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um: Remove file-based iomem emulation support

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The file-based iomem emulation was introduced to support writing
paravirtualized drivers based on emulated iomem regions. However,
the only driver that makes use of it is an example driver called
mmapper, which was written over two decades ago.

We now have several modern device emulation mechanisms, such as
vhost-user-based virtio-uml. Remove the file-based iomem emulation
support to reduce the maintenance burden.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20251027054519.1996090-5-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Tiwei Bie
2025-10-27 13:45:19 +08:00
committed by Johannes Berg
parent 9c84022c1d
commit a7f7dbae94
11 changed files with 4 additions and 293 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/um/Kconfig
View File

@@ -200,12 +200,6 @@ config KERNEL_STACK_ORDER
increase in the size of the state which needs to be saved when handling
signals.
config MMAPPER
tristate "iomem emulation driver"
help
This driver allows a host file to be used as emulated IO memory inside
UML.
config PGTABLE_LEVELS
int
default 4 if 64BIT

1
arch/um/drivers/Makefile
View File

@@ -29,7 +29,6 @@ obj-$(CONFIG_STDERR_CONSOLE) += stderr_console.o
obj-$(CONFIG_UML_NET_VECTOR) += vector.o
obj-$(CONFIG_MCONSOLE) += mconsole.o
obj-$(CONFIG_MMAPPER) += mmapper_kern.o
obj-$(CONFIG_BLK_DEV_UBD) += ubd.o
obj-$(CONFIG_UML_SOUND) += hostaudio.o
obj-$(CONFIG_NULL_CHAN) += null.o

135
arch/um/drivers/mmapper_kern.c
View File

@@ -1,135 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* arch/um/drivers/mmapper_kern.c
*
* BRIEF MODULE DESCRIPTION
*
* Copyright (C) 2000 RidgeRun, Inc.
* Author: RidgeRun, Inc.
* Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com
*
*/
#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <mem_user.h>
/* These are set in mmapper_init, which is called at boot time */
static unsigned long mmapper_size;
static unsigned long p_buf;
static char *v_buf;
static ssize_t mmapper_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
{
return simple_read_from_buffer(buf, count, ppos, v_buf, mmapper_size);
}
static ssize_t mmapper_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
if (*ppos > mmapper_size)
return -EINVAL;
return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count);
}
static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
return -ENOIOCTLCMD;
}
static int mmapper_mmap(struct file *file, struct vm_area_struct *vma)
{
int ret = -EINVAL;
int size;
if (vma->vm_pgoff != 0)
goto out;
size = vma->vm_end - vma->vm_start;
if (size > mmapper_size)
return -EFAULT;
/*
* XXX A comment above remap_pfn_range says it should only be
* called when the mm semaphore is held
*/
if (remap_pfn_range(vma, vma->vm_start, p_buf >> PAGE_SHIFT, size,
vma->vm_page_prot))
goto out;
ret = 0;
out:
return ret;
}
static int mmapper_open(struct inode *inode, struct file *file)
{
return 0;
}
static int mmapper_release(struct inode *inode, struct file *file)
{
return 0;
}
static const struct file_operations mmapper_fops = {
.owner = THIS_MODULE,
.read = mmapper_read,
.write = mmapper_write,
.unlocked_ioctl = mmapper_ioctl,
.mmap = mmapper_mmap,
.open = mmapper_open,
.release = mmapper_release,
.llseek = default_llseek,
};
/*
* No locking needed - only used (and modified) by below initcall and exitcall.
*/
static struct miscdevice mmapper_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "mmapper",
.fops = &mmapper_fops
};
static int __init mmapper_init(void)
{
int err;
printk(KERN_INFO "Mapper v0.1\n");
v_buf = (char *) find_iomem("mmapper", &mmapper_size);
if (mmapper_size == 0) {
printk(KERN_ERR "mmapper_init - find_iomem failed\n");
return -ENODEV;
}
p_buf = __pa(v_buf);
err = misc_register(&mmapper_dev);
if (err) {
printk(KERN_ERR "mmapper - misc_register failed, err = %d\n",
err);
return err;
}
return 0;
}
static void __exit mmapper_exit(void)
{
misc_deregister(&mmapper_dev);
}
module_init(mmapper_init);
module_exit(mmapper_exit);
MODULE_AUTHOR("Greg Lonnon <glonnon@ridgerun.com>");
MODULE_DESCRIPTION("DSPLinux simulator mmapper driver");
MODULE_LICENSE("GPL");

4
arch/um/include/asm/pgtable.h
View File

@@ -45,10 +45,10 @@ extern unsigned long *empty_zero_page;
* area for the same reason. ;)
*/
extern unsigned long end_iomem;
#include <as-layout.h> /* for high_physmem */
#define VMALLOC_OFFSET (__va_space)
#define VMALLOC_START ((end_iomem + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
#define VMALLOC_START ((high_physmem + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
#define VMALLOC_END (TASK_SIZE-2*PAGE_SIZE)
#define MODULES_VADDR VMALLOC_START
#define MODULES_END VMALLOC_END

1
arch/um/include/shared/kern_util.h
View File

@@ -39,7 +39,6 @@ extern void uml_pm_wake(void);
extern int start_uml(void);
extern void paging_init(void);
extern int parse_iomem(char *str, int *add);
extern void uml_cleanup(void);
extern void do_uml_exitcalls(void);

13
arch/um/include/shared/mem_user.h
View File

@@ -32,21 +32,8 @@
#ifndef _MEM_USER_H
#define _MEM_USER_H
struct iomem_region {
struct iomem_region *next;
char *driver;
int fd;
int size;
unsigned long phys;
unsigned long virt;
};
extern struct iomem_region *iomem_regions;
extern int iomem_size;
#define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
extern unsigned long find_iomem(char *driver, unsigned long *len_out);
extern void setup_physmem(unsigned long start, unsigned long usable,
unsigned long len);
extern void map_memory(unsigned long virt, unsigned long phys,

2
arch/um/kernel/mem.c
View File

@@ -197,7 +197,7 @@ void __init paging_init(void)
panic("%s: Failed to allocate %lu bytes align=%lx\n",
__func__, PAGE_SIZE, PAGE_SIZE);
max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
max_zone_pfn[ZONE_NORMAL] = high_physmem >> PAGE_SHIFT;
free_area_init(max_zone_pfn);
#if IS_ENABLED(CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA)

71
arch/um/kernel/physmem.c
View File

@@ -105,19 +105,6 @@ int phys_mapping(unsigned long phys, unsigned long long *offset_out)
fd = physmem_fd;
*offset_out = phys;
}
else if (phys < __pa(end_iomem)) {
struct iomem_region *region = iomem_regions;
while (region != NULL) {
if ((phys >= region->phys) &&
(phys < region->phys + region->size)) {
fd = region->fd;
*offset_out = phys - region->phys;
break;
}
region = region->next;
}
}
return fd;
}
@@ -140,61 +127,3 @@ __uml_setup("mem=", uml_mem_setup,
" be more, and the excess, if it's ever used, will just be swapped out.\n"
" Example: mem=64M\n\n"
);
__uml_setup("iomem=", parse_iomem,
"iomem=<name>,<file>\n"
" Configure <file> as an IO memory region named <name>.\n\n"
);
/*
* This list is constructed in parse_iomem and addresses filled in
* setup_iomem, both of which run during early boot. Afterwards, it's
* unchanged.
*/
struct iomem_region *iomem_regions;
/* Initialized in parse_iomem and unchanged thereafter */
int iomem_size;
unsigned long find_iomem(char *driver, unsigned long *len_out)
{
struct iomem_region *region = iomem_regions;
while (region != NULL) {
if (!strcmp(region->driver, driver)) {
*len_out = region->size;
return region->virt;
}
region = region->next;
}
return 0;
}
EXPORT_SYMBOL(find_iomem);
static int setup_iomem(void)
{
struct iomem_region *region = iomem_regions;
unsigned long iomem_start = high_physmem + PAGE_SIZE;
int err;
while (region != NULL) {
err = os_map_memory((void *) iomem_start, region->fd, 0,
region->size, 1, 1, 0);
if (err)
printk(KERN_ERR "Mapping iomem region for driver '%s' "
"failed, errno = %d\n", region->driver, -err);
else {
region->virt = iomem_start;
region->phys = __pa(region->virt);
}
iomem_start += region->size + PAGE_SIZE;
region = region->next;
}
return 0;
}
__initcall(setup_iomem);

7
arch/um/kernel/um_arch.c
View File

@@ -253,8 +253,6 @@ unsigned long task_size;
EXPORT_SYMBOL(task_size);
unsigned long brk_start;
unsigned long end_iomem;
EXPORT_SYMBOL(end_iomem);
#define MIN_VMALLOC (32 * 1024 * 1024)
@@ -363,9 +361,7 @@ int __init linux_main(int argc, char **argv, char **envp)
setup_machinename(init_utsname()->machine);
physmem_size = PAGE_ALIGN(physmem_size);
iomem_size = PAGE_ALIGN(iomem_size);
max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
max_physmem = TASK_SIZE - uml_physmem - MIN_VMALLOC;
if (physmem_size > max_physmem) {
physmem_size = max_physmem;
os_info("Physical memory size shrunk to %llu bytes\n",
@@ -373,7 +369,6 @@ int __init linux_main(int argc, char **argv, char **envp)
}
high_physmem = uml_physmem + physmem_size;
end_iomem = high_physmem + iomem_size;
start_vm = VMALLOC_START;

7
arch/um/os-Linux/skas/process.c
View File

@@ -298,7 +298,6 @@ static int userspace_tramp(void *data)
.seccomp = using_seccomp,
.stub_start = STUB_START,
};
struct iomem_region *iomem;
int ret;
if (using_seccomp) {
@@ -332,12 +331,6 @@ static int userspace_tramp(void *data)
fcntl(init_data.stub_data_fd, F_SETFD, 0);
/* In SECCOMP mode, these FDs are passed when needed */
if (!using_seccomp) {
for (iomem = iomem_regions; iomem; iomem = iomem->next)
fcntl(iomem->fd, F_SETFD, 0);
}
/* dup2 signaling FD/socket to STDIN */
if (dup2(tramp_data->sockpair[0], 0) < 0)
exit(3);

50
arch/um/os-Linux/start_up.c
View File

@@ -489,53 +489,3 @@ void __init os_early_checks(void)
fatal("Failed to initialize default registers");
stop_ptraced_child(pid, 1);
}
int __init parse_iomem(char *str, int *add)
{
struct iomem_region *new;
struct stat64 buf;
char *file, *driver;
int fd, size;
driver = str;
file = strchr(str,',');
if (file == NULL) {
os_warn("parse_iomem : failed to parse iomem\n");
goto out;
}
*file = '\0';
file++;
fd = open(file, O_RDWR, 0);
if (fd < 0) {
perror("parse_iomem - Couldn't open io file");
goto out;
}
if (fstat64(fd, &buf) < 0) {
perror("parse_iomem - cannot stat_fd file");
goto out_close;
}
new = malloc(sizeof(*new));
if (new == NULL) {
perror("Couldn't allocate iomem_region struct");
goto out_close;
}
size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
*new = ((struct iomem_region) { .next = iomem_regions,
.driver = driver,
.fd = fd,
.size = size,
.phys = 0,
.virt = 0 });
iomem_regions = new;
iomem_size += new->size + UM_KERN_PAGE_SIZE;
return 0;
out_close:
close(fd);
out:
return 1;
}