linux-toradex.git/kernel/trace/ftrace.c, branch v4.11-rc6

Merge tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2017-03-07T17:37:28+00:00

Pull tracing fixes from Steven Rostedt:
 "There was some breakage with the changes for jump labels in the 4.11
  merge window:

   - powerpc broke as jump labels uses the two LSB bits as flags in
     initialization.

     A check was added to make sure that all jump label entries were 4
     bytes aligned, but powerpc didn't work that way for modules. Adding
     an alignment in the module linker script appeared to be the best
     solution.

   - Jump labels also added an anonymous union to access those LSB bits
     as a normal long. But because this structure had static
     initialization, it broke older compilers that could not statically
     initialize anonymous unions without brackets.

   - The command line parameter for setting function graph filter broke
     the "EMPTY_HASH" descriptor by modifying it instead of creating a
     new hash to hold the entries.

   - The command line parameter ftrace_graph_max_depth was added to
     allow its setting at boot time. It uses existing code and only the
     command line hook was added.

     This is not really a fix, but as it uses existing code without
     affecting anything else, I added it to this release. It was ready
     before the merge window closed, but I wanted to let it sit in
     linux-next for a couple of days first"

* tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/graph: Add ftrace_graph_max_depth kernel parameter
  tracing: Add #undef to fix compile error
  jump_label: Add comment about initialization order for anonymous unions
  jump_label: Fix anonymous union initialization
  module: set __jump_table alignment to 8
  ftrace/graph: Do not modify the EMPTY_HASH for the function_graph filter
  tracing: Fix code comment for ftrace_ops_get_func()

ftrace/graph: Add ftrace_graph_max_depth kernel parameter

2017-03-03T14:45:01+00:00

Early trace callgraphs can be extremely large on systems with
several seconds of boot time. The max_depth parameter limits how
deep the graph trace goes and reduces the output size. This
parameter is the same as the max_graph_depth file in tracefs.

Link: http://lkml.kernel.org/r/1488499935-23216-1-git-send-email-todd.e.brandt@linux.intel.com

Signed-off-by: Todd Brandt 
[ changed comments about debugfs to tracefs ]
Signed-off-by: Steven Rostedt (VMware)

ftrace/graph: Do not modify the EMPTY_HASH for the function_graph filter

2017-03-03T14:44:17+00:00

On boot up, if the kernel command line sets a graph funtion with the kernel
command line options "ftrace_graph_filter" or "ftrace_graph_notrace" then it
updates the corresponding function graph hash, ftrace_graph_hash or
ftrace_graph_notrace_hash respectively. Unfortunately, at boot up, these
variables are pointers to the "EMPTY_HASH" which is a constant used as a
placeholder when a hash has no entities. The problem was that the comand
line version to set the hashes updated the actual EMPTY_HASH instead of
creating a new hash for the function graph. This broke the EMPTY_HASH
because not only did it modify a constant (not sure how that was allowed to
happen, except maybe because it was done at early boot, const variables were
still mutable), but it made the filters have functions listed in them when
they were actually empty.

The kernel command line function needs to allocate a new hash for the
function graph filters and assign the necessary variables to that new hash
instead.

Link: http://lkml.kernel.org/r/1488420091.7212.17.camel@linux.intel.com

Cc: Namhyung Kim 
Fixes: b9b0c831bed2 ("ftrace: Convert graph filter to use hash tables")
Reported-by: Todd Brandt 
Tested-by: Todd Brandt 
Signed-off-by: Steven Rostedt (VMware)

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:35+00:00

We are going to split  out of , which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

tracing: Fix code comment for ftrace_ops_get_func()

2017-02-27T16:11:26+00:00

There is no function 'ftrace_ops_recurs_func' existing in the current code,
it was renamed to ftrace_ops_assist_func() in commit c68c0fa29341
("ftrace: Have ftrace_ops_get_func() handle RCU and PER_CPU flags too").
Update the comment to the correct function name.

Link: http://lkml.kernel.org/r/1487723366-14463-1-git-send-email-chuhu@redhat.com

Signed-off-by: Chunyu Hu 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Have set_graph_function handle multiple functions in one write

2017-02-03T15:59:52+00:00

Currently, only one function can be written to set_graph_function and
set_graph_notrace. The last function in the list will have saved, even
though other functions will be added then removed.

Change the behavior to be the same as set_ftrace_function as to allow
multiple functions to be written. If any one fails, none of them will be
added. The addition of the functions are done at the end when the file is
closed.

Acked-by: Namhyung Kim 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Do not hold references of ftrace_graph_{notrace_}hash out of graph_lock

2017-02-03T15:59:42+00:00

The hashs ftrace_graph_hash and ftrace_graph_notrace_hash are modified
within the graph_lock being held. Holding a pointer to them and passing them
along can lead to a use of a stale pointer (fgd->hash). Move assigning the
pointer and its use to within the holding of the lock. Note, it's an
rcu_sched protected data, and other instances of referencing them are done
with preemption disabled. But the file manipuation code must be protected by
the lock.

The fgd->hash pointer is set to NULL when the lock is being released.

Acked-by: Namhyung Kim 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Have set_graph_functions handle write with RDWR

2017-02-03T15:59:23+00:00

Since reading the set_graph_functions uses seq functions, which sets the
file->private_data pointer to a seq_file descriptor. On writes the
ftrace_graph_data descriptor is set to file->private_data. But if the file
is opened for RDWR, the ftrace_graph_write() will incorrectly use the
file->private_data descriptor instead of
((struct seq_file *)file->private_data)->private pointer, and this can crash
the kernel.

Acked-by: Namhyung Kim 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Reset fgd->hash in ftrace_graph_write()

2017-02-03T15:59:06+00:00

fgd->hash is saved and then freed, but is never reset to either
ftrace_graph_hash nor ftrace_graph_notrace_hash. But if multiple writes are
performed, then the freed hash could be accessed again.

 # cd /sys/kernel/debug/tracing
 # head -1000 available_filter_functions > /tmp/funcs
 # cat /tmp/funcs > set_graph_function

Causes:

 general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
 Modules linked in:  [...]
 CPU: 2 PID: 1337 Comm: cat Not tainted 4.10.0-rc2-test-00010-g6b052e9 #32
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
 task: ffff880113a12200 task.stack: ffffc90001940000
 RIP: 0010:free_ftrace_hash+0x7c/0x160
 RSP: 0018:ffffc90001943db0 EFLAGS: 00010246
 RAX: 6b6b6b6b6b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: 6b6b6b6b6b6b6b6b
 RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffff8800ce1e1d40
 RBP: ffff8800ce1e1d50 R08: 0000000000000000 R09: 0000000000006400
 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
 R13: ffff8800ce1e1d40 R14: 0000000000004000 R15: 0000000000000001
 FS:  00007f9408a07740(0000) GS:ffff88011e500000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000aee1f0 CR3: 0000000116bb4000 CR4: 00000000001406e0
 Call Trace:
  ? ftrace_graph_write+0x150/0x190
  ? __vfs_write+0x1f6/0x210
  ? __audit_syscall_entry+0x17f/0x200
  ? rw_verify_area+0xdb/0x210
  ? _cond_resched+0x2b/0x50
  ? __sb_start_write+0xb4/0x130
  ? vfs_write+0x1c8/0x330
  ? SyS_write+0x62/0xf0
  ? do_syscall_64+0xa3/0x1b0
  ? entry_SYSCALL64_slow_path+0x25/0x25
 Code: 01 48 85 db 0f 84 92 00 00 00 b8 01 00 00 00 d3 e0 85 c0 7e 3f 83 e8 01 48 8d 6f 10 45 31 e4 4c 8d 34 c5 08 00 00 00 49 8b 45 08 <4a> 8b 34 20 48 85 f6 74 13 48 8b 1e 48 89 ef e8 20 fa ff ff 48
 RIP: free_ftrace_hash+0x7c/0x160 RSP: ffffc90001943db0
 ---[ end trace 999b48216bf4b393 ]---

Acked-by: Namhyung Kim 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Replace (void *)1 with a meaningful macro name FTRACE_GRAPH_EMPTY

2017-02-03T15:58:48+00:00

When the set_graph_function or set_graph_notrace contains no records, a
banner is displayed of either "#### all functions enabled ####" or
"#### all functions disabled ####" respectively. To tell the seq operations
to do this, (void *)1 is passed as a return value. Instead of using a
hardcoded meaningless variable, define it as a macro.

Acked-by: Namhyung Kim 
Signed-off-by: Steven Rostedt (VMware)