[PATCH v4 4/5] pstore: add pmsg

From: Mark Salyzyn
Date: Tue Jan 13 2015 - 19:16:31 EST

A secured user-space accessible pstore object. Writes
to /dev/pmsg0 are appended to the buffer, on reboot
the persistent contents are available in
/sys/fs/pstore/pmsg-ramoops-[ID].

One possible use is syslogd, or other daemon, can
write messages, then on reboot provides a means to
triage user-space activities leading up to a panic
as a companion to the pstore dmesg or console logs.

Signed-off-by: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
---
v2: switch from snprintf to scnprintf
v3: split out prz_ok checking into PATCH 3/5
replace pmsg_lseek with noop_llseek
use pr_fmt() macro
make write atomic and use a vmalloc'd bounce buffer
v4: use mutex_lock instead of of spin_lock.

fs/pstore/Kconfig | 10 ++++
fs/pstore/Makefile | 2 +
fs/pstore/inode.c | 3 ++
fs/pstore/internal.h | 6 +++
fs/pstore/platform.c | 1 +
fs/pstore/pmsg.c | 114 +++++++++++++++++++++++++++++++++++++++++++++
fs/pstore/ram.c | 34 +++++++++++++-
include/linux/pstore.h | 1 +
include/linux/pstore_ram.h | 1 +
9 files changed, 170 insertions(+), 2 deletions(-)
create mode 100644 fs/pstore/pmsg.c

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 983d951..916b8e2 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -21,6 +21,16 @@ config PSTORE_CONSOLE
When the option is enabled, pstore will log all kernel
messages, even if no oops or panic happened.

+config PSTORE_PMSG
+ bool "Log user space messages"
+ depends on PSTORE
+ help
+ When the option is enabled, pstore will export a character
+ interface /dev/pmsg0 to log user space messages. On reboot
+ data can be retrieved from /sys/fs/pstore/pmsg-ramoops-[ID].
+
+ If unsure, say N.
+
config PSTORE_FTRACE
bool "Persistent function tracer"
depends on PSTORE
diff --git a/fs/pstore/Makefile b/fs/pstore/Makefile
index 4c9095c..e647d8e 100644
--- a/fs/pstore/Makefile
+++ b/fs/pstore/Makefile
@@ -7,5 +7,7 @@ obj-y += pstore.o
pstore-objs += inode.o platform.o
obj-$(CONFIG_PSTORE_FTRACE) += ftrace.o

+obj-$(CONFIG_PSTORE_PMSG) += pmsg.o
+
ramoops-objs += ram.o ram_core.o
obj-$(CONFIG_PSTORE_RAM) += ramoops.o
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index d69586f..b32ce53 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -361,6 +361,9 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
psname, id);
break;
+ case PSTORE_TYPE_PMSG:
+ scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
+ break;
case PSTORE_TYPE_UNKNOWN:
scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
break;
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index 3b3d305..c36ba2c 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -45,6 +45,12 @@ extern void pstore_register_ftrace(void);
static inline void pstore_register_ftrace(void) {}
#endif

+#ifdef CONFIG_PSTORE_PMSG
+extern void pstore_register_pmsg(void);
+#else
+static inline void pstore_register_pmsg(void) {}
+#endif
+
extern struct pstore_info *psinfo;

extern void pstore_set_kmsg_bytes(int);
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 0a9b72c..15ee78c 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -447,6 +447,7 @@ int pstore_register(struct pstore_info *psi)
if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
pstore_register_console();
pstore_register_ftrace();
+ pstore_register_pmsg();
}

if (pstore_update_ms >= 0) {
diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c
new file mode 100644
index 0000000..feb5dd2
--- /dev/null
+++ b/fs/pstore/pmsg.c
@@ -0,0 +1,114 @@
+/*
+ * Copyright 2014 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ */
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include "internal.h"
+
+static DEFINE_MUTEX(pmsg_lock);
+#define PMSG_MAX_BOUNCE_BUFFER_SIZE (2*PAGE_SIZE)
+
+static ssize_t write_pmsg(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ size_t i, buffer_size;
+ char *buffer;
+
+ if (!count)
+ return 0;
+
+ if (!access_ok(VERIFY_READ, buf, count))
+ return -EFAULT;
+
+ buffer_size = count;
+ if (buffer_size > PMSG_MAX_BOUNCE_BUFFER_SIZE)
+ buffer_size = PMSG_MAX_BOUNCE_BUFFER_SIZE;
+ buffer = vmalloc(buffer_size);
+
+ mutex_lock(&pmsg_lock);
+ for (i = 0; i < count; ) {
+ size_t c = min(count - i, buffer_size);
+ u64 id;
+ long ret;
+
+ ret = __copy_from_user(buffer, buf + i, c);
+ if (unlikely(ret != 0)) {
+ mutex_unlock(&pmsg_lock);
+ vfree(buffer);
+ return -EFAULT;
+ }
+ psinfo->write_buf(PSTORE_TYPE_PMSG, 0, &id, 0, buffer, 0, c,
+ psinfo);
+
+ i += c;
+ }
+
+ mutex_unlock(&pmsg_lock);
+ vfree(buffer);
+ return count;
+}
+
+static const struct file_operations pmsg_fops = {
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+ .write = write_pmsg,
+};
+
+static struct class *pmsg_class;
+static int pmsg_major;
+#define PMSG_NAME "pmsg"
+#undef pr_fmt
+#define pr_fmt(fmt) PMSG_NAME ": " fmt
+
+static char *pmsg_devnode(struct device *dev, umode_t *mode)
+{
+ if (mode)
+ *mode = 0220;
+ return NULL;
+}
+
+void pstore_register_pmsg(void)
+{
+ struct device *pmsg_device;
+
+ pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops);
+ if (pmsg_major < 0) {
+ pr_err("register_chrdev failed\n");
+ goto err;
+ }
+
+ pmsg_class = class_create(THIS_MODULE, PMSG_NAME);
+ if (IS_ERR(pmsg_class)) {
+ pr_err("device class file already in use\n");
+ goto err_class;
+ }
+ pmsg_class->devnode = pmsg_devnode;
+
+ pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0),
+ NULL, "%s%d", PMSG_NAME, 0);
+ if (IS_ERR(pmsg_device)) {
+ pr_err("failed to create device\n");
+ goto err_device;
+ }
+ return;
+
+err_device:
+ class_destroy(pmsg_class);
+err_class:
+ unregister_chrdev(pmsg_major, PMSG_NAME);
+err:
+ return;
+}
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 6150e54..39d1373 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -51,6 +51,10 @@ static ulong ramoops_ftrace_size = MIN_MEM_SIZE;
module_param_named(ftrace_size, ramoops_ftrace_size, ulong, 0400);
MODULE_PARM_DESC(ftrace_size, "size of ftrace log");

+static ulong ramoops_pmsg_size = MIN_MEM_SIZE;
+module_param_named(pmsg_size, ramoops_pmsg_size, ulong, 0400);
+MODULE_PARM_DESC(pmsg_size, "size of user space message log");
+
static ulong mem_address;
module_param(mem_address, ulong, 0400);
MODULE_PARM_DESC(mem_address,
@@ -82,12 +86,14 @@ struct ramoops_context {
struct persistent_ram_zone **przs;
struct persistent_ram_zone *cprz;
struct persistent_ram_zone *fprz;
+ struct persistent_ram_zone *mprz;
phys_addr_t phys_addr;
unsigned long size;
unsigned int memtype;
size_t record_size;
size_t console_size;
size_t ftrace_size;
+ size_t pmsg_size;
int dump_oops;
struct persistent_ram_ecc_info ecc_info;
unsigned int max_dump_cnt;
@@ -96,6 +102,7 @@ struct ramoops_context {
unsigned int dump_read_cnt;
unsigned int console_read_cnt;
unsigned int ftrace_read_cnt;
+ unsigned int pmsg_read_cnt;
struct pstore_info pstore;
};

@@ -109,6 +116,7 @@ static int ramoops_pstore_open(struct pstore_info *psi)
cxt->dump_read_cnt = 0;
cxt->console_read_cnt = 0;
cxt->ftrace_read_cnt = 0;
+ cxt->pmsg_read_cnt = 0;
return 0;
}

@@ -191,6 +199,9 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
prz = ramoops_get_next_prz(&cxt->fprz, &cxt->ftrace_read_cnt,
1, id, type, PSTORE_TYPE_FTRACE, 0);
if (!prz_ok(prz))
+ prz = ramoops_get_next_prz(&cxt->mprz, &cxt->pmsg_read_cnt,
+ 1, id, type, PSTORE_TYPE_PMSG, 0);
+ if (!prz_ok(prz))
return 0;

if (!persistent_ram_old(prz))
@@ -258,6 +269,11 @@ static int notrace ramoops_pstore_write_buf(enum pstore_type_id type,
return -ENOMEM;
persistent_ram_write(cxt->fprz, buf, size);
return 0;
+ } else if (type == PSTORE_TYPE_PMSG) {
+ if (!cxt->mprz)
+ return -ENOMEM;
+ persistent_ram_write(cxt->mprz, buf, size);
+ return 0;
}

if (type != PSTORE_TYPE_DMESG)
@@ -315,6 +331,9 @@ static int ramoops_pstore_erase(enum pstore_type_id type, u64 id, int count,
case PSTORE_TYPE_FTRACE:
prz = cxt->fprz;
break;
+ case PSTORE_TYPE_PMSG:
+ prz = cxt->mprz;
+ break;
default:
return -EINVAL;
}
@@ -441,7 +460,7 @@ static int ramoops_probe(struct platform_device *pdev)
goto fail_out;

if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size &&
- !pdata->ftrace_size)) {
+ !pdata->ftrace_size && !pdata->pmsg_size)) {
pr_err("The memory size and the record/console size must be "
"non-zero\n");
goto fail_out;
@@ -453,6 +472,8 @@ static int ramoops_probe(struct platform_device *pdev)
pdata->console_size = rounddown_pow_of_two(pdata->console_size);
if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
+ if (pdata->pmsg_size && !is_power_of_2(pdata->pmsg_size))
+ pdata->pmsg_size = rounddown_pow_of_two(pdata->pmsg_size);

cxt->size = pdata->mem_size;
cxt->phys_addr = pdata->mem_address;
@@ -460,12 +481,14 @@ static int ramoops_probe(struct platform_device *pdev)
cxt->record_size = pdata->record_size;
cxt->console_size = pdata->console_size;
cxt->ftrace_size = pdata->ftrace_size;
+ cxt->pmsg_size = pdata->pmsg_size;
cxt->dump_oops = pdata->dump_oops;
cxt->ecc_info = pdata->ecc_info;

paddr = cxt->phys_addr;

- dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size;
+ dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
+ - cxt->pmsg_size;
err = ramoops_init_przs(dev, cxt, &paddr, dump_mem_sz);
if (err)
goto fail_out;
@@ -480,6 +503,10 @@ static int ramoops_probe(struct platform_device *pdev)
if (err)
goto fail_init_fprz;

+ err = ramoops_init_prz(dev, cxt, &cxt->mprz, &paddr, cxt->pmsg_size, 0);
+ if (err)
+ goto fail_init_mprz;
+
cxt->pstore.data = cxt;
/*
* Console can handle any buffer size, so prefer LOG_LINE_MAX. If we
@@ -523,6 +550,8 @@ fail_buf:
kfree(cxt->pstore.buf);
fail_clear:
cxt->pstore.bufsize = 0;
+ kfree(cxt->mprz);
+fail_init_mprz:
kfree(cxt->fprz);
fail_init_fprz:
kfree(cxt->cprz);
@@ -580,6 +609,7 @@ static void ramoops_register_dummy(void)
dummy_data->record_size = record_size;
dummy_data->console_size = ramoops_console_size;
dummy_data->ftrace_size = ramoops_ftrace_size;
+ dummy_data->pmsg_size = ramoops_pmsg_size;
dummy_data->dump_oops = dump_oops;
/*
* For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index ece0c6b..8884f6e 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -39,6 +39,7 @@ enum pstore_type_id {
PSTORE_TYPE_PPC_RTAS = 4,
PSTORE_TYPE_PPC_OF = 5,
PSTORE_TYPE_PPC_COMMON = 6,
+ PSTORE_TYPE_PMSG = 7,
PSTORE_TYPE_UNKNOWN = 255
};

diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index 4af3fdc..9c9d6c1 100644
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -81,6 +81,7 @@ struct ramoops_platform_data {
unsigned long record_size;
unsigned long console_size;
unsigned long ftrace_size;
+ unsigned long pmsg_size;
int dump_oops;
struct persistent_ram_ecc_info ecc_info;
};
--
2.2.0.rc0.207.ga3a616c

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