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Subject[PATCH 6/6] pstore/ram: Add ECC support
This is now straightforward: just introduce a module parameter and pass
the needed value to persistent_ram_new().

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Marco Stornelli <marco.stornelli@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
---
Documentation/ramoops.txt | 6 ++++++
fs/pstore/ram.c | 15 ++++++++++++---
include/linux/pstore_ram.h | 1 +
3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt
index 470d2c4..4ba7db2 100644
--- a/Documentation/ramoops.txt
+++ b/Documentation/ramoops.txt
@@ -30,6 +30,11 @@ variable while setting 0 in that variable dumps only the panics.
The module uses a counter to record multiple dumps but the counter gets reset
on restart (i.e. new dumps after the restart will overwrite old ones).

+Ramoops also supports software ECC protection of persistent memory regions.
+This might be useful when a hardware reset was used to bring the machine back
+to life (i.e. a watchdog triggered). In such cases, RAM may be somewhat
+corrupt, but usually it is restorable.
+
2. Setting the parameters

Setting the ramoops parameters can be done in 2 different manners:
@@ -46,6 +51,7 @@ static struct ramoops_platform_data ramoops_data = {
.mem_address = <...>,
.record_size = <...>,
.dump_oops = <...>,
+ .ecc = <...>,
};

static struct platform_device ramoops_dev = {
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 62b13ed..9123cce 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -56,12 +56,18 @@ module_param(dump_oops, int, 0600);
MODULE_PARM_DESC(dump_oops,
"set to 1 to dump oopses, 0 to only dump panics (default 1)");

+static int ramoops_ecc;
+module_param_named(ecc, ramoops_ecc, int, 0600);
+MODULE_PARM_DESC(ramoops_ecc,
+ "set to 1 to enable ECC support");
+
struct ramoops_context {
struct persistent_ram_zone **przs;
phys_addr_t phys_addr;
unsigned long size;
size_t record_size;
int dump_oops;
+ bool ecc;
unsigned int count;
unsigned int max_count;
unsigned int read_count;
@@ -236,6 +242,7 @@ static int __init ramoops_probe(struct platform_device *pdev)
cxt->phys_addr = pdata->mem_address;
cxt->record_size = pdata->record_size;
cxt->dump_oops = pdata->dump_oops;
+ cxt->ecc = pdata->ecc;

cxt->przs = kzalloc(sizeof(*cxt->przs) * cxt->max_count, GFP_KERNEL);
if (!cxt->przs) {
@@ -248,7 +255,7 @@ static int __init ramoops_probe(struct platform_device *pdev)
size_t sz = cxt->record_size;
phys_addr_t start = cxt->phys_addr + sz * i;

- cxt->przs[i] = persistent_ram_new(start, sz, 0);
+ cxt->przs[i] = persistent_ram_new(start, sz, cxt->ecc);
if (IS_ERR(cxt->przs[i])) {
err = PTR_ERR(cxt->przs[i]);
dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
@@ -281,9 +288,10 @@ static int __init ramoops_probe(struct platform_device *pdev)
record_size = pdata->record_size;
dump_oops = pdata->dump_oops;

- pr_info("attached 0x%lx@0x%llx (%ux0x%zx)\n",
+ pr_info("attached 0x%lx@0x%llx (%ux0x%zx), ecc: %s\n",
cxt->size, (unsigned long long)cxt->phys_addr,
- cxt->max_count, cxt->record_size);
+ cxt->max_count, cxt->record_size,
+ ramoops_ecc ? "on" : "off");

return 0;

@@ -347,6 +355,7 @@ static int __init ramoops_init(void)
dummy_data->mem_address = mem_address;
dummy_data->record_size = record_size;
dummy_data->dump_oops = dump_oops;
+ dummy_data->ecc = ramoops_ecc;
dummy = platform_create_bundle(&ramoops_driver, ramoops_probe,
NULL, 0, dummy_data,
sizeof(struct ramoops_platform_data));
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
index ffe24a5..7ed7fd4 100644
--- a/include/linux/pstore_ram.h
+++ b/include/linux/pstore_ram.h
@@ -92,6 +92,7 @@ struct ramoops_platform_data {
unsigned long mem_address;
unsigned long record_size;
int dump_oops;
+ bool ecc;
};

#endif
--
1.7.9.2

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