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| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
|---|---|
| 2 | /* Copyright (C) 2018 Cadence Design Systems Inc. */ |
| 3 | |
| 4 | #ifndef _ASM_XTENSA_JUMP_LABEL_H |
| 5 | #define _ASM_XTENSA_JUMP_LABEL_H |
| 6 | |
| 7 | #ifndef __ASSEMBLER__ |
| 8 | |
| 9 | #include <linux/types.h> |
| 10 | |
| 11 | #define JUMP_LABEL_NOP_SIZE 3 |
| 12 | |
| 13 | static __always_inline bool arch_static_branch(struct static_key *key, |
| 14 | bool branch) |
| 15 | { |
| 16 | asm goto("1:\n\t" |
| 17 | "_nop\n\t" |
| 18 | ".pushsection __jump_table, \"aw\"\n\t" |
| 19 | ".word 1b, %l[l_yes], %c0\n\t" |
| 20 | ".popsection\n\t" |
| 21 | : : "i" (&((char *)key)[branch]) : : l_yes); |
| 22 | |
| 23 | return false; |
| 24 | l_yes: |
| 25 | return true; |
| 26 | } |
| 27 | |
| 28 | static __always_inline bool arch_static_branch_jump(struct static_key *key, |
| 29 | bool branch) |
| 30 | { |
| 31 | /* |
| 32 | * Xtensa assembler will mark certain points in the code |
| 33 | * as unreachable, so that later assembler or linker relaxation |
| 34 | * passes could use them. A spot right after the J instruction |
| 35 | * is one such point. Assembler and/or linker may insert padding |
| 36 | * or literals here, breaking code flow in case the J instruction |
| 37 | * is later replaced with NOP. Put a label right after the J to |
| 38 | * make it reachable and wrap both into a no-transform block |
| 39 | * to avoid any assembler interference with this. |
| 40 | */ |
| 41 | asm goto("1:\n\t" |
| 42 | ".begin no-transform\n\t" |
| 43 | "_j %l[l_yes]\n\t" |
| 44 | "2:\n\t" |
| 45 | ".end no-transform\n\t" |
| 46 | ".pushsection __jump_table, \"aw\"\n\t" |
| 47 | ".word 1b, %l[l_yes], %c0\n\t" |
| 48 | ".popsection\n\t" |
| 49 | : : "i" (&((char *)key)[branch]) : : l_yes); |
| 50 | |
| 51 | return false; |
| 52 | l_yes: |
| 53 | return true; |
| 54 | } |
| 55 | |
| 56 | typedef u32 jump_label_t; |
| 57 | |
| 58 | struct jump_entry { |
| 59 | jump_label_t code; |
| 60 | jump_label_t target; |
| 61 | jump_label_t key; |
| 62 | }; |
| 63 | |
| 64 | #endif /* __ASSEMBLER__ */ |
| 65 | #endif |
| 66 |
Warning: This file is not a C or C++ file. It does not have highlighting.