/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Persistent Storage - pstore.h
*
* Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
*
* This code is the generic layer to export data records from platform
* level persistent storage via a file system.
*/
#ifndef _LINUX_PSTORE_H
#define _LINUX_PSTORE_H
#include <linux/compiler.h>
#include <linux/errno.h>
#include <linux/kmsg_dump.h>
#include <linux/mutex.h>
#include <linux/semaphore.h>
#include <linux/time.h>
#include <linux/types.h>
struct module;
/*
* pstore record types (see fs/pstore/platform.c for pstore_type_names[])
* These values may be written to storage (see EFI vars backend), so
* they are kind of an ABI. Be careful changing the mappings.
*/
enum pstore_type_id {
/* Frontend storage types */
PSTORE_TYPE_DMESG = 0,
PSTORE_TYPE_MCE = 1,
PSTORE_TYPE_CONSOLE = 2,
PSTORE_TYPE_FTRACE = 3,
/* PPC64-specific partition types */
PSTORE_TYPE_PPC_RTAS = 4,
PSTORE_TYPE_PPC_OF = 5,
PSTORE_TYPE_PPC_COMMON = 6,
PSTORE_TYPE_PMSG = 7,
PSTORE_TYPE_PPC_OPAL = 8,
/* End of the list */
PSTORE_TYPE_MAX
};
const char *pstore_type_to_name(enum pstore_type_id type);
enum pstore_type_id pstore_name_to_type(const char *name);
struct pstore_info;
/**
* struct pstore_record - details of a pstore record entry
* @psi: pstore backend driver information
* @type: pstore record type
* @id: per-type unique identifier for record
* @time: timestamp of the record
* @buf: pointer to record contents
* @size: size of @buf
* @ecc_notice_size:
* ECC information for @buf
*
* Valid for PSTORE_TYPE_DMESG @type:
*
* @count: Oops count since boot
* @reason: kdump reason for notification
* @part: position in a multipart record
* @compressed: whether the buffer is compressed
*
*/
struct pstore_record {
struct pstore_info *psi;
enum pstore_type_id type;
u64 id;
struct timespec64 time;
char *buf;
ssize_t size;
ssize_t ecc_notice_size;
int count;
enum kmsg_dump_reason reason;
unsigned int part;
bool compressed;
};
/**
* struct pstore_info - backend pstore driver structure
*
* @owner: module which is responsible for this backend driver
* @name: name of the backend driver
*
* @buf_lock: semaphore to serialize access to @buf
* @buf: preallocated crash dump buffer
* @bufsize: size of @buf available for crash dump bytes (must match
* smallest number of bytes available for writing to a
* backend entry, since compressed bytes don't take kindly
* to being truncated)
*
* @read_mutex: serializes @open, @read, @close, and @erase callbacks
* @flags: bitfield of frontends the backend can accept writes for
* @data: backend-private pointer passed back during callbacks
*
* Callbacks:
*
* @open:
* Notify backend that pstore is starting a full read of backend
* records. Followed by one or more @read calls, and a final @close.
*
* @psi: in: pointer to the struct pstore_info for the backend
*
* Returns 0 on success, and non-zero on error.
*
* @close:
* Notify backend that pstore has finished a full read of backend
* records. Always preceded by an @open call and one or more @read
* calls.
*
* @psi: in: pointer to the struct pstore_info for the backend
*
* Returns 0 on success, and non-zero on error. (Though pstore will
* ignore the error.)
*
* @read:
* Read next available backend record. Called after a successful
* @open.
*
* @record:
* pointer to record to populate. @buf should be allocated
* by the backend and filled. At least @type and @id should
* be populated, since these are used when creating pstorefs
* file names.
*
* Returns record size on success, zero when no more records are
* available, or negative on error.
*
* @write:
* A newly generated record needs to be written to backend storage.
*
* @record:
* pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
* @buf will be pointing to the preallocated @psi.buf, since
* memory allocation may be broken during an Oops. Regardless,
* @buf must be proccesed or copied before returning. The
* backend is also expected to write @id with something that
* can help identify this record to a future @erase callback.
* The @time field will be prepopulated with the current time,
* when available. The @size field will have the size of data
* in @buf.
*
* Returns 0 on success, and non-zero on error.
*
* @write_user:
* Perform a frontend write to a backend record, using a specified
* buffer that is coming directly from userspace, instead of the
* @record @buf.
*
* @record: pointer to record metadata.
* @buf: pointer to userspace contents to write to backend
*
* Returns 0 on success, and non-zero on error.
*
* @erase:
* Delete a record from backend storage. Different backends
* identify records differently, so entire original record is
* passed back to assist in identification of what the backend
* should remove from storage.
*
* @record: pointer to record metadata.
*
* Returns 0 on success, and non-zero on error.
*
*/
struct pstore_info {
struct module *owner;
char *name;
struct semaphore buf_lock;
char *buf;
size_t bufsize;
struct mutex read_mutex;
int flags;
void *data;
int (*open)(struct pstore_info *psi);
int (*close)(struct pstore_info *psi);
ssize_t (*read)(struct pstore_record *record);
int (*write)(struct pstore_record *record);
int (*write_user)(struct pstore_record *record,
const char __user *buf);
int (*erase)(struct pstore_record *record);
};
/* Supported frontends */
#define PSTORE_FLAGS_DMESG BIT(0)
#define PSTORE_FLAGS_CONSOLE BIT(1)
#define PSTORE_FLAGS_FTRACE BIT(2)
#define PSTORE_FLAGS_PMSG BIT(3)
extern int pstore_register(struct pstore_info *);
extern void pstore_unregister(struct pstore_info *);
struct pstore_ftrace_record {
unsigned long ip;
unsigned long parent_ip;
u64 ts;
};
/*
* ftrace related stuff: Both backends and frontends need these so expose
* them here.
*/
#if NR_CPUS <= 2 && defined([31mCONFIG_ARM_THUMB[0m)
#define PSTORE_CPU_IN_IP 0x1
#elif NR_CPUS <= 4 && defined([31mCONFIG_ARM[0m)
#define PSTORE_CPU_IN_IP 0x3
#endif
#define TS_CPU_SHIFT 8
#define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
/*
* If CPU number can be stored in IP, store it there, otherwise store it in
* the time stamp. This means more timestamp resolution is available when
* the CPU can be stored in the IP.
*/
#ifdef PSTORE_CPU_IN_IP
static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
{
rec->ip |= cpu;
}
static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
{
return rec->ip & PSTORE_CPU_IN_IP;
}
static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
{
return rec->ts;
}
static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
{
rec->ts = val;
}
#else
static inline void
pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
{
rec->ts &= ~(TS_CPU_MASK);
rec->ts |= cpu;
}
static inline unsigned int
pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
{
return rec->ts & TS_CPU_MASK;
}
static inline u64
pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
{
return rec->ts >> TS_CPU_SHIFT;
}
static inline void
pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
{
rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
}
#endif
#endif /*_LINUX_PSTORE_H*/