ftrace-direct-too.c

  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#if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32)
  7#include <asm/asm-offsets.h>
  8#endif
  9
 10extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
 11			   unsigned int flags, struct pt_regs *regs);
 12
 13void my_direct_func(struct vm_area_struct *vma, unsigned long address,
 14		    unsigned int flags, struct pt_regs *regs)
 15{
 16	trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
 17		     vma, address, flags, regs);
 18}
 19
 20extern void my_tramp(void *);
 21
 22#ifdef CONFIG_RISCV
 23#include <asm/asm.h>
 24
 25asm (
 26"       .pushsection    .text, \"ax\", @progbits\n"
 27"       .type           my_tramp, @function\n"
 28"       .globl          my_tramp\n"
 29"   my_tramp:\n"
 30"       addi	sp,sp,-5*"SZREG"\n"
 31"       "REG_S"	a0,0*"SZREG"(sp)\n"
 32"       "REG_S"	a1,1*"SZREG"(sp)\n"
 33"       "REG_S"	a2,2*"SZREG"(sp)\n"
 34"       "REG_S"	t0,3*"SZREG"(sp)\n"
 35"       "REG_S"	ra,4*"SZREG"(sp)\n"
 36"       call	my_direct_func\n"
 37"       "REG_L"	a0,0*"SZREG"(sp)\n"
 38"       "REG_L"	a1,1*"SZREG"(sp)\n"
 39"       "REG_L"	a2,2*"SZREG"(sp)\n"
 40"       "REG_L"	t0,3*"SZREG"(sp)\n"
 41"       "REG_L"	ra,4*"SZREG"(sp)\n"
 42"       addi	sp,sp,5*"SZREG"\n"
 43"       jr	t0\n"
 44"       .size           my_tramp, .-my_tramp\n"
 45"       .popsection\n"
 46);
 47
 48#endif /* CONFIG_RISCV */
 49
 50#ifdef CONFIG_X86_64
 51
 52#include <asm/ibt.h>
 53#include <asm/nospec-branch.h>
 54
 55asm (
 56"	.pushsection    .text, \"ax\", @progbits\n"
 57"	.type		my_tramp, @function\n"
 58"	.globl		my_tramp\n"
 59"   my_tramp:"
 60	ASM_ENDBR
 61"	pushq %rbp\n"
 62"	movq %rsp, %rbp\n"
 63	CALL_DEPTH_ACCOUNT
 64"	pushq %rdi\n"
 65"	pushq %rsi\n"
 66"	pushq %rdx\n"
 67"	pushq %rcx\n"
 68"	call my_direct_func\n"
 69"	popq %rcx\n"
 70"	popq %rdx\n"
 71"	popq %rsi\n"
 72"	popq %rdi\n"
 73"	leave\n"
 74	ASM_RET
 75"	.size		my_tramp, .-my_tramp\n"
 76"	.popsection\n"
 77);
 78
 79#endif /* CONFIG_X86_64 */
 80
 81#ifdef CONFIG_S390
 82
 83asm (
 84"	.pushsection	.text, \"ax\", @progbits\n"
 85"	.type		my_tramp, @function\n"
 86"	.globl		my_tramp\n"
 87"   my_tramp:"
 88"	lgr		%r1,%r15\n"
 89"	stmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 90"	stg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 91"	aghi		%r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
 92"	stg		%r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
 93"	brasl		%r14,my_direct_func\n"
 94"	aghi		%r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
 95"	lmg		%r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
 96"	lg		%r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
 97"	lgr		%r1,%r0\n"
 98"	br		%r1\n"
 99"	.size		my_tramp, .-my_tramp\n"
100"	.popsection\n"
101);
102
103#endif /* CONFIG_S390 */
104
105#ifdef CONFIG_ARM64
106
107asm (
108"	.pushsection	.text, \"ax\", @progbits\n"
109"	.type		my_tramp, @function\n"
110"	.globl		my_tramp\n"
111"   my_tramp:"
112"	hint	34\n" // bti	c
113"	sub	sp, sp, #48\n"
114"	stp	x9, x30, [sp]\n"
115"	stp	x0, x1, [sp, #16]\n"
116"	stp	x2, x3, [sp, #32]\n"
117"	bl	my_direct_func\n"
118"	ldp	x30, x9, [sp]\n"
119"	ldp	x0, x1, [sp, #16]\n"
120"	ldp	x2, x3, [sp, #32]\n"
121"	add	sp, sp, #48\n"
122"	ret	x9\n"
123"	.size		my_tramp, .-my_tramp\n"
124"	.popsection\n"
125);
126
127#endif /* CONFIG_ARM64 */
128
129#ifdef CONFIG_LOONGARCH
130
131asm (
132"	.pushsection	.text, \"ax\", @progbits\n"
133"	.type		my_tramp, @function\n"
134"	.globl		my_tramp\n"
135"   my_tramp:\n"
136"	addi.d	$sp, $sp, -48\n"
137"	st.d	$a0, $sp, 0\n"
138"	st.d	$a1, $sp, 8\n"
139"	st.d	$a2, $sp, 16\n"
140"	st.d	$t0, $sp, 24\n"
141"	st.d	$ra, $sp, 32\n"
142"	bl	my_direct_func\n"
143"	ld.d	$a0, $sp, 0\n"
144"	ld.d	$a1, $sp, 8\n"
145"	ld.d	$a2, $sp, 16\n"
146"	ld.d	$ra, $sp, 24\n"
147"	ld.d	$t0, $sp, 32\n"
148"	addi.d	$sp, $sp, 48\n"
149"	jr	$t0\n"
150"	.size		my_tramp, .-my_tramp\n"
151"	.popsection\n"
152);
153
154#endif /* CONFIG_LOONGARCH */
155
156#ifdef CONFIG_PPC
157#include <asm/ppc_asm.h>
158
159#ifdef CONFIG_PPC64
160#define STACK_FRAME_SIZE 64
161#define STACK_FRAME_ARG1 32
162#define STACK_FRAME_ARG2 40
163#define STACK_FRAME_ARG3 48
164#define STACK_FRAME_ARG4 56
165#else
166#define STACK_FRAME_SIZE 32
167#define STACK_FRAME_ARG1 16
168#define STACK_FRAME_ARG2 20
169#define STACK_FRAME_ARG3 24
170#define STACK_FRAME_ARG4 28
171#endif
172
173#if defined(CONFIG_PPC64_ELF_ABI_V2) && !defined(CONFIG_PPC_KERNEL_PCREL)
174#define PPC64_TOC_SAVE_AND_UPDATE			\
175"	std		2, 24(1)\n"			\
176"	bcl		20, 31, 1f\n"			\
177"   1:	mflr		12\n"				\
178"	ld		2, (99f - 1b)(12)\n"
179#define PPC64_TOC_RESTORE				\
180"	ld		2, 24(1)\n"
181#define PPC64_TOC					\
182"   99:	.quad		.TOC.@tocbase\n"
183#else
184#define PPC64_TOC_SAVE_AND_UPDATE ""
185#define PPC64_TOC_RESTORE ""
186#define PPC64_TOC ""
187#endif
188
189#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE
190#define PPC_FTRACE_RESTORE_LR				\
191	PPC_LL"		0, "__stringify(PPC_LR_STKOFF)"(1)\n"	\
192"	mtlr		0\n"
193#define PPC_FTRACE_RET					\
194"	blr\n"
195#else
196#define PPC_FTRACE_RESTORE_LR				\
197	PPC_LL"		0, "__stringify(PPC_LR_STKOFF)"(1)\n"	\
198"	mtctr		0\n"
199#define PPC_FTRACE_RET					\
200"	mtlr		0\n"				\
201"	bctr\n"
202#endif
203
204asm (
205"	.pushsection	.text, \"ax\", @progbits\n"
206"	.type		my_tramp, @function\n"
207"	.globl		my_tramp\n"
208"   my_tramp:\n"
209	PPC_STL"	0, "__stringify(PPC_LR_STKOFF)"(1)\n"
210	PPC_STLU"	1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n"
211"	mflr		0\n"
212	PPC_STL"	0, "__stringify(PPC_LR_STKOFF)"(1)\n"
213	PPC_STLU"	1, -"__stringify(STACK_FRAME_SIZE)"(1)\n"
214	PPC64_TOC_SAVE_AND_UPDATE
215	PPC_STL"	3, "__stringify(STACK_FRAME_ARG1)"(1)\n"
216	PPC_STL"	4, "__stringify(STACK_FRAME_ARG2)"(1)\n"
217	PPC_STL"	5, "__stringify(STACK_FRAME_ARG3)"(1)\n"
218	PPC_STL"	6, "__stringify(STACK_FRAME_ARG4)"(1)\n"
219"	bl		my_direct_func\n"
220	PPC_LL"		6, "__stringify(STACK_FRAME_ARG4)"(1)\n"
221	PPC_LL"		5, "__stringify(STACK_FRAME_ARG3)"(1)\n"
222	PPC_LL"		4, "__stringify(STACK_FRAME_ARG2)"(1)\n"
223	PPC_LL"		3, "__stringify(STACK_FRAME_ARG1)"(1)\n"
224	PPC64_TOC_RESTORE
225"	addi		1, 1, "__stringify(STACK_FRAME_SIZE)"\n"
226	PPC_FTRACE_RESTORE_LR
227"	addi		1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n"
228	PPC_LL"		0, "__stringify(PPC_LR_STKOFF)"(1)\n"
229	PPC_FTRACE_RET
230	PPC64_TOC
231"	.size		my_tramp, .-my_tramp\n"
232"	.popsection\n"
233);
234
235#endif /* CONFIG_PPC */
236
237static struct ftrace_ops direct;
238
239static int __init ftrace_direct_init(void)
240{
241	ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0);
242
243	return register_ftrace_direct(&direct, (unsigned long) my_tramp);
244}
245
246static void __exit ftrace_direct_exit(void)
247{
248	unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
249}
250
251module_init(ftrace_direct_init);
252module_exit(ftrace_direct_exit);
253
254MODULE_AUTHOR("Steven Rostedt");
255MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
256MODULE_LICENSE("GPL");