linux_dsm_epyc7002/drivers/acpi/apei/erst-dbg.c

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/*
* APEI Error Record Serialization Table debug support
*
* ERST is a way provided by APEI to save and retrieve hardware error
* information to and from a persistent store. This file provide the
* debugging/testing support for ERST kernel support and firmware
* implementation.
*
* Copyright 2010 Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <acpi/apei.h>
#include <linux/miscdevice.h>
#include "apei-internal.h"
#define ERST_DBG_PFX "ERST DBG: "
#define ERST_DBG_RECORD_LEN_MAX 0x4000
static void *erst_dbg_buf;
static unsigned int erst_dbg_buf_len;
/* Prevent erst_dbg_read/write from being invoked concurrently */
static DEFINE_MUTEX(erst_dbg_mutex);
static int erst_dbg_open(struct inode *inode, struct file *file)
{
int rc, *pos;
if (erst_disable)
return -ENODEV;
pos = (int *)&file->private_data;
rc = erst_get_record_id_begin(pos);
if (rc)
return rc;
return nonseekable_open(inode, file);
}
static int erst_dbg_release(struct inode *inode, struct file *file)
{
erst_get_record_id_end();
return 0;
}
static long erst_dbg_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
int rc;
u64 record_id;
u32 record_count;
switch (cmd) {
case APEI_ERST_CLEAR_RECORD:
rc = copy_from_user(&record_id, (void __user *)arg,
sizeof(record_id));
if (rc)
return -EFAULT;
return erst_clear(record_id);
case APEI_ERST_GET_RECORD_COUNT:
rc = erst_get_record_count();
if (rc < 0)
return rc;
record_count = rc;
rc = put_user(record_count, (u32 __user *)arg);
if (rc)
return rc;
return 0;
default:
return -ENOTTY;
}
}
static ssize_t erst_dbg_read(struct file *filp, char __user *ubuf,
size_t usize, loff_t *off)
{
int rc, *pos;
ssize_t len = 0;
u64 id;
if (*off)
return -EINVAL;
if (mutex_lock_interruptible(&erst_dbg_mutex) != 0)
return -EINTR;
pos = (int *)&filp->private_data;
retry_next:
rc = erst_get_record_id_next(pos, &id);
if (rc)
goto out;
/* no more record */
if (id == APEI_ERST_INVALID_RECORD_ID) {
/*
* If the persistent store is empty initially, the function
* 'erst_read' below will return "-ENOENT" value. This causes
* 'retry_next' label is entered again. The returned value
* should be zero indicating the read operation is EOF.
*/
len = 0;
goto out;
}
retry:
rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
/* The record may be cleared by others, try read next record */
if (rc == -ENOENT)
goto retry_next;
if (rc < 0)
goto out;
if (len > ERST_DBG_RECORD_LEN_MAX) {
pr_warning(ERST_DBG_PFX
"Record (ID: 0x%llx) length is too long: %zd\n",
id, len);
rc = -EIO;
goto out;
}
if (len > erst_dbg_buf_len) {
void *p;
rc = -ENOMEM;
p = kmalloc(len, GFP_KERNEL);
if (!p)
goto out;
kfree(erst_dbg_buf);
erst_dbg_buf = p;
erst_dbg_buf_len = len;
goto retry;
}
rc = -EINVAL;
if (len > usize)
goto out;
rc = -EFAULT;
if (copy_to_user(ubuf, erst_dbg_buf, len))
goto out;
rc = 0;
out:
mutex_unlock(&erst_dbg_mutex);
return rc ? rc : len;
}
static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
size_t usize, loff_t *off)
{
int rc;
struct cper_record_header *rcd;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (usize > ERST_DBG_RECORD_LEN_MAX) {
pr_err(ERST_DBG_PFX "Too long record to be written\n");
return -EINVAL;
}
if (mutex_lock_interruptible(&erst_dbg_mutex))
return -EINTR;
if (usize > erst_dbg_buf_len) {
void *p;
rc = -ENOMEM;
p = kmalloc(usize, GFP_KERNEL);
if (!p)
goto out;
kfree(erst_dbg_buf);
erst_dbg_buf = p;
erst_dbg_buf_len = usize;
}
rc = copy_from_user(erst_dbg_buf, ubuf, usize);
if (rc) {
rc = -EFAULT;
goto out;
}
rcd = erst_dbg_buf;
rc = -EINVAL;
if (rcd->record_length != usize)
goto out;
rc = erst_write(erst_dbg_buf);
out:
mutex_unlock(&erst_dbg_mutex);
return rc < 0 ? rc : usize;
}
static const struct file_operations erst_dbg_ops = {
.owner = THIS_MODULE,
.open = erst_dbg_open,
.release = erst_dbg_release,
.read = erst_dbg_read,
.write = erst_dbg_write,
.unlocked_ioctl = erst_dbg_ioctl,
llseek: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 23:52:59 +07:00
.llseek = no_llseek,
};
static struct miscdevice erst_dbg_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "erst_dbg",
.fops = &erst_dbg_ops,
};
static __init int erst_dbg_init(void)
{
if (erst_disable) {
pr_info(ERST_DBG_PFX "ERST support is disabled.\n");
return -ENODEV;
}
return misc_register(&erst_dbg_dev);
}
static __exit void erst_dbg_exit(void)
{
misc_deregister(&erst_dbg_dev);
kfree(erst_dbg_buf);
}
module_init(erst_dbg_init);
module_exit(erst_dbg_exit);
MODULE_AUTHOR("Huang Ying");
MODULE_DESCRIPTION("APEI Error Record Serialization Table debug support");
MODULE_LICENSE("GPL");