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, 346 insertions, 0 deletions

diff --git a/arch/mips/kvm/trace.h b/arch/mips/kvm/trace.h
new file mode 100644
index 000000000..136c3535a
--- /dev/null
+++ b/arch/mips/kvm/trace.h
@@ -0,0 +1,346 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
+ * Authors: Sanjay Lal <sanjayl@kymasys.com>
+ */
+
+#if !defined(_TRACE_KVM_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_KVM_H
+
+#include <linux/tracepoint.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM kvm
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE trace
+
+/*
+ * arch/mips/kvm/mips.c
+ */
+extern bool kvm_trace_guest_mode_change;
+int kvm_guest_mode_change_trace_reg(void);
+void kvm_guest_mode_change_trace_unreg(void);
+
+/*
+ * Tracepoints for VM enters
+ */
+DECLARE_EVENT_CLASS(kvm_transition,
+	TP_PROTO(struct kvm_vcpu *vcpu),
+	TP_ARGS(vcpu),
+	TP_STRUCT__entry(
+		__field(unsigned long, pc)
+	),
+
+	TP_fast_assign(
+		__entry->pc = vcpu->arch.pc;
+	),
+
+	TP_printk("PC: 0x%08lx",
+		  __entry->pc)
+);
+
+DEFINE_EVENT(kvm_transition, kvm_enter,
+	     TP_PROTO(struct kvm_vcpu *vcpu),
+	     TP_ARGS(vcpu));
+
+DEFINE_EVENT(kvm_transition, kvm_reenter,
+	     TP_PROTO(struct kvm_vcpu *vcpu),
+	     TP_ARGS(vcpu));
+
+DEFINE_EVENT(kvm_transition, kvm_out,
+	     TP_PROTO(struct kvm_vcpu *vcpu),
+	     TP_ARGS(vcpu));
+
+/* The first 32 exit reasons correspond to Cause.ExcCode */
+#define KVM_TRACE_EXIT_INT		 0
+#define KVM_TRACE_EXIT_TLBMOD		 1
+#define KVM_TRACE_EXIT_TLBMISS_LD	 2
+#define KVM_TRACE_EXIT_TLBMISS_ST	 3
+#define KVM_TRACE_EXIT_ADDRERR_LD	 4
+#define KVM_TRACE_EXIT_ADDRERR_ST	 5
+#define KVM_TRACE_EXIT_SYSCALL		 8
+#define KVM_TRACE_EXIT_BREAK_INST	 9
+#define KVM_TRACE_EXIT_RESVD_INST	10
+#define KVM_TRACE_EXIT_COP_UNUSABLE	11
+#define KVM_TRACE_EXIT_TRAP_INST	13
+#define KVM_TRACE_EXIT_MSA_FPE		14
+#define KVM_TRACE_EXIT_FPE		15
+#define KVM_TRACE_EXIT_MSA_DISABLED	21
+#define KVM_TRACE_EXIT_GUEST_EXIT	27
+/* Further exit reasons */
+#define KVM_TRACE_EXIT_WAIT		32
+#define KVM_TRACE_EXIT_CACHE		33
+#define KVM_TRACE_EXIT_SIGNAL		34
+/* 32 exit reasons correspond to GuestCtl0.GExcCode (VZ) */
+#define KVM_TRACE_EXIT_GEXCCODE_BASE	64
+#define KVM_TRACE_EXIT_GPSI		64	/*  0 */
+#define KVM_TRACE_EXIT_GSFC		65	/*  1 */
+#define KVM_TRACE_EXIT_HC		66	/*  2 */
+#define KVM_TRACE_EXIT_GRR		67	/*  3 */
+#define KVM_TRACE_EXIT_GVA		72	/*  8 */
+#define KVM_TRACE_EXIT_GHFC		73	/*  9 */
+#define KVM_TRACE_EXIT_GPA		74	/* 10 */
+
+/* Tracepoints for VM exits */
+#define kvm_trace_symbol_exit_types				\
+	{ KVM_TRACE_EXIT_INT,		"Interrupt" },		\
+	{ KVM_TRACE_EXIT_TLBMOD,	"TLB Mod" },		\
+	{ KVM_TRACE_EXIT_TLBMISS_LD,	"TLB Miss (LD)" },	\
+	{ KVM_TRACE_EXIT_TLBMISS_ST,	"TLB Miss (ST)" },	\
+	{ KVM_TRACE_EXIT_ADDRERR_LD,	"Address Error (LD)" },	\
+	{ KVM_TRACE_EXIT_ADDRERR_ST,	"Address Err (ST)" },	\
+	{ KVM_TRACE_EXIT_SYSCALL,	"System Call" },	\
+	{ KVM_TRACE_EXIT_BREAK_INST,	"Break Inst" },		\
+	{ KVM_TRACE_EXIT_RESVD_INST,	"Reserved Inst" },	\
+	{ KVM_TRACE_EXIT_COP_UNUSABLE,	"COP0/1 Unusable" },	\
+	{ KVM_TRACE_EXIT_TRAP_INST,	"Trap Inst" },		\
+	{ KVM_TRACE_EXIT_MSA_FPE,	"MSA FPE" },		\
+	{ KVM_TRACE_EXIT_FPE,		"FPE" },		\
+	{ KVM_TRACE_EXIT_MSA_DISABLED,	"MSA Disabled" },	\
+	{ KVM_TRACE_EXIT_GUEST_EXIT,	"Guest Exit" },		\
+	{ KVM_TRACE_EXIT_WAIT,		"WAIT" },		\
+	{ KVM_TRACE_EXIT_CACHE,		"CACHE" },		\
+	{ KVM_TRACE_EXIT_SIGNAL,	"Signal" },		\
+	{ KVM_TRACE_EXIT_GPSI,		"GPSI" },		\
+	{ KVM_TRACE_EXIT_GSFC,		"GSFC" },		\
+	{ KVM_TRACE_EXIT_HC,		"HC" },			\
+	{ KVM_TRACE_EXIT_GRR,		"GRR" },		\
+	{ KVM_TRACE_EXIT_GVA,		"GVA" },		\
+	{ KVM_TRACE_EXIT_GHFC,		"GHFC" },		\
+	{ KVM_TRACE_EXIT_GPA,		"GPA" }
+
+TRACE_EVENT(kvm_exit,
+	    TP_PROTO(struct kvm_vcpu *vcpu, unsigned int reason),
+	    TP_ARGS(vcpu, reason),
+	    TP_STRUCT__entry(
+			__field(unsigned long, pc)
+			__field(unsigned int, reason)
+	    ),
+
+	    TP_fast_assign(
+			__entry->pc = vcpu->arch.pc;
+			__entry->reason = reason;
+	    ),
+
+	    TP_printk("[%s]PC: 0x%08lx",
+		      __print_symbolic(__entry->reason,
+				       kvm_trace_symbol_exit_types),
+		      __entry->pc)
+);
+
+#define KVM_TRACE_MFC0		0
+#define KVM_TRACE_MTC0		1
+#define KVM_TRACE_DMFC0		2
+#define KVM_TRACE_DMTC0		3
+#define KVM_TRACE_RDHWR		4
+
+#define KVM_TRACE_HWR_COP0	0
+#define KVM_TRACE_HWR_HWR	1
+
+#define KVM_TRACE_COP0(REG, SEL)	((KVM_TRACE_HWR_COP0 << 8) |	\
+					 ((REG) << 3) | (SEL))
+#define KVM_TRACE_HWR(REG, SEL)		((KVM_TRACE_HWR_HWR  << 8) |	\
+					 ((REG) << 3) | (SEL))
+
+#define kvm_trace_symbol_hwr_ops				\
+	{ KVM_TRACE_MFC0,		"MFC0" },		\
+	{ KVM_TRACE_MTC0,		"MTC0" },		\
+	{ KVM_TRACE_DMFC0,		"DMFC0" },		\
+	{ KVM_TRACE_DMTC0,		"DMTC0" },		\
+	{ KVM_TRACE_RDHWR,		"RDHWR" }
+
+#define kvm_trace_symbol_hwr_cop				\
+	{ KVM_TRACE_HWR_COP0,		"COP0" },		\
+	{ KVM_TRACE_HWR_HWR,		"HWR" }
+
+#define kvm_trace_symbol_hwr_regs				\
+	{ KVM_TRACE_COP0( 0, 0),	"Index" },		\
+	{ KVM_TRACE_COP0( 2, 0),	"EntryLo0" },		\
+	{ KVM_TRACE_COP0( 3, 0),	"EntryLo1" },		\
+	{ KVM_TRACE_COP0( 4, 0),	"Context" },		\
+	{ KVM_TRACE_COP0( 4, 2),	"UserLocal" },		\
+	{ KVM_TRACE_COP0( 5, 0),	"PageMask" },		\
+	{ KVM_TRACE_COP0( 6, 0),	"Wired" },		\
+	{ KVM_TRACE_COP0( 7, 0),	"HWREna" },		\
+	{ KVM_TRACE_COP0( 8, 0),	"BadVAddr" },		\
+	{ KVM_TRACE_COP0( 9, 0),	"Count" },		\
+	{ KVM_TRACE_COP0(10, 0),	"EntryHi" },		\
+	{ KVM_TRACE_COP0(11, 0),	"Compare" },		\
+	{ KVM_TRACE_COP0(12, 0),	"Status" },		\
+	{ KVM_TRACE_COP0(12, 1),	"IntCtl" },		\
+	{ KVM_TRACE_COP0(12, 2),	"SRSCtl" },		\
+	{ KVM_TRACE_COP0(13, 0),	"Cause" },		\
+	{ KVM_TRACE_COP0(14, 0),	"EPC" },		\
+	{ KVM_TRACE_COP0(15, 0),	"PRId" },		\
+	{ KVM_TRACE_COP0(15, 1),	"EBase" },		\
+	{ KVM_TRACE_COP0(16, 0),	"Config" },		\
+	{ KVM_TRACE_COP0(16, 1),	"Config1" },		\
+	{ KVM_TRACE_COP0(16, 2),	"Config2" },		\
+	{ KVM_TRACE_COP0(16, 3),	"Config3" },		\
+	{ KVM_TRACE_COP0(16, 4),	"Config4" },		\
+	{ KVM_TRACE_COP0(16, 5),	"Config5" },		\
+	{ KVM_TRACE_COP0(16, 7),	"Config7" },		\
+	{ KVM_TRACE_COP0(17, 1),	"MAAR" },		\
+	{ KVM_TRACE_COP0(17, 2),	"MAARI" },		\
+	{ KVM_TRACE_COP0(26, 0),	"ECC" },		\
+	{ KVM_TRACE_COP0(30, 0),	"ErrorEPC" },		\
+	{ KVM_TRACE_COP0(31, 2),	"KScratch1" },		\
+	{ KVM_TRACE_COP0(31, 3),	"KScratch2" },		\
+	{ KVM_TRACE_COP0(31, 4),	"KScratch3" },		\
+	{ KVM_TRACE_COP0(31, 5),	"KScratch4" },		\
+	{ KVM_TRACE_COP0(31, 6),	"KScratch5" },		\
+	{ KVM_TRACE_COP0(31, 7),	"KScratch6" },		\
+	{ KVM_TRACE_HWR( 0, 0),		"CPUNum" },		\
+	{ KVM_TRACE_HWR( 1, 0),		"SYNCI_Step" },		\
+	{ KVM_TRACE_HWR( 2, 0),		"CC" },			\
+	{ KVM_TRACE_HWR( 3, 0),		"CCRes" },		\
+	{ KVM_TRACE_HWR(29, 0),		"ULR" }
+
+TRACE_EVENT(kvm_hwr,
+	    TP_PROTO(struct kvm_vcpu *vcpu, unsigned int op, unsigned int reg,
+		     unsigned long val),
+	    TP_ARGS(vcpu, op, reg, val),
+	    TP_STRUCT__entry(
+			__field(unsigned long, val)
+			__field(u16, reg)
+			__field(u8, op)
+	    ),
+
+	    TP_fast_assign(
+			__entry->val = val;
+			__entry->reg = reg;
+			__entry->op = op;
+	    ),
+
+	    TP_printk("%s %s (%s:%u:%u) 0x%08lx",
+		      __print_symbolic(__entry->op,
+				       kvm_trace_symbol_hwr_ops),
+		      __print_symbolic(__entry->reg,
+				       kvm_trace_symbol_hwr_regs),
+		      __print_symbolic(__entry->reg >> 8,
+				       kvm_trace_symbol_hwr_cop),
+		      (__entry->reg >> 3) & 0x1f,
+		      __entry->reg & 0x7,
+		      __entry->val)
+);
+
+#define KVM_TRACE_AUX_RESTORE		0
+#define KVM_TRACE_AUX_SAVE		1
+#define KVM_TRACE_AUX_ENABLE		2
+#define KVM_TRACE_AUX_DISABLE		3
+#define KVM_TRACE_AUX_DISCARD		4
+
+#define KVM_TRACE_AUX_FPU		1
+#define KVM_TRACE_AUX_MSA		2
+#define KVM_TRACE_AUX_FPU_MSA		3
+
+#define kvm_trace_symbol_aux_op		\
+	{ KVM_TRACE_AUX_RESTORE, "restore" },	\
+	{ KVM_TRACE_AUX_SAVE,    "save" },	\
+	{ KVM_TRACE_AUX_ENABLE,  "enable" },	\
+	{ KVM_TRACE_AUX_DISABLE, "disable" },	\
+	{ KVM_TRACE_AUX_DISCARD, "discard" }
+
+#define kvm_trace_symbol_aux_state		\
+	{ KVM_TRACE_AUX_FPU,     "FPU" },	\
+	{ KVM_TRACE_AUX_MSA,     "MSA" },	\
+	{ KVM_TRACE_AUX_FPU_MSA, "FPU & MSA" }
+
+TRACE_EVENT(kvm_aux,
+	    TP_PROTO(struct kvm_vcpu *vcpu, unsigned int op,
+		     unsigned int state),
+	    TP_ARGS(vcpu, op, state),
+	    TP_STRUCT__entry(
+			__field(unsigned long, pc)
+			__field(u8, op)
+			__field(u8, state)
+	    ),
+
+	    TP_fast_assign(
+			__entry->pc = vcpu->arch.pc;
+			__entry->op = op;
+			__entry->state = state;
+	    ),
+
+	    TP_printk("%s %s PC: 0x%08lx",
+		      __print_symbolic(__entry->op,
+				       kvm_trace_symbol_aux_op),
+		      __print_symbolic(__entry->state,
+				       kvm_trace_symbol_aux_state),
+		      __entry->pc)
+);
+
+TRACE_EVENT(kvm_asid_change,
+	    TP_PROTO(struct kvm_vcpu *vcpu, unsigned int old_asid,
+		     unsigned int new_asid),
+	    TP_ARGS(vcpu, old_asid, new_asid),
+	    TP_STRUCT__entry(
+			__field(unsigned long, pc)
+			__field(u8, old_asid)
+			__field(u8, new_asid)
+	    ),
+
+	    TP_fast_assign(
+			__entry->pc = vcpu->arch.pc;
+			__entry->old_asid = old_asid;
+			__entry->new_asid = new_asid;
+	    ),
+
+	    TP_printk("PC: 0x%08lx old: 0x%02x new: 0x%02x",
+		      __entry->pc,
+		      __entry->old_asid,
+		      __entry->new_asid)
+);
+
+TRACE_EVENT(kvm_guestid_change,
+	    TP_PROTO(struct kvm_vcpu *vcpu, unsigned int guestid),
+	    TP_ARGS(vcpu, guestid),
+	    TP_STRUCT__entry(
+			__field(unsigned int, guestid)
+	    ),
+
+	    TP_fast_assign(
+			__entry->guestid = guestid;
+	    ),
+
+	    TP_printk("GuestID: 0x%02x",
+		      __entry->guestid)
+);
+
+TRACE_EVENT_FN(kvm_guest_mode_change,
+	    TP_PROTO(struct kvm_vcpu *vcpu),
+	    TP_ARGS(vcpu),
+	    TP_STRUCT__entry(
+			__field(unsigned long, epc)
+			__field(unsigned long, pc)
+			__field(unsigned long, badvaddr)
+			__field(unsigned int, status)
+			__field(unsigned int, cause)
+	    ),
+
+	    TP_fast_assign(
+			__entry->epc = kvm_read_c0_guest_epc(&vcpu->arch.cop0);
+			__entry->pc = vcpu->arch.pc;
+			__entry->badvaddr = kvm_read_c0_guest_badvaddr(&vcpu->arch.cop0);
+			__entry->status = kvm_read_c0_guest_status(&vcpu->arch.cop0);
+			__entry->cause = kvm_read_c0_guest_cause(&vcpu->arch.cop0);
+	    ),
+
+	    TP_printk("EPC: 0x%08lx PC: 0x%08lx Status: 0x%08x Cause: 0x%08x BadVAddr: 0x%08lx",
+		      __entry->epc,
+		      __entry->pc,
+		      __entry->status,
+		      __entry->cause,
+		      __entry->badvaddr),
+
+	    kvm_guest_mode_change_trace_reg,
+	    kvm_guest_mode_change_trace_unreg
+);
+
+#endif /* _TRACE_KVM_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>