1// SPDX-License-Identifier: GPL-2.0-only
  2#include <linux/module.h>
  3
  4#include <linux/mm.h> /* for handle_mm_fault() */
  5#include <linux/ftrace.h>
  6#include <linux/sched/stat.h>
  7#if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32)
  8#include <asm/asm-offsets.h>
  9#endif
 10
 11extern void my_direct_func(unsigned long ip);
 12
 13void my_direct_func(unsigned long ip)
 14{
 15	trace_printk("ip %lx\n", ip);
 16}
 17
 18extern void my_tramp(void *);
 19
 20#ifdef CONFIG_RISCV
 21#include <asm/asm.h>
 22
 23asm (
 24"       .pushsection    .text, \"ax\", @progbits\n"
 25"       .type           my_tramp, @function\n"
 26"       .globl          my_tramp\n"
 27"   my_tramp:\n"
 28"       addi	sp,sp,-3*"SZREG"\n"
 29"       "REG_S"	a0,0*"SZREG"(sp)\n"
 30"       "REG_S"	t0,1*"SZREG"(sp)\n"
 31"       "REG_S"	ra,2*"SZREG"(sp)\n"
 32"       mv	a0,t0\n"
 33"       call	my_direct_func\n"
 34"       "REG_L"	a0,0*"SZREG"(sp)\n"
 35"       "REG_L"	t0,1*"SZREG"(sp)\n"
 36"       "REG_L"	ra,2*"SZREG"(sp)\n"
 37"       addi	sp,sp,3*"SZREG"\n"
 38"       jr	t0\n"
 39"       .size           my_tramp, .-my_tramp\n"
 40"       .popsection\n"
 41);
 42
 43#endif /* CONFIG_RISCV */
 44
 45#ifdef CONFIG_X86_64
 46
 47#include <asm/ibt.h>
 48#include <asm/nospec-branch.h>
 49
 50asm (
 51"	.pushsection    .text, \"ax\", @progbits\n"
 52"	.type		my_tramp, @function\n"
 53"	.globl		my_tramp\n"
 54"   my_tramp:"
 55	ASM_ENDBR
 56"	pushq %rbp\n"
 57"	movq %rsp, %rbp\n"
 58	CALL_DEPTH_ACCOUNT
 59"	pushq %rdi\n"
 60"	movq 8(%rbp), %rdi\n"
 61"	call my_direct_func\n"
 62"	popq %rdi\n"
 63"	leave\n"
 64	ASM_RET
 65"	.size		my_tramp, .-my_tramp\n"
 66"	.popsection\n"
 67);
 68
 69#endif /* CONFIG_X86_64 */
 70
 71#ifdef CONFIG_S390
 72
 73asm (
 74"	.pushsection	.text, \"ax\", @progbits\n"
 75"	.type		my_tramp, @function\n"
 76"	.globl		my_tramp\n"
 77"   my_tramp:"
 78"	lgr		%r1,%r15\n"
 79"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 80"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 81"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
 82"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
 83"	lgr		%r2,%r0\n"
 84"	brasl		%r14,my_direct_func\n"
 85"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
 86"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 87"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 88"	lgr		%r1,%r0\n"
 89"	br		%r1\n"
 90"	.size		my_tramp, .-my_tramp\n"
 91"	.popsection\n"
 92);
 93
 94#endif /* CONFIG_S390 */
 95
 96#ifdef CONFIG_ARM64
 97
 98asm (
 99"	.pushsection	.text, \"ax\", @progbits\n"
100"	.type		my_tramp, @function\n"
101"	.globl		my_tramp\n"
102"   my_tramp:"
103"	hint	34\n" // bti	c
104"	sub	sp, sp, #32\n"
105"	stp	x9, x30, [sp]\n"
106"	str	x0, [sp, #16]\n"
107"	mov	x0, x30\n"
108"	bl	my_direct_func\n"
109"	ldp	x30, x9, [sp]\n"
110"	ldr	x0, [sp, #16]\n"
111"	add	sp, sp, #32\n"
112"	ret	x9\n"
113"	.size		my_tramp, .-my_tramp\n"
114"	.popsection\n"
115);
116
117#endif /* CONFIG_ARM64 */
118
119#ifdef CONFIG_LOONGARCH
120
121#include <asm/asm.h>
122asm (
123"	.pushsection	.text, \"ax\", @progbits\n"
124"	.type		my_tramp, @function\n"
125"	.globl		my_tramp\n"
126"   my_tramp:\n"
127"	addi.d	$sp, $sp, -32\n"
128"	st.d	$a0, $sp, 0\n"
129"	st.d	$t0, $sp, 8\n"
130"	st.d	$ra, $sp, 16\n"
131"	move	$a0, $t0\n"
132"	bl	my_direct_func\n"
133"	ld.d	$a0, $sp, 0\n"
134"	ld.d	$t0, $sp, 8\n"
135"	ld.d	$ra, $sp, 16\n"
136"	addi.d	$sp, $sp, 32\n"
137"	jr	$t0\n"
138"	.size		my_tramp, .-my_tramp\n"
139"	.popsection\n"
140);
141
142#endif /* CONFIG_LOONGARCH */
143
144#ifdef CONFIG_PPC
145#include <asm/ppc_asm.h>
146
147#ifdef CONFIG_PPC64
148#define STACK_FRAME_SIZE 48
149#else
150#define STACK_FRAME_SIZE 24
151#endif
152
153#if defined(CONFIG_PPC64_ELF_ABI_V2) && !defined(CONFIG_PPC_KERNEL_PCREL)
154#define PPC64_TOC_SAVE_AND_UPDATE			\
155"	std		2, 24(1)\n"			\
156"	bcl		20, 31, 1f\n"			\
157"   1:	mflr		12\n"				\
158"	ld		2, (99f - 1b)(12)\n"
159#define PPC64_TOC_RESTORE				\
160"	ld		2, 24(1)\n"
161#define PPC64_TOC					\
162"   99:	.quad		.TOC.@tocbase\n"
163#else
164#define PPC64_TOC_SAVE_AND_UPDATE ""
165#define PPC64_TOC_RESTORE ""
166#define PPC64_TOC ""
167#endif
168
169#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
170#define PPC_FTRACE_RESTORE_LR				\
171	PPC_LL"		0, "__stringify(PPC_LR_STKOFF)"(1)\n"	\
172"	mtlr		0\n"
173#define PPC_FTRACE_RET					\
174"	blr\n"
175#define PPC_FTRACE_RECOVER_IP				\
176"	lwz		8, 4(3)\n"			\
177"	li		9, 6\n"				\
178"	slw		8, 8, 9\n"			\
179"	sraw		8, 8, 9\n"			\
180"	add		3, 3, 8\n"			\
181"	addi		3, 3, 4\n"
182#else
183#define PPC_FTRACE_RESTORE_LR				\
184	PPC_LL"		0, "__stringify(PPC_LR_STKOFF)"(1)\n"	\
185"	mtctr		0\n"
186#define PPC_FTRACE_RET					\
187"	mtlr		0\n"				\
188"	bctr\n"
189#define PPC_FTRACE_RECOVER_IP ""
190#endif
191
192asm (
193"	.pushsection	.text, \"ax\", @progbits\n"
194"	.type		my_tramp, @function\n"
195"	.globl		my_tramp\n"
196"   my_tramp:\n"
197	PPC_STL"	0, "__stringify(PPC_LR_STKOFF)"(1)\n"
198	PPC_STLU"	1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
199"	mflr		0\n"
200	PPC_STL"	0, "__stringify(PPC_LR_STKOFF)"(1)\n"
201	PPC_STLU"	1, -"__stringify(STACK_FRAME_SIZE)"(1)\n"
202	PPC64_TOC_SAVE_AND_UPDATE
203	PPC_STL"	3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
204"	mr		3, 0\n"
205	PPC_FTRACE_RECOVER_IP
206"	bl		my_direct_func\n"
207	PPC_LL"		3, "__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
208	PPC64_TOC_RESTORE
209"	addi		1, 1, "__stringify(STACK_FRAME_SIZE)"\n"
210	PPC_FTRACE_RESTORE_LR
211"	addi		1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n"
212	PPC_LL"		0, "__stringify(PPC_LR_STKOFF)"(1)\n"
213	PPC_FTRACE_RET
214	PPC64_TOC
215"	.size		my_tramp, .-my_tramp\n"
216"	.popsection\n"
217);
218
219#endif /* CONFIG_PPC */
220
221static struct ftrace_ops direct;
222
223static int __init ftrace_direct_multi_init(void)
224{
225	ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
226	ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
227
228	return register_ftrace_direct(&direct, (unsigned long) my_tramp);
229}
230
231static void __exit ftrace_direct_multi_exit(void)
232{
233	unregister_ftrace_direct(&direct, (unsigned long) my_tramp, true);
234}
235
236module_init(ftrace_direct_multi_init);
237module_exit(ftrace_direct_multi_exit);
238
239MODULE_AUTHOR("Jiri Olsa");
240MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
241MODULE_LICENSE("GPL");