delta/linux.git/kernel/debug/kdb, branch proc-cmdline

Merge tag 'for_linus-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb

2018-04-12T17:21:19+00:00

Pull kdb updates from Jason Wessel:

 - fix 2032 time access issues and new compiler warnings

 - minor regression test cleanup

 - formatting fixes for end user use of kdb

* tag 'for_linus-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  kdb: use memmove instead of overlapping memcpy
  kdb: use ktime_get_mono_fast_ns() instead of ktime_get_ts()
  kdb: bl: don't use tab character in output
  kdb: drop newline in unknown command output
  kdb: make "mdr" command repeat
  kdb: use __ktime_get_real_seconds instead of __current_kernel_time
  misc: kgdbts: Display progress of asynchronous tests

kdb: use memmove instead of overlapping memcpy

2018-02-05T03:29:53+00:00

gcc discovered that the memcpy() arguments in kdbnearsym() overlap, so
we should really use memmove(), which is defined to handle that correctly:

In function 'memcpy',
    inlined from 'kdbnearsym' at /git/arm-soc/kernel/debug/kdb/kdb_support.c:132:4:
/git/arm-soc/include/linux/string.h:353:9: error: '__builtin_memcpy' accessing 792 bytes at offsets 0 and 8 overlaps 784 bytes at offset 8 [-Werror=restrict]
  return __builtin_memcpy(p, q, size);

Signed-off-by: Arnd Bergmann 
Signed-off-by: Jason Wessel

kdb: use ktime_get_mono_fast_ns() instead of ktime_get_ts()

2018-02-01T03:31:09+00:00

The kdb code will print the monotonic time by ktime_get_ts(), but
the ktime_get_ts() will be protected by a sequence lock, that will
introduce one deadlock risk if the lock was already held in the
context from which we entered the debugger.

Thus we can use the ktime_get_mono_fast_ns() to get the monotonic
time, which is NMI safe access to clock monotonic. Moreover we can
remove the 'struct timespec', which is not y2038 safe.

Signed-off-by: Baolin Wang 
Reviewed-by: Daniel Thompson 
Reviewed-by: Arnd Bergmann 
Signed-off-by: Jason Wessel

kdb: bl: don't use tab character in output

2018-01-25T14:41:22+00:00

The "bl" (list breakpoints) command prints a '\t' (tab) character
in its output, but on a console (video device), that just prints
some odd graphics character. Instead of printing a tab character,
just align the output with spaces.

Signed-off-by: Randy Dunlap 
Cc: Daniel Thompson 
Cc: Jason Wessel 
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Jason Wessel

kdb: drop newline in unknown command output

2018-01-25T14:41:14+00:00

When an unknown command is entered, kdb prints "Unknown kdb command:"
and then the unknown text, including the newline character. This
causes the ending single-quote mark to be printed on the next line
by itself, so just change the ending newline character to a null
character (end of string) so that it won't be "printed."

Signed-off-by: Randy Dunlap 
Cc: Daniel Thompson 
Cc: Jason Wessel 
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Jason Wessel

kdb: make "mdr" command repeat

2018-01-25T14:41:07+00:00

The "mdr" command should repeat (continue) when only Enter/Return
is pressed, so make it do so.

Signed-off-by: Randy Dunlap 
Cc: Daniel Thompson 
Cc: Jason Wessel 
Cc: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: Jason Wessel

kdb: use __ktime_get_real_seconds instead of __current_kernel_time

2018-01-25T14:40:18+00:00

kdb is the only user of the __current_kernel_time() interface, which is
not y2038 safe and should be removed at some point.

The kdb code also goes to great lengths to print the time in a
human-readable format from 'struct timespec', again using a non-y2038-safe
re-implementation of the generic time_to_tm() code.

Using __current_kernel_time() here is necessary since the regular
accessors that require a sequence lock might hang when called during the
xtime update. However, this is safe in the particular case since kdb is
only interested in the tv_sec field that is updated atomically.

In order to make this y2038-safe, I'm converting the code to the generic
time64_to_tm helper, but that introduces the problem that we have no
interface like __current_kernel_time() that provides a 64-bit timestamp
in a lockless, safe and architecture-independent way. I have multiple
ideas for how to solve that:

- __ktime_get_real_seconds() is lockless, but can return
  incorrect results on 32-bit architectures in the special case that
  we are in the process of changing the time across the epoch, either
  during the timer tick that overflows the seconds in 2038, or while
  calling settimeofday.

- ktime_get_real_fast_ns() would work in this context, but does
  require a call into the clocksource driver to return a high-resolution
  timestamp. This may have undesired side-effects in the debugger,
  since we want to limit the interactions with the rest of the kernel.

- Adding a ktime_get_real_fast_seconds() based on tk_fast_mono
  plus tkr->base_real without the tk_clock_read() delta. Not sure about
  the value of adding yet another interface here.

- Changing the existing ktime_get_real_seconds() to use
  tk_fast_mono on 32-bit architectures rather than xtime_sec.  I think
  this could work, but am not entirely sure if this is an improvement.

I picked the first of those for simplicity here. It's technically
not correct but probably good enough as the time is only used for the
debugging output and the race will likely never be hit in practice.
Another downside is having to move the declaration into a public header
file.

Let me know if anyone has a different preference.

Cc: Andy Shevchenko 
Link: https://patchwork.kernel.org/patch/9775309/
Signed-off-by: Arnd Bergmann 
Signed-off-by: Jason Wessel

signal: Simplify and fix kdb_send_sig

2018-01-04T00:01:08+00:00

- Rename from kdb_send_sig_info to kdb_send_sig
  As there is no meaningful siginfo sent

- Use SEND_SIG_PRIV instead of generating a siginfo for a kdb
  signal.  The generated siginfo had a bogus rationale and was
  not correct in the face of pid namespaces.  SEND_SIG_PRIV
  is simpler and actually correct.

- As the code grabs siglock just send the signal with siglock
  held instead of dropping siglock and attempting to grab it again.

- Move the sig_valid test into kdb_kill where it can generate
  a good error message.

Signed-off-by: Eric W. Biederman

kdb: Fix handling of kallsyms_symbol_next() return value

2017-12-06T22:12:43+00:00

kallsyms_symbol_next() returns a boolean (true on success). Currently
kdb_read() tests the return value with an inequality that
unconditionally evaluates to true.

This is fixed in the obvious way and, since the conditional branch is
supposed to be unreachable, we also add a WARN_ON().

Reported-by: Dan Carpenter 
Signed-off-by: Daniel Thompson 
Cc: linux-stable 
Signed-off-by: Jason Wessel

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

2017-03-02T07:42:34+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