The intent is that if we aren't allowed to block because we're in an
NMI or an emergency then we only take the lock if it is uncontended.
Part of the problem is the test is reversed so we return -EBUSY if we
acquire the lock.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Seiji reported getting empty dmesg-* files, because the data was never
actually read in efi_pstore_read_func(), and so the memcpy() was copying
garbage data.
This patch necessitated adding __efivar_entry_get() which is callable
between efivar_entry_iter_{begin,end}(). We can also delete
__efivar_entry_size() because efi_pstore_read_func() was the only
caller.
Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
We need to remove the entry from the EFI variable list before we erase
it from the variable store and free the associated state, otherwise it's
possible to hit the following crash,
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8142ea0f>] __efivar_entry_iter+0xcf/0x120
PGD 19483f067 PUD 195426067 PMD 0
Oops: 0000 [#1] SMP
[...]
Call Trace:
[<ffffffff81430ebf>] efi_pstore_erase+0xef/0x140
[<ffffffff81003138>] ? math_error+0x288/0x2d0
[<ffffffff811ea491>] pstore_unlink+0x41/0x60
[<ffffffff811741ff>] vfs_unlink+0x9f/0x110
[<ffffffff8117813b>] do_unlinkat+0x18b/0x280
[<ffffffff8116d7e6>] ? sys_newfstatat+0x36/0x50
[<ffffffff81178472>] sys_unlinkat+0x22/0x40
[<ffffffff81543282>] system_call_fastpath+0x16/0x1b
Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Seiji reports hitting the following crash when erasing pstore dump
variables,
BUG: unable to handle kernel NULL pointer dereference at 0000000000000fa4
IP: [<ffffffff8142dadf>] __efivar_entry_iter+0x2f/0x120
PGD 18482a067 PUD 190724067 PMD 0
Oops: 0000 [#1] SMP
[...]
Call Trace:
[<ffffffff8143001f>] efi_pstore_erase+0xdf/0x130
[<ffffffff81200038>] ? cap_socket_create+0x8/0x10
[<ffffffff811ea491>] pstore_unlink+0x41/0x60
[<ffffffff811741ff>] vfs_unlink+0x9f/0x110
[<ffffffff8117813b>] do_unlinkat+0x18b/0x280
[<ffffffff81178472>] sys_unlinkat+0x22/0x40
[<ffffffff81542402>] system_call_fastpath+0x16/0x1b
'entry' needs to be initialised in efi_pstore_erase() when iterating
with __efivar_entry_iter(), otherwise the garbage pointer will be
dereferenced, leading to crashes like the above.
Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
This registers /sys/firmware/efi/{,systab,efivars/} whenever EFI is enabled
and the system is booted with EFI.
This allows
*) userspace to check for the existence of /sys/firmware/efi as a way
to determine whether or it is running on an EFI system.
*) 'mount -t efivarfs none /sys/firmware/efi/efivars' without manually
loading any modules.
[ Also, move the efivar API into vars.c and unconditionally compile it.
This allows us to move efivars.c, which now only contains the sysfs
variable code, into the firmware/efi directory. Note that the efivars.c
filename is kept to maintain backwards compatability with the old
efivars.ko module. With this patch it is now possible for efivarfs
to be built without CONFIG_EFI_VARS - Matt ]
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Chun-Yi Lee <jlee@suse.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Tobias Powalowski <tpowa@archlinux.org>
Signed-off-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
efivars.c has grown far too large and needs to be divided up. Create a
new directory and move the persistence storage code to efi-pstore.c now
that it uses the new efivar API. This helps us to greatly reduce the
size of efivars.c and paves the way for moving other code out of
efivars.c.
Note that because CONFIG_EFI_VARS can be built as a module efi-pstore
must also include support for building as a module.
Reviewed-by: Tom Gundersen <teg@jklm.no>
Tested-by: Tom Gundersen <teg@jklm.no>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
