linux-stable.git/kernel, branch linux-5.9.y Linux kernel stable tree membarrier: Explicitly sync remote cores when SYNC_CORE is requested 2020-12-21T12:28:20+00:00 Andy Lutomirski luto@kernel.org 2020-12-04T05:07:05+00:00 9fd3e9190dce7f7ed77141b869c2b70a01133144 commit 758c9373d84168dc7d039cf85a0e920046b17b41 upstream. membarrier() does not explicitly sync_core() remote CPUs; instead, it relies on the assumption that an IPI will result in a core sync. On x86, this may be true in practice, but it's not architecturally reliable. In particular, the SDM and APM do not appear to guarantee that interrupt delivery is serializing. While IRET does serialize, IPI return can schedule, thereby switching to another task in the same mm that was sleeping in a syscall. The new task could then SYSRET back to usermode without ever executing IRET. Make this more robust by explicitly calling sync_core_before_usermode() on remote cores. (This also helps people who search the kernel tree for instances of sync_core() and sync_core_before_usermode() -- one might be surprised that the core membarrier code doesn't currently show up in a such a search.) Fixes: 70216e18e519 ("membarrier: Provide core serializing command, *_SYNC_CORE") Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/776b448d5f7bd6b12690707f5ed67bcda7f1d427.1607058304.git.luto@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 758c9373d84168dc7d039cf85a0e920046b17b41 upstream.

membarrier() does not explicitly sync_core() remote CPUs; instead, it
relies on the assumption that an IPI will result in a core sync.  On x86,
this may be true in practice, but it's not architecturally reliable.  In
particular, the SDM and APM do not appear to guarantee that interrupt
delivery is serializing.  While IRET does serialize, IPI return can
schedule, thereby switching to another task in the same mm that was
sleeping in a syscall.  The new task could then SYSRET back to usermode
without ever executing IRET.

Make this more robust by explicitly calling sync_core_before_usermode()
on remote cores.  (This also helps people who search the kernel tree for
instances of sync_core() and sync_core_before_usermode() -- one might be
surprised that the core membarrier code doesn't currently show up in a
such a search.)

Fixes: 70216e18e519 ("membarrier: Provide core serializing command, *_SYNC_CORE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/776b448d5f7bd6b12690707f5ed67bcda7f1d427.1607058304.git.luto@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sched/idle: Fix arch_cpu_idle() vs tracing 2020-12-16T09:58:32+00:00 Peter Zijlstra peterz@infradead.org 2020-11-20T10:50:35+00:00 fb82d3ac7ec1ffb5f4758b025bfdcd1b82eeddd5 [ Upstream commit 58c644ba512cfbc2e39b758dd979edd1d6d00e27 ] We call arch_cpu_idle() with RCU disabled, but then use local_irq_{en,dis}able(), which invokes tracing, which relies on RCU. Switch all arch_cpu_idle() implementations to use raw_local_irq_{en,dis}able() and carefully manage the lockdep,rcu,tracing state like we do in entry. (XXX: we really should change arch_cpu_idle() to not return with interrupts enabled) Reported-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 58c644ba512cfbc2e39b758dd979edd1d6d00e27 ]

We call arch_cpu_idle() with RCU disabled, but then use
local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.

Switch all arch_cpu_idle() implementations to use
raw_local_irq_{en,dis}able() and carefully manage the
lockdep,rcu,tracing state like we do in entry.

(XXX: we really should change arch_cpu_idle() to not return with
interrupts enabled)

Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
kprobes: Tell lockdep about kprobe nesting 2020-12-16T09:58:25+00:00 Steven Rostedt (VMware) rostedt@goodmis.org 2020-12-10T15:31:09+00:00 65e536ebc63257774d2d0f07139c4a33ff8d3f86 commit 645f224e7ba2f4200bf163153d384ceb0de5462e upstream. Since the kprobe handlers have protection that prohibits other handlers from executing in other contexts (like if an NMI comes in while processing a kprobe, and executes the same kprobe, it will get fail with a "busy" return). Lockdep is unaware of this protection. Use lockdep's nesting api to differentiate between locks taken in INT3 context and other context to suppress the false warnings. Link: https://lore.kernel.org/r/20201102160234.fa0ae70915ad9e2b21c08b85@kernel.org Cc: stable@vger.kernel.org # 5.9.x Cc: Peter Zijlstra <peterz@infradead.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 645f224e7ba2f4200bf163153d384ceb0de5462e upstream.

Since the kprobe handlers have protection that prohibits other handlers from
executing in other contexts (like if an NMI comes in while processing a
kprobe, and executes the same kprobe, it will get fail with a "busy"
return). Lockdep is unaware of this protection. Use lockdep's nesting api to
differentiate between locks taken in INT3 context and other context to
suppress the false warnings.

Link: https://lore.kernel.org/r/20201102160234.fa0ae70915ad9e2b21c08b85@kernel.org

Cc: stable@vger.kernel.org # 5.9.x
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kprobes: Remove NMI context check 2020-12-16T09:58:24+00:00 Masami Hiramatsu mhiramat@kernel.org 2020-12-10T15:30:58+00:00 e501d3d4152016995c8d01fdeed519c3e8a9afdc commit e03b4a084ea6b0a18b0e874baec439e69090c168 upstream. The in_nmi() check in pre_handler_kretprobe() is meant to avoid recursion, and blindly assumes that anything NMI is recursive. However, since commit: 9b38cc704e84 ("kretprobe: Prevent triggering kretprobe from within kprobe_flush_task") there is a better way to detect and avoid actual recursion. By setting a dummy kprobe, any actual exceptions will terminate early (by trying to handle the dummy kprobe), and recursion will not happen. Employ this to avoid the kretprobe_table_lock() recursion, replacing the over-eager in_nmi() check. Cc: stable@vger.kernel.org # 5.9.x Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/159870615628.1229682.6087311596892125907.stgit@devnote2 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e03b4a084ea6b0a18b0e874baec439e69090c168 upstream.

The in_nmi() check in pre_handler_kretprobe() is meant to avoid
recursion, and blindly assumes that anything NMI is recursive.

However, since commit:

  9b38cc704e84 ("kretprobe: Prevent triggering kretprobe from within kprobe_flush_task")

there is a better way to detect and avoid actual recursion.

By setting a dummy kprobe, any actual exceptions will terminate early
(by trying to handle the dummy kprobe), and recursion will not happen.

Employ this to avoid the kretprobe_table_lock() recursion, replacing
the over-eager in_nmi() check.

Cc: stable@vger.kernel.org # 5.9.x
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/159870615628.1229682.6087311596892125907.stgit@devnote2
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: Fix propagation of 32-bit signed bounds from 64-bit bounds. 2020-12-11T12:22:13+00:00 Alexei Starovoitov ast@kernel.org 2020-12-08T18:01:51+00:00 0f8ad899df8c159d0ac293eb7aafeea3a536bd3a commit b02709587ea3d699a608568ee8157d8db4fd8cae upstream. The 64-bit signed bounds should not affect 32-bit signed bounds unless the verifier knows that upper 32-bits are either all 1s or all 0s. For example the register with smin_value==1 doesn't mean that s32_min_value is also equal to 1, since smax_value could be larger than 32-bit subregister can hold. The verifier refines the smax/s32_max return value from certain helpers in do_refine_retval_range(). Teach the verifier to recognize that smin/s32_min value is also bounded. When both smin and smax bounds fit into 32-bit subregister the verifier can propagate those bounds. Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking") Reported-by: Jean-Philippe Brucker <jean-philippe@linaro.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b02709587ea3d699a608568ee8157d8db4fd8cae upstream.

The 64-bit signed bounds should not affect 32-bit signed bounds unless the
verifier knows that upper 32-bits are either all 1s or all 0s. For example the
register with smin_value==1 doesn't mean that s32_min_value is also equal to 1,
since smax_value could be larger than 32-bit subregister can hold.
The verifier refines the smax/s32_max return value from certain helpers in
do_refine_retval_range(). Teach the verifier to recognize that smin/s32_min
value is also bounded. When both smin and smax bounds fit into 32-bit
subregister the verifier can propagate those bounds.

Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Reported-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
genirq/irqdomain: Add an irq_create_mapping_affinity() function 2020-12-11T12:22:09+00:00 Laurent Vivier lvivier@redhat.com 2020-11-26T08:28:51+00:00 b732e2c47f5925538917a34aff5ca7d120100a68 commit bb4c6910c8b41623104c2e64a30615682689a54d upstream. There is currently no way to convey the affinity of an interrupt via irq_create_mapping(), which creates issues for devices that expect that affinity to be managed by the kernel. In order to sort this out, rename irq_create_mapping() to irq_create_mapping_affinity() with an additional affinity parameter that can be passed down to irq_domain_alloc_descs(). irq_create_mapping() is re-implemented as a wrapper around irq_create_mapping_affinity(). No functional change. Fixes: e75eafb9b039 ("genirq/msi: Switch to new irq spreading infrastructure") Signed-off-by: Laurent Vivier <lvivier@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Greg Kurz <groug@kaod.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20201126082852.1178497-2-lvivier@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bb4c6910c8b41623104c2e64a30615682689a54d upstream.

There is currently no way to convey the affinity of an interrupt
via irq_create_mapping(), which creates issues for devices that
expect that affinity to be managed by the kernel.

In order to sort this out, rename irq_create_mapping() to
irq_create_mapping_affinity() with an additional affinity parameter that
can be passed down to irq_domain_alloc_descs().

irq_create_mapping() is re-implemented as a wrapper around
irq_create_mapping_affinity().

No functional change.

Fixes: e75eafb9b039 ("genirq/msi: Switch to new irq spreading infrastructure")
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kurz <groug@kaod.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201126082852.1178497-2-lvivier@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tracing: Fix userstacktrace option for instances 2020-12-11T12:22:08+00:00 Steven Rostedt (VMware) rostedt@goodmis.org 2020-12-04T21:36:16+00:00 f05f0db4db8bec05f4fa09d97870774f837ee9fe commit bcee5278958802b40ee8b26679155a6d9231783e upstream. When the instances were able to use their own options, the userstacktrace option was left hardcoded for the top level. This made the instance userstacktrace option bascially into a nop, and will confuse users that set it, but nothing happens (I was confused when it happened to me!) Cc: stable@vger.kernel.org Fixes: 16270145ce6b ("tracing: Add trace options for core options to instances") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bcee5278958802b40ee8b26679155a6d9231783e upstream.

When the instances were able to use their own options, the userstacktrace
option was left hardcoded for the top level. This made the instance
userstacktrace option bascially into a nop, and will confuse users that set
it, but nothing happens (I was confused when it happened to me!)

Cc: stable@vger.kernel.org
Fixes: 16270145ce6b ("tracing: Add trace options for core options to instances")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ftrace: Fix DYNAMIC_FTRACE_WITH_DIRECT_CALLS dependency 2020-12-11T12:22:06+00:00 Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com 2020-11-26T18:08:39+00:00 cd6bd84b19ac9d9cfd3c48eb8425f1dfabbb607a commit 49a962c075dfa41c78e34784772329bc8784d217 upstream. DYNAMIC_FTRACE_WITH_DIRECT_CALLS should depend on DYNAMIC_FTRACE_WITH_REGS since we need ftrace_regs_caller(). Link: https://lkml.kernel.org/r/fc4b257ea8689a36f086d2389a9ed989496ca63a.1606412433.git.naveen.n.rao@linux.vnet.ibm.com Cc: stable@vger.kernel.org Fixes: 763e34e74bb7d5c ("ftrace: Add register_ftrace_direct()") Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 49a962c075dfa41c78e34784772329bc8784d217 upstream.

DYNAMIC_FTRACE_WITH_DIRECT_CALLS should depend on
DYNAMIC_FTRACE_WITH_REGS since we need ftrace_regs_caller().

Link: https://lkml.kernel.org/r/fc4b257ea8689a36f086d2389a9ed989496ca63a.1606412433.git.naveen.n.rao@linux.vnet.ibm.com

Cc: stable@vger.kernel.org
Fixes: 763e34e74bb7d5c ("ftrace: Add register_ftrace_direct()")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ftrace: Fix updating FTRACE_FL_TRAMP 2020-12-11T12:22:06+00:00 Naveen N. Rao naveen.n.rao@linux.vnet.ibm.com 2020-11-26T18:08:38+00:00 009b4bd377a92c32ef76223a15727037af3ded9c commit 4c75b0ff4e4bf7a45b5aef9639799719c28d0073 upstream. On powerpc, kprobe-direct.tc triggered FTRACE_WARN_ON() in ftrace_get_addr_new() followed by the below message: Bad trampoline accounting at: 000000004222522f (wake_up_process+0xc/0x20) (f0000001) The set of steps leading to this involved: - modprobe ftrace-direct-too - enable_probe - modprobe ftrace-direct - rmmod ftrace-direct <-- trigger The problem turned out to be that we were not updating flags in the ftrace record properly. From the above message about the trampoline accounting being bad, it can be seen that the ftrace record still has FTRACE_FL_TRAMP set though ftrace-direct module is going away. This happens because we are checking if any ftrace_ops has the FTRACE_FL_TRAMP flag set _before_ updating the filter hash. The fix for this is to look for any _other_ ftrace_ops that also needs FTRACE_FL_TRAMP. Link: https://lkml.kernel.org/r/56c113aa9c3e10c19144a36d9684c7882bf09af5.1606412433.git.naveen.n.rao@linux.vnet.ibm.com Cc: stable@vger.kernel.org Fixes: a124692b698b0 ("ftrace: Enable trampoline when rec count returns back to one") Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4c75b0ff4e4bf7a45b5aef9639799719c28d0073 upstream.

On powerpc, kprobe-direct.tc triggered FTRACE_WARN_ON() in
ftrace_get_addr_new() followed by the below message:
  Bad trampoline accounting at: 000000004222522f (wake_up_process+0xc/0x20) (f0000001)

The set of steps leading to this involved:
- modprobe ftrace-direct-too
- enable_probe
- modprobe ftrace-direct
- rmmod ftrace-direct <-- trigger

The problem turned out to be that we were not updating flags in the
ftrace record properly. From the above message about the trampoline
accounting being bad, it can be seen that the ftrace record still has
FTRACE_FL_TRAMP set though ftrace-direct module is going away. This
happens because we are checking if any ftrace_ops has the
FTRACE_FL_TRAMP flag set _before_ updating the filter hash.

The fix for this is to look for any _other_ ftrace_ops that also needs
FTRACE_FL_TRAMP.

Link: https://lkml.kernel.org/r/56c113aa9c3e10c19144a36d9684c7882bf09af5.1606412433.git.naveen.n.rao@linux.vnet.ibm.com

Cc: stable@vger.kernel.org
Fixes: a124692b698b0 ("ftrace: Enable trampoline when rec count returns back to one")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ring-buffer: Always check to put back before stamp when crossing pages 2020-12-11T12:22:06+00:00 Steven Rostedt (VMware) rostedt@goodmis.org 2020-12-01T04:16:03+00:00 5b158d047fe6b7f3ccca36fc077ea653da527dca commit 68e10d5ff512b503dcba1246ad5620f32035e135 upstream. The current ring buffer logic checks to see if the updating of the event buffer was interrupted, and if it is, it will try to fix up the before stamp with the write stamp to make them equal again. This logic is flawed, because if it is not interrupted, the two are guaranteed to be different, as the current event just updated the before stamp before allocation. This guarantees that the next event (this one or another interrupting one) will think it interrupted the time updates of a previous event and inject an absolute time stamp to compensate. The correct logic is to always update the timestamps when traversing to a new sub buffer. Cc: stable@vger.kernel.org Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 68e10d5ff512b503dcba1246ad5620f32035e135 upstream.

The current ring buffer logic checks to see if the updating of the event
buffer was interrupted, and if it is, it will try to fix up the before stamp
with the write stamp to make them equal again. This logic is flawed, because
if it is not interrupted, the two are guaranteed to be different, as the
current event just updated the before stamp before allocation. This
guarantees that the next event (this one or another interrupting one) will
think it interrupted the time updates of a previous event and inject an
absolute time stamp to compensate.

The correct logic is to always update the timestamps when traversing to a
new sub buffer.

Cc: stable@vger.kernel.org
Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>