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Subject[PATCH] 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>
---
fs/pstore/ram.c | 16 +++++++++++++---
fs/pstore/ram_core.c | 11 +++++++----
include/linux/pstore_ram.h | 3 ++-
3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 6ea9cd801044..ffcff6516e89 100644
--- a/fs/pstore/ram.c
+++ b/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->memtype, flags);
+ &cxt->ecc_info,
+ 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);

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 0792595ebcfb..12e21f789194 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -438,11 +438,11 @@ 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;
@@ -470,7 +470,8 @@ 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__,
@@ -541,12 +542,13 @@ 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;
@@ -560,6 +562,7 @@ 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)
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index e6d226464838..602d64725222 100644
--- a/include/linux/pstore_ram.h
+++ b/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);

--
2.17.1

--
Kees Cook
Pixel Security

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