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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/uaccess.h>
#include <linux/stop_machine.h>
#include <asm/kprobes.h>
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
struct patch_insn {
void *addr;
u32 insn;
atomic_t cpu_count;
};
#ifdef CONFIG_MMU
static DEFINE_RAW_SPINLOCK(patch_lock);
static void __kprobes *patch_map(void *addr, 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 __kprobes patch_unmap(int fixmap)
{
clear_fixmap(fixmap);
}
static int __kprobes 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;
unsigned long flags = 0;
int ret;
raw_spin_lock_irqsave(&patch_lock, flags);
if (across_pages)
patch_map(addr + len, FIX_TEXT_POKE1);
waddr = patch_map(addr, FIX_TEXT_POKE0);
ret = probe_kernel_write(waddr, insn, len);
patch_unmap(FIX_TEXT_POKE0);
if (across_pages)
patch_unmap(FIX_TEXT_POKE1);
raw_spin_unlock_irqrestore(&patch_lock, flags);
return ret;
}
#else
static int __kprobes patch_insn_write(void *addr, const void *insn, size_t len)
{
return probe_kernel_write(addr, insn, len);
}
#endif /* CONFIG_MMU */
int __kprobes 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;
}
static int __kprobes 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;
}
int __kprobes 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);
}
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