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, 386 insertions, 0 deletions

diff --git a/arch/sparc/lib/NG4memcpy.S b/arch/sparc/lib/NG4memcpy.S
new file mode 100644
index 000000000..df0ec1bd1
--- /dev/null
+++ b/arch/sparc/lib/NG4memcpy.S
@@ -0,0 +1,386 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* NG4memcpy.S: Niagara-4 optimized memcpy.
+ *
+ * Copyright (C) 2012 David S. Miller (davem@davemloft.net)
+ */
+
+#ifdef __KERNEL__
+#include <linux/linkage.h>
+#include <asm/visasm.h>
+#include <asm/asi.h>
+#define GLOBAL_SPARE	%g7
+#else
+#define ASI_BLK_INIT_QUAD_LDD_P 0xe2
+#define FPRS_FEF  0x04
+
+/* On T4 it is very expensive to access ASRs like %fprs and
+ * %asi, avoiding a read or a write can save ~50 cycles.
+ */
+#define FPU_ENTER			\
+	rd	%fprs, %o5;		\
+	andcc	%o5, FPRS_FEF, %g0;	\
+	be,a,pn	%icc, 999f;		\
+	 wr	%g0, FPRS_FEF, %fprs;	\
+	999:
+
+#ifdef MEMCPY_DEBUG
+#define VISEntryHalf FPU_ENTER; \
+		     clr %g1; clr %g2; clr %g3; clr %g5; subcc %g0, %g0, %g0;
+#define VISExitHalf and %o5, FPRS_FEF, %o5; wr %o5, 0x0, %fprs
+#else
+#define VISEntryHalf FPU_ENTER
+#define VISExitHalf and %o5, FPRS_FEF, %o5; wr %o5, 0x0, %fprs
+#endif
+
+#define GLOBAL_SPARE	%g5
+#endif
+
+#ifndef STORE_ASI
+#ifndef SIMULATE_NIAGARA_ON_NON_NIAGARA
+#define STORE_ASI	ASI_BLK_INIT_QUAD_LDD_P
+#else
+#define STORE_ASI	0x80		/* ASI_P */
+#endif
+#endif
+
+#if !defined(EX_LD) && !defined(EX_ST)
+#define NON_USER_COPY
+#endif
+
+#ifndef EX_LD
+#define EX_LD(x,y)	x
+#endif
+#ifndef EX_LD_FP
+#define EX_LD_FP(x,y)	x
+#endif
+
+#ifndef EX_ST
+#define EX_ST(x,y)	x
+#endif
+#ifndef EX_ST_FP
+#define EX_ST_FP(x,y)	x
+#endif
+
+
+#ifndef LOAD
+#define LOAD(type,addr,dest)	type [addr], dest
+#endif
+
+#ifndef STORE
+#ifndef MEMCPY_DEBUG
+#define STORE(type,src,addr)	type src, [addr]
+#else
+#define STORE(type,src,addr)	type##a src, [addr] %asi
+#endif
+#endif
+
+#ifndef STORE_INIT
+#define STORE_INIT(src,addr)	stxa src, [addr] STORE_ASI
+#endif
+
+#ifndef FUNC_NAME
+#define FUNC_NAME	NG4memcpy
+#endif
+#ifndef PREAMBLE
+#define PREAMBLE
+#endif
+
+#ifndef XCC
+#define XCC xcc
+#endif
+
+	.register	%g2,#scratch
+	.register	%g3,#scratch
+
+	.text
+#ifndef EX_RETVAL
+#define EX_RETVAL(x)	x
+#endif
+	.align		64
+
+	.globl	FUNC_NAME
+	.type	FUNC_NAME,#function
+FUNC_NAME:	/* %o0=dst, %o1=src, %o2=len */
+#ifdef MEMCPY_DEBUG
+	wr		%g0, 0x80, %asi
+#endif
+	srlx		%o2, 31, %g2
+	cmp		%g2, 0
+	tne		%XCC, 5
+	PREAMBLE
+	mov		%o0, %o3
+	brz,pn		%o2, .Lexit
+	 cmp		%o2, 3
+	ble,pn		%icc, .Ltiny
+	 cmp		%o2, 19
+	ble,pn		%icc, .Lsmall
+	 or		%o0, %o1, %g2
+	cmp		%o2, 128
+	bl,pn		%icc, .Lmedium
+	 nop
+
+.Llarge:/* len >= 0x80 */
+	/* First get dest 8 byte aligned.  */
+	sub		%g0, %o0, %g1
+	and		%g1, 0x7, %g1
+	brz,pt		%g1, 51f
+	 sub		%o2, %g1, %o2
+
+
+1:	EX_LD(LOAD(ldub, %o1 + 0x00, %g2), memcpy_retl_o2_plus_g1)
+	add		%o1, 1, %o1
+	subcc		%g1, 1, %g1
+	add		%o0, 1, %o0
+	bne,pt		%icc, 1b
+	 EX_ST(STORE(stb, %g2, %o0 - 0x01), memcpy_retl_o2_plus_g1_plus_1)
+
+51:	LOAD(prefetch, %o1 + 0x040, #n_reads_strong)
+	LOAD(prefetch, %o1 + 0x080, #n_reads_strong)
+	LOAD(prefetch, %o1 + 0x0c0, #n_reads_strong)
+	LOAD(prefetch, %o1 + 0x100, #n_reads_strong)
+	LOAD(prefetch, %o1 + 0x140, #n_reads_strong)
+	LOAD(prefetch, %o1 + 0x180, #n_reads_strong)
+	LOAD(prefetch, %o1 + 0x1c0, #n_reads_strong)
+	LOAD(prefetch, %o1 + 0x200, #n_reads_strong)
+
+	/* Check if we can use the straight fully aligned
+	 * loop, or we require the alignaddr/faligndata variant.
+	 */
+	andcc		%o1, 0x7, %o5
+	bne,pn		%icc, .Llarge_src_unaligned
+	 sub		%g0, %o0, %g1
+
+	/* Legitimize the use of initializing stores by getting dest
+	 * to be 64-byte aligned.
+	 */
+	and		%g1, 0x3f, %g1
+	brz,pt		%g1, .Llarge_aligned
+	 sub		%o2, %g1, %o2
+
+1:	EX_LD(LOAD(ldx, %o1 + 0x00, %g2), memcpy_retl_o2_plus_g1)
+	add		%o1, 8, %o1
+	subcc		%g1, 8, %g1
+	add		%o0, 8, %o0
+	bne,pt		%icc, 1b
+	 EX_ST(STORE(stx, %g2, %o0 - 0x08), memcpy_retl_o2_plus_g1_plus_8)
+
+.Llarge_aligned:
+	/* len >= 0x80 && src 8-byte aligned && dest 8-byte aligned */
+	andn		%o2, 0x3f, %o4
+	sub		%o2, %o4, %o2
+
+1:	EX_LD(LOAD(ldx, %o1 + 0x00, %g1), memcpy_retl_o2_plus_o4)
+	add		%o1, 0x40, %o1
+	EX_LD(LOAD(ldx, %o1 - 0x38, %g2), memcpy_retl_o2_plus_o4)
+	subcc		%o4, 0x40, %o4
+	EX_LD(LOAD(ldx, %o1 - 0x30, %g3), memcpy_retl_o2_plus_o4_plus_64)
+	EX_LD(LOAD(ldx, %o1 - 0x28, GLOBAL_SPARE), memcpy_retl_o2_plus_o4_plus_64)
+	EX_LD(LOAD(ldx, %o1 - 0x20, %o5), memcpy_retl_o2_plus_o4_plus_64)
+	EX_ST(STORE_INIT(%g1, %o0), memcpy_retl_o2_plus_o4_plus_64)
+	add		%o0, 0x08, %o0
+	EX_ST(STORE_INIT(%g2, %o0), memcpy_retl_o2_plus_o4_plus_56)
+	add		%o0, 0x08, %o0
+	EX_LD(LOAD(ldx, %o1 - 0x18, %g2), memcpy_retl_o2_plus_o4_plus_48)
+	EX_ST(STORE_INIT(%g3, %o0), memcpy_retl_o2_plus_o4_plus_48)
+	add		%o0, 0x08, %o0
+	EX_LD(LOAD(ldx, %o1 - 0x10, %g3), memcpy_retl_o2_plus_o4_plus_40)
+	EX_ST(STORE_INIT(GLOBAL_SPARE, %o0), memcpy_retl_o2_plus_o4_plus_40)
+	add		%o0, 0x08, %o0
+	EX_LD(LOAD(ldx, %o1 - 0x08, GLOBAL_SPARE), memcpy_retl_o2_plus_o4_plus_32)
+	EX_ST(STORE_INIT(%o5, %o0), memcpy_retl_o2_plus_o4_plus_32)
+	add		%o0, 0x08, %o0
+	EX_ST(STORE_INIT(%g2, %o0), memcpy_retl_o2_plus_o4_plus_24)
+	add		%o0, 0x08, %o0
+	EX_ST(STORE_INIT(%g3, %o0), memcpy_retl_o2_plus_o4_plus_16)
+	add		%o0, 0x08, %o0
+	EX_ST(STORE_INIT(GLOBAL_SPARE, %o0), memcpy_retl_o2_plus_o4_plus_8)
+	add		%o0, 0x08, %o0
+	bne,pt		%icc, 1b
+	 LOAD(prefetch, %o1 + 0x200, #n_reads_strong)
+
+	membar		#StoreLoad | #StoreStore
+
+	brz,pn		%o2, .Lexit
+	 cmp		%o2, 19
+	ble,pn		%icc, .Lsmall_unaligned
+	 nop
+	ba,a,pt		%icc, .Lmedium_noprefetch
+
+.Lexit:	retl
+	 mov		EX_RETVAL(%o3), %o0
+
+.Llarge_src_unaligned:
+#ifdef NON_USER_COPY
+	VISEntryHalfFast(.Lmedium_vis_entry_fail)
+#else
+	VISEntryHalf
+#endif
+	andn		%o2, 0x3f, %o4
+	sub		%o2, %o4, %o2
+	alignaddr	%o1, %g0, %g1
+	add		%o1, %o4, %o1
+	EX_LD_FP(LOAD(ldd, %g1 + 0x00, %f0), memcpy_retl_o2_plus_o4)
+1:	EX_LD_FP(LOAD(ldd, %g1 + 0x08, %f2), memcpy_retl_o2_plus_o4)
+	subcc		%o4, 0x40, %o4
+	EX_LD_FP(LOAD(ldd, %g1 + 0x10, %f4), memcpy_retl_o2_plus_o4_plus_64)
+	EX_LD_FP(LOAD(ldd, %g1 + 0x18, %f6), memcpy_retl_o2_plus_o4_plus_64)
+	EX_LD_FP(LOAD(ldd, %g1 + 0x20, %f8), memcpy_retl_o2_plus_o4_plus_64)
+	EX_LD_FP(LOAD(ldd, %g1 + 0x28, %f10), memcpy_retl_o2_plus_o4_plus_64)
+	EX_LD_FP(LOAD(ldd, %g1 + 0x30, %f12), memcpy_retl_o2_plus_o4_plus_64)
+	EX_LD_FP(LOAD(ldd, %g1 + 0x38, %f14), memcpy_retl_o2_plus_o4_plus_64)
+	faligndata	%f0, %f2, %f16
+	EX_LD_FP(LOAD(ldd, %g1 + 0x40, %f0), memcpy_retl_o2_plus_o4_plus_64)
+	faligndata	%f2, %f4, %f18
+	add		%g1, 0x40, %g1
+	faligndata	%f4, %f6, %f20
+	faligndata	%f6, %f8, %f22
+	faligndata	%f8, %f10, %f24
+	faligndata	%f10, %f12, %f26
+	faligndata	%f12, %f14, %f28
+	faligndata	%f14, %f0, %f30
+	EX_ST_FP(STORE(std, %f16, %o0 + 0x00), memcpy_retl_o2_plus_o4_plus_64)
+	EX_ST_FP(STORE(std, %f18, %o0 + 0x08), memcpy_retl_o2_plus_o4_plus_56)
+	EX_ST_FP(STORE(std, %f20, %o0 + 0x10), memcpy_retl_o2_plus_o4_plus_48)
+	EX_ST_FP(STORE(std, %f22, %o0 + 0x18), memcpy_retl_o2_plus_o4_plus_40)
+	EX_ST_FP(STORE(std, %f24, %o0 + 0x20), memcpy_retl_o2_plus_o4_plus_32)
+	EX_ST_FP(STORE(std, %f26, %o0 + 0x28), memcpy_retl_o2_plus_o4_plus_24)
+	EX_ST_FP(STORE(std, %f28, %o0 + 0x30), memcpy_retl_o2_plus_o4_plus_16)
+	EX_ST_FP(STORE(std, %f30, %o0 + 0x38), memcpy_retl_o2_plus_o4_plus_8)
+	add		%o0, 0x40, %o0
+	bne,pt		%icc, 1b
+	 LOAD(prefetch, %g1 + 0x200, #n_reads_strong)
+#ifdef NON_USER_COPY
+	VISExitHalfFast
+#else
+	VISExitHalf
+#endif
+	brz,pn		%o2, .Lexit
+	 cmp		%o2, 19
+	ble,pn		%icc, .Lsmall_unaligned
+	 nop
+	ba,a,pt		%icc, .Lmedium_unaligned
+
+#ifdef NON_USER_COPY
+.Lmedium_vis_entry_fail:
+	 or		%o0, %o1, %g2
+#endif
+.Lmedium:
+	LOAD(prefetch, %o1 + 0x40, #n_reads_strong)
+	andcc		%g2, 0x7, %g0
+	bne,pn		%icc, .Lmedium_unaligned
+	 nop
+.Lmedium_noprefetch:
+	andncc		%o2, 0x20 - 1, %o5
+	be,pn		%icc, 2f
+	 sub		%o2, %o5, %o2
+1:	EX_LD(LOAD(ldx, %o1 + 0x00, %g1), memcpy_retl_o2_plus_o5)
+	EX_LD(LOAD(ldx, %o1 + 0x08, %g2), memcpy_retl_o2_plus_o5)
+	EX_LD(LOAD(ldx, %o1 + 0x10, GLOBAL_SPARE), memcpy_retl_o2_plus_o5)
+	EX_LD(LOAD(ldx, %o1 + 0x18, %o4), memcpy_retl_o2_plus_o5)
+	add		%o1, 0x20, %o1
+	subcc		%o5, 0x20, %o5
+	EX_ST(STORE(stx, %g1, %o0 + 0x00), memcpy_retl_o2_plus_o5_plus_32)
+	EX_ST(STORE(stx, %g2, %o0 + 0x08), memcpy_retl_o2_plus_o5_plus_24)
+	EX_ST(STORE(stx, GLOBAL_SPARE, %o0 + 0x10), memcpy_retl_o2_plus_o5_plus_16)
+	EX_ST(STORE(stx, %o4, %o0 + 0x18), memcpy_retl_o2_plus_o5_plus_8)
+	bne,pt		%icc, 1b
+	 add		%o0, 0x20, %o0
+2:	andcc		%o2, 0x18, %o5
+	be,pt		%icc, 3f
+	 sub		%o2, %o5, %o2
+
+1:	EX_LD(LOAD(ldx, %o1 + 0x00, %g1), memcpy_retl_o2_plus_o5)
+	add		%o1, 0x08, %o1
+	add		%o0, 0x08, %o0
+	subcc		%o5, 0x08, %o5
+	bne,pt		%icc, 1b
+	 EX_ST(STORE(stx, %g1, %o0 - 0x08), memcpy_retl_o2_plus_o5_plus_8)
+3:	brz,pt		%o2, .Lexit
+	 cmp		%o2, 0x04
+	bl,pn		%icc, .Ltiny
+	 nop
+	EX_LD(LOAD(lduw, %o1 + 0x00, %g1), memcpy_retl_o2)
+	add		%o1, 0x04, %o1
+	add		%o0, 0x04, %o0
+	subcc		%o2, 0x04, %o2
+	bne,pn		%icc, .Ltiny
+	 EX_ST(STORE(stw, %g1, %o0 - 0x04), memcpy_retl_o2_plus_4)
+	ba,a,pt		%icc, .Lexit
+.Lmedium_unaligned:
+	/* First get dest 8 byte aligned.  */
+	sub		%g0, %o0, %g1
+	and		%g1, 0x7, %g1
+	brz,pt		%g1, 2f
+	 sub		%o2, %g1, %o2
+
+1:	EX_LD(LOAD(ldub, %o1 + 0x00, %g2), memcpy_retl_o2_plus_g1)
+	add		%o1, 1, %o1
+	subcc		%g1, 1, %g1
+	add		%o0, 1, %o0
+	bne,pt		%icc, 1b
+	 EX_ST(STORE(stb, %g2, %o0 - 0x01), memcpy_retl_o2_plus_g1_plus_1)
+2:
+	and		%o1, 0x7, %g1
+	brz,pn		%g1, .Lmedium_noprefetch
+	 sll		%g1, 3, %g1
+	mov		64, %g2
+	sub		%g2, %g1, %g2
+	andn		%o1, 0x7, %o1
+	EX_LD(LOAD(ldx, %o1 + 0x00, %o4), memcpy_retl_o2)
+	sllx		%o4, %g1, %o4
+	andn		%o2, 0x08 - 1, %o5
+	sub		%o2, %o5, %o2
+1:	EX_LD(LOAD(ldx, %o1 + 0x08, %g3), memcpy_retl_o2_plus_o5)
+	add		%o1, 0x08, %o1
+	subcc		%o5, 0x08, %o5
+	srlx		%g3, %g2, GLOBAL_SPARE
+	or		GLOBAL_SPARE, %o4, GLOBAL_SPARE
+	EX_ST(STORE(stx, GLOBAL_SPARE, %o0 + 0x00), memcpy_retl_o2_plus_o5_plus_8)
+	add		%o0, 0x08, %o0
+	bne,pt		%icc, 1b
+	 sllx		%g3, %g1, %o4
+	srl		%g1, 3, %g1
+	add		%o1, %g1, %o1
+	brz,pn		%o2, .Lexit
+	 nop
+	ba,pt		%icc, .Lsmall_unaligned
+
+.Ltiny:
+	EX_LD(LOAD(ldub, %o1 + 0x00, %g1), memcpy_retl_o2)
+	subcc		%o2, 1, %o2
+	be,pn		%icc, .Lexit
+	 EX_ST(STORE(stb, %g1, %o0 + 0x00), memcpy_retl_o2_plus_1)
+	EX_LD(LOAD(ldub, %o1 + 0x01, %g1), memcpy_retl_o2)
+	subcc		%o2, 1, %o2
+	be,pn		%icc, .Lexit
+	 EX_ST(STORE(stb, %g1, %o0 + 0x01), memcpy_retl_o2_plus_1)
+	EX_LD(LOAD(ldub, %o1 + 0x02, %g1), memcpy_retl_o2)
+	ba,pt		%icc, .Lexit
+	 EX_ST(STORE(stb, %g1, %o0 + 0x02), memcpy_retl_o2)
+
+.Lsmall:
+	andcc		%g2, 0x3, %g0
+	bne,pn		%icc, .Lsmall_unaligned
+	 andn		%o2, 0x4 - 1, %o5
+	sub		%o2, %o5, %o2
+1:
+	EX_LD(LOAD(lduw, %o1 + 0x00, %g1), memcpy_retl_o2_plus_o5)
+	add		%o1, 0x04, %o1
+	subcc		%o5, 0x04, %o5
+	add		%o0, 0x04, %o0
+	bne,pt		%icc, 1b
+	 EX_ST(STORE(stw, %g1, %o0 - 0x04), memcpy_retl_o2_plus_o5_plus_4)
+	brz,pt		%o2, .Lexit
+	 nop
+	ba,a,pt		%icc, .Ltiny
+
+.Lsmall_unaligned:
+1:	EX_LD(LOAD(ldub, %o1 + 0x00, %g1), memcpy_retl_o2)
+	add		%o1, 1, %o1
+	add		%o0, 1, %o0
+	subcc		%o2, 1, %o2
+	bne,pt		%icc, 1b
+	 EX_ST(STORE(stb, %g1, %o0 - 0x01), memcpy_retl_o2_plus_1)
+	ba,a,pt		%icc, .Lexit
+	 nop
+	.size		FUNC_NAME, .-FUNC_NAME