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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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Fengguang reported random corruptions from various locations on x86-32
after commits d2852a224050 ("arch: add ARCH_HAS_SET_MEMORY config") and
9d876e79df6a ("bpf: fix unlocking of jited image when module ronx not set")
that uses the former. While x86-32 doesn't have a JIT like x86_64, the
bpf_prog_lock_ro() and bpf_prog_unlock_ro() got enabled due to
ARCH_HAS_SET_MEMORY, whereas Fengguang's test kernel doesn't have module
support built in and therefore never had the DEBUG_SET_MODULE_RONX setting
enabled.
After investigating the crashes further, it turned out that using
set_memory_ro() and set_memory_rw() didn't have the desired effect, for
example, setting the pages as read-only on x86-32 would still let
probe_kernel_write() succeed without error. This behavior would manifest
itself in situations where the vmalloc'ed buffer was accessed prior to
set_memory_*() such as in case of bpf_prog_alloc(). In cases where it
wasn't, the page attribute changes seemed to have taken effect, leading to
the conclusion that a TLB invalidate didn't happen. Moreover, it turned out
that this issue reproduced with qemu in "-cpu kvm64" mode, but not for
"-cpu host". When the issue occurs, change_page_attr_set_clr() did trigger
a TLB flush as expected via __flush_tlb_all() through cpa_flush_range(),
though.
There are 3 variants for issuing a TLB flush: invpcid_flush_all() (depends
on CPU feature bits X86_FEATURE_INVPCID, X86_FEATURE_PGE), cr4 based flush
(depends on X86_FEATURE_PGE), and cr3 based flush. For "-cpu host" case in
my setup, the flush used invpcid_flush_all() variant, whereas for "-cpu
kvm64", the flush was cr4 based. Switching the kvm64 case to cr3 manually
worked fine, and further investigating the cr4 one turned out that
X86_CR4_PGE bit was not set in cr4 register, meaning the
__native_flush_tlb_global_irq_disabled() wrote cr4 twice with the same
value instead of clearing X86_CR4_PGE in the first write to trigger the
flush.
It turned out that X86_CR4_PGE was cleared from cr4 during init from
lguest_arch_host_init() via adjust_pge(). The X86_FEATURE_PGE bit is also
cleared from there due to concerns of using PGE in guest kernel that can
lead to hard to trace bugs (see bff672e630a0 ("lguest: documentation V:
Host") in init()). The CPU feature bits are cleared in dynamic
boot_cpu_data, but they never propagated to __flush_tlb_all() as it uses
static_cpu_has() instead of boot_cpu_has() for testing which variant of TLB
flushing to use, meaning they still used the old setting of the host
kernel.
Clearing via setup_clear_cpu_cap(X86_FEATURE_PGE) so this would propagate
to static_cpu_has() checks is too late at this point as sections have been
patched already, so for now, it seems reasonable to switch back to
boot_cpu_has(X86_FEATURE_PGE) as it was prior to commit c109bf95992b
("x86/cpufeature: Remove cpu_has_pge"). This lets the TLB flush trigger via
cr3 as originally intended, properly makes the new page attributes visible
and thus fixes the crashes seen by Fengguang.
Fixes: c109bf95992b ("x86/cpufeature: Remove cpu_has_pge")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: bp@suse.de
Cc: Kees Cook <keescook@chromium.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: lkp@01.org
Cc: Laura Abbott <labbott@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernrl.org/r/20170301125426.l4nf65rx4wahohyl@wfg-t540p.sh.intel.com
Link: http://lkml.kernel.org/r/25c41ad9eca164be4db9ad84f768965b7eb19d9e.1489191673.git.daniel@iogearbox.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The purgatory code defines global variables which are referenced via a
symbol lookup in the kexec code (core and arch).
A recent commit addressing sparse warnings made these static and thereby
broke kexec_file.
Why did this happen? Simply because the whole machinery is undocumented and
lacks any form of forward declarations. The variable names are unspecific
and lack a prefix, so adding forward declarations creates shadow variables
in the core code. Aside of that the code relies on magic constants and
duplicate struct definitions with no way to ensure that these things stay
in sync. The section placement of the purgatory variables happened by
chance and not by design.
Unbreak kexec and cleanup the mess:
- Add proper forward declarations and document the usage
- Use common struct definition
- Use the proper common defines instead of magic constants
- Add a purgatory_ prefix to have a proper name space
- Use ARRAY_SIZE() instead of a homebrewn reimplementation
- Add proper sections to the purgatory variables [ From Mike ]
Fixes: 72042a8c7b01 ("x86/purgatory: Make functions and variables static")
Reported-by: Mike Galbraith <<efault@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Tobin C. Harding" <me@tobin.cc>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1703101315140.3681@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The reboot quirk for ASUS EeeBook X205TA contains a typo in
DMI_PRODUCT_NAME, improperly referring to X205TAW instead of
X205TA, which prevents the quirk from being triggered. The
model X205TAW already has a reboot quirk of its own.
This fix simply removes the inappropriate final letter W.
Fixes: 90b28ded88dd ("x86/reboot/quirks: Add ASUS EeeBook X205TA reboot quirk")
Signed-off-by: Matjaz Hegedic <matjaz.hegedic@gmail.com>
Link: http://lkml.kernel.org/r/1489064417-7445-1-git-send-email-matjaz.hegedic@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull sched.h split-up fixes for MIPS from Ingo Molnar:
"These are the fixes for MIPS build failures due to the sched.h
split-up, from Arnd Bergmann"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
MIPS: Add missing include files
Commit 13ad59df67f1 ("mm, page_alloc: avoid page_to_pfn() when merging
buddies") moved the check for memory holes out of page_is_buddy() and
had the callers do the check.
But this wasn't done correctly in one place which caused ia64 to crash
very early in boot.
Update to fix that and make ia64 boot again.
[ v2: Vlastimil pointed out we don't need to call page_to_pfn()
since we already have the result of that in "buddy_pfn" ]
Fixes: 13ad59df67f1 ("avoid page_to_pfn() when merging buddies")
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After the split of linux/sched.h, several platforms in arch/mips stopped building.
Add the respective additional #include statements to fix the problem I first
tried adding these into asm/processor.h, but ran into circular header
dependencies with that which I could not figure out.
The commit I listed as causing the problem is the branch merge, as there is
likely a combination of multiple patches in that branch.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: ralf@linux-mips.org
Fixes: 1827adb11ad2 ("Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")
Link: http://lkml.kernel.org/r/20170308072931.3836696-1-arnd@arndb.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull ktest fixes from Steven Rostedt:
"Greg Kroah-Hartman reported to me that the ktest of v4.11-rc1 locked
up in an infinite loop while doing the make mrproper.
Looking into the cause I noticed that a recent update to the function
run_command (used for running all shell commands, including "make
mrproper") changed the internal loop to use the function
wait_for_input.
The wait_for_input function uses select to look at two file
descriptors. One is the file descriptor of the command it is running,
the other is STDIN. The STDIN check was not checking the return status
of the sysread call, and was also just writing a lot of data into
syswrite without regard to the size of the data read.
Changing the code to check the return status of sysread, and also to
still process the passed in descriptor data without looping back to
the select fixed Greg's problem.
While looking at this code I also realized that the loop did not honor
the timeout if STDIN always had input (or for some reason return
error). this could prevent wait_for_input to timeout on the file
descriptor it is suppose to be waiting for. That is fixed too"
* tag 'ktest-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-ktest:
ktest: Make sure wait_for_input does honor the timeout
ktest: Fix while loop in wait_for_input
Pull x86 fixes from Ingo Molnar:
"Misc fixes and minor updates all over the place:
- an SGI/UV fix
- a defconfig update
- a build warning fix
- move the boot_params file to the arch location in debugfs
- a pkeys fix
- selftests fix
- boot message fixes
- sparse fixes
- a resume warning fix
- ioapic hotplug fixes
- reboot quirks
... plus various minor cleanups"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/build/x86_64_defconfig: Enable CONFIG_R8169
x86/reboot/quirks: Add ASUS EeeBook X205TA/W reboot quirk
x86/hpet: Prevent might sleep splat on resume
x86/boot: Correct setup_header.start_sys name
x86/purgatory: Fix sparse warning, symbol not declared
x86/purgatory: Make functions and variables static
x86/events: Remove last remnants of old filenames
x86/pkeys: Check against max pkey to avoid overflows
x86/ioapic: Split IOAPIC hot-removal into two steps
x86/PCI: Implement pcibios_release_device to release IRQ from IOAPIC
x86/intel_rdt: Remove duplicate inclusion of linux/cpu.h
x86/vmware: Remove duplicate inclusion of asm/timer.h
x86/hyperv: Hide unused label
x86/reboot/quirks: Add ASUS EeeBook X205TA reboot quirk
x86/platform/uv/BAU: Fix HUB errors by remove initial write to sw-ack register
x86/selftests: Add clobbers for int80 on x86_64
x86/apic: Simplify enable_IR_x2apic(), remove try_to_enable_IR()
x86/apic: Fix a warning message in logical CPU IDs allocation
x86/kdebugfs: Move boot params hierarchy under (debugfs)/x86/
This removes the extra include header file that was added in commit
e58bc927835a "Pull overlayfs updates from Miklos Szeredi" now that it
is no longer needed.
There are probably other such includes that got added during the
scheduler header splitup series, but this is the one that annoyed me
personally and I know about.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The function wait_for_input takes in a timeout, and even has a default
timeout. But if for some reason the STDIN descriptor keeps sending in data,
the function will never time out. The timout is to wait for the data from
the passed in file descriptor, not for STDIN. Adding a test in the case
where there's no data from the passed in file descriptor that checks to see
if the timeout passed, will ensure that it will timeout properly even if
there's input in STDIN.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull timer fixes from Ingo Molnar:
"This includes a fix for lockups caused by incorrect nsecs related
cleanup, and a capabilities check fix for timerfd"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
jiffies: Revert bogus conversion of NSEC_PER_SEC to TICK_NSEC
timerfd: Only check CAP_WAKE_ALARM when it is needed
Very common PCIe ethernet card. Already enabled in i386_defconfig.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Link: http://lkml.kernel.org/r/20170306085748.85957-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The scheduler header file split and cleanups ended up exposing a few
nasty header file dependencies, and in particular it showed how we in
<linux/wait.h> ended up depending on "signal_pending()", which now comes
from <linux/sched/signal.h>.
That's a very subtle and annoying dependency, which already caused a
semantic merge conflict (see commit e58bc927835a "Pull overlayfs updates
from Miklos Szeredi", which added that fixup in the merge commit).
It turns out that we can avoid this dependency _and_ improve code
generation by moving the guts of the fairly nasty helper #define
__wait_event_interruptible_locked() to out-of-line code. The code that
includes the signal_pending() check is all in the slow-path where we
actually go to sleep waiting for the event anyway, so using a helper
function is the right thing to do.
Using a helper function is also what we already did for the non-locked
versions, see the "__wait_event*()" macros and the "prepare_to_wait*()"
set of helper functions.
We might want to try to unify all these macro games, we have a _lot_ of
subtly different wait-event loops. But this is the minimal patch to fix
the annoying header dependency.
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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