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  1. 21 7月, 2019 5 次提交
    • T
      genirq: Add optional hardware synchronization for shutdown · 6074f604
      由 Thomas Gleixner 提交于 
      commit 62e0468650c30f0298822c580f382b16328119f6 upstream

free_irq() ensures that no hardware interrupt handler is executing on a
different CPU before actually releasing resources and deactivating the
interrupt completely in a domain hierarchy.

But that does not catch the case where the interrupt is on flight at the
hardware level but not yet serviced by the target CPU. That creates an
interesing race condition:

   CPU 0                  CPU 1               IRQ CHIP

                                              interrupt is raised
                                              sent to CPU1
			  Unable to handle
			  immediately
			  (interrupts off,
			   deep idle delay)
   mask()
   ...
   free()
     shutdown()
     synchronize_irq()
     release_resources()
                          do_IRQ()
                            -> resources are not available

That might be harmless and just trigger a spurious interrupt warning, but
some interrupt chips might get into a wedged state.

Utilize the existing irq_get_irqchip_state() callback for the
synchronization in free_irq().

synchronize_hardirq() is not using this mechanism as it might actually
deadlock unter certain conditions, e.g. when called with interrupts
disabled and the target CPU is the one on which the synchronization is
invoked. synchronize_irq() uses it because that function cannot be called
from non preemtible contexts as it might sleep.

No functional change intended and according to Marc the existing GIC
implementations where the driver supports the callback should be able
to cope with that core change. Famous last words.

Fixes: 464d1230 ("x86/vector: Switch IOAPIC to global reservation mode")
Reported-by: NRobert Hodaszi <Robert.Hodaszi@digi.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Tested-by: NMarc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20190628111440.279463375@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      6074f604
    • T
      genirq: Fix misleading synchronize_irq() documentation · 3f10ccc2
      由 Thomas Gleixner 提交于 
      commit 1d21f2af8571c6a6a44e7c1911780614847b0253 upstream

The function might sleep, so it cannot be called from interrupt
context. Not even with care.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20190628111440.189241552@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3f10ccc2
    • T
      genirq: Delay deactivation in free_irq() · 578db1aa
      由 Thomas Gleixner 提交于 
      commit 4001d8e8762f57d418b66e4e668601791900a1dd upstream

When interrupts are shutdown, they are immediately deactivated in the
irqdomain hierarchy. While this looks obviously correct there is a subtle
issue:

There might be an interrupt in flight when free_irq() is invoking the
shutdown. This is properly handled at the irq descriptor / primary handler
level, but the deactivation might completely disable resources which are
required to acknowledge the interrupt.

Split the shutdown code and deactivate the interrupt after synchronization
in free_irq(). Fixup all other usage sites where this is not an issue to
invoke the combined shutdown_and_deactivate() function instead.

This still might be an issue if the interrupt in flight servicing is
delayed on a remote CPU beyond the invocation of synchronize_irq(), but
that cannot be handled at that level and needs to be handled in the
synchronize_irq() context.

Fixes: f8264e34 ("irqdomain: Introduce new interfaces to support hierarchy irqdomains")
Reported-by: NRobert Hodaszi <Robert.Hodaszi@digi.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20190628111440.098196390@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      578db1aa
    • E
      cpu/hotplug: Fix out-of-bounds read when setting fail state · f6e01328
      由 Eiichi Tsukata 提交于 
      [ Upstream commit 33d4a5a7a5b4d02915d765064b2319e90a11cbde ]

Setting invalid value to /sys/devices/system/cpu/cpuX/hotplug/fail
can control `struct cpuhp_step *sp` address, results in the following
global-out-of-bounds read.

Reproducer:

  # echo -2 > /sys/devices/system/cpu/cpu0/hotplug/fail

KASAN report:

  BUG: KASAN: global-out-of-bounds in write_cpuhp_fail+0x2cd/0x2e0
  Read of size 8 at addr ffffffff89734438 by task bash/1941

  CPU: 0 PID: 1941 Comm: bash Not tainted 5.2.0-rc6+ #31
  Call Trace:
   write_cpuhp_fail+0x2cd/0x2e0
   dev_attr_store+0x58/0x80
   sysfs_kf_write+0x13d/0x1a0
   kernfs_fop_write+0x2bc/0x460
   vfs_write+0x1e1/0x560
   ksys_write+0x126/0x250
   do_syscall_64+0xc1/0x390
   entry_SYSCALL_64_after_hwframe+0x49/0xbe
  RIP: 0033:0x7f05e4f4c970

  The buggy address belongs to the variable:
   cpu_hotplug_lock+0x98/0xa0

  Memory state around the buggy address:
   ffffffff89734300: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
   ffffffff89734380: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
  >ffffffff89734400: 00 00 00 00 fa fa fa fa 00 00 00 00 fa fa fa fa
                                          ^
   ffffffff89734480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffffffff89734500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Add a sanity check for the value written from user space.

Fixes: 1db49484 ("smp/hotplug: Hotplug state fail injection")
Signed-off-by: NEiichi Tsukata <devel@etsukata.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Link: https://lkml.kernel.org/r/20190627024732.31672-1-devel@etsukata.comSigned-off-by: NSasha Levin <sashal@kernel.org>
      f6e01328
    • P
      perf/core: Fix perf_sample_regs_user() mm check · afda29dc
      由 Peter Zijlstra 提交于 
      [ Upstream commit 085ebfe937d7a7a5df1729f35a12d6d655fea68c ]

perf_sample_regs_user() uses 'current->mm' to test for the presence of
userspace, but this is insufficient, consider use_mm().

A better test is: '!(current->flags & PF_KTHREAD)', exec() clears
PF_KTHREAD after it sets the new ->mm but before it drops to userspace
for the first time.

Possibly obsoletes: bf05fc25 ("powerpc/perf: Fix oops when kthread execs user process")
Reported-by: NRavi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Reported-by: NYoung Xiao <92siuyang@gmail.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4018994f ("perf: Add ability to attach user level registers dump to sample")
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      afda29dc
  3. 14 7月, 2019 3 次提交
  5. 10 7月, 2019 8 次提交
    • D
      bpf: fix bpf_jit_limit knob for PAGE_SIZE >= 64K · 54e8cf41
      由 Daniel Borkmann 提交于 
      [ Upstream commit fdadd04931c2d7cd294dc5b2b342863f94be53a3 ]

Michael and Sandipan report:

  Commit ede95a63b5 introduced a bpf_jit_limit tuneable to limit BPF
  JIT allocations. At compile time it defaults to PAGE_SIZE * 40000,
  and is adjusted again at init time if MODULES_VADDR is defined.

  For ppc64 kernels, MODULES_VADDR isn't defined, so we're stuck with
  the compile-time default at boot-time, which is 0x9c400000 when
  using 64K page size. This overflows the signed 32-bit bpf_jit_limit
  value:

  root@ubuntu:/tmp# cat /proc/sys/net/core/bpf_jit_limit
  -1673527296

  and can cause various unexpected failures throughout the network
  stack. In one case `strace dhclient eth0` reported:

  setsockopt(5, SOL_SOCKET, SO_ATTACH_FILTER, {len=11, filter=0x105dd27f8},
             16) = -1 ENOTSUPP (Unknown error 524)

  and similar failures can be seen with tools like tcpdump. This doesn't
  always reproduce however, and I'm not sure why. The more consistent
  failure I've seen is an Ubuntu 18.04 KVM guest booted on a POWER9
  host would time out on systemd/netplan configuring a virtio-net NIC
  with no noticeable errors in the logs.

Given this and also given that in near future some architectures like
arm64 will have a custom area for BPF JIT image allocations we should
get rid of the BPF_JIT_LIMIT_DEFAULT fallback / default entirely. For
4.21, we have an overridable bpf_jit_alloc_exec(), bpf_jit_free_exec()
so therefore add another overridable bpf_jit_alloc_exec_limit() helper
function which returns the possible size of the memory area for deriving
the default heuristic in bpf_jit_charge_init().

Like bpf_jit_alloc_exec() and bpf_jit_free_exec(), the new
bpf_jit_alloc_exec_limit() assumes that module_alloc() is the default
JIT memory provider, and therefore in case archs implement their custom
module_alloc() we use MODULES_{END,_VADDR} for limits and otherwise for
vmalloc_exec() cases like on ppc64 we use VMALLOC_{END,_START}.

Additionally, for archs supporting large page sizes, we should change
the sysctl to be handled as long to not run into sysctl restrictions
in future.

Fixes: ede95a63b5e8 ("bpf: add bpf_jit_limit knob to restrict unpriv allocations")
Reported-by: NSandipan Das <sandipan@linux.ibm.com>
Reported-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Tested-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      54e8cf41
    • P
      ftrace/x86: Remove possible deadlock between register_kprobe() and ftrace_run_update_code() · c854d9b6
      由 Petr Mladek 提交于 
      commit d5b844a2cf507fc7642c9ae80a9d585db3065c28 upstream.

The commit 9f255b632bf12c4dd7 ("module: Fix livepatch/ftrace module text
permissions race") causes a possible deadlock between register_kprobe()
and ftrace_run_update_code() when ftrace is using stop_machine().

The existing dependency chain (in reverse order) is:

-> #1 (text_mutex){+.+.}:
       validate_chain.isra.21+0xb32/0xd70
       __lock_acquire+0x4b8/0x928
       lock_acquire+0x102/0x230
       __mutex_lock+0x88/0x908
       mutex_lock_nested+0x32/0x40
       register_kprobe+0x254/0x658
       init_kprobes+0x11a/0x168
       do_one_initcall+0x70/0x318
       kernel_init_freeable+0x456/0x508
       kernel_init+0x22/0x150
       ret_from_fork+0x30/0x34
       kernel_thread_starter+0x0/0xc

-> #0 (cpu_hotplug_lock.rw_sem){++++}:
       check_prev_add+0x90c/0xde0
       validate_chain.isra.21+0xb32/0xd70
       __lock_acquire+0x4b8/0x928
       lock_acquire+0x102/0x230
       cpus_read_lock+0x62/0xd0
       stop_machine+0x2e/0x60
       arch_ftrace_update_code+0x2e/0x40
       ftrace_run_update_code+0x40/0xa0
       ftrace_startup+0xb2/0x168
       register_ftrace_function+0x64/0x88
       klp_patch_object+0x1a2/0x290
       klp_enable_patch+0x554/0x980
       do_one_initcall+0x70/0x318
       do_init_module+0x6e/0x250
       load_module+0x1782/0x1990
       __s390x_sys_finit_module+0xaa/0xf0
       system_call+0xd8/0x2d0

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(text_mutex);
                               lock(cpu_hotplug_lock.rw_sem);
                               lock(text_mutex);
  lock(cpu_hotplug_lock.rw_sem);

It is similar problem that has been solved by the commit 2d1e38f5
("kprobes: Cure hotplug lock ordering issues"). Many locks are involved.
To be on the safe side, text_mutex must become a low level lock taken
after cpu_hotplug_lock.rw_sem.

This can't be achieved easily with the current ftrace design.
For example, arm calls set_all_modules_text_rw() already in
ftrace_arch_code_modify_prepare(), see arch/arm/kernel/ftrace.c.
This functions is called:

  + outside stop_machine() from ftrace_run_update_code()
  + without stop_machine() from ftrace_module_enable()

Fortunately, the problematic fix is needed only on x86_64. It is
the only architecture that calls set_all_modules_text_rw()
in ftrace path and supports livepatching at the same time.

Therefore it is enough to move text_mutex handling from the generic
kernel/trace/ftrace.c into arch/x86/kernel/ftrace.c:

   ftrace_arch_code_modify_prepare()
   ftrace_arch_code_modify_post_process()

This patch basically reverts the ftrace part of the problematic
commit 9f255b632bf12c4dd7 ("module: Fix livepatch/ftrace module
text permissions race"). And provides x86_64 specific-fix.

Some refactoring of the ftrace code will be needed when livepatching
is implemented for arm or nds32. These architectures call
set_all_modules_text_rw() and use stop_machine() at the same time.

Link: http://lkml.kernel.org/r/20190627081334.12793-1-pmladek@suse.com

Fixes: 9f255b632bf12c4dd7 ("module: Fix livepatch/ftrace module text permissions race")
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Reported-by: NMiroslav Benes <mbenes@suse.cz>
Reviewed-by: NMiroslav Benes <mbenes@suse.cz>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NPetr Mladek <pmladek@suse.com>
[
  As reviewed by Miroslav Benes <mbenes@suse.cz>, removed return value of
  ftrace_run_update_code() as it is a void function.
]
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c854d9b6
    • E
      tracing/snapshot: Resize spare buffer if size changed · c8790d7f
      由 Eiichi Tsukata 提交于 
      commit 46cc0b44428d0f0e81f11ea98217fc0edfbeab07 upstream.

Current snapshot implementation swaps two ring_buffers even though their
sizes are different from each other, that can cause an inconsistency
between the contents of buffer_size_kb file and the current buffer size.

For example:

  # cat buffer_size_kb
  7 (expanded: 1408)
  # echo 1 > events/enable
  # grep bytes per_cpu/cpu0/stats
  bytes: 1441020
  # echo 1 > snapshot             // current:1408, spare:1408
  # echo 123 > buffer_size_kb     // current:123,  spare:1408
  # echo 1 > snapshot             // current:1408, spare:123
  # grep bytes per_cpu/cpu0/stats
  bytes: 1443700
  # cat buffer_size_kb
  123                             // != current:1408

And also, a similar per-cpu case hits the following WARNING:

Reproducer:

  # echo 1 > per_cpu/cpu0/snapshot
  # echo 123 > buffer_size_kb
  # echo 1 > per_cpu/cpu0/snapshot

WARNING:

  WARNING: CPU: 0 PID: 1946 at kernel/trace/trace.c:1607 update_max_tr_single.part.0+0x2b8/0x380
  Modules linked in:
  CPU: 0 PID: 1946 Comm: bash Not tainted 5.2.0-rc6 #20
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
  RIP: 0010:update_max_tr_single.part.0+0x2b8/0x380
  Code: ff e8 dc da f9 ff 0f 0b e9 88 fe ff ff e8 d0 da f9 ff 44 89 ee bf f5 ff ff ff e8 33 dc f9 ff 41 83 fd f5 74 96 e8 b8 da f9 ff <0f> 0b eb 8d e8 af da f9 ff 0f 0b e9 bf fd ff ff e8 a3 da f9 ff 48
  RSP: 0018:ffff888063e4fca0 EFLAGS: 00010093
  RAX: ffff888066214380 RBX: ffffffff99850fe0 RCX: ffffffff964298a8
  RDX: 0000000000000000 RSI: 00000000fffffff5 RDI: 0000000000000005
  RBP: 1ffff1100c7c9f96 R08: ffff888066214380 R09: ffffed100c7c9f9b
  R10: ffffed100c7c9f9a R11: 0000000000000003 R12: 0000000000000000
  R13: 00000000ffffffea R14: ffff888066214380 R15: ffffffff99851060
  FS:  00007f9f8173c700(0000) GS:ffff88806d000000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000714dc0 CR3: 0000000066fa6000 CR4: 00000000000006f0
  Call Trace:
   ? trace_array_printk_buf+0x140/0x140
   ? __mutex_lock_slowpath+0x10/0x10
   tracing_snapshot_write+0x4c8/0x7f0
   ? trace_printk_init_buffers+0x60/0x60
   ? selinux_file_permission+0x3b/0x540
   ? tracer_preempt_off+0x38/0x506
   ? trace_printk_init_buffers+0x60/0x60
   __vfs_write+0x81/0x100
   vfs_write+0x1e1/0x560
   ksys_write+0x126/0x250
   ? __ia32_sys_read+0xb0/0xb0
   ? do_syscall_64+0x1f/0x390
   do_syscall_64+0xc1/0x390
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

This patch adds resize_buffer_duplicate_size() to check if there is a
difference between current/spare buffer sizes and resize a spare buffer
if necessary.

Link: http://lkml.kernel.org/r/20190625012910.13109-1-devel@etsukata.com

Cc: stable@vger.kernel.org
Fixes: ad909e21 ("tracing: Add internal tracing_snapshot() functions")
Signed-off-by: NEiichi Tsukata <devel@etsukata.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c8790d7f
    • J
      ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME · 54435b7f
      由 Jann Horn 提交于 
      commit 6994eefb0053799d2e07cd140df6c2ea106c41ee upstream.

Fix two issues:

When called for PTRACE_TRACEME, ptrace_link() would obtain an RCU
reference to the parent's objective credentials, then give that pointer
to get_cred().  However, the object lifetime rules for things like
struct cred do not permit unconditionally turning an RCU reference into
a stable reference.

PTRACE_TRACEME records the parent's credentials as if the parent was
acting as the subject, but that's not the case.  If a malicious
unprivileged child uses PTRACE_TRACEME and the parent is privileged, and
at a later point, the parent process becomes attacker-controlled
(because it drops privileges and calls execve()), the attacker ends up
with control over two processes with a privileged ptrace relationship,
which can be abused to ptrace a suid binary and obtain root privileges.

Fix both of these by always recording the credentials of the process
that is requesting the creation of the ptrace relationship:
current_cred() can't change under us, and current is the proper subject
for access control.

This change is theoretically userspace-visible, but I am not aware of
any code that it will actually break.

Fixes: 64b875f7 ("ptrace: Capture the ptracer's creds not PT_PTRACE_CAP")
Signed-off-by: NJann Horn <jannh@google.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      54435b7f
    • W
      ftrace: Fix NULL pointer dereference in free_ftrace_func_mapper() · 2b39351e
      由 Wei Li 提交于 
      [ Upstream commit 04e03d9a616c19a47178eaca835358610e63a1dd ]

The mapper may be NULL when called from register_ftrace_function_probe()
with probe->data == NULL.

This issue can be reproduced as follow (it may be covered by compiler
optimization sometime):

/ # cat /sys/kernel/debug/tracing/set_ftrace_filter
#### all functions enabled ####
/ # echo foo_bar:dump > /sys/kernel/debug/tracing/set_ftrace_filter
[  206.949100] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[  206.952402] Mem abort info:
[  206.952819]   ESR = 0x96000006
[  206.955326]   Exception class = DABT (current EL), IL = 32 bits
[  206.955844]   SET = 0, FnV = 0
[  206.956272]   EA = 0, S1PTW = 0
[  206.956652] Data abort info:
[  206.957320]   ISV = 0, ISS = 0x00000006
[  206.959271]   CM = 0, WnR = 0
[  206.959938] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000419f3a000
[  206.960483] [0000000000000000] pgd=0000000411a87003, pud=0000000411a83003, pmd=0000000000000000
[  206.964953] Internal error: Oops: 96000006 [#1] SMP
[  206.971122] Dumping ftrace buffer:
[  206.973677]    (ftrace buffer empty)
[  206.975258] Modules linked in:
[  206.976631] Process sh (pid: 281, stack limit = 0x(____ptrval____))
[  206.978449] CPU: 10 PID: 281 Comm: sh Not tainted 5.2.0-rc1+ #17
[  206.978955] Hardware name: linux,dummy-virt (DT)
[  206.979883] pstate: 60000005 (nZCv daif -PAN -UAO)
[  206.980499] pc : free_ftrace_func_mapper+0x2c/0x118
[  206.980874] lr : ftrace_count_free+0x68/0x80
[  206.982539] sp : ffff0000182f3ab0
[  206.983102] x29: ffff0000182f3ab0 x28: ffff8003d0ec1700
[  206.983632] x27: ffff000013054b40 x26: 0000000000000001
[  206.984000] x25: ffff00001385f000 x24: 0000000000000000
[  206.984394] x23: ffff000013453000 x22: ffff000013054000
[  206.984775] x21: 0000000000000000 x20: ffff00001385fe28
[  206.986575] x19: ffff000013872c30 x18: 0000000000000000
[  206.987111] x17: 0000000000000000 x16: 0000000000000000
[  206.987491] x15: ffffffffffffffb0 x14: 0000000000000000
[  206.987850] x13: 000000000017430e x12: 0000000000000580
[  206.988251] x11: 0000000000000000 x10: cccccccccccccccc
[  206.988740] x9 : 0000000000000000 x8 : ffff000013917550
[  206.990198] x7 : ffff000012fac2e8 x6 : ffff000012fac000
[  206.991008] x5 : ffff0000103da588 x4 : 0000000000000001
[  206.991395] x3 : 0000000000000001 x2 : ffff000013872a28
[  206.991771] x1 : 0000000000000000 x0 : 0000000000000000
[  206.992557] Call trace:
[  206.993101]  free_ftrace_func_mapper+0x2c/0x118
[  206.994827]  ftrace_count_free+0x68/0x80
[  206.995238]  release_probe+0xfc/0x1d0
[  206.995555]  register_ftrace_function_probe+0x4a8/0x868
[  206.995923]  ftrace_trace_probe_callback.isra.4+0xb8/0x180
[  206.996330]  ftrace_dump_callback+0x50/0x70
[  206.996663]  ftrace_regex_write.isra.29+0x290/0x3a8
[  206.997157]  ftrace_filter_write+0x44/0x60
[  206.998971]  __vfs_write+0x64/0xf0
[  206.999285]  vfs_write+0x14c/0x2f0
[  206.999591]  ksys_write+0xbc/0x1b0
[  206.999888]  __arm64_sys_write+0x3c/0x58
[  207.000246]  el0_svc_common.constprop.0+0x408/0x5f0
[  207.000607]  el0_svc_handler+0x144/0x1c8
[  207.000916]  el0_svc+0x8/0xc
[  207.003699] Code: aa0003f8 a9025bf5 aa0103f5 f946ea80 (f9400303)
[  207.008388] ---[ end trace 7b6d11b5f542bdf1 ]---
[  207.010126] Kernel panic - not syncing: Fatal exception
[  207.011322] SMP: stopping secondary CPUs
[  207.013956] Dumping ftrace buffer:
[  207.014595]    (ftrace buffer empty)
[  207.015632] Kernel Offset: disabled
[  207.017187] CPU features: 0x002,20006008
[  207.017985] Memory Limit: none
[  207.019825] ---[ end Kernel panic - not syncing: Fatal exception ]---

Link: http://lkml.kernel.org/r/20190606031754.10798-1-liwei391@huawei.comSigned-off-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      2b39351e
    • J
      module: Fix livepatch/ftrace module text permissions race · 93804417
      由 Josh Poimboeuf 提交于 
      [ Upstream commit 9f255b632bf12c4dd7fc31caee89aa991ef75176 ]

It's possible for livepatch and ftrace to be toggling a module's text
permissions at the same time, resulting in the following panic:

  BUG: unable to handle page fault for address: ffffffffc005b1d9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0003) - permissions violation
  PGD 3ea0c067 P4D 3ea0c067 PUD 3ea0e067 PMD 3cc13067 PTE 3b8a1061
  Oops: 0003 [#1] PREEMPT SMP PTI
  CPU: 1 PID: 453 Comm: insmod Tainted: G           O  K   5.2.0-rc1-a188339ca5 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014
  RIP: 0010:apply_relocate_add+0xbe/0x14c
  Code: fa 0b 74 21 48 83 fa 18 74 38 48 83 fa 0a 75 40 eb 08 48 83 38 00 74 33 eb 53 83 38 00 75 4e 89 08 89 c8 eb 0a 83 38 00 75 43 <89> 08 48 63 c1 48 39 c8 74 2e eb 48 83 38 00 75 32 48 29 c1 89 08
  RSP: 0018:ffffb223c00dbb10 EFLAGS: 00010246
  RAX: ffffffffc005b1d9 RBX: 0000000000000000 RCX: ffffffff8b200060
  RDX: 000000000000000b RSI: 0000004b0000000b RDI: ffff96bdfcd33000
  RBP: ffffb223c00dbb38 R08: ffffffffc005d040 R09: ffffffffc005c1f0
  R10: ffff96bdfcd33c40 R11: ffff96bdfcd33b80 R12: 0000000000000018
  R13: ffffffffc005c1f0 R14: ffffffffc005e708 R15: ffffffff8b2fbc74
  FS:  00007f5f447beba8(0000) GS:ffff96bdff900000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffffffffc005b1d9 CR3: 000000003cedc002 CR4: 0000000000360ea0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   klp_init_object_loaded+0x10f/0x219
   ? preempt_latency_start+0x21/0x57
   klp_enable_patch+0x662/0x809
   ? virt_to_head_page+0x3a/0x3c
   ? kfree+0x8c/0x126
   patch_init+0x2ed/0x1000 [livepatch_test02]
   ? 0xffffffffc0060000
   do_one_initcall+0x9f/0x1c5
   ? kmem_cache_alloc_trace+0xc4/0xd4
   ? do_init_module+0x27/0x210
   do_init_module+0x5f/0x210
   load_module+0x1c41/0x2290
   ? fsnotify_path+0x3b/0x42
   ? strstarts+0x2b/0x2b
   ? kernel_read+0x58/0x65
   __do_sys_finit_module+0x9f/0xc3
   ? __do_sys_finit_module+0x9f/0xc3
   __x64_sys_finit_module+0x1a/0x1c
   do_syscall_64+0x52/0x61
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

The above panic occurs when loading two modules at the same time with
ftrace enabled, where at least one of the modules is a livepatch module:

CPU0					CPU1
klp_enable_patch()
  klp_init_object_loaded()
    module_disable_ro()
    					ftrace_module_enable()
					  ftrace_arch_code_modify_post_process()
				    	    set_all_modules_text_ro()
      klp_write_object_relocations()
        apply_relocate_add()
	  *patches read-only code* - BOOM

A similar race exists when toggling ftrace while loading a livepatch
module.

Fix it by ensuring that the livepatch and ftrace code patching
operations -- and their respective permissions changes -- are protected
by the text_mutex.

Link: http://lkml.kernel.org/r/ab43d56ab909469ac5d2520c5d944ad6d4abd476.1560474114.git.jpoimboe@redhat.comReported-by: NJohannes Erdfelt <johannes@erdfelt.com>
Fixes: 444d13ff ("modules: add ro_after_init support")
Acked-by: NJessica Yu <jeyu@kernel.org>
Reviewed-by: NPetr Mladek <pmladek@suse.com>
Reviewed-by: NMiroslav Benes <mbenes@suse.cz>
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      93804417
    • V
      tracing: avoid build warning with HAVE_NOP_MCOUNT · 220adcc0
      由 Vasily Gorbik 提交于 
      [ Upstream commit cbdaeaf050b730ea02e9ab4ff844ce54d85dbe1d ]

Selecting HAVE_NOP_MCOUNT enables -mnop-mcount (if gcc supports it)
and sets CC_USING_NOP_MCOUNT. Reuse __is_defined (which is suitable for
testing CC_USING_* defines) to avoid conditional compilation and fix
the following gcc 9 warning on s390:

kernel/trace/ftrace.c:2514:1: warning: ‘ftrace_code_disable’ defined
but not used [-Wunused-function]

Link: http://lkml.kernel.org/r/patch.git-1a82d13f33ac.your-ad-here.call-01559732716-ext-6629@work.hours

Fixes: 2f4df001 ("tracing: Add -mcount-nop option support")
Signed-off-by: NVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      220adcc0
    • J
      cpuset: restore sanity to cpuset_cpus_allowed_fallback() · b7747ecb
      由 Joel Savitz 提交于 
      [ Upstream commit d477f8c202d1f0d4791ab1263ca7657bbe5cf79e ]

In the case that a process is constrained by taskset(1) (i.e.
sched_setaffinity(2)) to a subset of available cpus, and all of those are
subsequently offlined, the scheduler will set tsk->cpus_allowed to
the current value of task_cs(tsk)->effective_cpus.

This is done via a call to do_set_cpus_allowed() in the context of
cpuset_cpus_allowed_fallback() made by the scheduler when this case is
detected. This is the only call made to cpuset_cpus_allowed_fallback()
in the latest mainline kernel.

However, this is not sane behavior.

I will demonstrate this on a system running the latest upstream kernel
with the following initial configuration:

	# grep -i cpu /proc/$$/status
	Cpus_allowed:	ffffffff,fffffff
	Cpus_allowed_list:	0-63

(Where cpus 32-63 are provided via smt.)

If we limit our current shell process to cpu2 only and then offline it
and reonline it:

	# taskset -p 4 $$
	pid 2272's current affinity mask: ffffffffffffffff
	pid 2272's new affinity mask: 4

	# echo off > /sys/devices/system/cpu/cpu2/online
	# dmesg | tail -3
	[ 2195.866089] process 2272 (bash) no longer affine to cpu2
	[ 2195.872700] IRQ 114: no longer affine to CPU2
	[ 2195.879128] smpboot: CPU 2 is now offline

	# echo on > /sys/devices/system/cpu/cpu2/online
	# dmesg | tail -1
	[ 2617.043572] smpboot: Booting Node 0 Processor 2 APIC 0x4

We see that our current process now has an affinity mask containing
every cpu available on the system _except_ the one we originally
constrained it to:

	# grep -i cpu /proc/$$/status
	Cpus_allowed:   ffffffff,fffffffb
	Cpus_allowed_list:      0-1,3-63

This is not sane behavior, as the scheduler can now not only place the
process on previously forbidden cpus, it can't even schedule it on
the cpu it was originally constrained to!

Other cases result in even more exotic affinity masks. Take for instance
a process with an affinity mask containing only cpus provided by smt at
the moment that smt is toggled, in a configuration such as the following:

	# taskset -p f000000000 $$
	# grep -i cpu /proc/$$/status
	Cpus_allowed:	000000f0,00000000
	Cpus_allowed_list:	36-39

A double toggle of smt results in the following behavior:

	# echo off > /sys/devices/system/cpu/smt/control
	# echo on > /sys/devices/system/cpu/smt/control
	# grep -i cpus /proc/$$/status
	Cpus_allowed:	ffffff00,ffffffff
	Cpus_allowed_list:	0-31,40-63

This is even less sane than the previous case, as the new affinity mask
excludes all smt-provided cpus with ids less than those that were
previously in the affinity mask, as well as those that were actually in
the mask.

With this patch applied, both of these cases end in the following state:

	# grep -i cpu /proc/$$/status
	Cpus_allowed:	ffffffff,ffffffff
	Cpus_allowed_list:	0-63

The original policy is discarded. Though not ideal, it is the simplest way
to restore sanity to this fallback case without reinventing the cpuset
wheel that rolls down the kernel just fine in cgroup v2. A user who wishes
for the previous affinity mask to be restored in this fallback case can use
that mechanism instead.

This patch modifies scheduler behavior by instead resetting the mask to
task_cs(tsk)->cpus_allowed by default, and cpu_possible mask in legacy
mode. I tested the cases above on both modes.

Note that the scheduler uses this fallback mechanism if and only if
_every_ other valid avenue has been traveled, and it is the last resort
before calling BUG().
Suggested-by: NWaiman Long <longman@redhat.com>
Suggested-by: NPhil Auld <pauld@redhat.com>
Signed-off-by: NJoel Savitz <jsavitz@redhat.com>
Acked-by: NPhil Auld <pauld@redhat.com>
Acked-by: NWaiman Long <longman@redhat.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      b7747ecb
  7. 03 7月, 2019 5 次提交
    • D
      bpf: fix unconnected udp hooks · 613bc37f
      由 Daniel Borkmann 提交于 
      commit 983695fa676568fc0fe5ddd995c7267aabc24632 upstream.

Intention of cgroup bind/connect/sendmsg BPF hooks is to act transparently
to applications as also stated in original motivation in 7828f20e ("Merge
branch 'bpf-cgroup-bind-connect'"). When recently integrating the latter
two hooks into Cilium to enable host based load-balancing with Kubernetes,
I ran into the issue that pods couldn't start up as DNS got broken. Kubernetes
typically sets up DNS as a service and is thus subject to load-balancing.

Upon further debugging, it turns out that the cgroupv2 sendmsg BPF hooks API
is currently insufficient and thus not usable as-is for standard applications
shipped with most distros. To break down the issue we ran into with a simple
example:

  # cat /etc/resolv.conf
  nameserver 147.75.207.207
  nameserver 147.75.207.208

For the purpose of a simple test, we set up above IPs as service IPs and
transparently redirect traffic to a different DNS backend server for that
node:

  # cilium service list
  ID   Frontend            Backend
  1    147.75.207.207:53   1 => 8.8.8.8:53
  2    147.75.207.208:53   1 => 8.8.8.8:53

The attached BPF program is basically selecting one of the backends if the
service IP/port matches on the cgroup hook. DNS breaks here, because the
hooks are not transparent enough to applications which have built-in msg_name
address checks:

  # nslookup 1.1.1.1
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.208#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  [...]
  ;; connection timed out; no servers could be reached

  # dig 1.1.1.1
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.208#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  [...]

  ; <<>> DiG 9.11.3-1ubuntu1.7-Ubuntu <<>> 1.1.1.1
  ;; global options: +cmd
  ;; connection timed out; no servers could be reached

For comparison, if none of the service IPs is used, and we tell nslookup
to use 8.8.8.8 directly it works just fine, of course:

  # nslookup 1.1.1.1 8.8.8.8
  1.1.1.1.in-addr.arpa	name = one.one.one.one.

In order to fix this and thus act more transparent to the application,
this needs reverse translation on recvmsg() side. A minimal fix for this
API is to add similar recvmsg() hooks behind the BPF cgroups static key
such that the program can track state and replace the current sockaddr_in{,6}
with the original service IP. From BPF side, this basically tracks the
service tuple plus socket cookie in an LRU map where the reverse NAT can
then be retrieved via map value as one example. Side-note: the BPF cgroups
static key should be converted to a per-hook static key in future.

Same example after this fix:

  # cilium service list
  ID   Frontend            Backend
  1    147.75.207.207:53   1 => 8.8.8.8:53
  2    147.75.207.208:53   1 => 8.8.8.8:53

Lookups work fine now:

  # nslookup 1.1.1.1
  1.1.1.1.in-addr.arpa    name = one.one.one.one.

  Authoritative answers can be found from:

  # dig 1.1.1.1

  ; <<>> DiG 9.11.3-1ubuntu1.7-Ubuntu <<>> 1.1.1.1
  ;; global options: +cmd
  ;; Got answer:
  ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 51550
  ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

  ;; OPT PSEUDOSECTION:
  ; EDNS: version: 0, flags:; udp: 512
  ;; QUESTION SECTION:
  ;1.1.1.1.                       IN      A

  ;; AUTHORITY SECTION:
  .                       23426   IN      SOA     a.root-servers.net. nstld.verisign-grs.com. 2019052001 1800 900 604800 86400

  ;; Query time: 17 msec
  ;; SERVER: 147.75.207.207#53(147.75.207.207)
  ;; WHEN: Tue May 21 12:59:38 UTC 2019
  ;; MSG SIZE  rcvd: 111

And from an actual packet level it shows that we're using the back end
server when talking via 147.75.207.20{7,8} front end:

  # tcpdump -i any udp
  [...]
  12:59:52.698732 IP foo.42011 > google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38)
  12:59:52.698735 IP foo.42011 > google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38)
  12:59:52.701208 IP google-public-dns-a.google.com.domain > foo.42011: 18803 1/0/0 PTR one.one.one.one. (67)
  12:59:52.701208 IP google-public-dns-a.google.com.domain > foo.42011: 18803 1/0/0 PTR one.one.one.one. (67)
  [...]

In order to be flexible and to have same semantics as in sendmsg BPF
programs, we only allow return codes in [1,1] range. In the sendmsg case
the program is called if msg->msg_name is present which can be the case
in both, connected and unconnected UDP.

The former only relies on the sockaddr_in{,6} passed via connect(2) if
passed msg->msg_name was NULL. Therefore, on recvmsg side, we act in similar
way to call into the BPF program whenever a non-NULL msg->msg_name was
passed independent of sk->sk_state being TCP_ESTABLISHED or not. Note
that for TCP case, the msg->msg_name is ignored in the regular recvmsg
path and therefore not relevant.

For the case of ip{,v6}_recv_error() paths, picked up via MSG_ERRQUEUE,
the hook is not called. This is intentional as it aligns with the same
semantics as in case of TCP cgroup BPF hooks right now. This might be
better addressed in future through a different bpf_attach_type such
that this case can be distinguished from the regular recvmsg paths,
for example.

Fixes: 1cedee13 ("bpf: Hooks for sys_sendmsg")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrey Ignatov <rdna@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Acked-by: NMartynas Pumputis <m@lambda.lt>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      613bc37f
    • M
      bpf: fix nested bpf tracepoints with per-cpu data · a7177b94
      由 Matt Mullins 提交于 
      commit 9594dc3c7e71b9f52bee1d7852eb3d4e3aea9e99 upstream.

BPF_PROG_TYPE_RAW_TRACEPOINTs can be executed nested on the same CPU, as
they do not increment bpf_prog_active while executing.

This enables three levels of nesting, to support
  - a kprobe or raw tp or perf event,
  - another one of the above that irq context happens to call, and
  - another one in nmi context
(at most one of which may be a kprobe or perf event).

Fixes: 20b9d7ac ("bpf: avoid excessive stack usage for perf_sample_data")
Signed-off-by: NMatt Mullins <mmullins@fb.com>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a7177b94
    • J
      bpf: lpm_trie: check left child of last leftmost node for NULL · 4992d4af
      由 Jonathan Lemon 提交于 
      commit da2577fdd0932ea4eefe73903f1130ee366767d2 upstream.

If the leftmost parent node of the tree has does not have a child
on the left side, then trie_get_next_key (and bpftool map dump) will
not look at the child on the right.  This leads to the traversal
missing elements.

Lookup is not affected.

Update selftest to handle this case.

Reproducer:

 bpftool map create /sys/fs/bpf/lpm type lpm_trie key 6 \
     value 1 entries 256 name test_lpm flags 1
 bpftool map update pinned /sys/fs/bpf/lpm key  8 0 0 0  0   0 value 1
 bpftool map update pinned /sys/fs/bpf/lpm key 16 0 0 0  0 128 value 2
 bpftool map dump   pinned /sys/fs/bpf/lpm

Returns only 1 element. (2 expected)

Fixes: b471f2f1 ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE")
Signed-off-by: NJonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      4992d4af
    • G
      cpu/speculation: Warn on unsupported mitigations= parameter · b78ad216
      由 Geert Uytterhoeven 提交于 
      commit 1bf72720281770162c87990697eae1ba2f1d917a upstream.

Currently, if the user specifies an unsupported mitigation strategy on the
kernel command line, it will be ignored silently.  The code will fall back
to the default strategy, possibly leaving the system more vulnerable than
expected.

This may happen due to e.g. a simple typo, or, for a stable kernel release,
because not all mitigation strategies have been backported.

Inform the user by printing a message.

Fixes: 98af8452945c5565 ("cpu/speculation: Add 'mitigations=' cmdline option")
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190516070935.22546-1-geert@linux-m68k.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b78ad216
    • S
      Revert "x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP" · fec1a13b
      由 Sasha Levin 提交于 
      This reverts commit 1a3188d7, which was
upstream commit 4a6c91fbdef846ec7250b82f2eeeb87ac5f18cf9.

On Tue, Jun 25, 2019 at 09:39:45AM +0200, Sebastian Andrzej Siewior wrote:
>Please backport commit e74deb11931ff682b59d5b9d387f7115f689698e to
>stable _or_ revert the backport of commit 4a6c91fbdef84 ("x86/uaccess,
>ftrace: Fix ftrace_likely_update() vs. SMAP"). It uses
>user_access_{save|restore}() which has been introduced in the following
>commit.
Signed-off-by: NSasha Levin <sashal@kernel.org>
      fec1a13b
  9. 25 6月, 2019 1 次提交
    • M
      tracing: Silence GCC 9 array bounds warning · c493ead3
      由 Miguel Ojeda 提交于 
      commit 0c97bf863efce63d6ab7971dad811601e6171d2f upstream.

Starting with GCC 9, -Warray-bounds detects cases when memset is called
starting on a member of a struct but the size to be cleared ends up
writing over further members.

Such a call happens in the trace code to clear, at once, all members
after and including `seq` on struct trace_iterator:

    In function 'memset',
        inlined from 'ftrace_dump' at kernel/trace/trace.c:8914:3:
    ./include/linux/string.h:344:9: warning: '__builtin_memset' offset
    [8505, 8560] from the object at 'iter' is out of the bounds of
    referenced subobject 'seq' with type 'struct trace_seq' at offset
    4368 [-Warray-bounds]
      344 |  return __builtin_memset(p, c, size);
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

In order to avoid GCC complaining about it, we compute the address
ourselves by adding the offsetof distance instead of referring
directly to the member.

Since there are two places doing this clear (trace.c and trace_kdb.c),
take the chance to move the workaround into a single place in
the internal header.

Link: http://lkml.kernel.org/r/20190523124535.GA12931@gmail.comSigned-off-by: NMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>
[ Removed unnecessary parenthesis around "iter" ]
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      c493ead3
  11. 22 6月, 2019 3 次提交
    • P
      perf/ring-buffer: Always use {READ,WRITE}_ONCE() for rb->user_page data · 991ea848
      由 Peter Zijlstra 提交于 
      [ Upstream commit 4d839dd9e4356bbacf3eb0ab13a549b83b008c21 ]

We must use {READ,WRITE}_ONCE() on rb->user_page data such that
concurrent usage will see whole values. A few key sites were missing
this.
Suggested-by: NYabin Cui <yabinc@google.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Cc: mark.rutland@arm.com
Cc: namhyung@kernel.org
Fixes: 7b732a75 ("perf_counter: new output ABI - part 1")
Link: http://lkml.kernel.org/r/20190517115418.394192145@infradead.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      991ea848
    • P
      perf/ring_buffer: Add ordering to rb->nest increment · c133c9db
      由 Peter Zijlstra 提交于 
      [ Upstream commit 3f9fbe9bd86c534eba2faf5d840fd44c6049f50e ]

Similar to how decrementing rb->next too early can cause data_head to
(temporarily) be observed to go backward, so too can this happen when
we increment too late.

This barrier() ensures the rb->head load happens after the increment,
both the one in the 'goto again' path, as the one from
perf_output_get_handle() -- albeit very unlikely to matter for the
latter.
Suggested-by: NYabin Cui <yabinc@google.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Cc: mark.rutland@arm.com
Cc: namhyung@kernel.org
Fixes: ef60777c ("perf: Optimize the perf_output() path by removing IRQ-disables")
Link: http://lkml.kernel.org/r/20190517115418.309516009@infradead.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      c133c9db
    • Y
      perf/ring_buffer: Fix exposing a temporarily decreased data_head · cca19ab2
      由 Yabin Cui 提交于 
      [ Upstream commit 1b038c6e05ff70a1e66e3e571c2e6106bdb75f53 ]

In perf_output_put_handle(), an IRQ/NMI can happen in below location and
write records to the same ring buffer:

	...
	local_dec_and_test(&rb->nest)
	...                          <-- an IRQ/NMI can happen here
	rb->user_page->data_head = head;
	...

In this case, a value A is written to data_head in the IRQ, then a value
B is written to data_head after the IRQ. And A > B. As a result,
data_head is temporarily decreased from A to B. And a reader may see
data_head < data_tail if it read the buffer frequently enough, which
creates unexpected behaviors.

This can be fixed by moving dec(&rb->nest) to after updating data_head,
which prevents the IRQ/NMI above from updating data_head.

[ Split up by peterz. ]
Signed-off-by: NYabin Cui <yabinc@google.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: mark.rutland@arm.com
Fixes: ef60777c ("perf: Optimize the perf_output() path by removing IRQ-disables")
Link: http://lkml.kernel.org/r/20190517115418.224478157@infradead.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      cca19ab2
  13. 19 6月, 2019 5 次提交
  15. 15 6月, 2019 4 次提交
  17. 11 6月, 2019 1 次提交
    • J
      x86/power: Fix 'nosmt' vs hibernation triple fault during resume · 4d166206
      由 Jiri Kosina 提交于 
      commit ec527c318036a65a083ef68d8ba95789d2212246 upstream.

As explained in

	0cc3cd21 ("cpu/hotplug: Boot HT siblings at least once")

we always, no matter what, have to bring up x86 HT siblings during boot at
least once in order to avoid first MCE bringing the system to its knees.

That means that whenever 'nosmt' is supplied on the kernel command-line,
all the HT siblings are as a result sitting in mwait or cpudile after
going through the online-offline cycle at least once.

This causes a serious issue though when a kernel, which saw 'nosmt' on its
commandline, is going to perform resume from hibernation: if the resume
from the hibernated image is successful, cr3 is flipped in order to point
to the address space of the kernel that is being resumed, which in turn
means that all the HT siblings are all of a sudden mwaiting on address
which is no longer valid.

That results in triple fault shortly after cr3 is switched, and machine
reboots.

Fix this by always waking up all the SMT siblings before initiating the
'restore from hibernation' process; this guarantees that all the HT
siblings will be properly carried over to the resumed kernel waiting in
resume_play_dead(), and acted upon accordingly afterwards, based on the
target kernel configuration.

Symmetricaly, the resumed kernel has to push the SMT siblings to mwait
again in case it has SMT disabled; this means it has to online all
the siblings when resuming (so that they come out of hlt) and offline
them again to let them reach mwait.

Cc: 4.19+ <stable@vger.kernel.org> # v4.19+
Debugged-by: NThomas Gleixner <tglx@linutronix.de>
Fixes: 0cc3cd21 ("cpu/hotplug: Boot HT siblings at least once")
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Acked-by: NPavel Machek <pavel@ucw.cz>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      4d166206
  19. 09 6月, 2019 2 次提交
  21. 04 6月, 2019 1 次提交
  23. 31 5月, 2019 2 次提交
    • P
      rcuperf: Fix cleanup path for invalid perf_type strings · 506b28fb
      由 Paul E. McKenney 提交于 
      [ Upstream commit ad092c027713a68a34168942a5ef422e42e039f4 ]

If the specified rcuperf.perf_type is not in the rcu_perf_init()
function's perf_ops[] array, rcuperf prints some console messages and
then invokes rcu_perf_cleanup() to set state so that a future torture
test can run.  However, rcu_perf_cleanup() also attempts to end the
test that didn't actually start, and in doing so relies on the value
of cur_ops, a value that is not particularly relevant in this case.
This can result in confusing output or even follow-on failures due to
attempts to use facilities that have not been properly initialized.

This commit therefore sets the value of cur_ops to NULL in this case and
inserts a check near the beginning of rcu_perf_cleanup(), thus avoiding
relying on an irrelevant cur_ops value.
Signed-off-by: NPaul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      506b28fb
    • P
      rcutorture: Fix cleanup path for invalid torture_type strings · aa7919e3
      由 Paul E. McKenney 提交于 
      [ Upstream commit b813afae7ab6a5e91b4e16cc567331d9c2ae1f04 ]

If the specified rcutorture.torture_type is not in the rcu_torture_init()
function's torture_ops[] array, rcutorture prints some console messages
and then invokes rcu_torture_cleanup() to set state so that a future
torture test can run.  However, rcu_torture_cleanup() also attempts to
end the test that didn't actually start, and in doing so relies on the
value of cur_ops, a value that is not particularly relevant in this case.
This can result in confusing output or even follow-on failures due to
attempts to use facilities that have not been properly initialized.

This commit therefore sets the value of cur_ops to NULL in this case
and inserts a check near the beginning of rcu_torture_cleanup(),
thus avoiding relying on an irrelevant cur_ops value.
Reported-by: Nkernel test robot <rong.a.chen@intel.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
      aa7919e3