[PATCH 14/24] x86: Add a type field to alt_instr

[Peter Zijlstra]

Add a type field to the alternative description. For now this will be
used to annotate static_cpu_has() but possible future uses include
using it to implement alternative alignment and special NOP handling.

Suggested-by: Borislav Petkov <bp@xxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
 arch/x86/include/asm/alternative-asm.h |    3 ++-
 arch/x86/include/asm/alternative.h     |    6 +++++-
 arch/x86/include/asm/cpufeature.h      |    2 ++
 arch/x86/kernel/alternative.c          |    4 ++--
 tools/objtool/special.c                |    2 +-
 5 files changed, 12 insertions(+), 5 deletions(-)

--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -25,13 +25,14 @@
  * enough information for the alternatives patching code to patch an
  * instruction. See apply_alternatives().
  */
-.macro altinstruction_entry orig alt feature orig_len alt_len pad_len
+.macro altinstruction_entry orig alt feature orig_len alt_len pad_len type=0
 	.long \orig - .
 	.long \alt - .
 	.word \feature
 	.byte \orig_len
 	.byte \alt_len
 	.byte \pad_len
+	.byte \type
 .endm
 
 /*
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -45,6 +45,8 @@
 #define LOCK_PREFIX ""
 #endif
 
+#define ALT_TYPE_DEFAULT	0
+
 struct alt_instr {
 	s32 instr_offset;	/* original instruction */
 	s32 repl_offset;	/* offset to replacement instruction */
@@ -52,6 +54,7 @@ struct alt_instr {
 	u8  instrlen;		/* length of original instruction */
 	u8  replacementlen;	/* length of new instruction */
 	u8  padlen;		/* length of build-time padding */
+	u8  type;		/* type of alternative */
 } __packed;
 
 /*
@@ -127,7 +130,8 @@ static inline int alternatives_text_rese
 	" .word " __stringify(feature) "\n"		/* feature bit     */ \
 	" .byte " alt_total_slen "\n"			/* source len      */ \
 	" .byte " alt_rlen(num) "\n"			/* replacement len */ \
-	" .byte " alt_pad_len "\n"			/* pad len */
+	" .byte " alt_pad_len "\n"			/* pad len */	      \
+	" .byte 0 \n"					/* type */
 
 #define ALTINSTR_REPLACEMENT(newinstr, feature, num)	/* replacement */     \
 	b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t"
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -157,6 +157,7 @@ static __always_inline __pure bool _stat
 		 " .byte 3b - 1b\n"		/* src len */
 		 " .byte 5f - 4f\n"		/* repl len */
 		 " .byte 3b - 2b\n"		/* pad len */
+		 " .byte 0\n"			/* type */
 		 ".previous\n"
 		 ".section .altinstr_replacement,\"ax\"\n"
 		 "4: jmp %l[t_no]\n"
@@ -169,6 +170,7 @@ static __always_inline __pure bool _stat
 		 " .byte 3b - 1b\n"		/* src len */
 		 " .byte 0\n"			/* repl len */
 		 " .byte 0\n"			/* pad len */
+		 " .byte 0\n"			/* type */
 		 ".previous\n"
 		 ".section .altinstr_aux,\"ax\"\n"
 		 "6:\n"
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -400,11 +400,11 @@ void __init_or_module noinline apply_alt
 			continue;
 		}
 
-		DPRINTK("feat: %d*32+%d, old: (%p, len: %d), repl: (%p, len: %d), pad: %d",
+		DPRINTK("feat: %d*32+%d, old: (%p, len: %d), repl: (%p, len: %d), pad: %d, type: %d",
 			a->cpuid >> 5,
 			a->cpuid & 0x1f,
 			instr, a->instrlen,
-			replacement, a->replacementlen, a->padlen);
+			replacement, a->replacementlen, a->padlen, a->type);
 
 		DUMP_BYTES(instr, a->instrlen, "%p: old_insn: ", instr);
 		DUMP_BYTES(replacement, a->replacementlen, "%p: rpl_insn: ", replacement);
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -34,7 +34,7 @@
 #define JUMP_ORIG_OFFSET	0
 #define JUMP_NEW_OFFSET		8
 
-#define ALT_ENTRY_SIZE		13
+#define ALT_ENTRY_SIZE		14
 #define ALT_ORIG_OFFSET		0
 #define ALT_NEW_OFFSET		4
 #define ALT_FEATURE_OFFSET	8