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| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
|---|---|
| 2 | #ifndef _ASM_ARC_JUMP_LABEL_H |
| 3 | #define _ASM_ARC_JUMP_LABEL_H |
| 4 | |
| 5 | #ifndef __ASSEMBLER__ |
| 6 | |
| 7 | #include <linux/stringify.h> |
| 8 | #include <linux/types.h> |
| 9 | |
| 10 | #define JUMP_LABEL_NOP_SIZE 4 |
| 11 | |
| 12 | /* |
| 13 | * NOTE about '.balign 4': |
| 14 | * |
| 15 | * To make atomic update of patched instruction available we need to guarantee |
| 16 | * that this instruction doesn't cross L1 cache line boundary. |
| 17 | * |
| 18 | * As of today we simply align instruction which can be patched by 4 byte using |
| 19 | * ".balign 4" directive. In that case patched instruction is aligned with one |
| 20 | * 16-bit NOP_S if this is required. |
| 21 | * However 'align by 4' directive is much stricter than it actually required. |
| 22 | * It's enough that our 32-bit instruction don't cross L1 cache line boundary / |
| 23 | * L1 I$ fetch block boundary which can be achieved by using |
| 24 | * ".bundle_align_mode" assembler directive. That will save us from adding |
| 25 | * useless NOP_S padding in most of the cases. |
| 26 | * |
| 27 | * TODO: switch to ".bundle_align_mode" directive using whin it will be |
| 28 | * supported by ARC toolchain. |
| 29 | */ |
| 30 | |
| 31 | static __always_inline bool arch_static_branch(struct static_key *key, |
| 32 | bool branch) |
| 33 | { |
| 34 | asm goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n" |
| 35 | "1: \n" |
| 36 | "nop \n" |
| 37 | ".pushsection __jump_table, \"aw\" \n" |
| 38 | ".word 1b, %l[l_yes], %c0 \n" |
| 39 | ".popsection \n" |
| 40 | : : "i" (&((char *)key)[branch]) : : l_yes); |
| 41 | |
| 42 | return false; |
| 43 | l_yes: |
| 44 | return true; |
| 45 | } |
| 46 | |
| 47 | static __always_inline bool arch_static_branch_jump(struct static_key *key, |
| 48 | bool branch) |
| 49 | { |
| 50 | asm goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n" |
| 51 | "1: \n" |
| 52 | "b %l[l_yes] \n" |
| 53 | ".pushsection __jump_table, \"aw\" \n" |
| 54 | ".word 1b, %l[l_yes], %c0 \n" |
| 55 | ".popsection \n" |
| 56 | : : "i" (&((char *)key)[branch]) : : l_yes); |
| 57 | |
| 58 | return false; |
| 59 | l_yes: |
| 60 | return true; |
| 61 | } |
| 62 | |
| 63 | typedef u32 jump_label_t; |
| 64 | |
| 65 | struct jump_entry { |
| 66 | jump_label_t code; |
| 67 | jump_label_t target; |
| 68 | jump_label_t key; |
| 69 | }; |
| 70 | |
| 71 | #endif /* __ASSEMBLER__ */ |
| 72 | #endif |
| 73 |
Warning: This file is not a C or C++ file. It does not have highlighting.