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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright (C) 2020 SiFive
- */
- #include <linux/spinlock.h>
- #include <linux/mm.h>
- #include <linux/memory.h>
- #include <linux/uaccess.h>
- #include <linux/stop_machine.h>
- #include <asm/kprobes.h>
- #include <asm/cacheflush.h>
- #include <asm/fixmap.h>
- #include <asm/patch.h>
- struct patch_insn {
- void *addr;
- u32 insn;
- atomic_t cpu_count;
- };
- #ifdef CONFIG_MMU
- /*
- * The fix_to_virt(, idx) needs a const value (not a dynamic variable of
- * reg-a0) or BUILD_BUG_ON failed with "idx >= __end_of_fixed_addresses".
- * So use '__always_inline' and 'const unsigned int fixmap' here.
- */
- static __always_inline void *patch_map(void *addr, const unsigned int fixmap)
- {
- uintptr_t uintaddr = (uintptr_t) addr;
- struct page *page;
- if (core_kernel_text(uintaddr))
- page = phys_to_page(__pa_symbol(addr));
- else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
- page = vmalloc_to_page(addr);
- else
- return addr;
- BUG_ON(!page);
- return (void *)set_fixmap_offset(fixmap, page_to_phys(page) +
- (uintaddr & ~PAGE_MASK));
- }
- static void patch_unmap(int fixmap)
- {
- clear_fixmap(fixmap);
- }
- NOKPROBE_SYMBOL(patch_unmap);
- static int patch_insn_write(void *addr, const void *insn, size_t len)
- {
- void *waddr = addr;
- bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE;
- int ret;
- /*
- * Before reaching here, it was expected to lock the text_mutex
- * already, so we don't need to give another lock here and could
- * ensure that it was safe between each cores.
- */
- //lockdep_assert_held(&text_mutex);
- if (across_pages)
- patch_map(addr + len, FIX_TEXT_POKE1);
- waddr = patch_map(addr, FIX_TEXT_POKE0);
- ret = copy_to_kernel_nofault(waddr, insn, len);
- patch_unmap(FIX_TEXT_POKE0);
- if (across_pages)
- patch_unmap(FIX_TEXT_POKE1);
- return ret;
- }
- NOKPROBE_SYMBOL(patch_insn_write);
- #else
- static int patch_insn_write(void *addr, const void *insn, size_t len)
- {
- return copy_to_kernel_nofault(addr, insn, len);
- }
- NOKPROBE_SYMBOL(patch_insn_write);
- #endif /* CONFIG_MMU */
- int patch_text_nosync(void *addr, const void *insns, size_t len)
- {
- u32 *tp = addr;
- int ret;
- ret = patch_insn_write(tp, insns, len);
- if (!ret)
- flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len);
- return ret;
- }
- NOKPROBE_SYMBOL(patch_text_nosync);
- static int patch_text_cb(void *data)
- {
- struct patch_insn *patch = data;
- int ret = 0;
- if (atomic_inc_return(&patch->cpu_count) == 1) {
- ret =
- patch_text_nosync(patch->addr, &patch->insn,
- GET_INSN_LENGTH(patch->insn));
- atomic_inc(&patch->cpu_count);
- } else {
- while (atomic_read(&patch->cpu_count) <= num_online_cpus())
- cpu_relax();
- smp_mb();
- }
- return ret;
- }
- NOKPROBE_SYMBOL(patch_text_cb);
- int patch_text(void *addr, u32 insn)
- {
- struct patch_insn patch = {
- .addr = addr,
- .insn = insn,
- .cpu_count = ATOMIC_INIT(0),
- };
- return stop_machine_cpuslocked(patch_text_cb,
- &patch, cpu_online_mask);
- }
- NOKPROBE_SYMBOL(patch_text);
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