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Message-ID: <20250217101706.2104498-3-eugen.hristev@linaro.org>
Date: Mon, 17 Feb 2025 12:16:58 +0200
From: Eugen Hristev <eugen.hristev@...aro.org>
To: linux-arm-msm@...r.kernel.org,
linux-hardening@...r.kernel.org,
kees@...nel.org
Cc: linux-kernel@...r.kernel.org,
johannes@...solutions.net,
gregkh@...uxfoundation.org,
rafael@...nel.org,
dakr@...nel.org,
andersson@...nel.org,
konradybcio@...nel.org,
tony.luck@...el.com,
gpiccoli@...lia.com,
pmladek@...e.com,
rostedt@...dmis.org,
john.ogness@...utronix.de,
senozhatsky@...omium.org,
quic_mojha@...cinc.com,
linux-arm-kernel@...ts.infradead.org,
kernel@...cinc.com,
Eugen Hristev <eugen.hristev@...aro.org>
Subject: [RFC][PATCH 02/10] pstore/smem: add new pstore/smem type of pstore
Add shared memory type of pstore.
Signed-off-by: Eugen Hristev <eugen.hristev@...aro.org>
---
fs/pstore/Kconfig | 13 ++++
fs/pstore/Makefile | 3 +
fs/pstore/smem.c | 115 ++++++++++++++++++++++++++++++++++++
include/linux/pstore_smem.h | 9 +++
4 files changed, 140 insertions(+)
create mode 100644 fs/pstore/smem.c
create mode 100644 include/linux/pstore_smem.h
diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 3acc38600cd1..84f87edf9b8f 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -81,6 +81,19 @@ config PSTORE_RAM
For more information, see Documentation/admin-guide/ramoops.rst.
+config PSTORE_SMEM
+ tristate "Log panic/oops to a shared memory buffer"
+ depends on PSTORE
+ select PSTORE_ZONE
+ help
+ This enables panic and oops messages to be logged to memory
+ that is shared between different hardware blocks in the system.
+ This shared memory can be a static ram, a part of dynamic RAM,
+ a dedicated cache or memory area specific for crash dumps,
+ or even a memory on an attached device.
+
+ if unsure, say N.
+
config PSTORE_ZONE
tristate
depends on PSTORE
diff --git a/fs/pstore/Makefile b/fs/pstore/Makefile
index c270467aeece..f2a314ca03a0 100644
--- a/fs/pstore/Makefile
+++ b/fs/pstore/Makefile
@@ -18,3 +18,6 @@ obj-$(CONFIG_PSTORE_ZONE) += pstore_zone.o
pstore_blk-objs += blk.o
obj-$(CONFIG_PSTORE_BLK) += pstore_blk.o
+
+pstore_smem-objs += smem.o
+obj-$(CONFIG_PSTORE_SMEM) += pstore_smem.o
diff --git a/fs/pstore/smem.c b/fs/pstore/smem.c
new file mode 100644
index 000000000000..9eedd7df5446
--- /dev/null
+++ b/fs/pstore/smem.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Implements pstore backend driver for shared memory devices,
+ * using the pstore/zone API.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/string.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pstore_smem.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/init_syscalls.h>
+#include <linux/mount.h>
+
+/*
+ * All globals must only be accessed under the pstore_smem_lock
+ * during the register/unregister functions.
+ */
+static DEFINE_MUTEX(pstore_smem_lock);
+static struct pstore_device_info *pstore_device_info;
+
+static int __register_pstore_device(struct pstore_device_info *dev)
+{
+ int ret;
+
+ lockdep_assert_held(&pstore_smem_lock);
+
+ if (!dev) {
+ pr_err("NULL device info\n");
+ return -EINVAL;
+ }
+ if (!dev->zone.total_size) {
+ pr_err("zero sized device\n");
+ return -EINVAL;
+ }
+ if (!dev->zone.read) {
+ pr_err("no read handler for device\n");
+ return -EINVAL;
+ }
+ if (!dev->zone.write) {
+ pr_err("no write handler for device\n");
+ return -EINVAL;
+ }
+
+ /* someone already registered before */
+ if (pstore_device_info)
+ return -EBUSY;
+
+ /* zero means not limit on which backends to attempt to store. */
+ if (!dev->flags)
+ dev->flags = UINT_MAX;
+
+ /* Initialize required zone ownership details. */
+ dev->zone.name = KBUILD_MODNAME;
+ dev->zone.owner = THIS_MODULE;
+
+ ret = register_pstore_zone(&dev->zone);
+ if (ret == 0)
+ pstore_device_info = dev;
+
+ return ret;
+}
+/**
+ * register_pstore_smem_device() - register smem device to pstore
+ *
+ * @dev: smem device information
+ *
+ * Return:
+ * * 0 - OK
+ * * Others - some error.
+ */
+int register_pstore_smem_device(struct pstore_device_info *dev)
+{
+ int ret;
+
+ mutex_lock(&pstore_smem_lock);
+ ret = __register_pstore_device(dev);
+ mutex_unlock(&pstore_smem_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(register_pstore_smem_device);
+
+static void __unregister_pstore_device(struct pstore_device_info *dev)
+{
+ lockdep_assert_held(&pstore_smem_lock);
+ if (pstore_device_info && pstore_device_info == dev) {
+ unregister_pstore_zone(&dev->zone);
+ pstore_device_info = NULL;
+ }
+}
+
+/**
+ * unregister_pstore_smem_device() - unregister smem device from pstore
+ *
+ * @dev: smem device information
+ */
+void unregister_pstore_smem_device(struct pstore_device_info *dev)
+{
+ mutex_lock(&pstore_smem_lock);
+ __unregister_pstore_device(dev);
+ mutex_unlock(&pstore_smem_lock);
+}
+EXPORT_SYMBOL_GPL(unregister_pstore_smem_device);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Eugen Hristev <eugen.hristev@...aro.org>");
+MODULE_DESCRIPTION("pstore backend for smem devices");
diff --git a/include/linux/pstore_smem.h b/include/linux/pstore_smem.h
new file mode 100644
index 000000000000..f0ad23e117c4
--- /dev/null
+++ b/include/linux/pstore_smem.h
@@ -0,0 +1,9 @@
+#ifndef PSTORE_SMEM_H
+#define PSTORE_SMEM_H
+
+#include <linux/pstore_zone.h>
+
+int register_pstore_smem_device(struct pstore_device_info *dev);
+void unregister_pstore_smem_device(struct pstore_device_info *dev);
+
+#endif
--
2.43.0
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