[tip:x86/alternatives] x86/alternatives: Add an ALTERNATIVE_3() macro

tip-bot for Borislav Petkov
2019-01-16T11:59:30Z

Commit-ID: 71a93c26930471e976dd184ef91931b2a5393afc
Gitweb: https://git.kernel.org/tip/71a93c26930471e976dd184ef91931b2a5393afc
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Mon, 10 Dec 2018 16:17:23 +0100
Committer: Borislav Petkov <bp@suse.de>
CommitDate: Wed, 16 Jan 2019 12:42:50 +0100

x86/alternatives: Add an ALTERNATIVE_3() macro

Similar to ALTERNATIVE_2(), ALTERNATIVE_3() selects between 3 possible
variants. Will be used for adding RDTSCP to the rdtsc_ordered()
alternatives.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: X86 ML <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181211222326.14581-4-bp@alien8.de
---
arch/x86/include/asm/alternative.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 373e2baca6ce..4c74073a19cc 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -122,6 +122,16 @@ static inline int alternatives_text_reserved(void *start, void *end)
"(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")), 0x90\n" \
alt_end_marker ":\n"

+#define OLDINSTR_3(oldinsn, n1, n2, n3) \
+ "# ALT: oldinstr3\n" \
+ "661:\n\t" oldinsn "\n662:\n" \
+ "# ALT: padding3\n" \
+ ".skip -((" alt_max_short(alt_max_short(alt_rlen(n1), alt_rlen(n2)), alt_rlen(n3)) \
+ " - (" alt_slen ")) > 0) * " \
+ "(" alt_max_short(alt_max_short(alt_rlen(n1), alt_rlen(n2)), alt_rlen(n3)) \
+ " - (" alt_slen ")), 0x90\n" \
+ alt_end_marker ":\n"
+
#define ALTINSTR_ENTRY(feature, num) \
" .long 661b - .\n" /* label */ \
" .long " b_replacement(num)"f - .\n" /* new instruction */ \
@@ -155,6 +165,19 @@ static inline int alternatives_text_reserved(void *start, void *end)
ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \
".popsection\n"

+#define ALTERNATIVE_3(oldinsn, newinsn1, feat1, newinsn2, feat2, newinsn3, feat3) \
+ OLDINSTR_3(oldinsn, 1, 2, 3) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(feat1, 1) \
+ ALTINSTR_ENTRY(feat2, 2) \
+ ALTINSTR_ENTRY(feat3, 3) \
+ ".popsection\n" \
+ ".pushsection .altinstr_replacement, \"ax\"\n" \
+ ALTINSTR_REPLACEMENT(newinsn1, feat1, 1) \
+ ALTINSTR_REPLACEMENT(newinsn2, feat2, 2) \
+ ALTINSTR_REPLACEMENT(newinsn3, feat3, 3) \
+ ".popsection\n"
+
/*
* Alternative instructions for different CPU types or capabilities.
*