Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 979 insertions, 0 deletions

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
new file mode 100644
index 000000000..f3fa3625d
--- /dev/null
+++ b/fs/pstore/ram.c
@@ -0,0 +1,979 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * RAM Oops/Panic logger
+ *
+ * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
+ * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/pstore.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/compiler.h>
+#include <linux/pstore_ram.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include "internal.h"
+
+#define RAMOOPS_KERNMSG_HDR "===="
+#define MIN_MEM_SIZE 4096UL
+
+static ulong record_size = MIN_MEM_SIZE;
+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 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 unsigned long long mem_address;
+module_param_hw(mem_address, ullong, other, 0400);
+MODULE_PARM_DESC(mem_address,
+		"start of reserved RAM used to store oops/panic logs");
+
+static ulong mem_size;
+module_param(mem_size, ulong, 0400);
+MODULE_PARM_DESC(mem_size,
+		"size of reserved RAM used to store oops/panic logs");
+
+static unsigned int mem_type;
+module_param(mem_type, uint, 0400);
+MODULE_PARM_DESC(mem_type,
+		"memory type: 0=write-combined (default), 1=unbuffered, 2=cached");
+
+static int ramoops_max_reason = -1;
+module_param_named(max_reason, ramoops_max_reason, int, 0400);
+MODULE_PARM_DESC(max_reason,
+		 "maximum reason for kmsg dump (default 2: Oops and Panic) ");
+
+static int ramoops_ecc;
+module_param_named(ecc, ramoops_ecc, int, 0400);
+MODULE_PARM_DESC(ramoops_ecc,
+		"if non-zero, the option enables ECC support and specifies "
+		"ECC buffer size in bytes (1 is a special value, means 16 "
+		"bytes ECC)");
+
+static int ramoops_dump_oops = -1;
+module_param_named(dump_oops, ramoops_dump_oops, int, 0400);
+MODULE_PARM_DESC(dump_oops,
+		 "(deprecated: use max_reason instead) set to 1 to dump oopses & panics, 0 to only dump panics");
+
+struct ramoops_context {
+	struct persistent_ram_zone **dprzs;	/* Oops dump zones */
+	struct persistent_ram_zone *cprz;	/* Console zone */
+	struct persistent_ram_zone **fprzs;	/* Ftrace zones */
+	struct persistent_ram_zone *mprz;	/* PMSG zone */
+	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;
+	u32 flags;
+	struct persistent_ram_ecc_info ecc_info;
+	unsigned int max_dump_cnt;
+	unsigned int dump_write_cnt;
+	/* _read_cnt need clear on ramoops_pstore_open */
+	unsigned int dump_read_cnt;
+	unsigned int console_read_cnt;
+	unsigned int max_ftrace_cnt;
+	unsigned int ftrace_read_cnt;
+	unsigned int pmsg_read_cnt;
+	struct pstore_info pstore;
+};
+
+static struct platform_device *dummy;
+
+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;
+	cxt->ftrace_read_cnt = 0;
+	cxt->pmsg_read_cnt = 0;
+	return 0;
+}
+
+static struct persistent_ram_zone *
+ramoops_get_next_prz(struct persistent_ram_zone *przs[], int id,
+		     struct pstore_record *record)
+{
+	struct persistent_ram_zone *prz;
+
+	/* Give up if we never existed or have hit the end. */
+	if (!przs)
+		return NULL;
+
+	prz = przs[id];
+	if (!prz)
+		return NULL;
+
+	/* Update old/shadowed buffer. */
+	if (prz->type == PSTORE_TYPE_DMESG)
+		persistent_ram_save_old(prz);
+
+	if (!persistent_ram_old_size(prz))
+		return NULL;
+
+	record->type = prz->type;
+	record->id = id;
+
+	return prz;
+}
+
+static int ramoops_read_kmsg_hdr(char *buffer, struct timespec64 *time,
+				  bool *compressed)
+{
+	char data_type;
+	int header_length = 0;
+
+	if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu-%c\n%n",
+		   (time64_t *)&time->tv_sec, &time->tv_nsec, &data_type,
+		   &header_length) == 3) {
+		time->tv_nsec *= 1000;
+		if (data_type == 'C')
+			*compressed = true;
+		else
+			*compressed = false;
+	} else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu\n%n",
+			  (time64_t *)&time->tv_sec, &time->tv_nsec,
+			  &header_length) == 2) {
+		time->tv_nsec *= 1000;
+		*compressed = false;
+	} else {
+		time->tv_sec = 0;
+		time->tv_nsec = 0;
+		*compressed = false;
+	}
+	return header_length;
+}
+
+static bool prz_ok(struct persistent_ram_zone *prz)
+{
+	return !!prz && !!(persistent_ram_old_size(prz) +
+			   persistent_ram_ecc_string(prz, NULL, 0));
+}
+
+static ssize_t ramoops_pstore_read(struct pstore_record *record)
+{
+	ssize_t size = 0;
+	struct ramoops_context *cxt = record->psi->data;
+	struct persistent_ram_zone *prz = NULL;
+	int header_length = 0;
+	bool free_prz = false;
+
+	/*
+	 * Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but
+	 * PSTORE_TYPE_CONSOLE and PSTORE_TYPE_FTRACE don't currently have
+	 * valid time stamps, so it is initialized to zero.
+	 */
+	record->time.tv_sec = 0;
+	record->time.tv_nsec = 0;
+	record->compressed = false;
+
+	/* Find the next valid persistent_ram_zone for DMESG */
+	while (cxt->dump_read_cnt < cxt->max_dump_cnt && !prz) {
+		prz = ramoops_get_next_prz(cxt->dprzs, cxt->dump_read_cnt++,
+					   record);
+		if (!prz_ok(prz))
+			continue;
+		header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz),
+						      &record->time,
+						      &record->compressed);
+		/* Clear and skip this DMESG record if it has no valid header */
+		if (!header_length) {
+			persistent_ram_free_old(prz);
+			persistent_ram_zap(prz);
+			prz = NULL;
+		}
+	}
+
+	if (!prz_ok(prz) && !cxt->console_read_cnt++)
+		prz = ramoops_get_next_prz(&cxt->cprz, 0 /* single */, record);
+
+	if (!prz_ok(prz) && !cxt->pmsg_read_cnt++)
+		prz = ramoops_get_next_prz(&cxt->mprz, 0 /* single */, record);
+
+	/* ftrace is last since it may want to dynamically allocate memory. */
+	if (!prz_ok(prz)) {
+		if (!(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU) &&
+		    !cxt->ftrace_read_cnt++) {
+			prz = ramoops_get_next_prz(cxt->fprzs, 0 /* single */,
+						   record);
+		} else {
+			/*
+			 * Build a new dummy record which combines all the
+			 * per-cpu records including metadata and ecc info.
+			 */
+			struct persistent_ram_zone *tmp_prz, *prz_next;
+
+			tmp_prz = kzalloc(sizeof(struct persistent_ram_zone),
+					  GFP_KERNEL);
+			if (!tmp_prz)
+				return -ENOMEM;
+			prz = tmp_prz;
+			free_prz = true;
+
+			while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt) {
+				prz_next = ramoops_get_next_prz(cxt->fprzs,
+						cxt->ftrace_read_cnt++, record);
+
+				if (!prz_ok(prz_next))
+					continue;
+
+				tmp_prz->ecc_info = prz_next->ecc_info;
+				tmp_prz->corrected_bytes +=
+						prz_next->corrected_bytes;
+				tmp_prz->bad_blocks += prz_next->bad_blocks;
+
+				size = pstore_ftrace_combine_log(
+						&tmp_prz->old_log,
+						&tmp_prz->old_log_size,
+						prz_next->old_log,
+						prz_next->old_log_size);
+				if (size)
+					goto out;
+			}
+			record->id = 0;
+		}
+	}
+
+	if (!prz_ok(prz)) {
+		size = 0;
+		goto out;
+	}
+
+	size = persistent_ram_old_size(prz) - header_length;
+
+	/* ECC correction notice */
+	record->ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
+
+	record->buf = kmalloc(size + record->ecc_notice_size + 1, GFP_KERNEL);
+	if (record->buf == NULL) {
+		size = -ENOMEM;
+		goto out;
+	}
+
+	memcpy(record->buf, (char *)persistent_ram_old(prz) + header_length,
+	       size);
+
+	persistent_ram_ecc_string(prz, record->buf + size,
+				  record->ecc_notice_size + 1);
+
+out:
+	if (free_prz) {
+		kfree(prz->old_log);
+		kfree(prz);
+	}
+
+	return size;
+}
+
+static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
+				     struct pstore_record *record)
+{
+	char hdr[36]; /* "===="(4), %lld(20), "."(1), %06lu(6), "-%c\n"(3) */
+	size_t len;
+
+	len = scnprintf(hdr, sizeof(hdr),
+		RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
+		(time64_t)record->time.tv_sec,
+		record->time.tv_nsec / 1000,
+		record->compressed ? 'C' : 'D');
+	persistent_ram_write(prz, hdr, len);
+
+	return len;
+}
+
+static int notrace ramoops_pstore_write(struct pstore_record *record)
+{
+	struct ramoops_context *cxt = record->psi->data;
+	struct persistent_ram_zone *prz;
+	size_t size, hlen;
+
+	if (record->type == PSTORE_TYPE_CONSOLE) {
+		if (!cxt->cprz)
+			return -ENOMEM;
+		persistent_ram_write(cxt->cprz, record->buf, record->size);
+		return 0;
+	} else if (record->type == PSTORE_TYPE_FTRACE) {
+		int zonenum;
+
+		if (!cxt->fprzs)
+			return -ENOMEM;
+		/*
+		 * Choose zone by if we're using per-cpu buffers.
+		 */
+		if (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
+			zonenum = smp_processor_id();
+		else
+			zonenum = 0;
+
+		persistent_ram_write(cxt->fprzs[zonenum], record->buf,
+				     record->size);
+		return 0;
+	} else if (record->type == PSTORE_TYPE_PMSG) {
+		pr_warn_ratelimited("PMSG shouldn't call %s\n", __func__);
+		return -EINVAL;
+	}
+
+	if (record->type != PSTORE_TYPE_DMESG)
+		return -EINVAL;
+
+	/*
+	 * We could filter on record->reason here if we wanted to (which
+	 * would duplicate what happened before the "max_reason" setting
+	 * was added), but that would defeat the purpose of a system
+	 * changing printk.always_kmsg_dump, so instead log everything that
+	 * the kmsg dumper sends us, since it should be doing the filtering
+	 * based on the combination of printk.always_kmsg_dump and our
+	 * requested "max_reason".
+	 */
+
+	/*
+	 * Explicitly only take the first part of any new crash.
+	 * If our buffer is larger than kmsg_bytes, this can never happen,
+	 * and if our buffer is smaller than kmsg_bytes, we don't want the
+	 * report split across multiple records.
+	 */
+	if (record->part != 1)
+		return -ENOSPC;
+
+	if (!cxt->dprzs)
+		return -ENOSPC;
+
+	prz = cxt->dprzs[cxt->dump_write_cnt];
+
+	/*
+	 * Since this is a new crash dump, we need to reset the buffer in
+	 * case it still has an old dump present. Without this, the new dump
+	 * will get appended, which would seriously confuse anything trying
+	 * to check dump file contents. Specifically, ramoops_read_kmsg_hdr()
+	 * expects to find a dump header in the beginning of buffer data, so
+	 * we must to reset the buffer values, in order to ensure that the
+	 * header will be written to the beginning of the buffer.
+	 */
+	persistent_ram_zap(prz);
+
+	/* Build header and append record contents. */
+	hlen = ramoops_write_kmsg_hdr(prz, record);
+	if (!hlen)
+		return -ENOMEM;
+
+	size = record->size;
+	if (size + hlen > prz->buffer_size)
+		size = prz->buffer_size - hlen;
+	persistent_ram_write(prz, record->buf, size);
+
+	cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;
+
+	return 0;
+}
+
+static int notrace ramoops_pstore_write_user(struct pstore_record *record,
+					     const char __user *buf)
+{
+	if (record->type == PSTORE_TYPE_PMSG) {
+		struct ramoops_context *cxt = record->psi->data;
+
+		if (!cxt->mprz)
+			return -ENOMEM;
+		return persistent_ram_write_user(cxt->mprz, buf, record->size);
+	}
+
+	return -EINVAL;
+}
+
+static int ramoops_pstore_erase(struct pstore_record *record)
+{
+	struct ramoops_context *cxt = record->psi->data;
+	struct persistent_ram_zone *prz;
+
+	switch (record->type) {
+	case PSTORE_TYPE_DMESG:
+		if (record->id >= cxt->max_dump_cnt)
+			return -EINVAL;
+		prz = cxt->dprzs[record->id];
+		break;
+	case PSTORE_TYPE_CONSOLE:
+		prz = cxt->cprz;
+		break;
+	case PSTORE_TYPE_FTRACE:
+		if (record->id >= cxt->max_ftrace_cnt)
+			return -EINVAL;
+		prz = cxt->fprzs[record->id];
+		break;
+	case PSTORE_TYPE_PMSG:
+		prz = cxt->mprz;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	persistent_ram_free_old(prz);
+	persistent_ram_zap(prz);
+
+	return 0;
+}
+
+static struct ramoops_context oops_cxt = {
+	.pstore = {
+		.owner	= THIS_MODULE,
+		.name	= "ramoops",
+		.open	= ramoops_pstore_open,
+		.read	= ramoops_pstore_read,
+		.write	= ramoops_pstore_write,
+		.write_user	= ramoops_pstore_write_user,
+		.erase	= ramoops_pstore_erase,
+	},
+};
+
+static void ramoops_free_przs(struct ramoops_context *cxt)
+{
+	int i;
+
+	/* Free dump PRZs */
+	if (cxt->dprzs) {
+		for (i = 0; i < cxt->max_dump_cnt; i++)
+			persistent_ram_free(cxt->dprzs[i]);
+
+		kfree(cxt->dprzs);
+		cxt->max_dump_cnt = 0;
+	}
+
+	/* Free ftrace PRZs */
+	if (cxt->fprzs) {
+		for (i = 0; i < cxt->max_ftrace_cnt; i++)
+			persistent_ram_free(cxt->fprzs[i]);
+		kfree(cxt->fprzs);
+		cxt->max_ftrace_cnt = 0;
+	}
+}
+
+static int ramoops_init_przs(const char *name,
+			     struct device *dev, struct ramoops_context *cxt,
+			     struct persistent_ram_zone ***przs,
+			     phys_addr_t *paddr, size_t mem_sz,
+			     ssize_t record_size,
+			     unsigned int *cnt, u32 sig, u32 flags)
+{
+	int err = -ENOMEM;
+	int i;
+	size_t zone_sz;
+	struct persistent_ram_zone **prz_ar;
+
+	/* Allocate nothing for 0 mem_sz or 0 record_size. */
+	if (mem_sz == 0 || record_size == 0) {
+		*cnt = 0;
+		return 0;
+	}
+
+	/*
+	 * If we have a negative record size, calculate it based on
+	 * mem_sz / *cnt. If we have a positive record size, calculate
+	 * cnt from mem_sz / record_size.
+	 */
+	if (record_size < 0) {
+		if (*cnt == 0)
+			return 0;
+		record_size = mem_sz / *cnt;
+		if (record_size == 0) {
+			dev_err(dev, "%s record size == 0 (%zu / %u)\n",
+				name, mem_sz, *cnt);
+			goto fail;
+		}
+	} else {
+		*cnt = mem_sz / record_size;
+		if (*cnt == 0) {
+			dev_err(dev, "%s record count == 0 (%zu / %zu)\n",
+				name, mem_sz, record_size);
+			goto fail;
+		}
+	}
+
+	if (*paddr + mem_sz - cxt->phys_addr > cxt->size) {
+		dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
+			name,
+			mem_sz, (unsigned long long)*paddr,
+			cxt->size, (unsigned long long)cxt->phys_addr);
+		goto fail;
+	}
+
+	zone_sz = mem_sz / *cnt;
+	if (!zone_sz) {
+		dev_err(dev, "%s zone size == 0\n", name);
+		goto fail;
+	}
+
+	prz_ar = kcalloc(*cnt, sizeof(**przs), GFP_KERNEL);
+	if (!prz_ar)
+		goto fail;
+
+	for (i = 0; i < *cnt; i++) {
+		char *label;
+
+		if (*cnt == 1)
+			label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
+		else
+			label = kasprintf(GFP_KERNEL, "ramoops:%s(%d/%d)",
+					  name, i, *cnt - 1);
+		prz_ar[i] = persistent_ram_new(*paddr, zone_sz, sig,
+					       &cxt->ecc_info,
+					       cxt->memtype, flags, label);
+		kfree(label);
+		if (IS_ERR(prz_ar[i])) {
+			err = PTR_ERR(prz_ar[i]);
+			dev_err(dev, "failed to request %s mem region (0x%zx@0x%llx): %d\n",
+				name, record_size,
+				(unsigned long long)*paddr, err);
+
+			while (i > 0) {
+				i--;
+				persistent_ram_free(prz_ar[i]);
+			}
+			kfree(prz_ar);
+			goto fail;
+		}
+		*paddr += zone_sz;
+		prz_ar[i]->type = pstore_name_to_type(name);
+	}
+
+	*przs = prz_ar;
+	return 0;
+
+fail:
+	*cnt = 0;
+	return err;
+}
+
+static int ramoops_init_prz(const char *name,
+			    struct device *dev, struct ramoops_context *cxt,
+			    struct persistent_ram_zone **prz,
+			    phys_addr_t *paddr, size_t sz, u32 sig)
+{
+	char *label;
+
+	if (!sz)
+		return 0;
+
+	if (*paddr + sz - cxt->phys_addr > cxt->size) {
+		dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
+			name, sz, (unsigned long long)*paddr,
+			cxt->size, (unsigned long long)cxt->phys_addr);
+		return -ENOMEM;
+	}
+
+	label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
+	*prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info,
+				  cxt->memtype, PRZ_FLAG_ZAP_OLD, label);
+	kfree(label);
+	if (IS_ERR(*prz)) {
+		int err = PTR_ERR(*prz);
+
+		dev_err(dev, "failed to request %s mem region (0x%zx@0x%llx): %d\n",
+			name, sz, (unsigned long long)*paddr, err);
+		return err;
+	}
+
+	*paddr += sz;
+	(*prz)->type = pstore_name_to_type(name);
+
+	return 0;
+}
+
+/* Read a u32 from a dt property and make sure it's safe for an int. */
+static int ramoops_parse_dt_u32(struct platform_device *pdev,
+				const char *propname,
+				u32 default_value, u32 *value)
+{
+	u32 val32 = 0;
+	int ret;
+
+	ret = of_property_read_u32(pdev->dev.of_node, propname, &val32);
+	if (ret == -EINVAL) {
+		/* field is missing, use default value. */
+		val32 = default_value;
+	} else if (ret < 0) {
+		dev_err(&pdev->dev, "failed to parse property %s: %d\n",
+			propname, ret);
+		return ret;
+	}
+
+	/* Sanity check our results. */
+	if (val32 > INT_MAX) {
+		dev_err(&pdev->dev, "%s %u > INT_MAX\n", propname, val32);
+		return -EOVERFLOW;
+	}
+
+	*value = val32;
+	return 0;
+}
+
+static int ramoops_parse_dt(struct platform_device *pdev,
+			    struct ramoops_platform_data *pdata)
+{
+	struct device_node *of_node = pdev->dev.of_node;
+	struct device_node *parent_node;
+	struct resource *res;
+	u32 value;
+	int ret;
+
+	dev_dbg(&pdev->dev, "using Device Tree\n");
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev,
+			"failed to locate DT /reserved-memory resource\n");
+		return -EINVAL;
+	}
+
+	pdata->mem_size = resource_size(res);
+	pdata->mem_address = res->start;
+	/*
+	 * Setting "unbuffered" is deprecated and will be ignored if
+	 * "mem_type" is also specified.
+	 */
+	pdata->mem_type = of_property_read_bool(of_node, "unbuffered");
+	/*
+	 * Setting "no-dump-oops" is deprecated and will be ignored if
+	 * "max_reason" is also specified.
+	 */
+	if (of_property_read_bool(of_node, "no-dump-oops"))
+		pdata->max_reason = KMSG_DUMP_PANIC;
+	else
+		pdata->max_reason = KMSG_DUMP_OOPS;
+
+#define parse_u32(name, field, default_value) {				\
+		ret = ramoops_parse_dt_u32(pdev, name, default_value,	\
+					    &value);			\
+		if (ret < 0)						\
+			return ret;					\
+		field = value;						\
+	}
+
+	parse_u32("mem-type", pdata->mem_type, pdata->mem_type);
+	parse_u32("record-size", pdata->record_size, 0);
+	parse_u32("console-size", pdata->console_size, 0);
+	parse_u32("ftrace-size", pdata->ftrace_size, 0);
+	parse_u32("pmsg-size", pdata->pmsg_size, 0);
+	parse_u32("ecc-size", pdata->ecc_info.ecc_size, 0);
+	parse_u32("flags", pdata->flags, 0);
+	parse_u32("max-reason", pdata->max_reason, pdata->max_reason);
+
+#undef parse_u32
+
+	/*
+	 * Some old Chromebooks relied on the kernel setting the
+	 * console_size and pmsg_size to the record size since that's
+	 * what the downstream kernel did.  These same Chromebooks had
+	 * "ramoops" straight under the root node which isn't
+	 * according to the current upstream bindings (though it was
+	 * arguably acceptable under a prior version of the bindings).
+	 * Let's make those old Chromebooks work by detecting that
+	 * we're not a child of "reserved-memory" and mimicking the
+	 * expected behavior.
+	 */
+	parent_node = of_get_parent(of_node);
+	if (!of_node_name_eq(parent_node, "reserved-memory") &&
+	    !pdata->console_size && !pdata->ftrace_size &&
+	    !pdata->pmsg_size && !pdata->ecc_info.ecc_size) {
+		pdata->console_size = pdata->record_size;
+		pdata->pmsg_size = pdata->record_size;
+	}
+	of_node_put(parent_node);
+
+	return 0;
+}
+
+static int ramoops_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ramoops_platform_data *pdata = dev->platform_data;
+	struct ramoops_platform_data pdata_local;
+	struct ramoops_context *cxt = &oops_cxt;
+	size_t dump_mem_sz;
+	phys_addr_t paddr;
+	int err = -EINVAL;
+
+	/*
+	 * Only a single ramoops area allowed at a time, so fail extra
+	 * probes.
+	 */
+	if (cxt->max_dump_cnt) {
+		pr_err("already initialized\n");
+		goto fail_out;
+	}
+
+	if (dev_of_node(dev) && !pdata) {
+		pdata = &pdata_local;
+		memset(pdata, 0, sizeof(*pdata));
+
+		err = ramoops_parse_dt(pdev, pdata);
+		if (err < 0)
+			goto fail_out;
+	}
+
+	/* Make sure we didn't get bogus platform data pointer. */
+	if (!pdata) {
+		pr_err("NULL platform data\n");
+		err = -EINVAL;
+		goto fail_out;
+	}
+
+	if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size &&
+			!pdata->ftrace_size && !pdata->pmsg_size)) {
+		pr_err("The memory size and the record/console size must be "
+			"non-zero\n");
+		err = -EINVAL;
+		goto fail_out;
+	}
+
+	if (pdata->record_size && !is_power_of_2(pdata->record_size))
+		pdata->record_size = rounddown_pow_of_two(pdata->record_size);
+	if (pdata->console_size && !is_power_of_2(pdata->console_size))
+		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;
+	cxt->memtype = pdata->mem_type;
+	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->flags = pdata->flags;
+	cxt->ecc_info = pdata->ecc_info;
+
+	paddr = cxt->phys_addr;
+
+	dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
+			- cxt->pmsg_size;
+	err = ramoops_init_przs("dmesg", dev, cxt, &cxt->dprzs, &paddr,
+				dump_mem_sz, cxt->record_size,
+				&cxt->max_dump_cnt, 0, 0);
+	if (err)
+		goto fail_out;
+
+	err = ramoops_init_prz("console", dev, cxt, &cxt->cprz, &paddr,
+			       cxt->console_size, 0);
+	if (err)
+		goto fail_init_cprz;
+
+	cxt->max_ftrace_cnt = (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
+				? nr_cpu_ids
+				: 1;
+	err = ramoops_init_przs("ftrace", dev, cxt, &cxt->fprzs, &paddr,
+				cxt->ftrace_size, -1,
+				&cxt->max_ftrace_cnt, LINUX_VERSION_CODE,
+				(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
+					? PRZ_FLAG_NO_LOCK : 0);
+	if (err)
+		goto fail_init_fprz;
+
+	err = ramoops_init_prz("pmsg", dev, cxt, &cxt->mprz, &paddr,
+				cxt->pmsg_size, 0);
+	if (err)
+		goto fail_init_mprz;
+
+	cxt->pstore.data = cxt;
+	/*
+	 * Prepare frontend flags based on which areas are initialized.
+	 * For ramoops_init_przs() cases, the "max count" variable tells
+	 * if there are regions present. For ramoops_init_prz() cases,
+	 * the single region size is how to check.
+	 */
+	cxt->pstore.flags = 0;
+	if (cxt->max_dump_cnt) {
+		cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
+		cxt->pstore.max_reason = pdata->max_reason;
+	}
+	if (cxt->console_size)
+		cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
+	if (cxt->max_ftrace_cnt)
+		cxt->pstore.flags |= PSTORE_FLAGS_FTRACE;
+	if (cxt->pmsg_size)
+		cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
+
+	/*
+	 * Since bufsize is only used for dmesg crash dumps, it
+	 * must match the size of the dprz record (after PRZ header
+	 * and ECC bytes have been accounted for).
+	 */
+	if (cxt->pstore.flags & PSTORE_FLAGS_DMESG) {
+		cxt->pstore.bufsize = cxt->dprzs[0]->buffer_size;
+		cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
+		if (!cxt->pstore.buf) {
+			pr_err("cannot allocate pstore crash dump buffer\n");
+			err = -ENOMEM;
+			goto fail_clear;
+		}
+	}
+
+	err = pstore_register(&cxt->pstore);
+	if (err) {
+		pr_err("registering with pstore failed\n");
+		goto fail_buf;
+	}
+
+	/*
+	 * Update the module parameter variables as well so they are visible
+	 * through /sys/module/ramoops/parameters/
+	 */
+	mem_size = pdata->mem_size;
+	mem_address = pdata->mem_address;
+	record_size = pdata->record_size;
+	ramoops_max_reason = pdata->max_reason;
+	ramoops_console_size = pdata->console_size;
+	ramoops_pmsg_size = pdata->pmsg_size;
+	ramoops_ftrace_size = pdata->ftrace_size;
+
+	pr_info("using 0x%lx@0x%llx, ecc: %d\n",
+		cxt->size, (unsigned long long)cxt->phys_addr,
+		cxt->ecc_info.ecc_size);
+
+	return 0;
+
+fail_buf:
+	kfree(cxt->pstore.buf);
+fail_clear:
+	cxt->pstore.bufsize = 0;
+	persistent_ram_free(cxt->mprz);
+fail_init_mprz:
+fail_init_fprz:
+	persistent_ram_free(cxt->cprz);
+fail_init_cprz:
+	ramoops_free_przs(cxt);
+fail_out:
+	return err;
+}
+
+static int ramoops_remove(struct platform_device *pdev)
+{
+	struct ramoops_context *cxt = &oops_cxt;
+
+	pstore_unregister(&cxt->pstore);
+
+	kfree(cxt->pstore.buf);
+	cxt->pstore.bufsize = 0;
+
+	persistent_ram_free(cxt->mprz);
+	persistent_ram_free(cxt->cprz);
+	ramoops_free_przs(cxt);
+
+	return 0;
+}
+
+static const struct of_device_id dt_match[] = {
+	{ .compatible = "ramoops" },
+	{}
+};
+
+static struct platform_driver ramoops_driver = {
+	.probe		= ramoops_probe,
+	.remove		= ramoops_remove,
+	.driver		= {
+		.name		= "ramoops",
+		.of_match_table	= dt_match,
+	},
+};
+
+static inline void ramoops_unregister_dummy(void)
+{
+	platform_device_unregister(dummy);
+	dummy = NULL;
+}
+
+static void __init ramoops_register_dummy(void)
+{
+	struct ramoops_platform_data pdata;
+
+	/*
+	 * Prepare a dummy platform data structure to carry the module
+	 * parameters. If mem_size isn't set, then there are no module
+	 * parameters, and we can skip this.
+	 */
+	if (!mem_size)
+		return;
+
+	pr_info("using module parameters\n");
+
+	memset(&pdata, 0, sizeof(pdata));
+	pdata.mem_size = mem_size;
+	pdata.mem_address = mem_address;
+	pdata.mem_type = mem_type;
+	pdata.record_size = record_size;
+	pdata.console_size = ramoops_console_size;
+	pdata.ftrace_size = ramoops_ftrace_size;
+	pdata.pmsg_size = ramoops_pmsg_size;
+	/* If "max_reason" is set, its value has priority over "dump_oops". */
+	if (ramoops_max_reason >= 0)
+		pdata.max_reason = ramoops_max_reason;
+	/* Otherwise, if "dump_oops" is set, parse it into "max_reason". */
+	else if (ramoops_dump_oops != -1)
+		pdata.max_reason = ramoops_dump_oops ? KMSG_DUMP_OOPS
+						     : KMSG_DUMP_PANIC;
+	/* And if neither are explicitly set, use the default. */
+	else
+		pdata.max_reason = KMSG_DUMP_OOPS;
+	pdata.flags = RAMOOPS_FLAG_FTRACE_PER_CPU;
+
+	/*
+	 * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
+	 * (using 1 byte for ECC isn't much of use anyway).
+	 */
+	pdata.ecc_info.ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;
+
+	dummy = platform_device_register_data(NULL, "ramoops", -1,
+			&pdata, sizeof(pdata));
+	if (IS_ERR(dummy)) {
+		pr_info("could not create platform device: %ld\n",
+			PTR_ERR(dummy));
+		dummy = NULL;
+	}
+}
+
+static int __init ramoops_init(void)
+{
+	int ret;
+
+	ramoops_register_dummy();
+	ret = platform_driver_register(&ramoops_driver);
+	if (ret != 0)
+		ramoops_unregister_dummy();
+
+	return ret;
+}
+postcore_initcall(ramoops_init);
+
+static void __exit ramoops_exit(void)
+{
+	platform_driver_unregister(&ramoops_driver);
+	ramoops_unregister_dummy();
+}
+module_exit(ramoops_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marco Stornelli <marco.stornelli@gmail.com>");
+MODULE_DESCRIPTION("RAM Oops/Panic logger/driver");