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, 120 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-ccp b/Documentation/ABI/testing/sysfs-driver-ccp
new file mode 100644
index 000000000..6ec74b9a2
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-ccp
@@ -0,0 +1,120 @@
+What:		/sys/bus/pci/devices/<BDF>/fused_part
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/fused_part file reports
+		whether the CPU or APU has been fused to prevent tampering.
+		0: Not fused
+		1: Fused
+
+What:		/sys/bus/pci/devices/<BDF>/boot_integrity
+Date:		April 2026
+KernelVersion:	6.20
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/boot_integrity reports
+		whether the AMD CPU or APU is used for a hardware root of trust
+		during the boot process.
+		Possible values:
+		0: Not hardware root of trust.
+		1: Hardware root of trust
+
+		NOTE: Vendors may provide design specific alternative hardware
+		root of trust implementations.
+
+What:		/sys/bus/pci/devices/<BDF>/debug_lock_on
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/debug_lock_on reports
+		whether the AMD CPU or APU has been unlocked for debugging.
+		Possible values:
+		0: Not locked
+		1: Locked
+
+What:		/sys/bus/pci/devices/<BDF>/tsme_status
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/tsme_status file reports
+		the status of transparent secure memory encryption on AMD systems.
+		Possible values:
+		0: Not active
+		1: Active
+
+What:		/sys/bus/pci/devices/<BDF>/anti_rollback_status
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/anti_rollback_status file reports
+		whether the PSP is enforcing rollback protection.
+		Possible values:
+		0: Not enforcing
+		1: Enforcing
+
+What:		/sys/bus/pci/devices/<BDF>/rpmc_production_enabled
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/rpmc_production_enabled file reports
+		whether Replay Protected Monotonic Counter support has been enabled.
+		Possible values:
+		0: Not enabled
+		1: Enabled
+
+What:		/sys/bus/pci/devices/<BDF>/rpmc_spirom_available
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/rpmc_spirom_available file reports
+		whether an Replay Protected Monotonic Counter supported SPI is installed
+		on the system.
+		Possible values:
+		0: Not present
+		1: Present
+
+What:		/sys/bus/pci/devices/<BDF>/hsp_tpm_available
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/hsp_tpm_available file reports
+		whether the HSP TPM has been activated.
+		Possible values:
+		0: Not activated or present
+		1: Activated
+
+What:		/sys/bus/pci/devices/<BDF>/rom_armor_enforced
+Date:		June 2022
+KernelVersion:	5.19
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/rom_armor_enforced file reports
+		whether RomArmor SPI protection is enforced.
+		Possible values:
+		0: Not enforced
+		1: Enforced
+
+What:		/sys/bus/pci/devices/<BDF>/bootloader_version
+Date:		June 2023
+KernelVersion:	6.4
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/bootloader_version
+		file reports the firmware version of the AMD AGESA
+		bootloader.
+
+What:		/sys/bus/pci/devices/<BDF>/tee_version
+Date:		June 2023
+KernelVersion:	6.4
+Contact:	mario.limonciello@amd.com
+Description:
+		The /sys/bus/pci/devices/<BDF>/tee_version
+		file reports the firmware version of the AMD Trusted
+		Execution Environment (TEE).