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authorSeth Forshee <seth.forshee@canonical.com>2013-03-11 16:17:50 -0500
committerMatt Fleming <matt.fleming@intel.com>2013-03-21 12:43:46 +0000
commitec0971ba5372a4dfa753f232449d23a8fd98490e (patch)
tree1c364f3e1fbbd75a413edc80c1c237e210e997c0
parented9dc8ce7a1c8115dba9483a9b51df8b63a2e0ef (diff)
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efivars: Add module parameter to disable use as a pstore backend
We know that with some firmware implementations writing too much data to UEFI variables can lead to bricking machines. Recent changes attempt to address this issue, but for some it may still be prudent to avoid writing large amounts of data until the solution has been proven on a wide variety of hardware. Crash dumps or other data from pstore can potentially be a large data source. Add a pstore_module parameter to efivars to allow disabling its use as a backend for pstore. Also add a config option, CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE, to allow setting the default value of this paramter to true (i.e. disabled by default). Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Cc: Josh Boyer <jwboyer@redhat.com> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Seiji Aguchi <seiji.aguchi@hds.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
-rw-r--r--drivers/firmware/Kconfig9
-rw-r--r--drivers/firmware/efivars.c8
2 files changed, 16 insertions, 1 deletions
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 898023d8e486..42c759a4d047 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -62,6 +62,15 @@ config EFI_VARS_PSTORE
will allow writing console messages, crash dumps, or anything
else supported by pstore to EFI variables.
+config EFI_VARS_PSTORE_DEFAULT_DISABLE
+ bool "Disable using efivars as a pstore backend by default"
+ depends on EFI_VARS_PSTORE
+ default n
+ help
+ Saying Y here will disable the use of efivars as a storage
+ backend for pstore by default. This setting can be overridden
+ using the efivars module's pstore_disable parameter.
+
config EFI_PCDP
bool "Console device selection via EFI PCDP or HCDP table"
depends on ACPI && EFI && IA64
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 37b6f247399e..6607daf5a08d 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -103,6 +103,11 @@ MODULE_VERSION(EFIVARS_VERSION);
*/
#define GUID_LEN 36
+static bool efivars_pstore_disable =
+ IS_ENABLED(EFI_VARS_PSTORE_DEFAULT_DISABLE);
+
+module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
+
/*
* The maximum size of VariableName + Data = 1024
* Therefore, it's reasonable to save that much
@@ -2009,7 +2014,8 @@ int register_efivars(struct efivars *efivars,
if (error)
unregister_efivars(efivars);
- efivar_pstore_register(efivars);
+ if (!efivars_pstore_disable)
+ efivar_pstore_register(efivars);
register_filesystem(&efivarfs_type);