1/* SPDX-License-Identifier: GPL-2.0-or-later */
  2/*
  3 * Code to prepare detour buffer for optprobes in Kernel.
  4 *
  5 * Copyright 2017, Anju T, IBM Corp.
  6 */
  7
  8#include <asm/ppc_asm.h>
  9#include <asm/ptrace.h>
 10#include <asm/asm-offsets.h>
 11
 12#ifdef CONFIG_PPC64
 13#define SAVE_30GPRS(base) SAVE_GPRS(2, 31, base)
 14#define REST_30GPRS(base) REST_GPRS(2, 31, base)
 15#define TEMPLATE_FOR_IMM_LOAD_INSNS	nop; nop; nop; nop; nop
 16#else
 17#define SAVE_30GPRS(base) stmw	r2, GPR2(base)
 18#define REST_30GPRS(base) lmw	r2, GPR2(base)
 19#define TEMPLATE_FOR_IMM_LOAD_INSNS	nop; nop; nop
 20#endif
 21
 22#define	OPT_SLOT_SIZE	65536
 23
 24	.balign	4
 25
 26	/*
 27	 * Reserve an area to allocate slots for detour buffer.
 28	 * This is part of .text section (rather than vmalloc area)
 29	 * as this needs to be within 32MB of the probed address.
 30	 */
 31	.global optinsn_slot
 32optinsn_slot:
 33	.space	OPT_SLOT_SIZE
 34
 35	/*
 36	 * Optprobe template:
 37	 * This template gets copied into one of the slots in optinsn_slot
 38	 * and gets fixed up with real optprobe structures et al.
 39	 */
 40	.global optprobe_template_entry
 41optprobe_template_entry:
 42	/* Create an in-memory pt_regs */
 43	PPC_STLU	r1,-INT_FRAME_SIZE(r1)
 44	SAVE_GPR(0,r1)
 45	/* Save the previous SP into stack */
 46	addi	r0,r1,INT_FRAME_SIZE
 47	PPC_STL	r0,GPR1(r1)
 48	SAVE_30GPRS(r1)
 49	/* Save SPRS */
 50	mfmsr	r5
 51	PPC_STL	r5,_MSR(r1)
 52	li	r5,0x700
 53	PPC_STL	r5,_TRAP(r1)
 54	li	r5,0
 55	PPC_STL	r5,ORIG_GPR3(r1)
 56	PPC_STL	r5,RESULT(r1)
 57	mfctr	r5
 58	PPC_STL	r5,_CTR(r1)
 59	mflr	r5
 60	PPC_STL	r5,_LINK(r1)
 61	mfspr	r5,SPRN_XER
 62	PPC_STL	r5,_XER(r1)
 63	mfcr	r5
 64	PPC_STL	r5,_CCR(r1)
 65#ifdef CONFIG_PPC64
 66	lbz     r5,PACAIRQSOFTMASK(r13)
 67	std     r5,SOFTE(r1)
 68#endif
 69
 70	/*
 71	 * We may get here from a module, so load the kernel TOC in r2.
 72	 * The original TOC gets restored when pt_regs is restored
 73	 * further below.
 74	 */
 75#ifdef CONFIG_PPC64
 76	LOAD_PACA_TOC()
 77#endif
 78
 79	.global optprobe_template_op_address
 80optprobe_template_op_address:
 81	/*
 82	 * Parameters to optimized_callback():
 83	 * 1. optimized_kprobe structure in r3
 84	 */
 85	TEMPLATE_FOR_IMM_LOAD_INSNS
 86
 87	/* 2. pt_regs pointer in r4 */
 88	addi	r4,r1,STACK_INT_FRAME_REGS
 89
 90	.global optprobe_template_call_handler
 91optprobe_template_call_handler:
 92	/* Branch to optimized_callback() */
 93	nop
 94
 95	/*
 96	 * Parameters for instruction emulation:
 97	 * 1. Pass SP in register r3.
 98	 */
 99	addi	r3,r1,STACK_INT_FRAME_REGS
100
101	.global optprobe_template_insn
102optprobe_template_insn:
103	/* 2, Pass instruction to be emulated in r4 */
104	TEMPLATE_FOR_IMM_LOAD_INSNS
105
106	.global optprobe_template_call_emulate
107optprobe_template_call_emulate:
108	/* Branch to emulate_step()  */
109	nop
110
111	/*
112	 * All done.
113	 * Now, restore the registers...
114	 */
115	PPC_LL	r5,_MSR(r1)
116	mtmsr	r5
117	PPC_LL	r5,_CTR(r1)
118	mtctr	r5
119	PPC_LL	r5,_LINK(r1)
120	mtlr	r5
121	PPC_LL	r5,_XER(r1)
122	mtxer	r5
123	PPC_LL	r5,_CCR(r1)
124	mtcr	r5
125	REST_GPR(0,r1)
126	REST_30GPRS(r1)
127	/* Restore the previous SP */
128	addi	r1,r1,INT_FRAME_SIZE
129
130	.global optprobe_template_ret
131optprobe_template_ret:
132	/* ... and jump back from trampoline */
133	nop
134
135	.global optprobe_template_end
136optprobe_template_end: