM_EXTABLE(5b, .Lbad_get_user_8_clac)
+	_ASM_EXTABLE(4b, __get_user_8_handle_exception)
+	_ASM_EXTABLE(5b, __get_user_8_handle_exception)
 #endif
 
 /* __get_user */
-	_ASM_EXTABLE(6b, .Lbad_get_user_clac)
-	_ASM_EXTABLE(7b, .Lbad_get_user_clac)
-	_ASM_EXTABLE(8b, .Lbad_get_user_clac)
+	_ASM_EXTABLE(6b, __get_user_handle_exception)
+	_ASM_EXTABLE(7b, __get_user_handle_exception)
+	_ASM_EXTABLE(8b, __get_user_handle_exception)
 #ifdef CONFIG_X86_64
-	_ASM_EXTABLE(9b, .Lbad_get_user_clac)
+	_ASM_EXTABLE(9b, __get_user_handle_exception)
 #else
-	_ASM_EXTABLE(9b, .Lbad_get_user_8_clac)
-	_ASM_EXTABLE(10b, .Lbad_get_user_8_clac)
+	_ASM_EXTABLE(9b, __get_user_8_handle_exception)
+	_ASM_EXTABLE(10b, __get_user_8_handle_exception)
 #endif
diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S
index 3062d09..1451e0c 100644
--- a/arch/x86/lib/putuser.S
+++ b/arch/x86/lib/putuser.S
@@ -131,22 +131,22 @@ SYM_FUNC_START(__put_user_nocheck_8)
 SYM_FUNC_END(__put_user_nocheck_8)
 EXPORT_SYMBOL(__put_user_nocheck_8)
 
-SYM_CODE_START_LOCAL(.Lbad_put_user_clac)
+SYM_CODE_START_LOCAL(__put_user_handle_exception)
 	ASM_CLAC
 .Lbad_put_user:
 	movl $-EFAULT,%ecx
 	RET
-SYM_CODE_END(.Lbad_put_user_clac)
+SYM_CODE_END(__put_user_handle_exception)
 
-	_ASM_EXTABLE(1b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(2b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(3b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(4b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(5b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(6b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(7b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(9b, .Lbad_put_user_clac)
+	_ASM_EXTABLE(1b, __put_user_handle_exception)
+	_ASM_EXTABLE(2b, __put_user_handle_exception)
+	_ASM_EXTABLE(3b, __put_user_handle_exception)
+	_ASM_EXTABLE(4b, __put_user_handle_exception)
+	_ASM_EXTABLE(5b, __put_user_handle_exception)
+	_ASM_EXTABLE(6b, __put_user_handle_exception)
+	_ASM_EXTABLE(7b, __put_user_handle_exception)
+	_ASM_EXTABLE(9b, __put_user_handle_exception)
 #ifdef CONFIG_X86_32
-	_ASM_EXTABLE(8b, .Lbad_put_user_clac)
-	_ASM_EXTABLE(10b, .Lbad_put_user_clac)
+	_ASM_EXTABLE(8b, __put_user_handle_exception)
+	_ASM_EXTABLE(10b, __put_user_handle_exception)
 #endif