[Issue]
Currently, efi_pstore driver simply overwrites existing panic messages in NVRAM.
So, in the following scenario, we will lose 1st panic messages.
1. kernel panics.
2. efi_pstore is kicked and writes panic messages to NVRAM.
3. system reboots.
4. kernel panics again before a user checks the 1st panic messages in NVRAM.
[Solution]
A reasonable solution to fix the issue is just holding multiple logs without erasing
existing entries.
This patch freshly adds a logic erasing existing entries, which shared with a write callback,
to an erase callback.
To support holding multiple logs, the write callback doesn't need to erase any entries and
it will be removed in a subsequent patch.
Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx>
---
drivers/firmware/efivars.c | 46 +++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 45 insertions(+), 1 deletions(-)
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 37ac21a..bee14cc 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -784,7 +784,51 @@ static int efi_pstore_write(enum pstore_type_id type,
static int efi_pstore_erase(enum pstore_type_id type, u64 id,
struct pstore_info *psi)
{
- efi_pstore_write(type, 0, &id, (unsigned int)id, 0, psi);
+ char stub_name[DUMP_NAME_LEN];
+ efi_char16_t efi_name[DUMP_NAME_LEN];
+ efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+ struct efivars *efivars = psi->data;
+ struct efivar_entry *entry, *found = NULL;
+ int i;
+
+ sprintf(stub_name, "dump-type%u-%u-", type, (unsigned int)id);
+
+ spin_lock(&efivars->lock);
+
+ for (i = 0; i < DUMP_NAME_LEN; i++)
+ efi_name[i] = stub_name[i];
+
+ /*
+ * Clean up any entries with the same name
+ */
+
+ list_for_each_entry(entry, &efivars->list, list) {
+ get_var_data_locked(efivars, &entry->var);
+
+ if (efi_guidcmp(entry->var.VendorGuid, vendor))
+ continue;
+ if (utf16_strncmp(entry->var.VariableName, efi_name,
+ utf16_strlen(efi_name)))
+ continue;
+ /* Needs to be a prefix */
+ if (entry->var.VariableName[utf16_strlen(efi_name)] == 0)
+ continue;
+
+ /* found */
+ found = entry;
+ efivars->ops->set_variable(entry->var.VariableName,
+ &entry->var.VendorGuid,
+ PSTORE_EFI_ATTRIBUTES,
+ 0, NULL);
+ }
+
+ if (found)
+ list_del(&found->list);
+
+ spin_unlock(&efivars->lock);
+
+ if (found)
+ efivar_unregister(found);
return 0;
}
-- 1.7.1
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