linux-kernel - [PATCH v2 19/23] x86,usercopy_32: Simplify __copy_user_intel

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Date:   Wed, 10 Nov 2021 11:01:21 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        jpoimboe@...hat.com, mark.rutland@....com, dvyukov@...gle.com,
        seanjc@...gle.com, pbonzini@...hat.com, mbenes@...e.cz
Subject: [PATCH v2 19/23] x86,usercopy_32: Simplify __copy_user_intel_nocache()

Have an exception jump to a .fixup to only immediately jump out is
daft, jump to the right place in one go.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/lib/usercopy_32.c |   40 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -257,28 +257,28 @@ static unsigned long __copy_user_intel_n
 	       "8:\n"
 	       ".section .fixup,\"ax\"\n"
 	       "9:      lea 0(%%eax,%0,4),%0\n"
-	       "16:     jmp 8b\n"
+	       "        jmp 8b\n"
 	       ".previous\n"
-	       _ASM_EXTABLE_UA(0b, 16b)
-	       _ASM_EXTABLE_UA(1b, 16b)
-	       _ASM_EXTABLE_UA(2b, 16b)
-	       _ASM_EXTABLE_UA(21b, 16b)
-	       _ASM_EXTABLE_UA(3b, 16b)
-	       _ASM_EXTABLE_UA(31b, 16b)
-	       _ASM_EXTABLE_UA(4b, 16b)
-	       _ASM_EXTABLE_UA(41b, 16b)
-	       _ASM_EXTABLE_UA(10b, 16b)
-	       _ASM_EXTABLE_UA(51b, 16b)
-	       _ASM_EXTABLE_UA(11b, 16b)
-	       _ASM_EXTABLE_UA(61b, 16b)
-	       _ASM_EXTABLE_UA(12b, 16b)
-	       _ASM_EXTABLE_UA(71b, 16b)
-	       _ASM_EXTABLE_UA(13b, 16b)
-	       _ASM_EXTABLE_UA(81b, 16b)
-	       _ASM_EXTABLE_UA(14b, 16b)
-	       _ASM_EXTABLE_UA(91b, 16b)
+	       _ASM_EXTABLE_UA(0b, 8b)
+	       _ASM_EXTABLE_UA(1b, 8b)
+	       _ASM_EXTABLE_UA(2b, 8b)
+	       _ASM_EXTABLE_UA(21b, 8b)
+	       _ASM_EXTABLE_UA(3b, 8b)
+	       _ASM_EXTABLE_UA(31b, 8b)
+	       _ASM_EXTABLE_UA(4b, 8b)
+	       _ASM_EXTABLE_UA(41b, 8b)
+	       _ASM_EXTABLE_UA(10b, 8b)
+	       _ASM_EXTABLE_UA(51b, 8b)
+	       _ASM_EXTABLE_UA(11b, 8b)
+	       _ASM_EXTABLE_UA(61b, 8b)
+	       _ASM_EXTABLE_UA(12b, 8b)
+	       _ASM_EXTABLE_UA(71b, 8b)
+	       _ASM_EXTABLE_UA(13b, 8b)
+	       _ASM_EXTABLE_UA(81b, 8b)
+	       _ASM_EXTABLE_UA(14b, 8b)
+	       _ASM_EXTABLE_UA(91b, 8b)
 	       _ASM_EXTABLE_UA(6b, 9b)
-	       _ASM_EXTABLE_UA(7b, 16b)
+	       _ASM_EXTABLE_UA(7b, 8b)
 	       : "=&c"(size), "=&D" (d0), "=&S" (d1)
 	       :  "1"(to), "2"(from), "0"(size)
 	       : "eax", "edx", "memory");