Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 166 insertions, 0 deletions

diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
new file mode 100644
index 000000000..8336b1a48
--- /dev/null
+++ b/lib/Kconfig.kgdb
@@ -0,0 +1,166 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config HAVE_ARCH_KGDB
+	bool
+
+# set if architecture has the its kgdb_arch_handle_qxfer_pkt
+# function to enable gdb stub to address XML packet sent from GDB.
+config HAVE_ARCH_KGDB_QXFER_PKT
+	bool
+
+menuconfig KGDB
+	bool "KGDB: kernel debugger"
+	depends on HAVE_ARCH_KGDB
+	depends on DEBUG_KERNEL
+	help
+	  If you say Y here, it will be possible to remotely debug the
+	  kernel using gdb.  It is recommended but not required, that
+	  you also turn on the kernel config option
+	  CONFIG_FRAME_POINTER to aid in producing more reliable stack
+	  backtraces in the external debugger.  Documentation of
+	  kernel debugger is available at http://kgdb.sourceforge.net
+	  as well as in Documentation/process/debugging/kgdb.rst.  If
+	  unsure, say N.
+
+if KGDB
+
+config KGDB_HONOUR_BLOCKLIST
+	bool "KGDB: use kprobe blocklist to prohibit unsafe breakpoints"
+	depends on HAVE_KPROBES
+	depends on MODULES
+	select KPROBES
+	default y
+	help
+	  If set to Y the debug core will use the kprobe blocklist to
+	  identify symbols where it is unsafe to set breakpoints.
+	  In particular this disallows instrumentation of functions
+	  called during debug trap handling and thus makes it very
+	  difficult to inadvertently provoke recursive trap handling.
+
+	  If unsure, say Y.
+
+config KGDB_SERIAL_CONSOLE
+	tristate "KGDB: use kgdb over the serial console"
+	select CONSOLE_POLL
+	select MAGIC_SYSRQ
+	depends on TTY && VT
+	default y
+	help
+	  Share a serial console with kgdb. Sysrq-g must be used
+	  to break in initially.
+
+config KGDB_TESTS
+	bool "KGDB: internal test suite"
+	default n
+	help
+	  This is a kgdb I/O module specifically designed to test
+	  kgdb's internal functions.  This kgdb I/O module is
+	  intended to for the development of new kgdb stubs
+	  as well as regression testing the kgdb internals.
+	  See the drivers/misc/kgdbts.c for the details about
+	  the tests.  The most basic of this I/O module is to boot
+	  a kernel boot arguments "kgdbwait kgdbts=V1F100"
+
+config KGDB_TESTS_ON_BOOT
+	bool "KGDB: Run tests on boot"
+	depends on KGDB_TESTS
+	default n
+	help
+	  Run the kgdb tests on boot up automatically without the need
+	  to pass in a kernel parameter
+
+config KGDB_TESTS_BOOT_STRING
+	string "KGDB: which internal kgdb tests to run"
+	depends on KGDB_TESTS_ON_BOOT
+	default "V1F100"
+	help
+	  This is the command string to send the kgdb test suite on
+	  boot.  See the drivers/misc/kgdbts.c for detailed
+	  information about other strings you could use beyond the
+	  default of V1F100.
+
+config KGDB_LOW_LEVEL_TRAP
+       bool "KGDB: Allow debugging with traps in notifiers"
+       depends on X86 || MIPS
+       default n
+       help
+	 This will add an extra call back to kgdb for the breakpoint
+	 exception handler which will allow kgdb to step through a
+	 notify handler.
+
+config KGDB_KDB
+	bool "KGDB_KDB: include kdb frontend for kgdb"
+	default n
+	help
+	  KDB frontend for kernel
+
+config KDB_DEFAULT_ENABLE
+	hex "KDB: Select kdb command functions to be enabled by default"
+	depends on KGDB_KDB
+	default 0x1
+	help
+	  Specifiers which kdb commands are enabled by default. This may
+	  be set to 1 or 0 to enable all commands or disable almost all
+	  commands.
+
+	  Alternatively the following bitmask applies:
+
+	    0x0002 - allow arbitrary reads from memory and symbol lookup
+	    0x0004 - allow arbitrary writes to memory
+	    0x0008 - allow current register state to be inspected
+	    0x0010 - allow current register state to be modified
+	    0x0020 - allow passive inspection (backtrace, process list, lsmod)
+	    0x0040 - allow flow control management (breakpoint, single step)
+	    0x0080 - enable signalling of processes
+	    0x0100 - allow machine to be rebooted
+
+	  The config option merely sets the default at boot time. Both
+	  issuing 'echo X > /sys/module/kdb/parameters/cmd_enable' or
+	  setting with kdb.cmd_enable=X kernel command line option will
+	  override the default settings.
+
+config KDB_KEYBOARD
+	bool "KGDB_KDB: keyboard as input device"
+	depends on VT && KGDB_KDB && !PARISC
+	depends on HAS_IOPORT
+	default n
+	help
+	  KDB can use a PS/2 type keyboard for an input device
+
+config KDB_CONTINUE_CATASTROPHIC
+	int "KDB: continue after catastrophic errors"
+	depends on KGDB_KDB
+	default "0"
+	help
+	  This integer controls the behaviour of kdb when the kernel gets a
+	  catastrophic error, i.e. for a panic or oops.
+	  When KDB is active and a catastrophic error occurs, nothing extra
+	  will happen until you type 'go'.
+	  CONFIG_KDB_CONTINUE_CATASTROPHIC == 0 (default). The first time
+	  you type 'go', you will be warned by kdb. The secend time you type
+	  'go', KDB tries to continue. No guarantees that the
+	  kernel is still usable in this situation.
+	  CONFIG_KDB_CONTINUE_CATASTROPHIC == 1. KDB tries to continue.
+	  No guarantees that the kernel is still usable in this situation.
+	  CONFIG_KDB_CONTINUE_CATASTROPHIC == 2. KDB forces a reboot.
+	  If you are not sure, say 0.
+
+config ARCH_HAS_EARLY_DEBUG
+	bool
+	default n
+	help
+	  If an architecture can definitely handle entering the debugger
+	  when early_param's are parsed then it select this config.
+	  Otherwise, if "kgdbwait" is passed on the kernel command line it
+	  won't actually be processed until dbg_late_init() just after the
+	  call to kgdb_arch_late() is made.
+
+	  NOTE: Even if this isn't selected by an architecture we will
+	  still try to register kgdb to handle breakpoints and crashes
+	  when early_param's are parsed, we just won't act on the
+	  "kgdbwait" parameter until dbg_late_init().  If you get a
+	  crash and try to drop into kgdb somewhere between these two
+	  places you might or might not end up being able to use kgdb
+	  depending on exactly how far along the architecture has initted.
+
+endif # KGDB