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4735037b5d
Add text patching api's to use in subsequent jump_label implementation. We use a new fixmap FIX_TEXT_POKE0 entry to temporarily override MMU mappings to allow read only text pages to be written to. Previously, __set_fix was marked with __init as it was only used during the EARLYCON stage. Now that TEXT_POKE mappings require post-init usage (e.g., FIX_TEXT_POKE0), keeping __init would cause runtime bugs whenset_fixmap accesses invalid memory. Thus, we remove the __init flag to ensure __set_fix remains valid beyond initialization. A new function patch_insn_write is exposed to allow single instruction patching. Link: https://lore.kernel.org/openrisc/aJIC8o1WmVHol9RY@antec/T/#t Signed-off-by: chenmiao <chenmiao.ku@gmail.com> Signed-off-by: Stafford Horne <shorne@gmail.com>
80 lines
1.7 KiB
C
80 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (C) 2020 SiFive
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* Copyright (C) 2025 Chen Miao
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*/
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#include <linux/mm.h>
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#include <linux/kernel.h>
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#include <linux/spinlock.h>
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#include <linux/uaccess.h>
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#include <asm/insn-def.h>
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#include <asm/cacheflush.h>
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#include <asm/page.h>
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#include <asm/fixmap.h>
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#include <asm/text-patching.h>
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#include <asm/sections.h>
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static DEFINE_RAW_SPINLOCK(patch_lock);
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static __always_inline void *patch_map(void *addr, int fixmap)
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{
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uintptr_t uaddr = (uintptr_t) addr;
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phys_addr_t phys;
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if (core_kernel_text(uaddr)) {
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phys = __pa_symbol(addr);
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} else {
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struct page *page = vmalloc_to_page(addr);
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BUG_ON(!page);
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phys = page_to_phys(page) + offset_in_page(addr);
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}
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return (void *)set_fixmap_offset(fixmap, phys);
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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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static int __patch_insn_write(void *addr, u32 insn)
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{
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void *waddr = addr;
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unsigned long flags = 0;
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int ret;
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raw_spin_lock_irqsave(&patch_lock, flags);
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waddr = patch_map(addr, FIX_TEXT_POKE0);
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ret = copy_to_kernel_nofault(waddr, &insn, OPENRISC_INSN_SIZE);
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local_icache_range_inv((unsigned long)waddr,
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(unsigned long)waddr + OPENRISC_INSN_SIZE);
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patch_unmap(FIX_TEXT_POKE0);
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raw_spin_unlock_irqrestore(&patch_lock, flags);
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return ret;
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}
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/*
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* patch_insn_write - Write a single instruction to a specified memory location
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* This API provides a single-instruction patching, primarily used for runtime
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* code modification.
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* By the way, the insn size must be 4 bytes.
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*/
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int patch_insn_write(void *addr, u32 insn)
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{
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u32 *tp = addr;
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int ret;
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if ((uintptr_t) tp & 0x3)
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return -EINVAL;
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ret = __patch_insn_write(tp, insn);
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return ret;
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}
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