[PATCH v5 0/11] Merge ram_console into pstore

[PATCH v5 0/11] Merge ram_console into pstore

[Anton Vorontsov]

Hi all,

And another respin, v5 this time:

- Split out fixes into a separate series;
- Added proper spinlock protection to the pstore/console interface
  (the bug I found when was adding ftrace interface);
- And as I'm about to add ftrace support to pstore, to not touch
  the same lines of code twice, I reworked 'Factor ramoops_get_dump_prz()
  out of ramoops_pstore_read()' patch into 'Factor ramoops_get_next_prz()
  out of ramoops_pstore_read()'. This is just a more generic interface
  that will work for both console and ftrace przs.
  Since the patch changed drastically, it lost Kees' ack, so it needs a
  re-ack.
- The same as above happened w/ 'Introduce ramoops_context.max_dump_count'
  patch, it turned into 'Give proper names to dump-related variables', it
  also needs a re-ack.
- If anyone is willing to try the patches, for convenience they are now
  available in the git repository:
  	git://git.infradead.org/users/cbou/linux-pstore.git
  or gitweb:
  	http://git.infradead.org/users/cbou/linux-pstore.git

In v4:

- Per Kees Cook's comments, the patches no longer remove an automatic
  updates feature, but instead make the it configurable; plus disable
  it by default (in a separate patch);
- Fixed some bugs noticed by Colin Cross;
- Documented new continuous ramoops-console log behaviour (also
  noticed by Colin Cross).

In v3:

- Rebased on top of current staging-next;
- The series are getting bigger. This is partly because we now support
  different persistent zone sizes for oops records and console log,
  per Colin Cross' request.
  And I believe the code is now more manageable for further enhancements
  (e.g. if we'd want to add other message types, e.g. tracing);
- Addressed Kees Cook's comments on the unlinking matters;
- Removed automatic updates support. Please see the last patch
  description for rationale;
- A new fixup for pstore/inode, just getting rid of a sparse warning.

In v2:

- Updated documentation per Colin Cross' comments;
- Corrected return value in ramoops_pstore_write() (noticed by Kees Cook);
- Fixed large writes handling in pstore_console_write(), i.e. when
  log_buf write is larger than pstore bufsize. Also Noticed by Kees Cook.


And a boilerplate for the series:

Currently pstore doesn't support logging kernel messages in run-time,
it only dumps dmesg when kernel oopses/panics. This makes pstore
useless for debugging hangs caused by HW issues or improper use of HW
(e.g. weird device inserted -> driver tried to write reserved bits ->
SoC hanged. In that case we don't get any messages in the pstore.

This series add a new message type for pstore, i.e. PSTORE_TYPE_CONSOLE,
plus make pstore/ram.c handle the new messages.

The old ram_console driver is removed. This might probably cause
some pain for out-of-tree code, as it would need to be adjusted...
but "no pain, no gain"? :-) Though, if there's some serious resistance,
we can probably postpone the last two patches.

Thanks!

--- 
 Documentation/ramoops.txt             |   14 ++
 drivers/staging/android/Kconfig       |    5 -
 drivers/staging/android/Makefile      |    1 -
 drivers/staging/android/ram_console.c |  179 ------------------------
 fs/pstore/Kconfig                     |    7 +
 fs/pstore/inode.c                     |    3 +
 fs/pstore/platform.c                  |   54 +++++++-
 fs/pstore/ram.c                       |  246 ++++++++++++++++++++++++---------
 fs/pstore/ram_core.c                  |   81 +----------
 include/linux/pstore.h                |    1 +
 include/linux/pstore_ram.h            |   20 +--
 11 files changed, 261 insertions(+), 350 deletions(-)

-- 
Anton Vorontsov
Email: cbouatmailru@gmail.com

[PATCH 01/11] pstore: Add console log messages support

[Anton Vorontsov]

Pstore doesn't support logging kernel messages in run-time, it only
dumps dmesg when kernel oopses/panics. This makes pstore useless for
debugging hangs caused by HW issues or improper use of HW (e.g.
weird device inserted -> driver tried to write a reserved bits ->
SoC hanged. In that case we don't get any messages in the pstore.

Therefore, let's add a runtime logging support: PSTORE_TYPE_CONSOLE.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Colin Cross <ccross@android.com>
---
 fs/pstore/Kconfig      |    7 +++++++
 fs/pstore/inode.c      |    3 +++
 fs/pstore/platform.c   |   37 +++++++++++++++++++++++++++++++++++++
 include/linux/pstore.h |    1 +
 4 files changed, 48 insertions(+)

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 23ade26..d044de6 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -12,6 +12,13 @@ config PSTORE
 	   If you don't have a platform persistent store driver,
 	   say N.
 
+config PSTORE_CONSOLE
+	bool "Log kernel console messages"
+	depends on PSTORE
+	help
+	  When the option is enabled, pstore will log all kernel
+	  messages, even if no oops or panic happened.
+
 config PSTORE_RAM
 	tristate "Log panic/oops to a RAM buffer"
 	depends on PSTORE
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 49b40ea..fda1331 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -212,6 +212,9 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
 	case PSTORE_TYPE_DMESG:
 		sprintf(name, "dmesg-%s-%lld", psname, id);
 		break;
+	case PSTORE_TYPE_CONSOLE:
+		sprintf(name, "console-%s", psname);
+		break;
 	case PSTORE_TYPE_MCE:
 		sprintf(name, "mce-%s-%lld", psname, id);
 		break;
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 82c585f..61461ed 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -1,6 +1,7 @@
 /*
  * Persistent Storage - platform driver interface parts.
  *
+ * Copyright (C) 2007-2008 Google, Inc.
  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
  *
  *  This program is free software; you can redistribute it and/or modify
@@ -22,6 +23,7 @@
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/kmsg_dump.h>
+#include <linux/console.h>
 #include <linux/module.h>
 #include <linux/pstore.h>
 #include <linux/string.h>
@@ -156,6 +158,40 @@ static struct kmsg_dumper pstore_dumper = {
 	.dump = pstore_dump,
 };
 
+#ifdef CONFIG_PSTORE_CONSOLE
+static void pstore_console_write(struct console *con, const char *s, unsigned c)
+{
+	const char *e = s + c;
+
+	while (s < e) {
+		unsigned long flags;
+
+		if (c > psinfo->bufsize)
+			c = psinfo->bufsize;
+		spin_lock_irqsave(&psinfo->buf_lock, flags);
+		memcpy(psinfo->buf, s, c);
+		psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);
+		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
+		s += c;
+		c = e - s;
+	}
+}
+
+static struct console pstore_console = {
+	.name	= "pstore",
+	.write	= pstore_console_write,
+	.flags	= CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
+	.index	= -1,
+};
+
+static void pstore_register_console(void)
+{
+	register_console(&pstore_console);
+}
+#else
+static void pstore_register_console(void) {}
+#endif
+
 /*
  * platform specific persistent storage driver registers with
  * us here. If pstore is already mounted, call the platform
@@ -193,6 +229,7 @@ int pstore_register(struct pstore_info *psi)
 		pstore_get_records(0);
 
 	kmsg_dump_register(&pstore_dumper);
+	pstore_register_console();
 
 	pstore_timer.expires = jiffies + PSTORE_INTERVAL;
 	add_timer(&pstore_timer);
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index e1461e1..1bd014b 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -29,6 +29,7 @@
 enum pstore_type_id {
 	PSTORE_TYPE_DMESG	= 0,
 	PSTORE_TYPE_MCE		= 1,
+	PSTORE_TYPE_CONSOLE	= 2,
 	PSTORE_TYPE_UNKNOWN	= 255
 };
 
-- 
1.7.9.2

[PATCH 02/11] pstore/ram: Give proper names to dump-related variables

[Anton Vorontsov]

We're about to add support for other message types, so let's rename
some variables to not be confused later.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
 fs/pstore/ram.c |   34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 453030f..9b274b9 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -68,9 +68,9 @@ struct ramoops_context {
 	size_t record_size;
 	int dump_oops;
 	bool ecc;
-	unsigned int count;
-	unsigned int max_count;
-	unsigned int read_count;
+	unsigned int max_dump_cnt;
+	unsigned int dump_write_cnt;
+	unsigned int dump_read_cnt;
 	struct pstore_info pstore;
 };
 
@@ -81,7 +81,7 @@ static int ramoops_pstore_open(struct pstore_info *psi)
 {
 	struct ramoops_context *cxt = psi->data;
 
-	cxt->read_count = 0;
+	cxt->dump_read_cnt = 0;
 	return 0;
 }
 
@@ -94,10 +94,10 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 	struct ramoops_context *cxt = psi->data;
 	struct persistent_ram_zone *prz;
 
-	if (cxt->read_count >= cxt->max_count)
+	if (cxt->dump_read_cnt >= cxt->max_dump_cnt)
 		return -EINVAL;
 
-	*id = cxt->read_count++;
+	*id = cxt->dump_read_cnt++;
 	prz = cxt->przs[*id];
 
 	/* Only supports dmesg output so far. */
@@ -141,7 +141,7 @@ static int ramoops_pstore_write(enum pstore_type_id type,
 				size_t size, struct pstore_info *psi)
 {
 	struct ramoops_context *cxt = psi->data;
-	struct persistent_ram_zone *prz = cxt->przs[cxt->count];
+	struct persistent_ram_zone *prz = cxt->przs[cxt->dump_write_cnt];
 	size_t hlen;
 
 	/* Currently ramoops is designed to only store dmesg dumps. */
@@ -172,7 +172,7 @@ static int ramoops_pstore_write(enum pstore_type_id type,
 		size = prz->buffer_size - hlen;
 	persistent_ram_write(prz, cxt->pstore.buf, size);
 
-	cxt->count = (cxt->count + 1) % cxt->max_count;
+	cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;
 
 	return 0;
 }
@@ -182,7 +182,7 @@ static int ramoops_pstore_erase(enum pstore_type_id type, u64 id,
 {
 	struct ramoops_context *cxt = psi->data;
 
-	if (id >= cxt->max_count)
+	if (id >= cxt->max_dump_cnt)
 		return -EINVAL;
 
 	persistent_ram_free_old(cxt->przs[id]);
@@ -213,7 +213,7 @@ static int __init ramoops_probe(struct platform_device *pdev)
 	/* Only a single ramoops area allowed at a time, so fail extra
 	 * probes.
 	 */
-	if (cxt->max_count)
+	if (cxt->max_dump_cnt)
 		goto fail_out;
 
 	if (!pdata->mem_size || !pdata->record_size) {
@@ -239,22 +239,22 @@ static int __init ramoops_probe(struct platform_device *pdev)
 		goto fail_out;
 	}
 
-	cxt->max_count = pdata->mem_size / pdata->record_size;
-	cxt->count = 0;
+	cxt->max_dump_cnt = pdata->mem_size / pdata->record_size;
+	cxt->dump_read_cnt = 0;
 	cxt->size = pdata->mem_size;
 	cxt->phys_addr = pdata->mem_address;
 	cxt->record_size = pdata->record_size;
 	cxt->dump_oops = pdata->dump_oops;
 	cxt->ecc = pdata->ecc;
 
-	cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_count, GFP_KERNEL);
+	cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_dump_cnt, GFP_KERNEL);
 	if (!cxt->przs) {
 		err = -ENOMEM;
 		dev_err(dev, "failed to initialize a prz array\n");
 		goto fail_out;
 	}
 
-	for (i = 0; i < cxt->max_count; i++) {
+	for (i = 0; i < cxt->max_dump_cnt; i++) {
 		size_t sz = cxt->record_size;
 		phys_addr_t start = cxt->phys_addr + sz * i;
 
@@ -293,7 +293,7 @@ static int __init ramoops_probe(struct platform_device *pdev)
 
 	pr_info("attached 0x%lx@0x%llx (%ux0x%zx), ecc: %s\n",
 		cxt->size, (unsigned long long)cxt->phys_addr,
-		cxt->max_count, cxt->record_size,
+		cxt->max_dump_cnt, cxt->record_size,
 		ramoops_ecc ? "on" : "off");
 
 	return 0;
@@ -302,7 +302,7 @@ fail_buf:
 	kfree(cxt->pstore.buf);
 fail_clear:
 	cxt->pstore.bufsize = 0;
-	cxt->max_count = 0;
+	cxt->max_dump_cnt = 0;
 fail_przs:
 	for (i = 0; cxt->przs[i]; i++)
 		persistent_ram_free(cxt->przs[i]);
@@ -321,7 +321,7 @@ static int __exit ramoops_remove(struct platform_device *pdev)
 
 	iounmap(cxt->virt_addr);
 	release_mem_region(cxt->phys_addr, cxt->size);
-	cxt->max_count = 0;
+	cxt->max_dump_cnt = 0;
 
 	/* TODO(kees): When pstore supports unregistering, call it here. */
 	kfree(cxt->pstore.buf);
-- 
1.7.9.2

[PATCH 03/11] pstore/ram: Factor dmesg przs initialization out of probe()

[Anton Vorontsov]

This will help make code clearer when we'll add support for other
message types.

This also makes probe() much shorter and understandable, plus
makes mem/record size checking a bit easier.

Implementation detail: we now use a paddr pointer, this will
be used for allocating persistent ram zones for other message
types.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
---
 fs/pstore/ram.c |   99 ++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 62 insertions(+), 37 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 9b274b9..6b76767 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -202,13 +202,65 @@ static struct ramoops_context oops_cxt = {
 	},
 };
 
+static void ramoops_free_przs(struct ramoops_context *cxt)
+{
+	int i;
+
+	if (!cxt->przs)
+		return;
+
+	for (i = 0; cxt->przs[i]; i++)
+		persistent_ram_free(cxt->przs[i]);
+	kfree(cxt->przs);
+}
+
+static int ramoops_init_przs(struct device *dev, struct ramoops_context *cxt,
+			      phys_addr_t *paddr, size_t dump_mem_sz)
+{
+	int err = -ENOMEM;
+	int i;
+
+	if (!cxt->record_size)
+		return 0;
+
+	cxt->max_dump_cnt = dump_mem_sz / cxt->record_size;
+	if (!cxt->max_dump_cnt)
+		return -ENOMEM;
+
+	cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_dump_cnt,
+			     GFP_KERNEL);
+	if (!cxt->przs) {
+		dev_err(dev, "failed to initialize a prz array for dumps\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < cxt->max_dump_cnt; i++) {
+		size_t sz = cxt->record_size;
+
+		cxt->przs[i] = persistent_ram_new(*paddr, sz, cxt->ecc);
+		if (IS_ERR(cxt->przs[i])) {
+			err = PTR_ERR(cxt->przs[i]);
+			dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
+				sz, (unsigned long long)*paddr, err);
+			goto fail_prz;
+		}
+		*paddr += sz;
+	}
+
+	return 0;
+fail_prz:
+	ramoops_free_przs(cxt);
+	return err;
+}
+
 static int __init ramoops_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct ramoops_platform_data *pdata = pdev->dev.platform_data;
 	struct ramoops_context *cxt = &oops_cxt;
+	size_t dump_mem_sz;
+	phys_addr_t paddr;
 	int err = -EINVAL;
-	int i;
 
 	/* Only a single ramoops area allowed at a time, so fail extra
 	 * probes.
@@ -225,21 +277,6 @@ static int __init ramoops_probe(struct platform_device *pdev)
 	pdata->mem_size = rounddown_pow_of_two(pdata->mem_size);
 	pdata->record_size = rounddown_pow_of_two(pdata->record_size);
 
-	/* Check for the minimum memory size */
-	if (pdata->mem_size < MIN_MEM_SIZE &&
-			pdata->record_size < MIN_MEM_SIZE) {
-		pr_err("memory size too small, minimum is %lu\n",
-			MIN_MEM_SIZE);
-		goto fail_out;
-	}
-
-	if (pdata->mem_size < pdata->record_size) {
-		pr_err("The memory size must be larger than the "
-			"records size\n");
-		goto fail_out;
-	}
-
-	cxt->max_dump_cnt = pdata->mem_size / pdata->record_size;
 	cxt->dump_read_cnt = 0;
 	cxt->size = pdata->mem_size;
 	cxt->phys_addr = pdata->mem_address;
@@ -247,24 +284,14 @@ static int __init ramoops_probe(struct platform_device *pdev)
 	cxt->dump_oops = pdata->dump_oops;
 	cxt->ecc = pdata->ecc;
 
-	cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_dump_cnt, GFP_KERNEL);
-	if (!cxt->przs) {
-		err = -ENOMEM;
-		dev_err(dev, "failed to initialize a prz array\n");
-		goto fail_out;
-	}
-
-	for (i = 0; i < cxt->max_dump_cnt; i++) {
-		size_t sz = cxt->record_size;
-		phys_addr_t start = cxt->phys_addr + sz * i;
+	paddr = cxt->phys_addr;
 
-		cxt->przs[i] = persistent_ram_new(start, sz, cxt->ecc);
-		if (IS_ERR(cxt->przs[i])) {
-			err = PTR_ERR(cxt->przs[i]);
-			dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
-				sz, (unsigned long long)start, err);
-			goto fail_przs;
-		}
+	dump_mem_sz = cxt->size;
+	err = ramoops_init_przs(dev, cxt, &paddr, dump_mem_sz);
+	if (err) {
+		pr_err("memory size too small, minimum is %lu\n",
+			cxt->record_size);
+		goto fail_count;
 	}
 
 	cxt->pstore.data = cxt;
@@ -303,10 +330,8 @@ fail_buf:
 fail_clear:
 	cxt->pstore.bufsize = 0;
 	cxt->max_dump_cnt = 0;
-fail_przs:
-	for (i = 0; cxt->przs[i]; i++)
-		persistent_ram_free(cxt->przs[i]);
-	kfree(cxt->przs);
+fail_count:
+	ramoops_free_przs(cxt);
 fail_out:
 	return err;
 }
-- 
1.7.9.2

[PATCH 04/11] pstore/ram: Factor ramoops_get_next_prz() out of ramoops_pstore_read()

[Anton Vorontsov]

This will help make code clearer when we'll add support for other
message types.

The patch also changes return value from -EINVAL to 0 in case of
end-of-records. The exact value doesn't matter for pstore (it should
be just <= 0), but 0 feels more correct.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
 fs/pstore/ram.c |   41 ++++++++++++++++++++++++++++++++---------
 1 file changed, 32 insertions(+), 9 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 6b76767..d770d72 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -85,6 +85,33 @@ static int ramoops_pstore_open(struct pstore_info *psi)
 	return 0;
 }
 
+static struct persistent_ram_zone *
+ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
+		     u64 *id,
+		     enum pstore_type_id *typep, enum pstore_type_id type,
+		     bool update)
+{
+	struct persistent_ram_zone *prz;
+	int i = (*c)++;
+
+	if (i >= max)
+		return NULL;
+
+	prz = przs[i];
+
+	if (update) {
+		/* Update old/shadowed buffer. */
+		persistent_ram_save_old(prz);
+		if (!persistent_ram_old_size(prz))
+			return NULL;
+	}
+
+	*typep = type;
+	*id = i;
+
+	return prz;
+}
+
 static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 				   struct timespec *time,
 				   char **buf,
@@ -94,20 +121,16 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 	struct ramoops_context *cxt = psi->data;
 	struct persistent_ram_zone *prz;
 
-	if (cxt->dump_read_cnt >= cxt->max_dump_cnt)
-		return -EINVAL;
-
-	*id = cxt->dump_read_cnt++;
-	prz = cxt->przs[*id];
+	prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt,
+				   cxt->max_dump_cnt, id, type,
+				   PSTORE_TYPE_DMESG, 1);
+	if (!prz)
+		return 0;
 
-	/* Only supports dmesg output so far. */
-	*type = PSTORE_TYPE_DMESG;
 	/* TODO(kees): Bogus time for the moment. */
 	time->tv_sec = 0;
 	time->tv_nsec = 0;
 
-	/* Update old/shadowed buffer. */
-	persistent_ram_save_old(prz);
 	size = persistent_ram_old_size(prz);
 	*buf = kmalloc(size, GFP_KERNEL);
 	if (*buf == NULL)
-- 
1.7.9.2

[PATCH 05/11] pstore/ram: Add console messages handling

[Anton Vorontsov]

The console log size is configurable via ramoops.console_size
module option, and the log itself is available via
<pstore-mount>/console-ramoops file.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
---
 fs/pstore/ram.c            |  100 +++++++++++++++++++++++++++++++++++++-------
 include/linux/pstore_ram.h |    1 +
 2 files changed, 87 insertions(+), 14 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index d770d72..c7acf94 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -41,6 +41,10 @@ module_param(record_size, ulong, 0400);
 MODULE_PARM_DESC(record_size,
 		"size of each dump done on oops/panic");
 
+static ulong ramoops_console_size = MIN_MEM_SIZE;
+module_param_named(console_size, ramoops_console_size, ulong, 0400);
+MODULE_PARM_DESC(console_size, "size of kernel console log");
+
 static ulong mem_address;
 module_param(mem_address, ulong, 0400);
 MODULE_PARM_DESC(mem_address,
@@ -63,14 +67,17 @@ MODULE_PARM_DESC(ramoops_ecc,
 
 struct ramoops_context {
 	struct persistent_ram_zone **przs;
+	struct persistent_ram_zone *cprz;
 	phys_addr_t phys_addr;
 	unsigned long size;
 	size_t record_size;
+	size_t console_size;
 	int dump_oops;
 	bool ecc;
 	unsigned int max_dump_cnt;
 	unsigned int dump_write_cnt;
 	unsigned int dump_read_cnt;
+	unsigned int console_read_cnt;
 	struct pstore_info pstore;
 };
 
@@ -82,6 +89,7 @@ static int ramoops_pstore_open(struct pstore_info *psi)
 	struct ramoops_context *cxt = psi->data;
 
 	cxt->dump_read_cnt = 0;
+	cxt->console_read_cnt = 0;
 	return 0;
 }
 
@@ -125,6 +133,9 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 				   cxt->max_dump_cnt, id, type,
 				   PSTORE_TYPE_DMESG, 1);
 	if (!prz)
+		prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt,
+					   1, id, type, PSTORE_TYPE_CONSOLE, 0);
+	if (!prz)
 		return 0;
 
 	/* TODO(kees): Bogus time for the moment. */
@@ -167,7 +178,13 @@ static int ramoops_pstore_write(enum pstore_type_id type,
 	struct persistent_ram_zone *prz = cxt->przs[cxt->dump_write_cnt];
 	size_t hlen;
 
-	/* Currently ramoops is designed to only store dmesg dumps. */
+	if (type == PSTORE_TYPE_CONSOLE) {
+		if (!cxt->cprz)
+			return -ENOMEM;
+		persistent_ram_write(cxt->cprz, cxt->pstore.buf, size);
+		return 0;
+	}
+
 	if (type != PSTORE_TYPE_DMESG)
 		return -EINVAL;
 
@@ -204,12 +221,23 @@ static int ramoops_pstore_erase(enum pstore_type_id type, u64 id,
 				struct pstore_info *psi)
 {
 	struct ramoops_context *cxt = psi->data;
+	struct persistent_ram_zone *prz;
 
-	if (id >= cxt->max_dump_cnt)
+	switch (type) {
+	case PSTORE_TYPE_DMESG:
+		if (id >= cxt->max_dump_cnt)
+			return -EINVAL;
+		prz = cxt->przs[id];
+		break;
+	case PSTORE_TYPE_CONSOLE:
+		prz = cxt->cprz;
+		break;
+	default:
 		return -EINVAL;
+	}
 
-	persistent_ram_free_old(cxt->przs[id]);
-	persistent_ram_zap(cxt->przs[id]);
+	persistent_ram_free_old(prz);
+	persistent_ram_zap(prz);
 
 	return 0;
 }
@@ -276,6 +304,32 @@ fail_prz:
 	return err;
 }
 
+static int ramoops_init_prz(struct device *dev, struct ramoops_context *cxt,
+			    struct persistent_ram_zone **prz,
+			    phys_addr_t *paddr, size_t sz)
+{
+	if (!sz)
+		return 0;
+
+	if (*paddr + sz > *paddr + cxt->size)
+		return -ENOMEM;
+
+	*prz = persistent_ram_new(*paddr, sz, cxt->ecc);
+	if (IS_ERR(*prz)) {
+		int err = PTR_ERR(*prz);
+
+		dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
+			sz, (unsigned long long)*paddr, err);
+		return err;
+	}
+
+	persistent_ram_zap(*prz);
+
+	*paddr += sz;
+
+	return 0;
+}
+
 static int __init ramoops_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -291,34 +345,50 @@ static int __init ramoops_probe(struct platform_device *pdev)
 	if (cxt->max_dump_cnt)
 		goto fail_out;
 
-	if (!pdata->mem_size || !pdata->record_size) {
-		pr_err("The memory size and the record size must be "
+	if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size)) {
+		pr_err("The memory size and the record/console size must be "
 			"non-zero\n");
 		goto fail_out;
 	}
 
 	pdata->mem_size = rounddown_pow_of_two(pdata->mem_size);
 	pdata->record_size = rounddown_pow_of_two(pdata->record_size);
+	pdata->console_size = rounddown_pow_of_two(pdata->console_size);
 
 	cxt->dump_read_cnt = 0;
 	cxt->size = pdata->mem_size;
 	cxt->phys_addr = pdata->mem_address;
 	cxt->record_size = pdata->record_size;
+	cxt->console_size = pdata->console_size;
 	cxt->dump_oops = pdata->dump_oops;
 	cxt->ecc = pdata->ecc;
 
 	paddr = cxt->phys_addr;
 
-	dump_mem_sz = cxt->size;
+	dump_mem_sz = cxt->size - cxt->console_size;
 	err = ramoops_init_przs(dev, cxt, &paddr, dump_mem_sz);
-	if (err) {
+	if (err)
+		goto fail_out;
+
+	err = ramoops_init_prz(dev, cxt, &cxt->cprz, &paddr, cxt->console_size);
+	if (err)
+		goto fail_init_cprz;
+
+	if (!cxt->przs && !cxt->cprz) {
 		pr_err("memory size too small, minimum is %lu\n",
-			cxt->record_size);
-		goto fail_count;
+			cxt->console_size + cxt->record_size);
+		goto fail_cnt;
 	}
 
 	cxt->pstore.data = cxt;
-	cxt->pstore.bufsize = cxt->przs[0]->buffer_size;
+	/*
+	 * Console can handle any buffer size, so prefer dumps buffer
+	 * size since usually it is smaller.
+	 */
+	if (cxt->przs)
+		cxt->pstore.bufsize = cxt->przs[0]->buffer_size;
+	else
+		cxt->pstore.bufsize = cxt->cprz->buffer_size;
 	cxt->pstore.buf = kmalloc(cxt->pstore.bufsize, GFP_KERNEL);
 	spin_lock_init(&cxt->pstore.buf_lock);
 	if (!cxt->pstore.buf) {
@@ -341,9 +411,8 @@ static int __init ramoops_probe(struct platform_device *pdev)
 	record_size = pdata->record_size;
 	dump_oops = pdata->dump_oops;
 
-	pr_info("attached 0x%lx@0x%llx (%ux0x%zx), ecc: %s\n",
+	pr_info("attached 0x%lx@0x%llx, ecc: %s\n",
 		cxt->size, (unsigned long long)cxt->phys_addr,
-		cxt->max_dump_cnt, cxt->record_size,
 		ramoops_ecc ? "on" : "off");
 
 	return 0;
@@ -353,7 +422,9 @@ fail_buf:
 fail_clear:
 	cxt->pstore.bufsize = 0;
 	cxt->max_dump_cnt = 0;
-fail_count:
+fail_cnt:
+	kfree(cxt->cprz);
+fail_init_cprz:
 	ramoops_free_przs(cxt);
 fail_out:
 	return err;
@@ -405,6 +476,7 @@ static int __init ramoops_init(void)
 		dummy_data->mem_size = mem_size;
 		dummy_data->mem_address = mem_address;
 		dummy_data->record_size = record_size;
+		dummy_data->console_size = ramoops_console_size;
 		dummy_data->dump_oops = dump_oops;
 		dummy_data->ecc = ramoops_ecc;
 		dummy = platform_create_bundle(&ramoops_driver, ramoops_probe,
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index 3b823d4..9385d41 100644
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -93,6 +93,7 @@ struct ramoops_platform_data {
 	unsigned long	mem_size;
 	unsigned long	mem_address;
 	unsigned long	record_size;
+	unsigned long	console_size;
 	int		dump_oops;
 	bool		ecc;
 };
-- 
1.7.9.2

[PATCH 06/11] pstore/ram_core: Silence some printks

[Anton Vorontsov]

Since we use multiple regions, the messages are somewhat annoying.
We do print total mapped memory already, so no need to print the
information for each region in the library routines.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Colin Cross <ccross@android.com>
---
 fs/pstore/ram_core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index c5fbdbb..78f6d4b 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -409,14 +409,14 @@ static int __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool
 				" size %zu, start %zu\n",
 			       buffer_size(prz), buffer_start(prz));
 		else {
-			pr_info("persistent_ram: found existing buffer,"
+			pr_debug("persistent_ram: found existing buffer,"
 				" size %zu, start %zu\n",
 			       buffer_size(prz), buffer_start(prz));
 			persistent_ram_save_old(prz);
 			return 0;
 		}
 	} else {
-		pr_info("persistent_ram: no valid data in buffer"
+		pr_debug("persistent_ram: no valid data in buffer"
 			" (sig = 0x%08x)\n", prz->buffer->sig);
 	}
 
-- 
1.7.9.2

[PATCH 07/11] pstore/ram: Add some more documentation and examples

[Anton Vorontsov]

Suggested-by: Shuah Khan <shuahkhan@gmail.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Colin Cross <ccross@android.com>
---
 Documentation/ramoops.txt |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt
index 4ba7db2..59a74a8 100644
--- a/Documentation/ramoops.txt
+++ b/Documentation/ramoops.txt
@@ -40,6 +40,12 @@ corrupt, but usually it is restorable.
 Setting the ramoops parameters can be done in 2 different manners:
  1. Use the module parameters (which have the names of the variables described
  as before).
+ For quick debugging, you can also reserve parts of memory during boot
+ and then use the reserved memory for ramoops. For example, assuming a machine
+ with > 128 MB of memory, the following kernel command line will tell the
+ kernel to use only the first 128 MB of memory, and place ECC-protected ramoops
+ region at 128 MB boundary:
+ "mem=128M ramoops.mem_address=0x8000000 ramoops.ecc=1"
  2. Use a platform device and set the platform data. The parameters can then
  be set through that platform data. An example of doing that is:
 
@@ -70,6 +76,14 @@ if (ret) {
 	return ret;
 }
 
+You can specify either RAM memory or peripheral devices' memory. However, when
+specifying RAM, be sure to reserve the memory by issuing memblock_reserve()
+very early in the architecture code, e.g.:
+
+#include <linux/memblock.h>
+
+memblock_reserve(ramoops_data.mem_address, ramoops_data.mem_size);
+
 3. Dump format
 
 The data dump begins with a header, currently defined as "====" followed by a
-- 
1.7.9.2

[PATCH 08/11] staging/android: Remove ram_console driver

[Anton Vorontsov]

All the functionality is now supported by pstore and pstore_ram drivers.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Colin Cross <ccross@android.com>
---
 drivers/staging/android/Kconfig       |    5 -
 drivers/staging/android/Makefile      |    1 -
 drivers/staging/android/ram_console.c |  179 ---------------------------------
 3 files changed, 185 deletions(-)
 delete mode 100644 drivers/staging/android/ram_console.c

diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
index 0e16b59..0ce50d1 100644
--- a/drivers/staging/android/Kconfig
+++ b/drivers/staging/android/Kconfig
@@ -25,11 +25,6 @@ config ANDROID_LOGGER
 	tristate "Android log driver"
 	default n
 
-config ANDROID_RAM_CONSOLE
-	bool "Android RAM buffer console"
-	depends on !S390 && !UML && HAVE_MEMBLOCK && PSTORE_RAM=y
-	default n
-
 config ANDROID_TIMED_OUTPUT
 	bool "Timed output class driver"
 	default y
diff --git a/drivers/staging/android/Makefile b/drivers/staging/android/Makefile
index 98711e2..e16fcd5 100644
--- a/drivers/staging/android/Makefile
+++ b/drivers/staging/android/Makefile
@@ -1,7 +1,6 @@
 obj-$(CONFIG_ANDROID_BINDER_IPC)	+= binder.o
 obj-$(CONFIG_ASHMEM)			+= ashmem.o
 obj-$(CONFIG_ANDROID_LOGGER)		+= logger.o
-obj-$(CONFIG_ANDROID_RAM_CONSOLE)	+= ram_console.o
 obj-$(CONFIG_ANDROID_TIMED_OUTPUT)	+= timed_output.o
 obj-$(CONFIG_ANDROID_TIMED_GPIO)	+= timed_gpio.o
 obj-$(CONFIG_ANDROID_LOW_MEMORY_KILLER)	+= lowmemorykiller.o
diff --git a/drivers/staging/android/ram_console.c b/drivers/staging/android/ram_console.c
deleted file mode 100644
index 82323bb..0000000
--- a/drivers/staging/android/ram_console.c
+++ /dev/null
@@ -1,179 +0,0 @@
-/* drivers/android/ram_console.c
- *
- * Copyright (C) 2007-2008 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/console.h>
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/platform_device.h>
-#include <linux/proc_fs.h>
-#include <linux/string.h>
-#include <linux/uaccess.h>
-#include <linux/io.h>
-#include <linux/pstore_ram.h>
-#include "ram_console.h"
-
-static struct persistent_ram_zone *ram_console_zone;
-static const char *bootinfo;
-static size_t bootinfo_size;
-
-static void
-ram_console_write(struct console *console, const char *s, unsigned int count)
-{
-	struct persistent_ram_zone *prz = console->data;
-	persistent_ram_write(prz, s, count);
-}
-
-static struct console ram_console = {
-	.name	= "ram",
-	.write	= ram_console_write,
-	.flags	= CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
-	.index	= -1,
-};
-
-void ram_console_enable_console(int enabled)
-{
-	if (enabled)
-		ram_console.flags |= CON_ENABLED;
-	else
-		ram_console.flags &= ~CON_ENABLED;
-}
-
-static int __init ram_console_probe(struct platform_device *pdev)
-{
-	struct ram_console_platform_data *pdata = pdev->dev.platform_data;
-	struct persistent_ram_zone *prz;
-
-	prz = persistent_ram_init_ringbuffer(&pdev->dev, true);
-	if (IS_ERR(prz))
-		return PTR_ERR(prz);
-
-
-	if (pdata) {
-		bootinfo = kstrdup(pdata->bootinfo, GFP_KERNEL);
-		if (bootinfo)
-			bootinfo_size = strlen(bootinfo);
-	}
-
-	ram_console_zone = prz;
-	ram_console.data = prz;
-
-	register_console(&ram_console);
-
-	return 0;
-}
-
-static struct platform_driver ram_console_driver = {
-	.driver		= {
-		.name	= "ram_console",
-	},
-};
-
-static int __init ram_console_module_init(void)
-{
-	return platform_driver_probe(&ram_console_driver, ram_console_probe);
-}
-
-#ifndef CONFIG_PRINTK
-#define dmesg_restrict	0
-#endif
-
-static ssize_t ram_console_read_old(struct file *file, char __user *buf,
-				    size_t len, loff_t *offset)
-{
-	loff_t pos = *offset;
-	ssize_t count;
-	struct persistent_ram_zone *prz = ram_console_zone;
-	size_t old_log_size = persistent_ram_old_size(prz);
-	const char *old_log = persistent_ram_old(prz);
-	char *str;
-	int ret;
-
-	if (dmesg_restrict && !capable(CAP_SYSLOG))
-		return -EPERM;
-
-	/* Main last_kmsg log */
-	if (pos < old_log_size) {
-		count = min(len, (size_t)(old_log_size - pos));
-		if (copy_to_user(buf, old_log + pos, count))
-			return -EFAULT;
-		goto out;
-	}
-
-	/* ECC correction notice */
-	pos -= old_log_size;
-	count = persistent_ram_ecc_string(prz, NULL, 0);
-	if (pos < count) {
-		str = kmalloc(count, GFP_KERNEL);
-		if (!str)
-			return -ENOMEM;
-		persistent_ram_ecc_string(prz, str, count + 1);
-		count = min(len, (size_t)(count - pos));
-		ret = copy_to_user(buf, str + pos, count);
-		kfree(str);
-		if (ret)
-			return -EFAULT;
-		goto out;
-	}
-
-	/* Boot info passed through pdata */
-	pos -= count;
-	if (pos < bootinfo_size) {
-		count = min(len, (size_t)(bootinfo_size - pos));
-		if (copy_to_user(buf, bootinfo + pos, count))
-			return -EFAULT;
-		goto out;
-	}
-
-	/* EOF */
-	return 0;
-
-out:
-	*offset += count;
-	return count;
-}
-
-static const struct file_operations ram_console_file_ops = {
-	.owner = THIS_MODULE,
-	.read = ram_console_read_old,
-};
-
-static int __init ram_console_late_init(void)
-{
-	struct proc_dir_entry *entry;
-	struct persistent_ram_zone *prz = ram_console_zone;
-
-	if (!prz)
-		return 0;
-
-	if (persistent_ram_old_size(prz) == 0)
-		return 0;
-
-	entry = create_proc_entry("last_kmsg", S_IFREG | S_IRUGO, NULL);
-	if (!entry) {
-		printk(KERN_ERR "ram_console: failed to create proc entry\n");
-		persistent_ram_free_old(prz);
-		return 0;
-	}
-
-	entry->proc_fops = &ram_console_file_ops;
-	entry->size = persistent_ram_old_size(prz) +
-		persistent_ram_ecc_string(prz, NULL, 0) +
-		bootinfo_size;
-
-	return 0;
-}
-
-late_initcall(ram_console_late_init);
-postcore_initcall(ram_console_module_init);
-- 
1.7.9.2

[PATCH 09/11] pstore/ram_core: Remove now unused code

[Anton Vorontsov]

The code tried to maintain the global list of persistent ram zones,
which isn't a great idea overall, plus since Android's ram_console
is no longer there, we can remove some unused functions.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Colin Cross <ccross@android.com>
---
 fs/pstore/ram_core.c       |   77 --------------------------------------------
 include/linux/pstore_ram.h |   19 -----------
 2 files changed, 96 deletions(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 78f6d4b..0fd8161 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -35,8 +35,6 @@ struct persistent_ram_buffer {
 
 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
 
-static __initdata LIST_HEAD(persistent_ram_list);
-
 static inline size_t buffer_size(struct persistent_ram_zone *prz)
 {
 	return atomic_read(&prz->buffer->size);
@@ -462,78 +460,3 @@ err:
 	kfree(prz);
 	return ERR_PTR(ret);
 }
-
-#ifndef MODULE
-static int __init persistent_ram_buffer_init(const char *name,
-		struct persistent_ram_zone *prz)
-{
-	int i;
-	struct persistent_ram *ram;
-	struct persistent_ram_descriptor *desc;
-	phys_addr_t start;
-
-	list_for_each_entry(ram, &persistent_ram_list, node) {
-		start = ram->start;
-		for (i = 0; i < ram->num_descs; i++) {
-			desc = &ram->descs[i];
-			if (!strcmp(desc->name, name))
-				return persistent_ram_buffer_map(start,
-						desc->size, prz);
-			start += desc->size;
-		}
-	}
-
-	return -EINVAL;
-}
-
-static  __init
-struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
-{
-	struct persistent_ram_zone *prz;
-	int ret = -ENOMEM;
-
-	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
-	if (!prz) {
-		pr_err("persistent_ram: failed to allocate persistent ram zone\n");
-		goto err;
-	}
-
-	ret = persistent_ram_buffer_init(dev_name(dev), prz);
-	if (ret) {
-		pr_err("persistent_ram: failed to initialize buffer\n");
-		goto err;
-	}
-
-	persistent_ram_post_init(prz, ecc);
-
-	return prz;
-err:
-	kfree(prz);
-	return ERR_PTR(ret);
-}
-
-struct persistent_ram_zone * __init
-persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
-{
-	return __persistent_ram_init(dev, ecc);
-}
-
-int __init persistent_ram_early_init(struct persistent_ram *ram)
-{
-	int ret;
-
-	ret = memblock_reserve(ram->start, ram->size);
-	if (ret) {
-		pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
-			(long)ram->start, (long)(ram->start + ram->size - 1));
-		return ret;
-	}
-
-	list_add_tail(&ram->node, &persistent_ram_list);
-
-	pr_info("Initialized persistent memory from %08lx-%08lx\n",
-		(long)ram->start, (long)(ram->start + ram->size - 1));
-
-	return 0;
-}
-#endif
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index 9385d41..2470bb5 100644
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -25,21 +25,6 @@
 
 struct persistent_ram_buffer;
 
-struct persistent_ram_descriptor {
-	const char	*name;
-	phys_addr_t	size;
-};
-
-struct persistent_ram {
-	phys_addr_t	start;
-	phys_addr_t	size;
-
-	int					num_descs;
-	struct persistent_ram_descriptor	*descs;
-
-	struct list_head node;
-};
-
 struct persistent_ram_zone {
 	phys_addr_t paddr;
 	size_t size;
@@ -63,15 +48,11 @@ struct persistent_ram_zone {
 	size_t old_log_size;
 };
 
-int persistent_ram_early_init(struct persistent_ram *ram);
-
 struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
 						       size_t size,
 						       bool ecc);
 void persistent_ram_free(struct persistent_ram_zone *prz);
 void persistent_ram_zap(struct persistent_ram_zone *prz);
-struct persistent_ram_zone *persistent_ram_init_ringbuffer(struct device *dev,
-		bool ecc);
 
 int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
 	unsigned int count);
-- 
1.7.9.2

[PATCH 10/11] pstore/platform: Make automatic updates interval configurable

[Anton Vorontsov]

There is no behavioural change, the default value is still 60 seconds.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
---
 fs/pstore/platform.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 61461ed..34ca314 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -31,6 +31,7 @@
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
+#include <linux/jiffies.h>
 #include <linux/workqueue.h>
 
 #include "internal.h"
@@ -40,7 +41,10 @@
  * whether the system is actually still running well enough
  * to let someone see the entry
  */
-#define	PSTORE_INTERVAL	(60 * HZ)
+static int pstore_update_ms = 60000;
+module_param_named(update_ms, pstore_update_ms, int, 0600);
+MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
+		 "(default is 60000; -1 means runtime updates are disabled)");
 
 static int pstore_new_entry;
 
@@ -231,8 +235,11 @@ int pstore_register(struct pstore_info *psi)
 	kmsg_dump_register(&pstore_dumper);
 	pstore_register_console();
 
-	pstore_timer.expires = jiffies + PSTORE_INTERVAL;
-	add_timer(&pstore_timer);
+	if (pstore_update_ms >= 0) {
+		pstore_timer.expires = jiffies +
+			msecs_to_jiffies(pstore_update_ms);
+		add_timer(&pstore_timer);
+	}
 
 	return 0;
 }
@@ -291,7 +298,7 @@ static void pstore_timefunc(unsigned long dummy)
 		schedule_work(&pstore_work);
 	}
 
-	mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL);
+	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
 }
 
 module_param(backend, charp, 0444);
-- 
1.7.9.2

[PATCH 11/11] pstore/platform: Disable automatic updates by default

[Anton Vorontsov]

Having automatic updates seems pointless for production system, and
even dangerous and thus counter-productive:

1. If we can mount pstore, or read files, we can as well read
   /proc/kmsg. So, there's little point in duplicating the
   functionality and present the same information but via another
   userland ABI;

2. Expecting the kernel to behave sanely after oops/panic is naive.
   It might work, but you'd rather not try it. Screwed up kernel
   can do rather bad things, like recursive faults[1]; and pstore
   rather provoking bad things to happen. It uses:

   1. Timers (assumes sane interrupts state);
   2. Workqueues and mutexes (assumes scheduler in a sane state);
   3. kzalloc (a working slab allocator);

   That's too much for a dead kernel, so the debugging facility
   itself might just make debugging harder, which is not what
   we want.

Maybe for non-oops message types it would make sense to re-enable
automatic updates, but so far I don't see any use case for this.
Even for tracing, it has its own run-time/normal ABI, so we're
only interested in pstore upon next boot, to retrieve what has
gone wrong with HW or SW.

So, let's disable the updates by default.

[1]
BUG: unable to handle kernel paging request at fffffffffffffff8
IP: [<ffffffff8104801b>] kthread_data+0xb/0x20
[...]
Process kworker/0:1 (pid: 14, threadinfo ffff8800072c0000, task ffff88000725b100)
[...
Call Trace:
 [<ffffffff81043710>] wq_worker_sleeping+0x10/0xa0
 [<ffffffff813687a8>] __schedule+0x568/0x7d0
 [<ffffffff8106c24d>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffff81087e22>] ? call_rcu_sched+0x12/0x20
 [<ffffffff8102b596>] ? release_task+0x156/0x2d0
 [<ffffffff8102b45e>] ? release_task+0x1e/0x2d0
 [<ffffffff8106c24d>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffff81368ac4>] schedule+0x24/0x70
 [<ffffffff8102cba8>] do_exit+0x1f8/0x370
 [<ffffffff810051e7>] oops_end+0x77/0xb0
 [<ffffffff8135c301>] no_context+0x1a6/0x1b5
 [<ffffffff8135c4de>] __bad_area_nosemaphore+0x1ce/0x1ed
 [<ffffffff81053156>] ? ttwu_queue+0xc6/0xe0
 [<ffffffff8135c50b>] bad_area_nosemaphore+0xe/0x10
 [<ffffffff8101fa47>] do_page_fault+0x2c7/0x450
 [<ffffffff8106e34b>] ? __lock_release+0x6b/0xe0
 [<ffffffff8106bf21>] ? mark_held_locks+0x61/0x140
 [<ffffffff810502fe>] ? __wake_up+0x4e/0x70
 [<ffffffff81185f7d>] ? trace_hardirqs_off_thunk+0x3a/0x3c
 [<ffffffff81158970>] ? pstore_register+0x120/0x120
 [<ffffffff8136a37f>] page_fault+0x1f/0x30
 [<ffffffff81158970>] ? pstore_register+0x120/0x120
 [<ffffffff81185ab8>] ? memcpy+0x68/0x110
 [<ffffffff8115875a>] ? pstore_get_records+0x3a/0x130
 [<ffffffff811590f4>] ? persistent_ram_copy_old+0x64/0x90
 [<ffffffff81158bf4>] ramoops_pstore_read+0x84/0x130
 [<ffffffff81158799>] pstore_get_records+0x79/0x130
 [<ffffffff81042536>] ? process_one_work+0x116/0x450
 [<ffffffff81158970>] ? pstore_register+0x120/0x120
 [<ffffffff8115897e>] pstore_dowork+0xe/0x10
 [<ffffffff81042594>] process_one_work+0x174/0x450
 [<ffffffff81042536>] ? process_one_work+0x116/0x450
 [<ffffffff81042e13>] worker_thread+0x123/0x2d0
 [<ffffffff81042cf0>] ? manage_workers.isra.28+0x120/0x120
 [<ffffffff81047d8e>] kthread+0x8e/0xa0
 [<ffffffff8136ba74>] kernel_thread_helper+0x4/0x10
 [<ffffffff8136a199>] ? retint_restore_args+0xe/0xe
 [<ffffffff81047d00>] ? __init_kthread_worker+0x70/0x70
 [<ffffffff8136ba70>] ? gs_change+0xb/0xb
Code: be e2 00 00 00 48 c7 c7 d1 2a 4e 81 e8 bf fb fd ff 48 8b 5d f0 4c 8b 65 f8 c9 c3 0f 1f 44 00 00 48 8b 87 08 02 00 00 55 48 89 e5 <48> 8b 40 f8 5d c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00
RIP  [<ffffffff8104801b>] kthread_data+0xb/0x20
 RSP <ffff8800072c1888>
CR2: fffffffffffffff8
---[ end trace 996a332dc399111d ]---
Fixing recursive fault but reboot is needed!

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
 fs/pstore/platform.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 34ca314..be4614f 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -41,10 +41,12 @@
  * whether the system is actually still running well enough
  * to let someone see the entry
  */
-static int pstore_update_ms = 60000;
+static int pstore_update_ms = -1;
 module_param_named(update_ms, pstore_update_ms, int, 0600);
 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
-		 "(default is 60000; -1 means runtime updates are disabled)");
+		 "(default is -1, which means runtime updates are disabled; "
+		 "enabling this option is not safe, it may lead to further "
+		 "corruption on Oopses)");
 
 static int pstore_new_entry;
 
-- 
1.7.9.2

Re: [PATCH 03/11] pstore/ram: Factor dmesg przs initialization out of probe()

[Stephen Boyd]

On 5/26/2012 6:20 AM, Anton Vorontsov wrote:
> +static int ramoops_init_przs(struct device *dev, struct ramoops_context *cxt,
> +			      phys_addr_t *paddr, size_t dump_mem_sz)
> +{
> +	int err = -ENOMEM;
> +	int i;
> +
> +	if (!cxt->record_size)
> +		return 0;
> +
> +	cxt->max_dump_cnt = dump_mem_sz / cxt->record_size;
> +	if (!cxt->max_dump_cnt)
> +		return -ENOMEM;
> +
> +	cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_dump_cnt,
> +			     GFP_KERNEL);

kcalloc would be better but I see you're just moving code here so it
doesn't need to be changed in this patch.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

Re: [PATCH 02/11] pstore/ram: Give proper names to dump-related variables

[Kees Cook]

On Sat, May 26, 2012 at 6:20 AM, Anton Vorontsov
<anton.vorontsov@linaro.org> wrote:
> We're about to add support for other message types, so let's rename
> some variables to not be confused later.

Acked-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook
Chrome OS Security

Re: [PATCH 04/11] pstore/ram: Factor ramoops_get_next_prz() out of ramoops_pstore_read()

[Kees Cook]

On Sat, May 26, 2012 at 6:20 AM, Anton Vorontsov
<anton.vorontsov@linaro.org> wrote:
> This will help make code clearer when we'll add support for other
> message types.
>
> The patch also changes return value from -EINVAL to 0 in case of
> end-of-records. The exact value doesn't matter for pstore (it should
> be just <= 0), but 0 feels more correct.

Acked-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook
Chrome OS Security

Re: [PATCH v5 0/11] Merge ram_console into pstore

[Greg Kroah-Hartman]

On Sat, May 26, 2012 at 06:17:48AM -0700, Anton Vorontsov wrote:
> The old ram_console driver is removed. This might probably cause
> some pain for out-of-tree code, as it would need to be adjusted...
> but "no pain, no gain"? :-) Though, if there's some serious resistance,
> we can probably postpone the last two patches.

What out-of-tree code would care about this?

Anyway, all now applied, thanks for working on this.

greg k-h

Re: [PATCH v5 0/11] Merge ram_console into pstore

[John Stultz]

On 06/13/2012 05:05 PM, Greg Kroah-Hartman wrote:
> On Sat, May 26, 2012 at 06:17:48AM -0700, Anton Vorontsov wrote:
>> The old ram_console driver is removed. This might probably cause
>> some pain for out-of-tree code, as it would need to be adjusted...
>> but "no pain, no gain"? :-) Though, if there's some serious resistance,
>> we can probably postpone the last two patches.
> What out-of-tree code would care about this?
I think he's referring to the persistent_ftrace work in the Android tree.

Anton did send out patches to try to get equivalent functionality 
working with pstore, but I don't know if Colin or anyone else from the 
Android team has had a chance to review it and make sure its sufficient.

thanks
-john

Re: [PATCH v5 0/11] Merge ram_console into pstore

[Greg Kroah-Hartman]

On Wed, Jun 13, 2012 at 05:12:14PM -0700, John Stultz wrote:
> On 06/13/2012 05:05 PM, Greg Kroah-Hartman wrote:
> >On Sat, May 26, 2012 at 06:17:48AM -0700, Anton Vorontsov wrote:
> >>The old ram_console driver is removed. This might probably cause
> >>some pain for out-of-tree code, as it would need to be adjusted...
> >>but "no pain, no gain"? :-) Though, if there's some serious resistance,
> >>we can probably postpone the last two patches.
> >What out-of-tree code would care about this?
> I think he's referring to the persistent_ftrace work in the Android tree.
> 
> Anton did send out patches to try to get equivalent functionality
> working with pstore, but I don't know if Colin or anyone else from
> the Android team has had a chance to review it and make sure its
> sufficient.

I thought Colin did review these, as I see his acked-by on a number of
these patches...

Re: [PATCH v5 0/11] Merge ram_console into pstore

[Anton Vorontsov]

On Wed, Jun 13, 2012 at 05:05:04PM -0700, Greg Kroah-Hartman wrote:
> On Sat, May 26, 2012 at 06:17:48AM -0700, Anton Vorontsov wrote:
> > The old ram_console driver is removed. This might probably cause
> > some pain for out-of-tree code, as it would need to be adjusted...
> > but "no pain, no gain"? :-) Though, if there's some serious resistance,
> > we can probably postpone the last two patches.
> 
> What out-of-tree code would care about this?

Vendors' board-support code, namely Android/ARM out-of-tree board
support files that happened to use ram_console for debugging. The
affected code in question would be just a few lines related to the
ram_console platform device registration, so no big deal.

> Anyway, all now applied, thanks for working on this.

Thank you!

-- 
Anton Vorontsov
Email: cbouatmailru@gmail.com

Re: [PATCH v5 0/11] Merge ram_console into pstore

[John Stultz]

On 06/13/2012 05:20 PM, Greg Kroah-Hartman wrote:
> On Wed, Jun 13, 2012 at 05:12:14PM -0700, John Stultz wrote:
>> On 06/13/2012 05:05 PM, Greg Kroah-Hartman wrote:
>>> On Sat, May 26, 2012 at 06:17:48AM -0700, Anton Vorontsov wrote:
>>>> The old ram_console driver is removed. This might probably cause
>>>> some pain for out-of-tree code, as it would need to be adjusted...
>>>> but "no pain, no gain"? :-) Though, if there's some serious resistance,
>>>> we can probably postpone the last two patches.
>>> What out-of-tree code would care about this?
>> I think he's referring to the persistent_ftrace work in the Android tree.
>>
>> Anton did send out patches to try to get equivalent functionality
>> working with pstore, but I don't know if Colin or anyone else from
>> the Android team has had a chance to review it and make sure its
>> sufficient.
> I thought Colin did review these, as I see his acked-by on a number of
> these patches...
Right, Colin reviewed the ram_console/pstore work, but I didn't see any 
comment on Anton's "Function tracing support for pstore".

So hopefully the ack from Colin for removing the code is sufficient then.

thanks
-john

Re: [PATCH v5 0/11] Merge ram_console into pstore

[Anton Vorontsov]

On Wed, Jun 13, 2012 at 05:20:05PM -0700, Greg Kroah-Hartman wrote:
> On Wed, Jun 13, 2012 at 05:12:14PM -0700, John Stultz wrote:
> > On 06/13/2012 05:05 PM, Greg Kroah-Hartman wrote:
> > >On Sat, May 26, 2012 at 06:17:48AM -0700, Anton Vorontsov wrote:
> > >>The old ram_console driver is removed. This might probably cause
> > >>some pain for out-of-tree code, as it would need to be adjusted...
> > >>but "no pain, no gain"? :-) Though, if there's some serious resistance,
> > >>we can probably postpone the last two patches.
> > >What out-of-tree code would care about this?
> > I think he's referring to the persistent_ftrace work in the Android tree.

Oh, well.. that too, true. Thanks John!

> > Anton did send out patches to try to get equivalent functionality
> > working with pstore, but I don't know if Colin or anyone else from
> > the Android team has had a chance to review it and make sure its
> > sufficient.
> 
> I thought Colin did review these, as I see his acked-by on a number of
> these patches...

Yup, and these patches are all fine. John is just saying that some
removed functions are still used by the persistent_ftrace code, which
is out-of-tree (it is in Android kernel git tree only).

But we're going to replace persistent_ftrace by pstore/ftrace, and
the patches were posted already; so functinality-wise, we didn't
lose anything.

Thanks,

-- 
Anton Vorontsov
Email: cbouatmailru@gmail.com