arm64: alternatives: use cpucap naming

To more clearly align the various users of the cpucap enumeration, this patch
changes the alternative code to use the term `cpucap` in favour of `feature`.
The alternative_has_feature_{likely,unlikely}() functions are renamed to
alternative_has_cap_<likely,unlikely}() to more clearly align with the
cpus_have_{const_,}cap() helpers.

At the same time remove the stale comment referring to the "ARM64_CB
bit", which is evidently a typo for ARM64_CB_PATCH, which was removed in
commit:

  4c0bd995 ("arm64: alternatives: have callbacks take a cap")

There should be no functional change as a result of this patch; this is
purely a renaming exercise.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230607164846.3967305-3-mark.rutland@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/alternative-macros.h

@@ -23,17 +23,17 @@
 
 #include <linux/stringify.h>
 
-#define ALTINSTR_ENTRY(feature)					              \
+#define ALTINSTR_ENTRY(cpucap)					              \
 	" .word 661b - .\n"				/* label           */ \
 	" .word 663f - .\n"				/* new instruction */ \
-	" .hword " __stringify(feature) "\n"		/* feature bit     */ \
+	" .hword " __stringify(cpucap) "\n"		/* cpucap          */ \
 	" .byte 662b-661b\n"				/* source len      */ \
 	" .byte 664f-663f\n"				/* replacement len */
 
-#define ALTINSTR_ENTRY_CB(feature, cb)					      \
+#define ALTINSTR_ENTRY_CB(cpucap, cb)					      \
 	" .word 661b - .\n"				/* label           */ \
-	" .word " __stringify(cb) "- .\n"		/* callback */	      \
-	" .hword " __stringify(feature) "\n"		/* feature bit     */ \
+	" .word " __stringify(cb) "- .\n"		/* callback        */ \
+	" .hword " __stringify(cpucap) "\n"		/* cpucap          */ \
 	" .byte 662b-661b\n"				/* source len      */ \
 	" .byte 664f-663f\n"				/* replacement len */
 
@@ -53,13 +53,13 @@
  *
  * Alternatives with callbacks do not generate replacement instructions.
  */
-#define __ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg_enabled)	\
+#define __ALTERNATIVE_CFG(oldinstr, newinstr, cpucap, cfg_enabled)	\
 	".if "__stringify(cfg_enabled)" == 1\n"				\
 	"661:\n\t"							\
 	oldinstr "\n"							\
 	"662:\n"							\
 	".pushsection .altinstructions,\"a\"\n"				\
-	ALTINSTR_ENTRY(feature)						\
+	ALTINSTR_ENTRY(cpucap)						\
 	".popsection\n"							\
 	".subsection 1\n"						\
 	"663:\n\t"							\
@@ -70,31 +70,31 @@
 	".previous\n"							\
 	".endif\n"
 
-#define __ALTERNATIVE_CFG_CB(oldinstr, feature, cfg_enabled, cb)	\
+#define __ALTERNATIVE_CFG_CB(oldinstr, cpucap, cfg_enabled, cb)	\
 	".if "__stringify(cfg_enabled)" == 1\n"				\
 	"661:\n\t"							\
 	oldinstr "\n"							\
 	"662:\n"							\
 	".pushsection .altinstructions,\"a\"\n"				\
-	ALTINSTR_ENTRY_CB(feature, cb)					\
+	ALTINSTR_ENTRY_CB(cpucap, cb)					\
 	".popsection\n"							\
 	"663:\n\t"							\
 	"664:\n\t"							\
 	".endif\n"
 
-#define _ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg, ...)	\
-	__ALTERNATIVE_CFG(oldinstr, newinstr, feature, IS_ENABLED(cfg))
+#define _ALTERNATIVE_CFG(oldinstr, newinstr, cpucap, cfg, ...)	\
+	__ALTERNATIVE_CFG(oldinstr, newinstr, cpucap, IS_ENABLED(cfg))
 
-#define ALTERNATIVE_CB(oldinstr, feature, cb) \
-	__ALTERNATIVE_CFG_CB(oldinstr, (1 << ARM64_CB_SHIFT) | (feature), 1, cb)
+#define ALTERNATIVE_CB(oldinstr, cpucap, cb) \
+	__ALTERNATIVE_CFG_CB(oldinstr, (1 << ARM64_CB_SHIFT) | (cpucap), 1, cb)
 #else
 
 #include <asm/assembler.h>
 
-.macro altinstruction_entry orig_offset alt_offset feature orig_len alt_len
+.macro altinstruction_entry orig_offset alt_offset cpucap orig_len alt_len
 	.word \orig_offset - .
 	.word \alt_offset - .
-	.hword (\feature)
+	.hword (\cpucap)
 	.byte \orig_len
 	.byte \alt_len
 .endm
@@ -210,9 +210,9 @@ alternative_endif
 #endif  /*  __ASSEMBLY__  */
 
 /*
- * Usage: asm(ALTERNATIVE(oldinstr, newinstr, feature));
+ * Usage: asm(ALTERNATIVE(oldinstr, newinstr, cpucap));
  *
- * Usage: asm(ALTERNATIVE(oldinstr, newinstr, feature, CONFIG_FOO));
+ * Usage: asm(ALTERNATIVE(oldinstr, newinstr, cpucap, CONFIG_FOO));
  * N.B. If CONFIG_FOO is specified, but not selected, the whole block
  *      will be omitted, including oldinstr.
  */
@@ -224,15 +224,15 @@ alternative_endif
 #include <linux/types.h>
 
 static __always_inline bool
-alternative_has_feature_likely(const unsigned long feature)
+alternative_has_cap_likely(const unsigned long cpucap)
 {
-	compiletime_assert(feature < ARM64_NCAPS,
-			   "feature must be < ARM64_NCAPS");
+	compiletime_assert(cpucap < ARM64_NCAPS,
+			   "cpucap must be < ARM64_NCAPS");
 
 	asm_volatile_goto(
-	ALTERNATIVE_CB("b	%l[l_no]", %[feature], alt_cb_patch_nops)
+	ALTERNATIVE_CB("b	%l[l_no]", %[cpucap], alt_cb_patch_nops)
 	:
-	: [feature] "i" (feature)
+	: [cpucap] "i" (cpucap)
 	:
 	: l_no);
 
@@ -242,15 +242,15 @@ alternative_has_feature_likely(const unsigned long feature)
 }
 
 static __always_inline bool
-alternative_has_feature_unlikely(const unsigned long feature)
+alternative_has_cap_unlikely(const unsigned long cpucap)
 {
-	compiletime_assert(feature < ARM64_NCAPS,
-			   "feature must be < ARM64_NCAPS");
+	compiletime_assert(cpucap < ARM64_NCAPS,
+			   "cpucap must be < ARM64_NCAPS");
 
 	asm_volatile_goto(
-	ALTERNATIVE("nop", "b	%l[l_yes]", %[feature])
+	ALTERNATIVE("nop", "b	%l[l_yes]", %[cpucap])
 	:
-	: [feature] "i" (feature)
+	: [cpucap] "i" (cpucap)
 	:
 	: l_yes);
 

arch/arm64/include/asm/alternative.h

@@ -13,7 +13,7 @@
 struct alt_instr {
 	s32 orig_offset;	/* offset to original instruction */
 	s32 alt_offset;		/* offset to replacement instruction */
-	u16 cpufeature;		/* cpufeature bit set for replacement */
+	u16 cpucap;		/* cpucap bit set for replacement */
 	u8  orig_len;		/* size of original instruction(s) */
 	u8  alt_len;		/* size of new instruction(s), <= orig_len */
 };
@@ -23,7 +23,7 @@ typedef void (*alternative_cb_t)(struct alt_instr *alt,
 
 void __init apply_boot_alternatives(void);
 void __init apply_alternatives_all(void);
-bool alternative_is_applied(u16 cpufeature);
+bool alternative_is_applied(u16 cpucap);
 
 #ifdef CONFIG_MODULES
 void apply_alternatives_module(void *start, size_t length);

arch/arm64/include/asm/cpufeature.h

@@ -437,7 +437,7 @@ unsigned long cpu_get_elf_hwcap2(void);
 
 static __always_inline bool system_capabilities_finalized(void)
 {
-	return alternative_has_feature_likely(ARM64_ALWAYS_SYSTEM);
+	return alternative_has_cap_likely(ARM64_ALWAYS_SYSTEM);
 }
 
 /*
@@ -464,7 +464,7 @@ static __always_inline bool __cpus_have_const_cap(int num)
 {
 	if (num >= ARM64_NCAPS)
 		return false;
-	return alternative_has_feature_unlikely(num);
+	return alternative_has_cap_unlikely(num);
 }
 
 /*

arch/arm64/include/asm/irqflags.h

@@ -24,7 +24,7 @@
 static __always_inline bool __irqflags_uses_pmr(void)
 {
 	return IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) &&
-	       alternative_has_feature_unlikely(ARM64_HAS_GIC_PRIO_MASKING);
+	       alternative_has_cap_unlikely(ARM64_HAS_GIC_PRIO_MASKING);
 }
 
 static __always_inline void __daif_local_irq_enable(void)

arch/arm64/include/asm/lse.h

@@ -18,7 +18,7 @@
 
 static __always_inline bool system_uses_lse_atomics(void)
 {
-	return alternative_has_feature_likely(ARM64_HAS_LSE_ATOMICS);
+	return alternative_has_cap_likely(ARM64_HAS_LSE_ATOMICS);
 }
 
 #define __lse_ll_sc_body(op, ...)					\

arch/arm64/kernel/alternative.c

@@ -24,8 +24,8 @@
 #define ALT_ORIG_PTR(a)		__ALT_PTR(a, orig_offset)
 #define ALT_REPL_PTR(a)		__ALT_PTR(a, alt_offset)
 
-#define ALT_CAP(a)		((a)->cpufeature & ~ARM64_CB_BIT)
-#define ALT_HAS_CB(a)		((a)->cpufeature & ARM64_CB_BIT)
+#define ALT_CAP(a)		((a)->cpucap & ~ARM64_CB_BIT)
+#define ALT_HAS_CB(a)		((a)->cpucap & ARM64_CB_BIT)
 
 /* Volatile, as we may be patching the guts of READ_ONCE() */
 static volatile int all_alternatives_applied;
@@ -37,12 +37,12 @@ struct alt_region {
 	struct alt_instr *end;
 };
 
-bool alternative_is_applied(u16 cpufeature)
+bool alternative_is_applied(u16 cpucap)
 {
-	if (WARN_ON(cpufeature >= ARM64_NCAPS))
+	if (WARN_ON(cpucap >= ARM64_NCAPS))
 		return false;
 
-	return test_bit(cpufeature, applied_alternatives);
+	return test_bit(cpucap, applied_alternatives);
 }
 
 /*
@@ -141,7 +141,7 @@ static void clean_dcache_range_nopatch(u64 start, u64 end)
 
 static void __apply_alternatives(const struct alt_region *region,
 				 bool is_module,
-				 unsigned long *feature_mask)
+				 unsigned long *cpucap_mask)
 {
 	struct alt_instr *alt;
 	__le32 *origptr, *updptr;
@@ -151,7 +151,7 @@ static void __apply_alternatives(const struct alt_region *region,
 		int nr_inst;
 		int cap = ALT_CAP(alt);
 
-		if (!test_bit(cap, feature_mask))
+		if (!test_bit(cap, cpucap_mask))
 			continue;
 
 		if (!cpus_have_cap(cap))
@@ -188,9 +188,8 @@ static void __apply_alternatives(const struct alt_region *region,
 		icache_inval_all_pou();
 		isb();
 
-		/* Ignore ARM64_CB bit from feature mask */
 		bitmap_or(applied_alternatives, applied_alternatives,
-			  feature_mask, ARM64_NCAPS);
+			  cpucap_mask, ARM64_NCAPS);
 		bitmap_and(applied_alternatives, applied_alternatives,
 			   system_cpucaps, ARM64_NCAPS);
 	}