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-rw-r--r--arch/xtensa/include/asm/jump_label.h65
1 files changed, 65 insertions, 0 deletions
diff --git a/arch/xtensa/include/asm/jump_label.h b/arch/xtensa/include/asm/jump_label.h
new file mode 100644
index 000000000..c812bf850
--- /dev/null
+++ b/arch/xtensa/include/asm/jump_label.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018 Cadence Design Systems Inc. */
+
+#ifndef _ASM_XTENSA_JUMP_LABEL_H
+#define _ASM_XTENSA_JUMP_LABEL_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+
+#define JUMP_LABEL_NOP_SIZE 3
+
+static __always_inline bool arch_static_branch(struct static_key *key,
+ bool branch)
+{
+ asm_volatile_goto("1:\n\t"
+ "_nop\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".word 1b, %l[l_yes], %c0\n\t"
+ ".popsection\n\t"
+ : : "i" (&((char *)key)[branch]) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key,
+ bool branch)
+{
+ /*
+ * Xtensa assembler will mark certain points in the code
+ * as unreachable, so that later assembler or linker relaxation
+ * passes could use them. A spot right after the J instruction
+ * is one such point. Assembler and/or linker may insert padding
+ * or literals here, breaking code flow in case the J instruction
+ * is later replaced with NOP. Put a label right after the J to
+ * make it reachable and wrap both into a no-transform block
+ * to avoid any assembler interference with this.
+ */
+ asm_volatile_goto("1:\n\t"
+ ".begin no-transform\n\t"
+ "_j %l[l_yes]\n\t"
+ "2:\n\t"
+ ".end no-transform\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".word 1b, %l[l_yes], %c0\n\t"
+ ".popsection\n\t"
+ : : "i" (&((char *)key)[branch]) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+typedef u32 jump_label_t;
+
+struct jump_entry {
+ jump_label_t code;
+ jump_label_t target;
+ jump_label_t key;
+};
+
+#endif /* __ASSEMBLY__ */
+#endif