x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 272 insertions, 0 deletions

diff --git a/Documentation/input/devices/amijoy.rst b/Documentation/input/devices/amijoy.rst
new file mode 100644
index 000000000..a81e9de48
--- /dev/null
+++ b/Documentation/input/devices/amijoy.rst
@@ -0,0 +1,272 @@
+===============
+Amiga joysticks
+===============
+
+Pinouts
+=======
+
+Amiga 4-joystick parallel port extension
+----------------------------------------
+
+Parallel port pins:
+
+=====  ======== ====   ==========
+Pin    Meaning  Pin    Meaning
+=====  ======== ====   ==========
+ 2     Up1	 6     Up2
+ 3     Down1	 7     Down2
+ 4     Left1	 8     Left2
+ 5     Right1	 9     Right2
+13     Fire1	11     Fire2
+19     Gnd1	18     Gnd2
+=====  ======== ====   ==========
+
+Amiga digital joystick
+----------------------
+
+=== ============
+Pin Meaning
+=== ============
+1   Up
+2   Down
+3   Left
+4   Right
+5   n/c
+6   Fire button
+7   +5V (50mA)
+8   Gnd
+9   Thumb button
+=== ============
+
+Amiga mouse
+-----------
+
+=== ============
+Pin Meaning
+=== ============
+1   V-pulse
+2   H-pulse
+3   VQ-pulse
+4   HQ-pulse
+5   Middle button
+6   Left button
+7   +5V (50mA)
+8   Gnd
+9   Right button
+=== ============
+
+Amiga analog joystick
+---------------------
+
+=== ==============
+Pin Meaning
+=== ==============
+1   Top button
+2   Top2 button
+3   Trigger button
+4   Thumb button
+5   Analog X
+6   n/c
+7   +5V (50mA)
+8   Gnd
+9   Analog Y
+=== ==============
+
+Amiga lightpen
+--------------
+
+=== =============
+Pin Meaning
+=== =============
+1   n/c
+2   n/c
+3   n/c
+4   n/c
+5   Touch button
+6   /Beamtrigger
+7   +5V (50mA)
+8   Gnd
+9   Stylus button
+=== =============
+
+Register addresses
+==================
+
+JOY0DAT/JOY1DAT
+---------------
+
+======== === ==== ==== ====== ===========================================
+NAME     rev ADDR type chip   Description
+======== === ==== ==== ====== ===========================================
+JOY0DAT      00A   R   Denise Joystick-mouse 0 data (left vert., horiz.)
+JOY1DAT      00C   R   Denise Joystick-mouse 1 data (right vert., horiz.)
+======== === ==== ==== ====== ===========================================
+
+        These addresses each read a 16 bit register. These in turn
+        are loaded from the MDAT serial stream and are clocked in on
+        the rising edge of SCLK. MLD output is used to parallel load
+        the external parallel-to-serial converter. This in turn is
+        loaded with the 4 quadrature inputs from each of two game
+        controller ports (8 total) plus 8 miscellaneous control bits
+        which are new for LISA and can be read in upper 8 bits of
+        LISAID.
+
+        Register bits are as follows:
+
+        - Mouse counter usage (pins 1,3 =Yclock, pins 2,4 =Xclock)
+
+======== === === === === === === === === ====== === === === === === === ===
+    BIT#  15  14  13  12  11  10  09  08     07  06  05  04  03  02  01  00
+======== === === === === === === === === ====== === === === === === === ===
+JOY0DAT   Y7  Y6  Y5  Y4  Y3  Y2  Y1  Y0     X7  X6  X5  X4  X3  X2  X1  X0
+JOY1DAT   Y7  Y6  Y5  Y4  Y3  Y2  Y1  Y0     X7  X6  X5  X4  X3  X2  X1  X0
+======== === === === === === === === === ====== === === === === === === ===
+
+        0=LEFT CONTROLLER PAIR, 1=RIGHT CONTROLLER PAIR.
+        (4 counters total). The bit usage for both left and right
+        addresses is shown below. Each 6 bit counter (Y7-Y2,X7-X2) is
+        clocked by 2 of the signals input from the mouse serial
+        stream. Starting with first bit received:
+
+         +--------+----------+-----------------------------------------+
+         | Serial | Bit Name | Description                             |
+         +========+==========+=========================================+
+         |   0    | M0H      | JOY0DAT Horizontal Clock                |
+         +--------+----------+-----------------------------------------+
+         |   1    | M0HQ     | JOY0DAT Horizontal Clock (quadrature)   |
+         +--------+----------+-----------------------------------------+
+         |   2    | M0V      | JOY0DAT Vertical Clock                  |
+         +--------+----------+-----------------------------------------+
+         |   3    | M0VQ     | JOY0DAT Vertical Clock  (quadrature)    |
+         +--------+----------+-----------------------------------------+
+         |   4    | M1V      | JOY1DAT Horizontal Clock                |
+         +--------+----------+-----------------------------------------+
+         |   5    | M1VQ     | JOY1DAT Horizontal Clock (quadrature)   |
+         +--------+----------+-----------------------------------------+
+         |   6    | M1V      | JOY1DAT Vertical Clock                  |
+         +--------+----------+-----------------------------------------+
+         |   7    | M1VQ     | JOY1DAT Vertical Clock (quadrature)     |
+         +--------+----------+-----------------------------------------+
+
+         Bits 1 and 0 of each counter (Y1-Y0,X1-X0) may be
+         read to determine the state of the related input signal pair.
+         This allows these pins to double as joystick switch inputs.
+         Joystick switch closures can be deciphered as follows:
+
+         +------------+------+---------------------------------+
+         | Directions | Pin# | Counter bits                    |
+         +============+======+=================================+
+         | Forward    |  1   | Y1 xor Y0 (BIT#09 xor BIT#08)   |
+         +------------+------+---------------------------------+
+         | Left       |  3   | Y1                              |
+         +------------+------+---------------------------------+
+         | Back       |  2   | X1 xor X0 (BIT#01 xor BIT#00)   |
+         +------------+------+---------------------------------+
+         | Right      |  4   | X1                              |
+         +------------+------+---------------------------------+
+
+JOYTEST
+-------
+
+========  === ==== ==== ====== =================================================
+NAME      rev ADDR type chip    Description
+========  === ==== ==== ====== =================================================
+JOYTEST       036   W   Denise  Write to all 4  joystick-mouse counters at once.
+========  === ==== ==== ====== =================================================
+
+                  Mouse counter write test data:
+
+========= === === === === === === === === ====== === === === === === === ===
+     BIT#  15  14  13  12  11  10  09  08     07  06  05  04  03  02  01  00
+========= === === === === === === === === ====== === === === === === === ===
+  JOYxDAT  Y7  Y6  Y5  Y4  Y3  Y2  xx  xx     X7  X6  X5  X4  X3  X2  xx  xx
+  JOYxDAT  Y7  Y6  Y5  Y4  Y3  Y2  xx  xx     X7  X6  X5  X4  X3  X2  xx  xx
+========= === === === === === === === === ====== === === === === === === ===
+
+POT0DAT/POT1DAT
+---------------
+
+======= === ==== ==== ====== ===========================================
+NAME    rev ADDR type chip   Description
+======= === ==== ==== ====== ===========================================
+POT0DAT  h  012   R   Paula  Pot counter data left pair (vert., horiz.)
+POT1DAT  h  014   R   Paula  Pot counter data right pair (vert., horiz.)
+======= === ==== ==== ====== ===========================================
+
+        These addresses each read a pair of 8 bit pot counters.
+        (4 counters total). The bit assignment for both
+        addresses is shown below. The counters are stopped by signals
+        from 2 controller connectors (left-right) with 2 pins each.
+
+====== === === === === === === === === ====== === === === === === === ===
+  BIT#  15  14  13  12  11  10  09  08     07  06  05  04  03  02  01  00
+====== === === === === === === === === ====== === === === === === === ===
+ RIGHT  Y7  Y6  Y5  Y4  Y3  Y2  Y1  Y0     X7  X6  X5  X4  X3  X2  X1  X0
+  LEFT  Y7  Y6  Y5  Y4  Y3  Y2  Y1  Y0     X7  X6  X5  X4  X3  X2  X1  X0
+====== === === === === === === === === ====== === === === === === === ===
+
+         +--------------------------+-------+
+         | CONNECTORS               | PAULA |
+         +-------+------+-----+-----+-------+
+         | Loc.  | Dir. | Sym | pin | pin   |
+         +=======+======+=====+=====+=======+
+         | RIGHT | Y    | RX  | 9   | 33    |
+         +-------+------+-----+-----+-------+
+         | RIGHT | X    | RX  | 5   | 32    |
+         +-------+------+-----+-----+-------+
+         | LEFT  | Y    | LY  | 9   | 36    |
+         +-------+------+-----+-----+-------+
+         | LEFT  | X    | LX  | 5   | 35    |
+         +-------+------+-----+-----+-------+
+
+         With normal (NTSC or PAL) horiz. line rate, the pots will
+         give a full scale (FF) reading with about 500k ohm in one
+         frame time. With proportionally faster horiz. line times,
+         the counters will count proportionally faster.
+         This should be noted when doing variable beam displays.
+
+POTGO
+-----
+
+====== === ==== ==== ====== ================================================
+NAME   rev ADDR type chip   Description
+====== === ==== ==== ====== ================================================
+POTGO      034   W   Paula  Pot port (4 bit) bi-direction and data, and pot
+			    counter start.
+====== === ==== ==== ====== ================================================
+
+POTINP
+------
+
+====== === ==== ==== ====== ================================================
+NAME   rev ADDR type chip   Description
+====== === ==== ==== ====== ================================================
+POTINP     016   R   Paula  Pot pin data read
+====== === ==== ==== ====== ================================================
+
+        This register controls a 4 bit bi-direction I/O port
+        that shares the same 4 pins as the 4 pot counters above.
+
+         +-------+----------+----------------------------------------------+
+         | BIT#  | FUNCTION | DESCRIPTION                                  |
+         +=======+==========+==============================================+
+         | 15    | OUTRY    | Output enable for Paula pin 33               |
+         +-------+----------+----------------------------------------------+
+         | 14    | DATRY    | I/O data Paula pin 33                        |
+         +-------+----------+----------------------------------------------+
+         | 13    | OUTRX    | Output enable for Paula pin 32               |
+         +-------+----------+----------------------------------------------+
+         | 12    | DATRX    | I/O data Paula pin 32                        |
+         +-------+----------+----------------------------------------------+
+         | 11    | OUTLY    | Out put enable for Paula pin 36              |
+         +-------+----------+----------------------------------------------+
+         | 10    | DATLY    | I/O data Paula pin 36                        |
+         +-------+----------+----------------------------------------------+
+         | 09    | OUTLX    | Output enable for Paula pin 35               |
+         +-------+----------+----------------------------------------------+
+         | 08    | DATLX    | I/O data  Paula pin 35                       |
+         +-------+----------+----------------------------------------------+
+         | 07-01 |   X      | Not used                                     |
+         +-------+----------+----------------------------------------------+
+         | 00    | START    | Start pots (dump capacitors, start counters) |
+         +-------+----------+----------------------------------------------+