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

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 373e2baca6ce1ec8b1965612e57d5ba0a108f55e..4c74073a19ccd4b2aa93078c734729e54e65bdd7 100644 (file)
--- 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.
  *