pstore/ram: Clarify resource reservation labels

When ramoops reserved a memory region in the kernel, it had an unhelpful
label of "persistent_memory". When reading /proc/iomem, it would be
repeated many times, did not hint that it was ramoops in particular,
and didn't clarify very much about what each was used for:

400000000-407ffffff : Persistent Memory (legacy)
  400000000-400000fff : persistent_memory
  400001000-400001fff : persistent_memory
...
  4000ff000-4000fffff : persistent_memory

Instead, this adds meaningful labels for how the various regions are
being used:

400000000-407ffffff : Persistent Memory (legacy)
  400000000-400000fff : ramoops:dump(0/252)
  400001000-400001fff : ramoops:dump(1/252)
...
  4000fc000-4000fcfff : ramoops:dump(252/252)
  4000fd000-4000fdfff : ramoops:console
  4000fe000-4000fe3ff : ramoops:ftrace(0/3)
  4000fe400-4000fe7ff : ramoops:ftrace(1/3)
  4000fe800-4000febff : ramoops:ftrace(2/3)
  4000fec00-4000fefff : ramoops:ftrace(3/3)
  4000ff000-4000fffff : ramoops:pmsg

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Tested-by: Guenter Roeck <groeck@chromium.org>

fs/pstore/ram.c

@@ -587,9 +587,16 @@ static int ramoops_init_przs(const char *name,
 		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->ecc_info,
-						  cxt->memtype, flags);
+					       cxt->memtype, flags, 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",
@@ -619,6 +626,8 @@ static int ramoops_init_prz(const char *name,
 			    struct persistent_ram_zone **prz,
 			    phys_addr_t *paddr, size_t sz, u32 sig)
 {
+	char *label;
+
 	if (!sz)
 		return 0;
 
@@ -629,8 +638,9 @@ static int ramoops_init_prz(const char *name,
 		return -ENOMEM;
 	}
 
+	label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
 	*prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info,
-				  cxt->memtype, 0);
+				  cxt->memtype, 0, label);
 	if (IS_ERR(*prz)) {
 		int err = PTR_ERR(*prz);
 

fs/pstore/ram_core.c

@@ -433,11 +433,11 @@ static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 }
 
 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
-		unsigned int memtype)
+		unsigned int memtype, char *label)
 {
 	void *va;
 
-	if (!request_mem_region(start, size, "persistent_ram")) {
+	if (!request_mem_region(start, size, label ?: "ramoops")) {
 		pr_err("request mem region (0x%llx@0x%llx) failed\n",
 			(unsigned long long)size, (unsigned long long)start);
 		return NULL;
@@ -460,7 +460,8 @@ static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 	if (pfn_valid(start >> PAGE_SHIFT))
 		prz->vaddr = persistent_ram_vmap(start, size, memtype);
 	else
-		prz->vaddr = persistent_ram_iomap(start, size, memtype);
+		prz->vaddr = persistent_ram_iomap(start, size, memtype,
+						  prz->label);
 
 	if (!prz->vaddr) {
 		pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
@@ -530,12 +531,13 @@ void persistent_ram_free(struct persistent_ram_zone *prz)
 	prz->ecc_info.par = NULL;
 
 	persistent_ram_free_old(prz);
+	kfree(prz->label);
 	kfree(prz);
 }
 
 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)
+			unsigned int memtype, u32 flags, char *label)
 {
 	struct persistent_ram_zone *prz;
 	int ret = -ENOMEM;
@@ -549,6 +551,7 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 	/* Initialize general buffer state. */
 	raw_spin_lock_init(&prz->buffer_lock);
 	prz->flags = flags;
+	prz->label = label;
 
 	ret = persistent_ram_buffer_map(start, size, prz, memtype);
 	if (ret)

include/linux/pstore_ram.h

@@ -46,6 +46,7 @@ struct persistent_ram_zone {
 	phys_addr_t paddr;
 	size_t size;
 	void *vaddr;
+	char *label;
 	struct persistent_ram_buffer *buffer;
 	size_t buffer_size;
 	u32 flags;
@@ -65,7 +66,7 @@ struct persistent_ram_zone {
 
 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);
+			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);