linux-stable.git/kernel/debug/kdb/kdb_private.h, branch v4.14.331

kdb: Make memory allocations more robust

2021-03-03T17:22:36+00:00

commit 93f7a6d818deef69d0ba652d46bae6fbabbf365c upstream.

Currently kdb uses in_interrupt() to determine whether its library
code has been called from the kgdb trap handler or from a saner calling
context such as driver init. This approach is broken because
in_interrupt() alone isn't able to determine kgdb trap handler entry from
normal task context. This can happen during normal use of basic features
such as breakpoints and can also be trivially reproduced using:
echo g > /proc/sysrq-trigger

We can improve this by adding check for in_dbg_master() instead which
explicitly determines if we are running in debugger context.

Cc: stable@vger.kernel.org
Signed-off-by: Sumit Garg 
Link: https://lore.kernel.org/r/1611313556-4004-1-git-send-email-sumit.garg@linaro.org
Signed-off-by: Daniel Thompson 
Signed-off-by: Greg Kroah-Hartman

kdb: Use strscpy with destination buffer size

2018-12-01T08:42:54+00:00

[ Upstream commit c2b94c72d93d0929f48157eef128c4f9d2e603ce ]

gcc 8.1.0 warns with:

kernel/debug/kdb/kdb_support.c: In function ‘kallsyms_symbol_next’:
kernel/debug/kdb/kdb_support.c:239:4: warning: ‘strncpy’ specified bound depends on the length of the source argument [-Wstringop-overflow=]
     strncpy(prefix_name, name, strlen(name)+1);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/debug/kdb/kdb_support.c:239:31: note: length computed here

Use strscpy() with the destination buffer size, and use ellipses when
displaying truncated symbols.

v2: Use strscpy()

Signed-off-by: Prarit Bhargava 
Cc: Jonathan Toppins 
Cc: Jason Wessel 
Cc: Daniel Thompson 
Cc: kgdb-bugreport@lists.sourceforge.net
Reviewed-by: Daniel Thompson 
Signed-off-by: Daniel Thompson 
Signed-off-by: Sasha Levin

kdb: properly synchronize vkdb_printf() calls with other CPUs

2016-12-15T00:04:08+00:00

kdb_printf_lock does not prevent other CPUs from entering the critical
section because it is ignored when KDB_STATE_PRINTF_LOCK is set.

The problematic situation might look like:

CPU0					CPU1

vkdb_printf()
  if (!KDB_STATE(PRINTF_LOCK))
    KDB_STATE_SET(PRINTF_LOCK);
    spin_lock_irqsave(&kdb_printf_lock, flags);

					vkdb_printf()
					  if (!KDB_STATE(PRINTF_LOCK))

BANG: The PRINTF_LOCK state is set and CPU1 is entering the critical
section without spinning on the lock.

The problem is that the code tries to implement locking using two state
variables that are not handled atomically.  Well, we need a custom
locking because we want to allow reentering the critical section on the
very same CPU.

Let's use solution from Petr Zijlstra that was proposed for a similar
scenario, see
https://lkml.kernel.org/r/20161018171513.734367391@infradead.org

This patch uses the same trick with cmpxchg().  The only difference is
that we want to handle only recursion from the same context and
therefore we disable interrupts.

In addition, KDB_STATE_PRINTF_LOCK is removed.  In fact, we are not able
to set it a non-racy way.

Link: http://lkml.kernel.org/r/1480412276-16690-3-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek 
Reviewed-by: Daniel Thompson 
Cc: Jason Wessel 
Cc: Peter Zijlstra 
Cc: Sergey Senozhatsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kdb: Const qualifier for kdb_getstr's prompt argument

2015-02-19T18:39:03+00:00

All current callers of kdb_getstr() can pass constant pointers via the
prompt argument. This patch adds a const qualification to make explicit
the fact that this is safe.

Signed-off-by: Daniel Thompson 
Signed-off-by: Jason Wessel

kdb: Provide forward search at more prompt

2015-02-19T18:39:03+00:00

Currently kdb allows the output of comamnds to be filtered using the
| grep feature. This is useful but does not permit the output emitted
shortly after a string match to be examined without wading through the
entire unfiltered output of the command. Such a feature is particularly
useful to navigate function traces because these traces often have a
useful trigger string *before* the point of interest.

This patch reuses the existing filtering logic to introduce a simple
forward search to kdb that can be triggered from the more prompt.

Signed-off-by: Daniel Thompson 
Signed-off-by: Jason Wessel

kdb: Rename kdb_repeat_t to kdb_cmdflags_t, cmd_repeat to cmd_flags

2014-11-11T15:31:51+00:00

We're about to add more options for command behaviour, so let's expand
the meaning of kdb_repeat_t.

So far we just do various renames, there should be no functional changes.

Signed-off-by: Anton Vorontsov 
Signed-off-by: John Stultz 
Signed-off-by: Daniel Thompson 
Cc: Jason Wessel 
Signed-off-by: Jason Wessel

kdb: Remove currently unused kdbtab_t->cmd_flags

2014-11-11T15:31:51+00:00

The struct member is never used in the code, so we can remove it.

We will introduce real flags soon by renaming cmd_repeat to cmd_flags.

Signed-off-by: Anton Vorontsov 
Signed-off-by: John Stultz 
Signed-off-by: Daniel Thompson 
Cc: Jason Wessel 
Signed-off-by: Jason Wessel

kdb: Remove unhandled ssb command

2013-03-02T14:52:20+00:00

The 'ssb' command can only be handled when we have a disassembler, to check for
branches, so remove the 'ssb' command for now.

Signed-off-by: Vincent Stehlé 
Signed-off-by: Jason Wessel

printk: Remove kdb_syslog_data

2012-07-21T17:34:00+00:00

The function is no longer needed, so remove it.

Signed-off-by: Anton Vorontsov 
Signed-off-by: Linus Torvalds

KDB: Fix usability issues relating to the 'enter' key.

2012-03-22T20:07:15+00:00

This fixes the following problems:
1) Typematic-repeat of 'enter' gives warning message
   and leaks make/break if KDB exits. Repeats
   look something like 0x1c 0x1c .... 0x9c
2) Use of 'keypad enter' gives warning message and
   leaks the ENTER break/make code out if KDB exits.
   KP ENTER repeats look someting like 0xe0 0x1c
   0xe0 0x1c ... 0xe0 0x9c.
3) Lag on the order of seconds between "break" and "make" when
   expecting the enter "break" code. Seen under virtualized
   environments such as VMware ESX.

The existing special enter handler tries to glob the enter break code,
but this fails if the other (KP) enter was used, or if there was a key
repeat. It also fails if you mashed some keys along with enter, and
you ended up with a non-enter make or non-enter break code coming
after the enter make code. So first, we modify the handler to handle
these cases. But performing these actions on every enter is annoying
since now you can't hold ENTER down to scroll d messages in
KDB. Since this special behaviour is only necessary to handle the
exiting KDB ('g' + ENTER) without leaking scancodes to the OS.  This
cleanup needs to get executed anytime the kdb_main loop exits.

Tested on QEMU. Set a bp on atkbd.c to verify no scan code was leaked.

Cc: Andrei Warkentin 
[jason.wessel@windriver.com: move cleanup calls to kdb_main.c]
Signed-off-by: Andrei Warkentin 
Signed-off-by: Jason Wessel