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Diffstat (limited to 'arch/arm64/include/asm/alternative.h')
-rw-r--r--arch/arm64/include/asm/alternative.h78
1 files changed, 74 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h
index c385a0c40..d56ec0715 100644
--- a/arch/arm64/include/asm/alternative.h
+++ b/arch/arm64/include/asm/alternative.h
@@ -3,6 +3,8 @@
#ifndef __ASSEMBLY__
+#include <linux/init.h>
+#include <linux/kconfig.h>
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/stringify.h>
@@ -15,7 +17,7 @@ struct alt_instr {
u8 alt_len; /* size of new instruction(s), <= orig_len */
};
-void apply_alternatives_all(void);
+void __init apply_alternatives_all(void);
void apply_alternatives(void *start, size_t length);
void free_alternatives_memory(void);
@@ -40,7 +42,8 @@ void free_alternatives_memory(void);
* be fixed in a binutils release posterior to 2.25.51.0.2 (anything
* containing commit 4e4d08cf7399b606 or c1baaddf8861).
*/
-#define ALTERNATIVE(oldinstr, newinstr, feature) \
+#define __ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg_enabled) \
+ ".if "__stringify(cfg_enabled)" == 1\n" \
"661:\n\t" \
oldinstr "\n" \
"662:\n" \
@@ -53,7 +56,11 @@ void free_alternatives_memory(void);
"664:\n\t" \
".popsection\n\t" \
".org . - (664b-663b) + (662b-661b)\n\t" \
- ".org . - (662b-661b) + (664b-663b)\n"
+ ".org . - (662b-661b) + (664b-663b)\n" \
+ ".endif\n"
+
+#define _ALTERNATIVE_CFG(oldinstr, newinstr, feature, cfg, ...) \
+ __ALTERNATIVE_CFG(oldinstr, newinstr, feature, IS_ENABLED(cfg))
#else
@@ -65,7 +72,8 @@ void free_alternatives_memory(void);
.byte \alt_len
.endm
-.macro alternative_insn insn1 insn2 cap
+.macro alternative_insn insn1, insn2, cap, enable = 1
+ .if \enable
661: \insn1
662: .pushsection .altinstructions, "a"
altinstruction_entry 661b, 663f, \cap, 662b-661b, 664f-663f
@@ -75,8 +83,70 @@ void free_alternatives_memory(void);
664: .popsection
.org . - (664b-663b) + (662b-661b)
.org . - (662b-661b) + (664b-663b)
+ .endif
+.endm
+
+/*
+ * Begin an alternative code sequence.
+ *
+ * The code that follows this macro will be assembled and linked as
+ * normal. There are no restrictions on this code.
+ */
+.macro alternative_if_not cap, enable = 1
+ .if \enable
+ .pushsection .altinstructions, "a"
+ altinstruction_entry 661f, 663f, \cap, 662f-661f, 664f-663f
+ .popsection
+661:
+ .endif
+.endm
+
+/*
+ * Provide the alternative code sequence.
+ *
+ * The code that follows this macro is assembled into a special
+ * section to be used for dynamic patching. Code that follows this
+ * macro must:
+ *
+ * 1. Be exactly the same length (in bytes) as the default code
+ * sequence.
+ *
+ * 2. Not contain a branch target that is used outside of the
+ * alternative sequence it is defined in (branches into an
+ * alternative sequence are not fixed up).
+ */
+.macro alternative_else, enable = 1
+ .if \enable
+662: .pushsection .altinstr_replacement, "ax"
+663:
+ .endif
.endm
+/*
+ * Complete an alternative code sequence.
+ */
+.macro alternative_endif, enable = 1
+ .if \enable
+664: .popsection
+ .org . - (664b-663b) + (662b-661b)
+ .org . - (662b-661b) + (664b-663b)
+ .endif
+.endm
+
+#define _ALTERNATIVE_CFG(insn1, insn2, cap, cfg, ...) \
+ alternative_insn insn1, insn2, cap, IS_ENABLED(cfg)
+
+
#endif /* __ASSEMBLY__ */
+/*
+ * Usage: asm(ALTERNATIVE(oldinstr, newinstr, feature));
+ *
+ * Usage: asm(ALTERNATIVE(oldinstr, newinstr, feature, CONFIG_FOO));
+ * N.B. If CONFIG_FOO is specified, but not selected, the whole block
+ * will be omitted, including oldinstr.
+ */
+#define ALTERNATIVE(oldinstr, newinstr, ...) \
+ _ALTERNATIVE_CFG(oldinstr, newinstr, __VA_ARGS__, 1)
+
#endif /* __ASM_ALTERNATIVE_H */