linux-kernel - [PATCH v1 09/12] x86, alternative: Convert X86_INVD

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Message-Id: <1422987390-17878-10-git-send-email-bp@alien8.de>
Date:	Tue,  3 Feb 2015 19:16:27 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	X86 ML <x86@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v1 09/12] x86, alternative: Convert X86_INVD_BUG to generic macro

From: Borislav Petkov <bp@...e.de>

Booting a 486 kernel on an AMD guest says:

[    0.416564] apply_alternatives: feat: 0*32+25, old: (c160a475, len: 5), repl: (c19557d4, len: 5)
[    0.420009] c160a475: alt_insn: 68 10 35 00 c1
[    0.425106] c19557d4: rpl_insn: 68 80 39 00 c1

which looks ok:

old insn VA: 0xc160a475, CPU feat: X86_FEATURE_XMM, size: 5
simd_coprocessor_error:
         c160a475:      68 10 35 00 c1          push $0xc1003510 <do_general_protection>
repl insn: 0xc19557d4, size: 5
         c160a475:      68 80 39 00 c1          push $0xc1003980 <do_simd_coprocessor_error>

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/entry_32.S | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 000d4199b03e..b910577d1ff9 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -816,15 +816,9 @@ ENTRY(simd_coprocessor_error)
 	pushl_cfi $0
 #ifdef CONFIG_X86_INVD_BUG
 	/* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
-661:	pushl_cfi $do_general_protection
-662:
-.section .altinstructions,"a"
-	altinstruction_entry 661b, 663f, X86_FEATURE_XMM, 662b-661b, 664f-663f
-.previous
-.section .altinstr_replacement,"ax"
-663:	pushl $do_simd_coprocessor_error
-664:
-.previous
+	ALTERNATIVE "pushl_cfi $do_general_protection",	\
+		    "pushl $do_simd_coprocessor_error", \
+		    X86_FEATURE_XMM
 #else
 	pushl_cfi $do_simd_coprocessor_error
 #endif
-- 
2.2.0.33.gc18b867

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