linux/drivers/char/mspec.c
Tony Luck a119365586 [IA64] Redefine ATOMIC_INIT and ATOMIC64_INIT to drop the casts
The following build error occured during a ia64 build with
swap-over-NFS patches applied.

net/core/sock.c:274:36: error: initializer element is not constant
net/core/sock.c:274:36: error: (near initialization for 'memalloc_socks')
net/core/sock.c:274:36: error: initializer element is not constant

This is identical to a parisc build error. Fengguang Wu, Mel Gorman
and James Bottomley did all the legwork to track the root cause of
the problem. This fix and entire commit log is shamelessly copied
from them with one extra detail to change a dubious runtime use of
ATOMIC_INIT() to atomic_set() in drivers/char/mspec.c

Dave Anglin says:
> Here is the line in sock.i:
>
> struct static_key memalloc_socks = ((struct static_key) { .enabled =
> ((atomic_t) { (0) }) });

The above line contains two compound literals.  It also uses a designated
initializer to initialize the field enabled.  A compound literal is not a
constant expression.

The location of the above statement isn't fully clear, but if a compound
literal occurs outside the body of a function, the initializer list must
consist of constant expressions.

Cc: <stable@vger.kernel.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2012-07-26 10:55:26 -07:00

451 lines
11 KiB
C

/*
* Copyright (C) 2001-2006 Silicon Graphics, Inc. All rights
* reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2 of the GNU General Public License
* as published by the Free Software Foundation.
*/
/*
* SN Platform Special Memory (mspec) Support
*
* This driver exports the SN special memory (mspec) facility to user
* processes.
* There are three types of memory made available thru this driver:
* fetchops, uncached and cached.
*
* Fetchops are atomic memory operations that are implemented in the
* memory controller on SGI SN hardware.
*
* Uncached are used for memory write combining feature of the ia64
* cpu.
*
* Cached are used for areas of memory that are used as cached addresses
* on our partition and used as uncached addresses from other partitions.
* Due to a design constraint of the SN2 Shub, you can not have processors
* on the same FSB perform both a cached and uncached reference to the
* same cache line. These special memory cached regions prevent the
* kernel from ever dropping in a TLB entry and therefore prevent the
* processor from ever speculating a cache line from this page.
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/vmalloc.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/numa.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <linux/atomic.h>
#include <asm/tlbflush.h>
#include <asm/uncached.h>
#include <asm/sn/addrs.h>
#include <asm/sn/arch.h>
#include <asm/sn/mspec.h>
#include <asm/sn/sn_cpuid.h>
#include <asm/sn/io.h>
#include <asm/sn/bte.h>
#include <asm/sn/shubio.h>
#define FETCHOP_ID "SGI Fetchop,"
#define CACHED_ID "Cached,"
#define UNCACHED_ID "Uncached"
#define REVISION "4.0"
#define MSPEC_BASENAME "mspec"
/*
* Page types allocated by the device.
*/
enum mspec_page_type {
MSPEC_FETCHOP = 1,
MSPEC_CACHED,
MSPEC_UNCACHED
};
#ifdef CONFIG_SGI_SN
static int is_sn2;
#else
#define is_sn2 0
#endif
/*
* One of these structures is allocated when an mspec region is mmaped. The
* structure is pointed to by the vma->vm_private_data field in the vma struct.
* This structure is used to record the addresses of the mspec pages.
* This structure is shared by all vma's that are split off from the
* original vma when split_vma()'s are done.
*
* The refcnt is incremented atomically because mm->mmap_sem does not
* protect in fork case where multiple tasks share the vma_data.
*/
struct vma_data {
atomic_t refcnt; /* Number of vmas sharing the data. */
spinlock_t lock; /* Serialize access to this structure. */
int count; /* Number of pages allocated. */
enum mspec_page_type type; /* Type of pages allocated. */
int flags; /* See VMD_xxx below. */
unsigned long vm_start; /* Original (unsplit) base. */
unsigned long vm_end; /* Original (unsplit) end. */
unsigned long maddr[0]; /* Array of MSPEC addresses. */
};
#define VMD_VMALLOCED 0x1 /* vmalloc'd rather than kmalloc'd */
/* used on shub2 to clear FOP cache in the HUB */
static unsigned long scratch_page[MAX_NUMNODES];
#define SH2_AMO_CACHE_ENTRIES 4
static inline int
mspec_zero_block(unsigned long addr, int len)
{
int status;
if (is_sn2) {
if (is_shub2()) {
int nid;
void *p;
int i;
nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
p = (void *)TO_AMO(scratch_page[nid]);
for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
p += FETCHOP_VAR_SIZE;
}
}
status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
} else {
memset((char *) addr, 0, len);
status = 0;
}
return status;
}
/*
* mspec_open
*
* Called when a device mapping is created by a means other than mmap
* (via fork, munmap, etc.). Increments the reference count on the
* underlying mspec data so it is not freed prematurely.
*/
static void
mspec_open(struct vm_area_struct *vma)
{
struct vma_data *vdata;
vdata = vma->vm_private_data;
atomic_inc(&vdata->refcnt);
}
/*
* mspec_close
*
* Called when unmapping a device mapping. Frees all mspec pages
* belonging to all the vma's sharing this vma_data structure.
*/
static void
mspec_close(struct vm_area_struct *vma)
{
struct vma_data *vdata;
int index, last_index;
unsigned long my_page;
vdata = vma->vm_private_data;
if (!atomic_dec_and_test(&vdata->refcnt))
return;
last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
for (index = 0; index < last_index; index++) {
if (vdata->maddr[index] == 0)
continue;
/*
* Clear the page before sticking it back
* into the pool.
*/
my_page = vdata->maddr[index];
vdata->maddr[index] = 0;
if (!mspec_zero_block(my_page, PAGE_SIZE))
uncached_free_page(my_page, 1);
else
printk(KERN_WARNING "mspec_close(): "
"failed to zero page %ld\n", my_page);
}
if (vdata->flags & VMD_VMALLOCED)
vfree(vdata);
else
kfree(vdata);
}
/*
* mspec_fault
*
* Creates a mspec page and maps it to user space.
*/
static int
mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
unsigned long paddr, maddr;
unsigned long pfn;
pgoff_t index = vmf->pgoff;
struct vma_data *vdata = vma->vm_private_data;
maddr = (volatile unsigned long) vdata->maddr[index];
if (maddr == 0) {
maddr = uncached_alloc_page(numa_node_id(), 1);
if (maddr == 0)
return VM_FAULT_OOM;
spin_lock(&vdata->lock);
if (vdata->maddr[index] == 0) {
vdata->count++;
vdata->maddr[index] = maddr;
} else {
uncached_free_page(maddr, 1);
maddr = vdata->maddr[index];
}
spin_unlock(&vdata->lock);
}
if (vdata->type == MSPEC_FETCHOP)
paddr = TO_AMO(maddr);
else
paddr = maddr & ~__IA64_UNCACHED_OFFSET;
pfn = paddr >> PAGE_SHIFT;
/*
* vm_insert_pfn can fail with -EBUSY, but in that case it will
* be because another thread has installed the pte first, so it
* is no problem.
*/
vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
return VM_FAULT_NOPAGE;
}
static const struct vm_operations_struct mspec_vm_ops = {
.open = mspec_open,
.close = mspec_close,
.fault = mspec_fault,
};
/*
* mspec_mmap
*
* Called when mmapping the device. Initializes the vma with a fault handler
* and private data structure necessary to allocate, track, and free the
* underlying pages.
*/
static int
mspec_mmap(struct file *file, struct vm_area_struct *vma,
enum mspec_page_type type)
{
struct vma_data *vdata;
int pages, vdata_size, flags = 0;
if (vma->vm_pgoff != 0)
return -EINVAL;
if ((vma->vm_flags & VM_SHARED) == 0)
return -EINVAL;
if ((vma->vm_flags & VM_WRITE) == 0)
return -EPERM;
pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
if (vdata_size <= PAGE_SIZE)
vdata = kzalloc(vdata_size, GFP_KERNEL);
else {
vdata = vzalloc(vdata_size);
flags = VMD_VMALLOCED;
}
if (!vdata)
return -ENOMEM;
vdata->vm_start = vma->vm_start;
vdata->vm_end = vma->vm_end;
vdata->flags = flags;
vdata->type = type;
spin_lock_init(&vdata->lock);
atomic_set(&vdata->refcnt, 1);
vma->vm_private_data = vdata;
vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);
if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
vma->vm_ops = &mspec_vm_ops;
return 0;
}
static int
fetchop_mmap(struct file *file, struct vm_area_struct *vma)
{
return mspec_mmap(file, vma, MSPEC_FETCHOP);
}
static int
cached_mmap(struct file *file, struct vm_area_struct *vma)
{
return mspec_mmap(file, vma, MSPEC_CACHED);
}
static int
uncached_mmap(struct file *file, struct vm_area_struct *vma)
{
return mspec_mmap(file, vma, MSPEC_UNCACHED);
}
static const struct file_operations fetchop_fops = {
.owner = THIS_MODULE,
.mmap = fetchop_mmap,
.llseek = noop_llseek,
};
static struct miscdevice fetchop_miscdev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "sgi_fetchop",
.fops = &fetchop_fops
};
static const struct file_operations cached_fops = {
.owner = THIS_MODULE,
.mmap = cached_mmap,
.llseek = noop_llseek,
};
static struct miscdevice cached_miscdev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "mspec_cached",
.fops = &cached_fops
};
static const struct file_operations uncached_fops = {
.owner = THIS_MODULE,
.mmap = uncached_mmap,
.llseek = noop_llseek,
};
static struct miscdevice uncached_miscdev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "mspec_uncached",
.fops = &uncached_fops
};
/*
* mspec_init
*
* Called at boot time to initialize the mspec facility.
*/
static int __init
mspec_init(void)
{
int ret;
int nid;
/*
* The fetchop device only works on SN2 hardware, uncached and cached
* memory drivers should both be valid on all ia64 hardware
*/
#ifdef CONFIG_SGI_SN
if (ia64_platform_is("sn2")) {
is_sn2 = 1;
if (is_shub2()) {
ret = -ENOMEM;
for_each_node_state(nid, N_ONLINE) {
int actual_nid;
int nasid;
unsigned long phys;
scratch_page[nid] = uncached_alloc_page(nid, 1);
if (scratch_page[nid] == 0)
goto free_scratch_pages;
phys = __pa(scratch_page[nid]);
nasid = get_node_number(phys);
actual_nid = nasid_to_cnodeid(nasid);
if (actual_nid != nid)
goto free_scratch_pages;
}
}
ret = misc_register(&fetchop_miscdev);
if (ret) {
printk(KERN_ERR
"%s: failed to register device %i\n",
FETCHOP_ID, ret);
goto free_scratch_pages;
}
}
#endif
ret = misc_register(&cached_miscdev);
if (ret) {
printk(KERN_ERR "%s: failed to register device %i\n",
CACHED_ID, ret);
if (is_sn2)
misc_deregister(&fetchop_miscdev);
goto free_scratch_pages;
}
ret = misc_register(&uncached_miscdev);
if (ret) {
printk(KERN_ERR "%s: failed to register device %i\n",
UNCACHED_ID, ret);
misc_deregister(&cached_miscdev);
if (is_sn2)
misc_deregister(&fetchop_miscdev);
goto free_scratch_pages;
}
printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
CACHED_ID, UNCACHED_ID);
return 0;
free_scratch_pages:
for_each_node(nid) {
if (scratch_page[nid] != 0)
uncached_free_page(scratch_page[nid], 1);
}
return ret;
}
static void __exit
mspec_exit(void)
{
int nid;
misc_deregister(&uncached_miscdev);
misc_deregister(&cached_miscdev);
if (is_sn2) {
misc_deregister(&fetchop_miscdev);
for_each_node(nid) {
if (scratch_page[nid] != 0)
uncached_free_page(scratch_page[nid], 1);
}
}
}
module_init(mspec_init);
module_exit(mspec_exit);
MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
MODULE_LICENSE("GPL");