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, 64 insertions, 0 deletions

diff --git a/arch/powerpc/crypto/Kconfig b/arch/powerpc/crypto/Kconfig
new file mode 100644
index 000000000..b247f7ed9
--- /dev/null
+++ b/arch/powerpc/crypto/Kconfig
@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menu "Accelerated Cryptographic Algorithms for CPU (powerpc)"
+
+config CRYPTO_AES_PPC_SPE
+	tristate "Ciphers: AES, modes: ECB/CBC/CTR/XTS (SPE)"
+	depends on SPE
+	select CRYPTO_LIB_AES
+	select CRYPTO_SKCIPHER
+	help
+	  Length-preserving ciphers: AES with ECB, CBC, CTR, and XTS modes
+
+	  Architecture: powerpc using:
+	  - SPE (Signal Processing Engine) extensions
+
+	  SPE is available for:
+	  - Processor Type: Freescale 8500
+	  - CPU selection: e500 (8540)
+
+	  This module should only be used for low power (router) devices
+	  without hardware AES acceleration (e.g. caam crypto). It reduces the
+	  size of the AES tables from 16KB to 8KB + 256 bytes and mitigates
+	  timining attacks. Nevertheless it might be not as secure as other
+	  architecture specific assembler implementations that work on 1KB
+	  tables or 256 bytes S-boxes.
+
+config CRYPTO_AES_GCM_P10
+	tristate "Stitched AES/GCM acceleration support on P10 or later CPU (PPC)"
+	depends on PPC64 && CPU_LITTLE_ENDIAN && VSX
+	select CRYPTO_LIB_AES
+	select CRYPTO_ALGAPI
+	select CRYPTO_AEAD
+	select CRYPTO_SKCIPHER
+	select CRYPTO_SIMD
+	help
+	  AEAD cipher: AES cipher algorithms (FIPS-197)
+	  GCM (Galois/Counter Mode) authenticated encryption mode (NIST SP800-38D)
+	  Architecture: powerpc64 using:
+	    - little-endian
+	    - Power10 or later features
+
+	  Support for cryptographic acceleration instructions on Power10 or
+	  later CPU. This module supports stitched acceleration for AES/GCM.
+
+config CRYPTO_DEV_VMX
+        bool "Support for VMX cryptographic acceleration instructions"
+        depends on PPC64 && VSX
+        help
+          Support for VMX cryptographic acceleration instructions.
+
+config CRYPTO_DEV_VMX_ENCRYPT
+	tristate "Encryption acceleration support on P8 CPU"
+	depends on CRYPTO_DEV_VMX
+	select CRYPTO_AES
+	select CRYPTO_CBC
+	select CRYPTO_CTR
+	select CRYPTO_XTS
+	default m
+	help
+	  Support for VMX cryptographic acceleration instructions on Power8 CPU.
+	  This module supports acceleration for AES in hardware. If you choose
+	  'M' here, this module will be called vmx-crypto.
+
+endmenu