linux-stable.git/kernel/trace/trace_output.c, branch v4.14.331

tracing: Make sure trace_printk() can output as soon as it can be used

2023-02-06T06:46:31+00:00

commit 3bb06eb6e9acf7c4a3e1b5bc87aed398ff8e2253 upstream.

Currently trace_printk() can be used as soon as early_trace_init() is
called from start_kernel(). But if a crash happens, and
"ftrace_dump_on_oops" is set on the kernel command line, all you get will
be:

  [    0.456075]   -0         0dN.2. 347519us : Unknown type 6
  [    0.456075]   -0         0dN.2. 353141us : Unknown type 6
  [    0.456075]   -0         0dN.2. 358684us : Unknown type 6

This is because the trace_printk() event (type 6) hasn't been registered
yet. That gets done via an early_initcall(), which may be early, but not
early enough.

Instead of registering the trace_printk() event (and other ftrace events,
which are not trace events) via an early_initcall(), have them registered at
the same time that trace_printk() can be used. This way, if there is a
crash before early_initcall(), then the trace_printk()s will actually be
useful.

Link: https://lkml.kernel.org/r/20230104161412.019f6c55@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Fixes: e725c731e3bb1 ("tracing: Split tracing initialization into two for early initialization")
Reported-by: "Joel Fernandes (Google)" 
Tested-by: Joel Fernandes (Google) 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing: Reorder display of TGID to be after PID

2018-07-17T09:39:30+00:00

commit f8494fa3dd10b52eab47a9666a8bc34719a129aa upstream.

Currently ftrace displays data in trace output like so:

                                       _-----=> irqs-off
                                      / _----=> need-resched
                                     | / _---=> hardirq/softirq
                                     || / _--=> preempt-depth
                                     ||| /     delay
            TASK-PID   CPU    TGID   ||||    TIMESTAMP  FUNCTION
               | |       |      |    ||||       |         |
            bash-1091  [000] ( 1091) d..2    28.313544: sched_switch:

However Android's trace visualization tools expect a slightly different
format due to an out-of-tree patch patch that was been carried for a
decade, notice that the TGID and CPU fields are reversed:

                                       _-----=> irqs-off
                                      / _----=> need-resched
                                     | / _---=> hardirq/softirq
                                     || / _--=> preempt-depth
                                     ||| /     delay
            TASK-PID    TGID   CPU   ||||    TIMESTAMP  FUNCTION
               | |        |      |   ||||       |         |
            bash-1091  ( 1091) [002] d..2    64.965177: sched_switch:

From kernel v4.13 onwards, during which TGID was introduced, tracing
with systrace on all Android kernels will break (most Android kernels
have been on 4.9 with Android patches, so this issues hasn't been seen
yet). From v4.13 onwards things will break.

The chrome browser's tracing tools also embed the systrace viewer which
uses the legacy TGID format and updates to that are known to be
difficult to make.

Considering this, I suggest we make this change to the upstream kernel
and backport it to all Android kernels. I believe this feature is merged
recently enough into the upstream kernel that it shouldn't be a problem.
Also logically, IMO it makes more sense to group the TGID with the
TASK-PID and the CPU after these.

Link: http://lkml.kernel.org/r/20180626000822.113931-1-joel@joelfernandes.org

Cc: jreck@google.com
Cc: tkjos@google.com
Cc: stable@vger.kernel.org
Fixes: 441dae8f2f29 ("tracing: Add support for display of tgid in trace output")
Signed-off-by: Joel Fernandes (Google) 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

sched/tracing: Use common task-state helpers

2017-09-29T09:02:45+00:00

Remove yet another task-state char instance.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

tracing: Add support for display of tgid in trace output

2017-06-27T17:30:28+00:00

Earlier patches introduced ability to record the tgid using the 'record-tgid'
option. Here we read the tgid and output it if the option is enabled.

Link: http://lkml.kernel.org/r/20170626053844.5746-3-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar 
Tested-by: Michael Sartain 
Signed-off-by: Joel Fernandes 
Signed-off-by: Steven Rostedt (VMware)

tracing: Show address when function names are not found

2017-06-22T21:10:06+00:00

Currently, when a function is not found in kallsyms, instead of simply
showing the function address, it shows nothing at all:

 # echo ':mod:kvm_intel' > /sys/kernel/tracing/set_ftrace_filter
 # echo function > /sys/kernel/tracing/set_ftrace_filter
 # qemu -enable-kvm /home/my-qemu-image
   
 # rmmod kvm_intel
 # cat /sys/kernel/tracing/trace
 qemu-system-x86-2408  [001] d..2   135.013238:  <-kvm_arch_hardware_enable
 qemu-system-x86-2408  [001] ....   135.014574:  <-kvm_arch_vm_ioctl
 qemu-system-x86-2408  [001] ....   135.015420:  <-kvm_vm_ioctl_check_extension
 qemu-system-x86-2408  [001] ....   135.045411:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ...1   135.045413:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045413:  <-__do_cpuid_ent

When it should show:

 qemu-system-x86-2408  [001] d..2   135.013238: 0xffffffffa02a39f0 <-kvm_arch_hardware_enable
 qemu-system-x86-2408  [001] ....   135.014574: 0xffffffffa02a2ba0 <-kvm_arch_vm_ioctl
 qemu-system-x86-2408  [001] ....   135.015420: 0xffffffffa029e4e0 <-kvm_vm_ioctl_check_extension
 qemu-system-x86-2408  [001] ....   135.045411: 0xffffffffa02a1380 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412: 0xffffffffa029e160 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412: 0xffffffffa029e180 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412: 0xffffffffa029e520 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ...1   135.045413: 0xffffffffa02a13b0 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045413: 0xffffffffa02a1380 <-__do_cpuid_ent

instead.

Signed-off-by: Steven Rostedt (VMware)

trace: make trace_hwlat timestamp y2038 safe

2017-05-09T00:15:15+00:00

struct timespec is not y2038 safe on 32 bit machines and needs to be
replaced by struct timespec64 in order to represent times beyond year
2038 on such machines.

Fix all the timestamp representation in struct trace_hwlat and all the
corresponding implementations.

Link: http://lkml.kernel.org/r/1491613030-11599-3-git-send-email-deepa.kernel@gmail.com
Signed-off-by: Deepa Dinamani 
Acked-by: Steven Rostedt (VMware) 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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

2017-03-02T07:42:28+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.

The APIs that are going to be moved first are:

   mm_alloc()
   __mmdrop()
   mmdrop()
   mmdrop_async_fn()
   mmdrop_async()
   mmget_not_zero()
   mmput()
   mmput_async()
   get_task_mm()
   mm_access()
   mm_release()

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

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

2017-03-02T07:42:27+00:00

We are going to split  out of , which
will have to be picked up from other headers and .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: add __print_flags_u64()

2017-02-23T00:41:26+00:00

Patch series "DAX tracepoints, mm argument simplification", v4.

This contains both my DAX tracepoint code and Dave Jiang's MM argument
simplifications.  Dave's code was written with my tracepoint code as a
baseline, so it seemed simplest to keep them together in a single series.

This patch (of 7):

Add __print_flags_u64() and the helper trace_print_flags_seq_u64() in the
same spirit as __print_symbolic_u64() and trace_print_symbols_seq_u64().
These functions allow us to print symbols associated with flags that are
64 bits wide even on 32 bit machines.

These will be used by the DAX code so that we can print the flags set in a
pfn_t such as PFN_SG_CHAIN, PFN_SG_LAST, PFN_DEV and PFN_MAP.

Without this new function I was getting errors like the following when
compiling for i386:

  include/linux/pfn_t.h:13:22: warning: large integer implicitly truncated to unsigned type [-Woverflow]
   #define PFN_SG_CHAIN (1ULL << (BITS_PER_LONG_LONG - 1))
    ^

Link: http://lkml.kernel.org/r/1484085142-2297-2-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler 
Reviewed-by: Steven Rostedt 
Cc: Dave Chinner 
Cc: Dave Jiang 
Cc: Jan Kara 
Cc: Matthew Wilcox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

trace: rename trace_print_hex_seq arg and add kdoc

2017-02-03T20:50:18+00:00

Steven suggested to improve trace_print_hex_seq() a bit after commit
2acae0d5b0f7 ("trace: add variant without spacing in trace_print_hex_seq")
in two ways: i) by adding a kdoc comment for the helper function
itself and ii) by renaming 'spacing' argument into 'concatenate'
to better denote that we don't add spaces between each hex bytes.

Suggested-by: Steven Rostedt 
Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller