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, 69 insertions, 0 deletions

diff --git a/drivers/regulator/mpq7920.h b/drivers/regulator/mpq7920.h
new file mode 100644
index 000000000..489924655
--- /dev/null
+++ b/drivers/regulator/mpq7920.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * mpq7920.h  -  Regulator definitions for mpq7920
+ *
+ * Copyright 2019 Monolithic Power Systems, Inc
+ *
+ */
+
+#ifndef __MPQ7920_H__
+#define __MPQ7920_H__
+
+#define MPQ7920_REG_CTL0		0x00
+#define MPQ7920_REG_CTL1		0x01
+#define MPQ7920_REG_CTL2		0x02
+#define MPQ7920_BUCK1_REG_A		0x03
+#define MPQ7920_BUCK1_REG_B		0x04
+#define MPQ7920_BUCK1_REG_C		0x05
+#define MPQ7920_BUCK1_REG_D		0x06
+#define MPQ7920_BUCK2_REG_A		0x07
+#define MPQ7920_BUCK2_REG_B		0x08
+#define MPQ7920_BUCK2_REG_C		0x09
+#define MPQ7920_BUCK2_REG_D		0x0a
+#define MPQ7920_BUCK3_REG_A		0x0b
+#define MPQ7920_BUCK3_REG_B		0x0c
+#define MPQ7920_BUCK3_REG_C		0x0d
+#define MPQ7920_BUCK3_REG_D		0x0e
+#define MPQ7920_BUCK4_REG_A		0x0f
+#define MPQ7920_BUCK4_REG_B		0x10
+#define MPQ7920_BUCK4_REG_C		0x11
+#define MPQ7920_BUCK4_REG_D		0x12
+#define MPQ7920_LDO1_REG_A		0x13
+#define MPQ7920_LDO1_REG_B		0x0
+#define MPQ7920_LDO2_REG_A		0x14
+#define MPQ7920_LDO2_REG_B		0x15
+#define MPQ7920_LDO2_REG_C		0x16
+#define MPQ7920_LDO3_REG_A		0x17
+#define MPQ7920_LDO3_REG_B		0x18
+#define MPQ7920_LDO3_REG_C		0x19
+#define MPQ7920_LDO4_REG_A		0x1a
+#define MPQ7920_LDO4_REG_B		0x1b
+#define MPQ7920_LDO4_REG_C		0x1c
+#define MPQ7920_LDO5_REG_A		0x1d
+#define MPQ7920_LDO5_REG_B		0x1e
+#define MPQ7920_LDO5_REG_C		0x1f
+#define MPQ7920_REG_MODE		0x20
+#define MPQ7920_REG_REGULATOR_EN	0x22
+
+#define MPQ7920_MASK_VREF		0x7f
+#define MPQ7920_MASK_BUCK_ILIM		0xc0
+#define MPQ7920_MASK_LDO_ILIM		BIT(6)
+#define MPQ7920_MASK_DISCHARGE		BIT(5)
+#define MPQ7920_MASK_MODE		0xc0
+#define MPQ7920_MASK_SOFTSTART		0x0c
+#define MPQ7920_MASK_SWITCH_FREQ	0x30
+#define MPQ7920_MASK_BUCK_PHASE_DEALY	0x30
+#define MPQ7920_MASK_DVS_SLEWRATE	0xc0
+#define MPQ7920_MASK_OVP		0x40
+#define MPQ7920_OVP_DISABLE		~(0x40)
+#define MPQ7920_DISCHARGE_ON		BIT(5)
+
+#define MPQ7920_REGULATOR_EN_OFFSET	7
+
+/* values in mV */
+#define MPQ7920_BUCK_VOLT_MIN		400000
+#define MPQ7920_LDO_VOLT_MIN		650000
+#define MPQ7920_VOLT_MAX		3587500
+#define MPQ7920_VOLT_STEP		12500
+
+#endif /* __MPQ7920_H__ */