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// SPDX-License-Identifier: GPL-2.0
/*
* Trapped io support
*
* Copyright (C) 2008 Magnus Damm
*
* Intercept io operations by trapping.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/bitops.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/init.h>
#include <asm/mmu_context.h>
#include <linux/uaccess.h>
#include <asm/io.h>
#include <asm/io_trapped.h>
#define TRAPPED_PAGES_MAX 16
#ifdef CONFIG_HAS_IOPORT_MAP
LIST_HEAD(trapped_io);
EXPORT_SYMBOL_GPL(trapped_io);
#endif
#ifdef CONFIG_HAS_IOMEM
LIST_HEAD(trapped_mem);
EXPORT_SYMBOL_GPL(trapped_mem);
#endif
static DEFINE_SPINLOCK(trapped_lock);
static int trapped_io_disable __read_mostly;
static int __init trapped_io_setup(char *__unused)
{
trapped_io_disable = 1;
return 1;
}
__setup("noiotrap", trapped_io_setup);
int register_trapped_io(struct trapped_io *tiop)
{
struct resource *res;
unsigned long len = 0, flags = 0;
struct page *pages[TRAPPED_PAGES_MAX];
int k, n;
if (unlikely(trapped_io_disable))
return 0;
/* structure must be page aligned */
if ((unsigned long)tiop & (PAGE_SIZE - 1))
goto bad;
for (k = 0; k < tiop->num_resources; k++) {
res = tiop->resource + k;
len += roundup(resource_size(res), PAGE_SIZE);
flags |= res->flags;
}
/* support IORESOURCE_IO _or_ MEM, not both */
if (hweight_long(flags) != 1)
goto bad;
n = len >> PAGE_SHIFT;
if (n >= TRAPPED_PAGES_MAX)
goto bad;
for (k = 0; k < n; k++)
pages[k] = virt_to_page(tiop);
tiop->virt_base = vmap(pages, n, VM_MAP, PAGE_NONE);
if (!tiop->virt_base)
goto bad;
len = 0;
for (k = 0; k < tiop->num_resources; k++) {
res = tiop->resource + k;
pr_info("trapped io 0x%08lx overrides %s 0x%08lx\n",
(unsigned long)(tiop->virt_base + len),
res->flags & IORESOURCE_IO ? "io" : "mmio",
(unsigned long)res->start);
len += roundup(resource_size(res), PAGE_SIZE);
}
tiop->magic = IO_TRAPPED_MAGIC;
INIT_LIST_HEAD(&tiop->list);
spin_lock_irq(&trapped_lock);
#ifdef CONFIG_HAS_IOPORT_MAP
if (flags & IORESOURCE_IO)
list_add(&tiop->list, &trapped_io);
#endif
#ifdef CONFIG_HAS_IOMEM
if (flags & IORESOURCE_MEM)
list_add(&tiop->list, &trapped_mem);
#endif
spin_unlock_irq(&trapped_lock);
return 0;
bad:
pr_warn("unable to install trapped io filter\n");
return -1;
}
void __iomem *match_trapped_io_handler(struct list_head *list,
unsigned long offset,
unsigned long size)
{
unsigned long voffs;
struct trapped_io *tiop;
struct resource *res;
int k, len;
unsigned long flags;
spin_lock_irqsave(&trapped_lock, flags);
list_for_each_entry(tiop, list, list) {
voffs = 0;
for (k = 0; k < tiop->num_resources; k++) {
res = tiop->resource + k;
if (res->start == offset) {
spin_unlock_irqrestore(&trapped_lock, flags);
return tiop->virt_base + voffs;
}
len = resource_size(res);
voffs += roundup(len, PAGE_SIZE);
}
}
spin_unlock_irqrestore(&trapped_lock, flags);
return NULL;
}
static struct trapped_io *lookup_tiop(unsigned long address)
{
pgd_t *pgd_k;
p4d_t *p4d_k;
pud_t *pud_k;
pmd_t *pmd_k;
pte_t *pte_k;
pte_t entry;
pgd_k = swapper_pg_dir + pgd_index(address);
if (!pgd_present(*pgd_k))
return NULL;
p4d_k = p4d_offset(pgd_k, address);
if (!p4d_present(*p4d_k))
return NULL;
pud_k = pud_offset(p4d_k, address);
if (!pud_present(*pud_k))
return NULL;
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
return NULL;
pte_k = pte_offset_kernel(pmd_k, address);
entry = *pte_k;
return pfn_to_kaddr(pte_pfn(entry));
}
static unsigned long lookup_address(struct trapped_io *tiop,
unsigned long address)
{
struct resource *res;
unsigned long vaddr = (unsigned long)tiop->virt_base;
unsigned long len;
int k;
for (k = 0; k < tiop->num_resources; k++) {
res = tiop->resource + k;
len = roundup(resource_size(res), PAGE_SIZE);
if (address < (vaddr + len))
return res->start + (address - vaddr);
vaddr += len;
}
return 0;
}
static unsigned long long copy_word(unsigned long src_addr, int src_len,
unsigned long dst_addr, int dst_len)
{
unsigned long long tmp = 0;
switch (src_len) {
case 1:
tmp = __raw_readb(src_addr);
break;
case 2:
tmp = __raw_readw(src_addr);
break;
case 4:
tmp = __raw_readl(src_addr);
break;
case 8:
tmp = __raw_readq(src_addr);
break;
}
switch (dst_len) {
case 1:
__raw_writeb(tmp, dst_addr);
break;
case 2:
__raw_writew(tmp, dst_addr);
break;
case 4:
__raw_writel(tmp, dst_addr);
break;
case 8:
__raw_writeq(tmp, dst_addr);
break;
}
return tmp;
}
static unsigned long from_device(void *dst, const void *src, unsigned long cnt)
{
struct trapped_io *tiop;
unsigned long src_addr = (unsigned long)src;
unsigned long long tmp;
pr_debug("trapped io read 0x%08lx (%ld)\n", src_addr, cnt);
tiop = lookup_tiop(src_addr);
WARN_ON(!tiop || (tiop->magic != IO_TRAPPED_MAGIC));
src_addr = lookup_address(tiop, src_addr);
if (!src_addr)
return cnt;
tmp = copy_word(src_addr,
max_t(unsigned long, cnt,
(tiop->minimum_bus_width / 8)),
(unsigned long)dst, cnt);
pr_debug("trapped io read 0x%08lx -> 0x%08llx\n", src_addr, tmp);
return 0;
}
static unsigned long to_device(void *dst, const void *src, unsigned long cnt)
{
struct trapped_io *tiop;
unsigned long dst_addr = (unsigned long)dst;
unsigned long long tmp;
pr_debug("trapped io write 0x%08lx (%ld)\n", dst_addr, cnt);
tiop = lookup_tiop(dst_addr);
WARN_ON(!tiop || (tiop->magic != IO_TRAPPED_MAGIC));
dst_addr = lookup_address(tiop, dst_addr);
if (!dst_addr)
return cnt;
tmp = copy_word((unsigned long)src, cnt,
dst_addr, max_t(unsigned long, cnt,
(tiop->minimum_bus_width / 8)));
pr_debug("trapped io write 0x%08lx -> 0x%08llx\n", dst_addr, tmp);
return 0;
}
static struct mem_access trapped_io_access = {
from_device,
to_device,
};
int handle_trapped_io(struct pt_regs *regs, unsigned long address)
{
insn_size_t instruction;
int tmp;
if (trapped_io_disable)
return 0;
if (!lookup_tiop(address))
return 0;
WARN_ON(user_mode(regs));
if (copy_from_kernel_nofault(&instruction, (void *)(regs->pc),
sizeof(instruction))) {
return 0;
}
tmp = handle_unaligned_access(instruction, regs,
&trapped_io_access, 1, address);
return tmp == 0;
}
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