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