csky/kernel/jump_label.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002
0003 #include <linux/jump_label.h>
0004 #include <linux/kernel.h>
0005 #include <linux/memory.h>
0006 #include <linux/mutex.h>
0007 #include <linux/uaccess.h>
0008 #include <asm/cacheflush.h>
0009
0010 #define NOP32_HI    0xc400
0011 #define NOP32_LO    0x4820
0012 #define BSR_LINK    0xe000
0013
0014 void arch_jump_label_transform(struct jump_entry *entry,
0015                    enum jump_label_type type)
0016 {
0017     unsigned long addr = jump_entry_code(entry);
0018     u16 insn[2];
0019     int ret = 0;
0020
0021     if (type == JUMP_LABEL_JMP) {
0022         long offset = jump_entry_target(entry) - jump_entry_code(entry);
0023
0024         if (WARN_ON(offset & 1 || offset < -67108864 || offset >= 67108864))
0025             return;
0026
0027         offset = offset >> 1;
0028
0029         insn[0] = BSR_LINK |
0030             ((uint16_t)((unsigned long) offset >> 16) & 0x3ff);
0031         insn[1] = (uint16_t)((unsigned long) offset & 0xffff);
0032     } else {
0033         insn[0] = NOP32_HI;
0034         insn[1] = NOP32_LO;
0035     }
0036
0037     ret = copy_to_kernel_nofault((void *)addr, insn, 4);
0038     WARN_ON(ret);
0039
0040     flush_icache_range(addr, addr + 4);
0041 }
0042
0043 void arch_jump_label_transform_static(struct jump_entry *entry,
0044                       enum jump_label_type type)
0045 {
0046     /*
0047      * We use the same instructions in the arch_static_branch and
0048      * arch_static_branch_jump inline functions, so there's no
0049      * need to patch them up here.
0050      * The core will call arch_jump_label_transform  when those
0051      * instructions need to be replaced.
0052      */
0053     arch_jump_label_transform(entry, type);
0054 }