user/sven/linux.git/include/linux/efi.h, branch v3.12.48

efivars, efi-pstore: Hold off deletion of sysfs entry until the scan is completed

2013-12-12T06:37:53Z

commit e0d59733f6b1796b8d6692642c87d7dd862c3e3a upstream. Currently, when mounting pstore file system, a read callback of efi_pstore driver runs mutiple times as below. - In the first read callback, scan efivar_sysfs_list from head and pass a kmsg buffer of a entry to an upper pstore layer. - In the second read callback, rescan efivar_sysfs_list from the entry and pass another kmsg buffer to it. - Repeat the scan and pass until the end of efivar_sysfs_list. In this process, an entry is read across the multiple read function calls. To avoid race between the read and erasion, the whole process above is protected by a spinlock, holding in open() and releasing in close(). At the same time, kmemdup() is called to pass the buffer to pstore filesystem during it. And then, it causes a following lockdep warning. To make the dynamic memory allocation runnable without taking spinlock, holding off a deletion of sysfs entry if it happens while scanning it via efi_pstore, and deleting it after the scan is completed. To implement it, this patch introduces two flags, scanning and deleting, to efivar_entry. On the code basis, it seems that all the scanning and deleting logic is not needed because __efivars->lock are not dropped when reading from the EFI variable store. But, the scanning and deleting logic is still needed because an efi-pstore and a pstore filesystem works as follows. In case an entry(A) is found, the pointer is saved to psi->data. And efi_pstore_read() passes the entry(A) to a pstore filesystem by releasing __efivars->lock. And then, the pstore filesystem calls efi_pstore_read() again and the same entry(A), which is saved to psi->data, is used for resuming to scan a sysfs-list. So, to protect the entry(A), the logic is needed. [ 1.143710] ------------[ cut here ]------------ [ 1.144058] WARNING: CPU: 1 PID: 1 at kernel/lockdep.c:2740 lockdep_trace_alloc+0x104/0x110() [ 1.144058] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) [ 1.144058] Modules linked in: [ 1.144058] CPU: 1 PID: 1 Comm: systemd Not tainted 3.11.0-rc5 #2 [ 1.144058] 0000000000000009 ffff8800797e9ae0 ffffffff816614a5 ffff8800797e9b28 [ 1.144058] ffff8800797e9b18 ffffffff8105510d 0000000000000080 0000000000000046 [ 1.144058] 00000000000000d0 00000000000003af ffffffff81ccd0c0 ffff8800797e9b78 [ 1.144058] Call Trace: [ 1.144058] [] dump_stack+0x54/0x74 [ 1.144058] [] warn_slowpath_common+0x7d/0xa0 [ 1.144058] [] warn_slowpath_fmt+0x4c/0x50 [ 1.144058] [] ? vsscanf+0x57f/0x7b0 [ 1.144058] [] lockdep_trace_alloc+0x104/0x110 [ 1.144058] [] __kmalloc_track_caller+0x50/0x280 [ 1.144058] [] ? efi_pstore_read_func.part.1+0x12b/0x170 [ 1.144058] [] kmemdup+0x20/0x50 [ 1.144058] [] efi_pstore_read_func.part.1+0x12b/0x170 [ 1.144058] [] ? efi_pstore_read_func.part.1+0x170/0x170 [ 1.144058] [] efi_pstore_read_func+0xb4/0xe0 [ 1.144058] [] __efivar_entry_iter+0xfb/0x120 [ 1.144058] [] efi_pstore_read+0x3f/0x50 [ 1.144058] [] pstore_get_records+0x9a/0x150 [ 1.158207] [] ? selinux_d_instantiate+0x1c/0x20 [ 1.158207] [] ? parse_options+0x80/0x80 [ 1.158207] [] pstore_fill_super+0xa5/0xc0 [ 1.158207] [] mount_single+0xa2/0xd0 [ 1.158207] [] pstore_mount+0x18/0x20 [ 1.158207] [] mount_fs+0x39/0x1b0 [ 1.158207] [] ? __alloc_percpu+0x10/0x20 [ 1.158207] [] vfs_kern_mount+0x63/0xf0 [ 1.158207] [] do_mount+0x23e/0xa20 [ 1.158207] [] ? strndup_user+0x4b/0xf0 [ 1.158207] [] SyS_mount+0x83/0xc0 [ 1.158207] [] system_call_fastpath+0x16/0x1b [ 1.158207] ---[ end trace 61981bc62de9f6f4 ]--- Signed-off-by: Seiji Aguchi Tested-by: Madper Xie Signed-off-by: Matt Fleming Signed-off-by: Greg Kroah-Hartman

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-07-06T21:09:38Z

Pull timer core updates from Thomas Gleixner: "The timer changes contain: - posix timer code consolidation and fixes for odd corner cases - sched_clock implementation moved from ARM to core code to avoid duplication by other architectures - alarm timer updates - clocksource and clockevents unregistration facilities - clocksource/events support for new hardware - precise nanoseconds RTC readout (Xen feature) - generic support for Xen suspend/resume oddities - the usual lot of fixes and cleanups all over the place The parts which touch other areas (ARM/XEN) have been coordinated with the relevant maintainers. Though this results in an handful of trivial to solve merge conflicts, which we preferred over nasty cross tree merge dependencies. The patches which have been committed in the last few days are bug fixes plus the posix timer lot. The latter was in akpms queue and next for quite some time; they just got forgotten and Frederic collected them last minute." * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (59 commits) hrtimer: Remove unused variable hrtimers: Move SMP function call to thread context clocksource: Reselect clocksource when watchdog validated high-res capability posix-cpu-timers: don't account cpu timer after stopped thread runtime accounting posix_timers: fix racy timer delta caching on task exit posix-timers: correctly get dying task time sample in posix_cpu_timer_schedule() selftests: add basic posix timers selftests posix_cpu_timers: consolidate expired timers check posix_cpu_timers: consolidate timer list cleanups posix_cpu_timer: consolidate expiry time type tick: Sanitize broadcast control logic tick: Prevent uncontrolled switch to oneshot mode tick: Make oneshot broadcast robust vs. CPU offlining x86: xen: Sync the CMOS RTC as well as the Xen wallclock x86: xen: Sync the wallclock when the system time is set timekeeping: Indicate that clock was set in the pvclock gtod notifier timekeeping: Pass flags instead of multiple bools to timekeeping_update() xen: Remove clock_was_set() call in the resume path hrtimers: Support resuming with two or more CPUs online (but stopped) timer: Fix jiffies wrap behavior of round_jiffies_common() ...

efi: Convert runtime services function ptrs

2013-06-11T06:39:26Z

... to void * like the boot services and lose all the void * casts. No functionality change. Signed-off-by: Borislav Petkov Signed-off-by: Matt Fleming

x86: Increase precision of x86_platform.get/set_wallclock()

2013-05-28T21:00:59Z

All the virtualized platforms (KVM, lguest and Xen) have persistent wallclocks that have more than one second of precision. read_persistent_wallclock() and update_persistent_wallclock() allow for nanosecond precision but their implementation on x86 with x86_platform.get/set_wallclock() only allows for one second precision. This means guests may see a wallclock time that is off by up to 1 second. Make set_wallclock() and get_wallclock() take a struct timespec parameter (which allows for nanosecond precision) so KVM and Xen guests may start with a more accurate wallclock time and a Xen dom0 can maintain a more accurate wallclock for guests. Signed-off-by: David Vrabel Signed-off-by: John Stultz

efi, pstore: Read data from variable store before memcpy()

2013-04-30T15:03:10Z

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 Tested-by: Seiji Aguchi Cc: Tony Luck Cc: Matthew Garrett Signed-off-by: Matt Fleming

Merge tag 'v3.9' into efi-for-tip2

2013-04-30T10:42:13Z

Resolve conflicts for Ingo. Conflicts: drivers/firmware/Kconfig drivers/firmware/efivars.c Signed-off-by: Matt Fleming

efi: split efisubsystem from efivars

2013-04-17T12:27:06Z

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 Cc: Tony Luck Cc: Mike Waychison Cc: Kay Sievers Cc: Jeremy Kerr Cc: Matthew Garrett Cc: Chun-Yi Lee Cc: Andy Whitcroft Cc: Tobias Powalowski Signed-off-by: Tom Gundersen Signed-off-by: Matt Fleming

efivars: Move pstore code into the new EFI directory

2013-04-17T12:24:01Z

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 Tested-by: Tom Gundersen Cc: Seiji Aguchi Cc: Anton Vorontsov Cc: Colin Cross Cc: Kees Cook Cc: Matthew Garrett Cc: Tony Luck Signed-off-by: Matt Fleming

efivars: efivar_entry API

2013-04-17T12:23:59Z

There isn't really a formal interface for dealing with EFI variables or struct efivar_entry. Historically, this has led to various bits of code directly accessing the generic EFI variable ops, which inherently ties it to specific EFI variable operations instead of indirectly using whatever ops were registered with register_efivars(). This lead to the efivarfs code only working with the generic EFI variable ops and not CONFIG_GOOGLE_SMI. Encapsulate everything that needs to access '__efivars' inside an efivar_entry_* API and use the new API in the pstore, sysfs and efivarfs code. Much of the efivars code had to be rewritten to use this new API. For instance, it is now up to the users of the API to build the initial list of EFI variables in their efivar_init() callback function. The variable list needs to be passed to efivar_init() which allows us to keep work arounds for things like implementation bugs in GetNextVariable() in a central location. Allowing users of the API to use a callback function to build the list greatly benefits the efivarfs code which needs to allocate inodes and dentries for every variable. It previously did this in a racy way because the code ran without holding the variable spinlock. Both the sysfs and efivarfs code maintain their own lists which means the two interfaces can be running simultaneously without interference, though it should be noted that because no synchronisation is performed it is very easy to create inconsistencies. efibootmgr doesn't currently use efivarfs and users are likely to also require the old sysfs interface, so it makes sense to allow both to be built. Reviewed-by: Tom Gundersen Tested-by: Tom Gundersen Cc: Seiji Aguchi Cc: Matthew Garrett Cc: Jeremy Kerr Cc: Tony Luck Cc: Mike Waychison Signed-off-by: Matt Fleming

efi: move utf16 string functions to efi.h

2013-04-17T07:28:21Z

There are currently two implementations of the utf16 string functions. Somewhat confusingly, they've got different names. Centralise the functions in efi.h. Reviewed-by: Tom Gundersen Tested-by: Tom Gundersen Reviewed-by: Mike Waychison Signed-off-by: Matt Fleming