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

4 files changed, 216 insertions, 0 deletions

diff --git a/Documentation/arch/parisc/debugging.rst b/Documentation/arch/parisc/debugging.rst
new file mode 100644
index 000000000..de1b60402
--- /dev/null
+++ b/Documentation/arch/parisc/debugging.rst
@@ -0,0 +1,46 @@
+=================
+PA-RISC Debugging
+=================
+
+okay, here are some hints for debugging the lower-level parts of
+linux/parisc.
+
+
+1. Absolute addresses
+=====================
+
+A lot of the assembly code currently runs in real mode, which means
+absolute addresses are used instead of virtual addresses as in the
+rest of the kernel.  To translate an absolute address to a virtual
+address you can lookup in System.map, add __PAGE_OFFSET (0x10000000
+currently).
+
+
+2. HPMCs
+========
+
+When real-mode code tries to access non-existent memory, you'll get
+an HPMC instead of a kernel oops.  To debug an HPMC, try to find
+the System Responder/Requestor addresses.  The System Requestor
+address should match (one of the) processor HPAs (high addresses in
+the I/O range); the System Responder address is the address real-mode
+code tried to access.
+
+Typical values for the System Responder address are addresses larger
+than __PAGE_OFFSET (0x10000000) which mean a virtual address didn't
+get translated to a physical address before real-mode code tried to
+access it.
+
+
+3. Q bit fun
+============
+
+Certain, very critical code has to clear the Q bit in the PSW.  What
+happens when the Q bit is cleared is the CPU does not update the
+registers interruption handlers read to find out where the machine
+was interrupted - so if you get an interruption between the instruction
+that clears the Q bit and the RFI that sets it again you don't know
+where exactly it happened.  If you're lucky the IAOQ will point to the
+instruction that cleared the Q bit, if you're not it points anywhere
+at all.  Usually Q bit problems will show themselves in unexplainable
+system hangs or running off the end of physical memory.
diff --git a/Documentation/arch/parisc/features.rst b/Documentation/arch/parisc/features.rst
new file mode 100644
index 000000000..b3aa4d243
--- /dev/null
+++ b/Documentation/arch/parisc/features.rst
@@ -0,0 +1,3 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. kernel-feat:: features parisc
diff --git a/Documentation/arch/parisc/index.rst b/Documentation/arch/parisc/index.rst
new file mode 100644
index 000000000..15ccc787f
--- /dev/null
+++ b/Documentation/arch/parisc/index.rst
@@ -0,0 +1,13 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+PA-RISC Architecture
+====================
+
+.. toctree::
+   :maxdepth: 2
+
+   debugging
+   registers
+
+   features
diff --git a/Documentation/arch/parisc/registers.rst b/Documentation/arch/parisc/registers.rst
new file mode 100644
index 000000000..59c8ecf3e
--- /dev/null
+++ b/Documentation/arch/parisc/registers.rst
@@ -0,0 +1,154 @@
+================================
+Register Usage for Linux/PA-RISC
+================================
+
+[ an asterisk is used for planned usage which is currently unimplemented ]
+
+General Registers as specified by ABI
+=====================================
+
+Control Registers
+-----------------
+
+===============================	===============================================
+CR 0 (Recovery Counter)		used for ptrace
+CR 1-CR 7(undefined)		unused
+CR 8 (Protection ID)		per-process value*
+CR 9, 12, 13 (PIDS)		unused
+CR10 (CCR)			lazy FPU saving*
+CR11				as specified by ABI (SAR)
+CR14 (interruption vector)	initialized to fault_vector
+CR15 (EIEM)			initialized to all ones*
+CR16 (Interval Timer)		read for cycle count/write starts Interval Tmr
+CR17-CR22			interruption parameters
+CR19				Interrupt Instruction Register
+CR20				Interrupt Space Register
+CR21				Interrupt Offset Register
+CR22				Interrupt PSW
+CR23 (EIRR)			read for pending interrupts/write clears bits
+CR24 (TR 0)			Kernel Space Page Directory Pointer
+CR25 (TR 1)			User   Space Page Directory Pointer
+CR26 (TR 2)			not used
+CR27 (TR 3)			Thread descriptor pointer
+CR28 (TR 4)			not used
+CR29 (TR 5)			not used
+CR30 (TR 6)			current / 0
+CR31 (TR 7)			Temporary register, used in various places
+===============================	===============================================
+
+Space Registers (kernel mode)
+-----------------------------
+
+===============================	===============================================
+SR0				temporary space register
+SR4-SR7 			set to 0
+SR1				temporary space register
+SR2				kernel should not clobber this
+SR3				used for userspace accesses (current process)
+===============================	===============================================
+
+Space Registers (user mode)
+---------------------------
+
+===============================	===============================================
+SR0				temporary space register
+SR1                             temporary space register
+SR2                             holds space of linux gateway page
+SR3                             holds user address space value while in kernel
+SR4-SR7                         Defines short address space for user/kernel
+===============================	===============================================
+
+
+Processor Status Word
+---------------------
+
+===============================	===============================================
+W (64-bit addresses)		0
+E (Little-endian)		0
+S (Secure Interval Timer)	0
+T (Taken Branch Trap)		0
+H (Higher-privilege trap)	0
+L (Lower-privilege trap)	0
+N (Nullify next instruction)	used by C code
+X (Data memory break disable)	0
+B (Taken Branch)		used by C code
+C (code address translation)	1, 0 while executing real-mode code
+V (divide step correction)	used by C code
+M (HPMC mask)			0, 1 while executing HPMC handler*
+C/B (carry/borrow bits)		used by C code
+O (ordered references)		1*
+F (performance monitor)		0
+R (Recovery Counter trap)	0
+Q (collect interruption state)	1 (0 in code directly preceding an rfi)
+P (Protection Identifiers)	1*
+D (Data address translation)	1, 0 while executing real-mode code
+I (external interrupt mask)	used by cli()/sti() macros
+===============================	===============================================
+
+"Invisible" Registers
+---------------------
+
+===============================	===============================================
+PSW default W value		0
+PSW default E value		0
+Shadow Registers		used by interruption handler code
+TOC enable bit			1
+===============================	===============================================
+
+-------------------------------------------------------------------------
+
+The PA-RISC architecture defines 7 registers as "shadow registers".
+Those are used in RETURN FROM INTERRUPTION AND RESTORE instruction to reduce
+the state save and restore time by eliminating the need for general register
+(GR) saves and restores in interruption handlers.
+Shadow registers are the GRs 1, 8, 9, 16, 17, 24, and 25.
+
+-------------------------------------------------------------------------
+
+Register usage notes, originally from John Marvin, with some additional
+notes from Randolph Chung.
+
+For the general registers:
+
+r1,r2,r19-r26,r28,r29 & r31 can be used without saving them first. And of
+course, you need to save them if you care about them, before calling
+another procedure. Some of the above registers do have special meanings
+that you should be aware of:
+
+    r1:
+	The addil instruction is hardwired to place its result in r1,
+	so if you use that instruction be aware of that.
+
+    r2:
+	This is the return pointer. In general you don't want to
+	use this, since you need the pointer to get back to your
+	caller. However, it is grouped with this set of registers
+	since the caller can't rely on the value being the same
+	when you return, i.e. you can copy r2 to another register
+	and return through that register after trashing r2, and
+	that should not cause a problem for the calling routine.
+
+    r19-r22:
+	these are generally regarded as temporary registers.
+	Note that in 64 bit they are arg7-arg4.
+
+    r23-r26:
+	these are arg3-arg0, i.e. you can use them if you
+	don't care about the values that were passed in anymore.
+
+    r28,r29:
+	are ret0 and ret1. They are what you pass return values
+	in. r28 is the primary return. When returning small structures
+	r29 may also be used to pass data back to the caller.
+
+    r30:
+	stack pointer
+
+    r31:
+	the ble instruction puts the return pointer in here.
+
+
+    r3-r18,r27,r30 need to be saved and restored. r3-r18 are just
+    general purpose registers. r27 is the data pointer, and is
+    used to make references to global variables easier. r30 is
+    the stack pointer.