LXR linux/arch/xtensa/kernel/jump

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (C) 2018 Cadence Design Systems Inc.
   3
   4#include <linux/cpu.h>
   5#include <linux/jump_label.h>
   6#include <linux/kernel.h>
   7#include <linux/memory.h>
   8#include <linux/stop_machine.h>
   9#include <linux/types.h>
  10
  11#include <asm/cacheflush.h>
  12
  13#define J_OFFSET_MASK 0x0003ffff
  14#define J_SIGN_MASK (~(J_OFFSET_MASK >> 1))
  15
  16#if defined(__XTENSA_EL__)
  17#define J_INSN 0x6
  18#define NOP_INSN 0x0020f0
  19#elif defined(__XTENSA_EB__)
  20#define J_INSN 0x60000000
  21#define NOP_INSN 0x0f020000
  22#else
  23#error Unsupported endianness.
  24#endif
  25
  26struct patch {
  27        atomic_t cpu_count;
  28        unsigned long addr;
  29        size_t sz;
  30        const void *data;
  31};
  32
  33static void local_patch_text(unsigned long addr, const void *data, size_t sz)
  34{
  35        memcpy((void *)addr, data, sz);
  36        local_flush_icache_range(addr, addr + sz);
  37}
  38
  39static int patch_text_stop_machine(void *data)
  40{
  41        struct patch *patch = data;
  42
  43        if (atomic_inc_return(&patch->cpu_count) == 1) {
  44                local_patch_text(patch->addr, patch->data, patch->sz);
  45                atomic_inc(&patch->cpu_count);
  46        } else {
  47                while (atomic_read(&patch->cpu_count) <= num_online_cpus())
  48                        cpu_relax();
  49                __invalidate_icache_range(patch->addr, patch->sz);
  50        }
  51        return 0;
  52}
  53
  54static void patch_text(unsigned long addr, const void *data, size_t sz)
  55{
  56        if (IS_ENABLED(CONFIG_SMP)) {
  57                struct patch patch = {
  58                        .cpu_count = ATOMIC_INIT(0),
  59                        .addr = addr,
  60                        .sz = sz,
  61                        .data = data,
  62                };
  63                stop_machine_cpuslocked(patch_text_stop_machine,
  64                                        &patch, NULL);
  65        } else {
  66                unsigned long flags;
  67
  68                local_irq_save(flags);
  69                local_patch_text(addr, data, sz);
  70                local_irq_restore(flags);
  71        }
  72}
  73
  74void arch_jump_label_transform(struct jump_entry *e,
  75                               enum jump_label_type type)
  76{
  77        u32 d = (jump_entry_target(e) - (jump_entry_code(e) + 4));
  78        u32 insn;
  79
  80        /* Jump only works within 128K of the J instruction. */
  81        BUG_ON(!((d & J_SIGN_MASK) == 0 ||
  82                 (d & J_SIGN_MASK) == J_SIGN_MASK));
  83
  84        if (type == JUMP_LABEL_JMP) {
  85#if defined(__XTENSA_EL__)
  86                insn = ((d & J_OFFSET_MASK) << 6) | J_INSN;
  87#elif defined(__XTENSA_EB__)
  88                insn = ((d & J_OFFSET_MASK) << 8) | J_INSN;
  89#endif
  90        } else {
  91                insn = NOP_INSN;
  92        }
  93
  94        patch_text(jump_entry_code(e), &insn, JUMP_LABEL_NOP_SIZE);
  95}
  96