linux-stable.git/kernel/trace/trace.h, branch v4.19.151

ftrace: Protect ftrace_graph_hash with ftrace_sync

2020-02-11T12:34:05+00:00

[ Upstream commit 54a16ff6f2e50775145b210bcd94d62c3c2af117 ]

As function_graph tracer can run when RCU is not "watching", it can not be
protected by synchronize_rcu() it requires running a task on each CPU before
it can be freed. Calling schedule_on_each_cpu(ftrace_sync) needs to be used.

Link: https://lore.kernel.org/r/20200205131110.GT2935@paulmck-ThinkPad-P72

Cc: stable@vger.kernel.org
Fixes: b9b0c831bed26 ("ftrace: Convert graph filter to use hash tables")
Reported-by: "Paul E. McKenney" 
Reviewed-by: Joel Fernandes (Google) 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

ftrace: Add comment to why rcu_dereference_sched() is open coded

2020-02-11T12:34:04+00:00

[ Upstream commit 16052dd5bdfa16dbe18d8c1d4cde2ddab9d23177 ]

Because the function graph tracer can execute in sections where RCU is not
"watching", the rcu_dereference_sched() for the has needs to be open coded.
This is fine because the RCU "flavor" of the ftrace hash is protected by
its own RCU handling (it does its own little synchronization on every CPU
and does not rely on RCU sched).

Acked-by: Joel Fernandes (Google) 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu

2020-02-11T12:34:04+00:00

[ Upstream commit fd0e6852c407dd9aefc594f54ddcc21d84803d3b ]

Fix following instances of sparse error
kernel/trace/ftrace.c:5667:29: error: incompatible types in comparison
kernel/trace/ftrace.c:5813:21: error: incompatible types in comparison
kernel/trace/ftrace.c:5868:36: error: incompatible types in comparison
kernel/trace/ftrace.c:5870:25: error: incompatible types in comparison

Use rcu_dereference_protected to dereference the newly annotated pointer.

Link: http://lkml.kernel.org/r/20200205055701.30195-1-frextrite@gmail.com

Signed-off-by: Amol Grover 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

tracing: Annotate ftrace_graph_hash pointer with __rcu

2020-02-11T12:34:04+00:00

[ Upstream commit 24a9729f831462b1d9d61dc85ecc91c59037243f ]

Fix following instances of sparse error
kernel/trace/ftrace.c:5664:29: error: incompatible types in comparison
kernel/trace/ftrace.c:5785:21: error: incompatible types in comparison
kernel/trace/ftrace.c:5864:36: error: incompatible types in comparison
kernel/trace/ftrace.c:5866:25: error: incompatible types in comparison

Use rcu_dereference_protected to access the __rcu annotated pointer.

Link: http://lkml.kernel.org/r/20200201072703.17330-1-frextrite@gmail.com

Reviewed-by: Joel Fernandes (Google) 
Signed-off-by: Amol Grover 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

tracing: Silence GCC 9 array bounds warning

2019-06-25T03:35:52+00:00

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.com

Signed-off-by: Miguel Ojeda 
[ Removed unnecessary parenthesis around "iter" ]
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing/fgraph: Fix set_graph_function from showing interrupts

2018-12-08T11:59:07+00:00

commit 5cf99a0f3161bc3ae2391269d134d6bf7e26f00e upstream.

The tracefs file set_graph_function is used to only function graph functions
that are listed in that file (or all functions if the file is empty). The
way this is implemented is that the function graph tracer looks at every
function, and if the current depth is zero and the function matches
something in the file then it will trace that function. When other functions
are called, the depth will be greater than zero (because the original
function will be at depth zero), and all functions will be traced where the
depth is greater than zero.

The issue is that when a function is first entered, and the handler that
checks this logic is called, the depth is set to zero. If an interrupt comes
in and a function in the interrupt handler is traced, its depth will be
greater than zero and it will automatically be traced, even if the original
function was not. But because the logic only looks at depth it may trace
interrupts when it should not be.

The recent design change of the function graph tracer to fix other bugs
caused the depth to be zero while the function graph callback handler is
being called for a longer time, widening the race of this happening. This
bug was actually there for a longer time, but because the race window was so
small it seldom happened. The Fixes tag below is for the commit that widen
the race window, because that commit belongs to a series that will also help
fix the original bug.

Cc: stable@kernel.org
Fixes: 39eb456dacb5 ("function_graph: Use new curr_ret_depth to manage depth instead of curr_ret_stack")
Reported-by: Joe Lawrence 
Tested-by: Joe Lawrence 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix SPDX format headers to use C++ style comments

2018-08-16T23:08:06+00:00

The Linux kernel adopted the SPDX License format headers to ease license
compliance management, and uses the C++ '//' style comments for the SPDX
header tags. Some files in the tracing directory used the C style /* */
comments for them. To be consistent across all files, replace the /* */
C style SPDX tags with the C++ // SPDX tags.

Signed-off-by: Steven Rostedt (VMware)

tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage"

2018-08-10T19:12:00+00:00

Joel Fernandes created a nice patch that cleaned up the duplicate hooks used
by lockdep and irqsoff latency tracer. It made both use tracepoints. But the
latency tracer is triggering warnings when using tracepoints to call into
the latency tracer's routines. Mainly, they can be called from NMI context.
If that happens, then the SRCU may not work properly because on some
architectures, SRCU is not safe to be called in both NMI and non-NMI
context.

This is a partial revert of the clean up patch c3bc8fd637a9 ("tracing:
Centralize preemptirq tracepoints and unify their usage") that adds back the
direct calls into the latency tracer. It also only calls the trace events
when not in NMI.

Link: http://lkml.kernel.org/r/20180809210654.622445925@goodmis.org
Reviewed-by: Joel Fernandes (Google) 
Fixes: c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and unify their usage")
Signed-off-by: Steven Rostedt (VMware)

tracing: Make tracer_tracing_is_on() return bool

2018-08-01T20:08:57+00:00

There's code that expects tracer_tracing_is_on() to be either true or false,
not some random number. Currently, it should only return one or zero, but
just in case, change its return value to bool, to enforce it.

Signed-off-by: Steven Rostedt (VMware)

tracing: Remove orphaned function using_ftrace_ops_list_func().

2018-07-26T14:53:05+00:00

Remove using_ftrace_ops_list_func() since it is no longer used.

Using ftrace_ops_list_func() has been introduced by commit 7eea4fce0246
("tracing/stack_trace: Skip 4 instead of 3 when using ftrace_ops_list_func")
as a helper function, but its caller has been removed by commit 72ac426a5bb0
("tracing: Clean up stack tracing and fix fentry updates").  So it is not
called anymore.

Link: http://lkml.kernel.org/r/153260904427.12474.9952096317439329851.stgit@devbox

Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)