pstore updates for v6.2-rc1

- Reporting improvements and return path fixes (Guilherme G. Piccoli,
   Wang Yufen, Kees Cook).
 
 - Clean up kmsg_bytes module parameter usage (Guilherme G. Piccoli).
 
 - Add Guilherme to pstore MAINTAINERS entry.
 
 - Choose friendlier allocation flags (Qiujun Huang, Stephen Boyd).
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Merge tag 'pstore-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull pstore updates from Kees Cook:
 "A small collection of bug fixes, refactorings, and general
  improvements:

   - Reporting improvements and return path fixes (Guilherme G. Piccoli,
     Wang Yufen, Kees Cook)

   - Clean up kmsg_bytes module parameter usage (Guilherme G. Piccoli)

   - Add Guilherme to pstore MAINTAINERS entry

   - Choose friendlier allocation flags (Qiujun Huang, Stephen Boyd)"

* tag 'pstore-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  pstore: Avoid kcore oops by vmap()ing with VM_IOREMAP
  pstore/ram: Fix error return code in ramoops_probe()
  pstore: Alert on backend write error
  MAINTAINERS: Update pstore maintainers
  pstore/ram: Set freed addresses to NULL
  pstore/ram: Move internal definitions out of kernel-wide include
  pstore/ram: Move pmsg init earlier
  pstore/ram: Consolidate kfree() paths
  efi: pstore: Follow convention for the efi-pstore backend name
  pstore: Inform unregistered backend names as well
  pstore: Expose kmsg_bytes as a module parameter
  pstore: Improve error reporting in case of backend overlap
  pstore/zone: Use GFP_ATOMIC to allocate zone buffer

MAINTAINERS

@@ -16661,10 +16661,10 @@ F:	net/psample
 
 PSTORE FILESYSTEM
 M:	Kees Cook <keescook@chromium.org>
-M:	Anton Vorontsov <anton@enomsg.org>
+R:	Tony Luck <tony.luck@intel.com>
-M:	Colin Cross <ccross@android.com>
+R:	Guilherme G. Piccoli <gpiccoli@igalia.com>
-M:	Tony Luck <tony.luck@intel.com>
+L:	linux-hardening@vger.kernel.org
-S:	Maintained
+S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/pstore
 F:	Documentation/admin-guide/ramoops.rst
 F:	Documentation/admin-guide/pstore-blk.rst

drivers/firmware/efi/efi-pstore.c

@@ -207,7 +207,7 @@ static int efi_pstore_erase(struct pstore_record *record)
 
 static struct pstore_info efi_pstore_info = {
 	.owner		= THIS_MODULE,
-	.name		= "efi",
+	.name		= KBUILD_MODNAME,
 	.flags		= PSTORE_FLAGS_DMESG,
 	.open		= efi_pstore_open,
 	.close		= efi_pstore_close,

fs/pstore/platform.c

@@ -89,6 +89,11 @@ static char *compress =
 module_param(compress, charp, 0444);
 MODULE_PARM_DESC(compress, "compression to use");
 
+/* How much of the kernel log to snapshot */
+unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
+module_param(kmsg_bytes, ulong, 0444);
+MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
+
 /* Compression parameters */
 static struct crypto_comp *tfm;
 
@@ -100,9 +105,6 @@ struct pstore_zbackend {
 static char *big_oops_buf;
 static size_t big_oops_buf_sz;
 
-/* How much of the console log to snapshot */
-unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
-
 void pstore_set_kmsg_bytes(int bytes)
 {
 	kmsg_bytes = bytes;
@@ -391,6 +393,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 	const char	*why;
 	unsigned int	part = 1;
 	unsigned long	flags = 0;
+	int		saved_ret = 0;
 	int		ret;
 
 	why = kmsg_dump_reason_str(reason);
@@ -461,12 +464,21 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 		if (ret == 0 && reason == KMSG_DUMP_OOPS) {
 			pstore_new_entry = 1;
 			pstore_timer_kick();
+		} else {
+			/* Preserve only the first non-zero returned value. */
+			if (!saved_ret)
+				saved_ret = ret;
 		}
 
 		total += record.size;
 		part++;
 	}
 	spin_unlock_irqrestore(&psinfo->buf_lock, flags);
+
+	if (saved_ret) {
+		pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
+			    saved_ret);
+	}
 }
 
 static struct kmsg_dumper pstore_dumper = {
@@ -562,8 +574,9 @@ out:
 int pstore_register(struct pstore_info *psi)
 {
 	if (backend && strcmp(backend, psi->name)) {
-		pr_warn("ignoring unexpected backend '%s'\n", psi->name);
+		pr_warn("backend '%s' already in use: ignoring '%s'\n",
-		return -EPERM;
+			backend, psi->name);
+		return -EBUSY;
 	}
 
 	/* Sanity check flags. */
@@ -662,6 +675,8 @@ void pstore_unregister(struct pstore_info *psi)
 	psinfo = NULL;
 	kfree(backend);
 	backend = NULL;
+
+	pr_info("Unregistered %s as persistent store backend\n", psi->name);
 	mutex_unlock(&psinfo_lock);
 }
 EXPORT_SYMBOL_GPL(pstore_unregister);

fs/pstore/ram.c

@@ -18,10 +18,11 @@
 #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"
+#include "ram_internal.h"
 
 #define RAMOOPS_KERNMSG_HDR "===="
 #define MIN_MEM_SIZE 4096UL
@@ -451,20 +452,28 @@ static void ramoops_free_przs(struct ramoops_context *cxt)
 {
 	int i;
 
+	/* Free pmsg PRZ */
+	persistent_ram_free(&cxt->mprz);
+
+	/* Free console PRZ */
+	persistent_ram_free(&cxt->cprz);
+
 	/* Free dump PRZs */
 	if (cxt->dprzs) {
 		for (i = 0; i < cxt->max_dump_cnt; i++)
-			persistent_ram_free(cxt->dprzs[i]);
+			persistent_ram_free(&cxt->dprzs[i]);
 
 		kfree(cxt->dprzs);
+		cxt->dprzs = NULL;
 		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]);
+			persistent_ram_free(&cxt->fprzs[i]);
 		kfree(cxt->fprzs);
+		cxt->fprzs = NULL;
 		cxt->max_ftrace_cnt = 0;
 	}
 }
@@ -548,9 +557,10 @@ static int ramoops_init_przs(const char *name,
 
 			while (i > 0) {
 				i--;
-				persistent_ram_free(prz_ar[i]);
+				persistent_ram_free(&prz_ar[i]);
 			}
 			kfree(prz_ar);
+			prz_ar = NULL;
 			goto fail;
 		}
 		*paddr += zone_sz;
@@ -735,6 +745,7 @@ static int ramoops_probe(struct platform_device *pdev)
 	/* Make sure we didn't get bogus platform data pointer. */
 	if (!pdata) {
 		pr_err("NULL platform data\n");
+		err = -EINVAL;
 		goto fail_out;
 	}
 
@@ -742,6 +753,7 @@ static int ramoops_probe(struct platform_device *pdev)
 			!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;
 	}
 
@@ -772,12 +784,17 @@ static int ramoops_probe(struct platform_device *pdev)
 				dump_mem_sz, cxt->record_size,
 				&cxt->max_dump_cnt, 0, 0);
 	if (err)
-		goto fail_out;
+		goto fail_init;
 
 	err = ramoops_init_prz("console", dev, cxt, &cxt->cprz, &paddr,
 			       cxt->console_size, 0);
 	if (err)
-		goto fail_init_cprz;
+		goto fail_init;
+
+	err = ramoops_init_prz("pmsg", dev, cxt, &cxt->mprz, &paddr,
+				cxt->pmsg_size, 0);
+	if (err)
+		goto fail_init;
 
 	cxt->max_ftrace_cnt = (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
 				? nr_cpu_ids
@@ -788,12 +805,7 @@ static int ramoops_probe(struct platform_device *pdev)
 				(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
 					? PRZ_FLAG_NO_LOCK : 0);
 	if (err)
-		goto fail_init_fprz;
+		goto fail_init;
-
-	err = ramoops_init_prz("pmsg", dev, cxt, &cxt->mprz, &paddr,
-				cxt->pmsg_size, 0);
-	if (err)
-		goto fail_init_mprz;
 
 	cxt->pstore.data = cxt;
 	/*
@@ -857,11 +869,7 @@ fail_buf:
 	kfree(cxt->pstore.buf);
 fail_clear:
 	cxt->pstore.bufsize = 0;
-	persistent_ram_free(cxt->mprz);
+fail_init:
-fail_init_mprz:
-fail_init_fprz:
-	persistent_ram_free(cxt->cprz);
-fail_init_cprz:
 	ramoops_free_przs(cxt);
 fail_out:
 	return err;
@@ -876,8 +884,6 @@ static int ramoops_remove(struct platform_device *pdev)
 	kfree(cxt->pstore.buf);
 	cxt->pstore.bufsize = 0;
 
-	persistent_ram_free(cxt->mprz);
-	persistent_ram_free(cxt->cprz);
 	ramoops_free_przs(cxt);
 
 	return 0;

fs/pstore/ram_core.c

@@ -13,13 +13,14 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/memblock.h>
-#include <linux/pstore_ram.h>
 #include <linux/rslib.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
 #include <asm/page.h>
 
+#include "ram_internal.h"
+
 /**
  * struct persistent_ram_buffer - persistent circular RAM buffer
  *
@@ -439,7 +440,11 @@ static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 		phys_addr_t addr = page_start + i * PAGE_SIZE;
 		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 	}
-	vaddr = vmap(pages, page_count, VM_MAP, prot);
+	/*
+	 * VM_IOREMAP used here to bypass this region during vread()
+	 * and kmap_atomic() (i.e. kcore) to avoid __va() failures.
+	 */
+	vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
 	kfree(pages);
 
 	/*
@@ -543,8 +548,14 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 	return 0;
 }
 
-void persistent_ram_free(struct persistent_ram_zone *prz)
+void persistent_ram_free(struct persistent_ram_zone **_prz)
 {
+	struct persistent_ram_zone *prz;
+
+	if (!_prz)
+		return;
+
+	prz = *_prz;
 	if (!prz)
 		return;
 
@@ -568,6 +579,7 @@ void persistent_ram_free(struct persistent_ram_zone *prz)
 	persistent_ram_free_old(prz);
 	kfree(prz->label);
 	kfree(prz);
+	*_prz = NULL;
 }
 
 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
@@ -604,6 +616,6 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 
 	return prz;
 err:
-	persistent_ram_free(prz);
+	persistent_ram_free(&prz);
 	return ERR_PTR(ret);
 }

fs/pstore/ram_internal.h

@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
+ * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
+ * Copyright (C) 2011 Google, Inc.
+ */
+
+#include <linux/pstore_ram.h>
+
+/*
+ * Choose whether access to the RAM zone requires locking or not.  If a zone
+ * can be written to from different CPUs like with ftrace for example, then
+ * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required.
+ */
+#define PRZ_FLAG_NO_LOCK	BIT(0)
+/*
+ * If a PRZ should only have a single-boot lifetime, this marks it as
+ * getting wiped after its contents get copied out after boot.
+ */
+#define PRZ_FLAG_ZAP_OLD	BIT(1)
+
+/**
+ * struct persistent_ram_zone - Details of a persistent RAM zone (PRZ)
+ *                              used as a pstore backend
+ *
+ * @paddr:	physical address of the mapped RAM area
+ * @size:	size of mapping
+ * @label:	unique name of this PRZ
+ * @type:	frontend type for this PRZ
+ * @flags:	holds PRZ_FLAGS_* bits
+ *
+ * @buffer_lock:
+ *	locks access to @buffer "size" bytes and "start" offset
+ * @buffer:
+ *	pointer to actual RAM area managed by this PRZ
+ * @buffer_size:
+ *	bytes in @buffer->data (not including any trailing ECC bytes)
+ *
+ * @par_buffer:
+ *	pointer into @buffer->data containing ECC bytes for @buffer->data
+ * @par_header:
+ *	pointer into @buffer->data containing ECC bytes for @buffer header
+ *	(i.e. all fields up to @data)
+ * @rs_decoder:
+ *	RSLIB instance for doing ECC calculations
+ * @corrected_bytes:
+ *	ECC corrected bytes accounting since boot
+ * @bad_blocks:
+ *	ECC uncorrectable bytes accounting since boot
+ * @ecc_info:
+ *	ECC configuration details
+ *
+ * @old_log:
+ *	saved copy of @buffer->data prior to most recent wipe
+ * @old_log_size:
+ *	bytes contained in @old_log
+ *
+ */
+struct persistent_ram_zone {
+	phys_addr_t paddr;
+	size_t size;
+	void *vaddr;
+	char *label;
+	enum pstore_type_id type;
+	u32 flags;
+
+	raw_spinlock_t buffer_lock;
+	struct persistent_ram_buffer *buffer;
+	size_t buffer_size;
+
+	char *par_buffer;
+	char *par_header;
+	struct rs_control *rs_decoder;
+	int corrected_bytes;
+	int bad_blocks;
+	struct persistent_ram_ecc_info ecc_info;
+
+	char *old_log;
+	size_t old_log_size;
+};
+
+struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
+			u32 sig, struct persistent_ram_ecc_info *ecc_info,
+			unsigned int memtype, u32 flags, char *label);
+void persistent_ram_free(struct persistent_ram_zone **_prz);
+void persistent_ram_zap(struct persistent_ram_zone *prz);
+
+int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
+			 unsigned int count);
+int persistent_ram_write_user(struct persistent_ram_zone *prz,
+			      const void __user *s, unsigned int count);
+
+void persistent_ram_save_old(struct persistent_ram_zone *prz);
+size_t persistent_ram_old_size(struct persistent_ram_zone *prz);
+void *persistent_ram_old(struct persistent_ram_zone *prz);
+void persistent_ram_free_old(struct persistent_ram_zone *prz);
+ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
+	char *str, size_t len);

fs/pstore/zone.c

@@ -761,7 +761,7 @@ static inline int notrace psz_kmsg_write_record(struct psz_context *cxt,
 		/* avoid destroying old data, allocate a new one */
 		len = zone->buffer_size + sizeof(*zone->buffer);
 		zone->oldbuf = zone->buffer;
-		zone->buffer = kzalloc(len, GFP_KERNEL);
+		zone->buffer = kzalloc(len, GFP_ATOMIC);
 		if (!zone->buffer) {
 			zone->buffer = zone->oldbuf;
 			return -ENOMEM;

include/linux/pstore_ram.h

@@ -8,28 +8,7 @@
 #ifndef __LINUX_PSTORE_RAM_H__
 #define __LINUX_PSTORE_RAM_H__
 
-#include <linux/compiler.h>
-#include <linux/device.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/list.h>
 #include <linux/pstore.h>
-#include <linux/types.h>
-
-/*
- * Choose whether access to the RAM zone requires locking or not.  If a zone
- * can be written to from different CPUs like with ftrace for example, then
- * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required.
- */
-#define PRZ_FLAG_NO_LOCK	BIT(0)
-/*
- * If a PRZ should only have a single-boot lifetime, this marks it as
- * getting wiped after its contents get copied out after boot.
- */
-#define PRZ_FLAG_ZAP_OLD	BIT(1)
-
-struct persistent_ram_buffer;
-struct rs_control;
 
 struct persistent_ram_ecc_info {
 	int block_size;
@@ -39,84 +18,6 @@ struct persistent_ram_ecc_info {
 	uint16_t *par;
 };
 
-/**
- * struct persistent_ram_zone - Details of a persistent RAM zone (PRZ)
- *                              used as a pstore backend
- *
- * @paddr:	physical address of the mapped RAM area
- * @size:	size of mapping
- * @label:	unique name of this PRZ
- * @type:	frontend type for this PRZ
- * @flags:	holds PRZ_FLAGS_* bits
- *
- * @buffer_lock:
- *	locks access to @buffer "size" bytes and "start" offset
- * @buffer:
- *	pointer to actual RAM area managed by this PRZ
- * @buffer_size:
- *	bytes in @buffer->data (not including any trailing ECC bytes)
- *
- * @par_buffer:
- *	pointer into @buffer->data containing ECC bytes for @buffer->data
- * @par_header:
- *	pointer into @buffer->data containing ECC bytes for @buffer header
- *	(i.e. all fields up to @data)
- * @rs_decoder:
- *	RSLIB instance for doing ECC calculations
- * @corrected_bytes:
- *	ECC corrected bytes accounting since boot
- * @bad_blocks:
- *	ECC uncorrectable bytes accounting since boot
- * @ecc_info:
- *	ECC configuration details
- *
- * @old_log:
- *	saved copy of @buffer->data prior to most recent wipe
- * @old_log_size:
- *	bytes contained in @old_log
- *
- */
-struct persistent_ram_zone {
-	phys_addr_t paddr;
-	size_t size;
-	void *vaddr;
-	char *label;
-	enum pstore_type_id type;
-	u32 flags;
-
-	raw_spinlock_t buffer_lock;
-	struct persistent_ram_buffer *buffer;
-	size_t buffer_size;
-
-	char *par_buffer;
-	char *par_header;
-	struct rs_control *rs_decoder;
-	int corrected_bytes;
-	int bad_blocks;
-	struct persistent_ram_ecc_info ecc_info;
-
-	char *old_log;
-	size_t old_log_size;
-};
-
-struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
-			u32 sig, struct persistent_ram_ecc_info *ecc_info,
-			unsigned int memtype, u32 flags, char *label);
-void persistent_ram_free(struct persistent_ram_zone *prz);
-void persistent_ram_zap(struct persistent_ram_zone *prz);
-
-int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
-			 unsigned int count);
-int persistent_ram_write_user(struct persistent_ram_zone *prz,
-			      const void __user *s, unsigned int count);
-
-void persistent_ram_save_old(struct persistent_ram_zone *prz);
-size_t persistent_ram_old_size(struct persistent_ram_zone *prz);
-void *persistent_ram_old(struct persistent_ram_zone *prz);
-void persistent_ram_free_old(struct persistent_ram_zone *prz);
-ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
-	char *str, size_t len);
-
 /*
  * Ramoops platform data
  * @mem_size	memory size for ramoops