1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 *  Copyright (C) 2017  Steven Rostedt, VMware Inc.
  4 */
  5
  6#include <linux/linkage.h>
  7#include <asm/page_types.h>
  8#include <asm/segment.h>
  9#include <asm/export.h>
 10#include <asm/ftrace.h>
 11#include <asm/nospec-branch.h>
 
 
 12
 13#ifdef CC_USING_FENTRY
 14# define function_hook	__fentry__
 15EXPORT_SYMBOL(__fentry__)
 16#else
 17# define function_hook	mcount
 18EXPORT_SYMBOL(mcount)
 19#endif
 20
 21#ifdef CONFIG_DYNAMIC_FTRACE
 22
 23/* mcount uses a frame pointer even if CONFIG_FRAME_POINTER is not set */
 24#if !defined(CC_USING_FENTRY) || defined(CONFIG_FRAME_POINTER)
 25# define USING_FRAME_POINTER
 26#endif
 27
 28#ifdef USING_FRAME_POINTER
 29# define MCOUNT_FRAME			1	/* using frame = true  */
 30#else
 31# define MCOUNT_FRAME			0	/* using frame = false */
 32#endif
 33
 34ENTRY(function_hook)
 35	ret
 36END(function_hook)
 37
 38ENTRY(ftrace_caller)
 39
 40#ifdef USING_FRAME_POINTER
 41# ifdef CC_USING_FENTRY
 42	/*
 43	 * Frame pointers are of ip followed by bp.
 44	 * Since fentry is an immediate jump, we are left with
 45	 * parent-ip, function-ip. We need to add a frame with
 46	 * parent-ip followed by ebp.
 47	 */
 48	pushl	4(%esp)				/* parent ip */
 49	pushl	%ebp
 50	movl	%esp, %ebp
 51	pushl	2*4(%esp)			/* function ip */
 52# endif
 53	/* For mcount, the function ip is directly above */
 54	pushl	%ebp
 55	movl	%esp, %ebp
 56#endif
 57	pushl	%eax
 58	pushl	%ecx
 59	pushl	%edx
 60	pushl	$0				/* Pass NULL as regs pointer */
 61
 62#ifdef USING_FRAME_POINTER
 63	/* Load parent ebp into edx */
 64	movl	4*4(%esp), %edx
 65#else
 66	/* There's no frame pointer, load the appropriate stack addr instead */
 67	lea	4*4(%esp), %edx
 68#endif
 69
 70	movl	(MCOUNT_FRAME+4)*4(%esp), %eax	/* load the rip */
 71	/* Get the parent ip */
 72	movl	4(%edx), %edx			/* edx has ebp */
 73
 74	movl	function_trace_op, %ecx
 75	subl	$MCOUNT_INSN_SIZE, %eax
 76
 77.globl ftrace_call
 78ftrace_call:
 79	call	ftrace_stub
 80
 81	addl	$4, %esp			/* skip NULL pointer */
 82	popl	%edx
 83	popl	%ecx
 84	popl	%eax
 85#ifdef USING_FRAME_POINTER
 86	popl	%ebp
 87# ifdef CC_USING_FENTRY
 88	addl	$4,%esp				/* skip function ip */
 89	popl	%ebp				/* this is the orig bp */
 90	addl	$4, %esp			/* skip parent ip */
 91# endif
 92#endif
 93.Lftrace_ret:
 94#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 95.globl ftrace_graph_call
 96ftrace_graph_call:
 97	jmp	ftrace_stub
 98#endif
 99
100/* This is weak to keep gas from relaxing the jumps */
101WEAK(ftrace_stub)
102	ret
103END(ftrace_caller)
104
105ENTRY(ftrace_regs_caller)
106	/*
107	 * i386 does not save SS and ESP when coming from kernel.
108	 * Instead, to get sp, &regs->sp is used (see ptrace.h).
109	 * Unfortunately, that means eflags must be at the same location
110	 * as the current return ip is. We move the return ip into the
111	 * regs->ip location, and move flags into the return ip location.
 
 
 
 
 
 
 
 
 
 
 
112	 */
113	pushl	$__KERNEL_CS
114	pushl	4(%esp)				/* Save the return ip */
115	pushl	$0				/* Load 0 into orig_ax */
 
 
 
 
 
 
116	pushl	%gs
117	pushl	%fs
118	pushl	%es
119	pushl	%ds
120	pushl	%eax
121
122	/* Get flags and place them into the return ip slot */
123	pushf
124	popl	%eax
125	movl	%eax, 8*4(%esp)
126
 
127	pushl	%ebp
128	pushl	%edi
129	pushl	%esi
130	pushl	%edx
131	pushl	%ecx
132	pushl	%ebx
133
134	movl	12*4(%esp), %eax		/* Load ip (1st parameter) */
135	subl	$MCOUNT_INSN_SIZE, %eax		/* Adjust ip */
136#ifdef CC_USING_FENTRY
137	movl	15*4(%esp), %edx		/* Load parent ip (2nd parameter) */
138#else
139	movl	0x4(%ebp), %edx			/* Load parent ip (2nd parameter) */
140#endif
141	movl	function_trace_op, %ecx		/* Save ftrace_pos in 3rd parameter */
142	pushl	%esp				/* Save pt_regs as 4th parameter */
143
144GLOBAL(ftrace_regs_call)
145	call	ftrace_stub
146
147	addl	$4, %esp			/* Skip pt_regs */
148
149	/* restore flags */
150	push	14*4(%esp)
151	popf
152
153	/* Move return ip back to its original location */
154	movl	12*4(%esp), %eax
155	movl	%eax, 14*4(%esp)
 
156
157	popl	%ebx
158	popl	%ecx
159	popl	%edx
160	popl	%esi
161	popl	%edi
162	popl	%ebp
163	popl	%eax
164	popl	%ds
165	popl	%es
166	popl	%fs
167	popl	%gs
168
169	/* use lea to not affect flags */
170	lea	3*4(%esp), %esp			/* Skip orig_ax, ip and cs */
171
172	jmp	.Lftrace_ret
173#else /* ! CONFIG_DYNAMIC_FTRACE */
174
175ENTRY(function_hook)
176	cmpl	$__PAGE_OFFSET, %esp
177	jb	ftrace_stub			/* Paging not enabled yet? */
178
179	cmpl	$ftrace_stub, ftrace_trace_function
180	jnz	.Ltrace
181#ifdef CONFIG_FUNCTION_GRAPH_TRACER
182	cmpl	$ftrace_stub, ftrace_graph_return
183	jnz	ftrace_graph_caller
184
185	cmpl	$ftrace_graph_entry_stub, ftrace_graph_entry
186	jnz	ftrace_graph_caller
187#endif
188.globl ftrace_stub
189ftrace_stub:
190	ret
191
192	/* taken from glibc */
193.Ltrace:
194	pushl	%eax
195	pushl	%ecx
196	pushl	%edx
197	movl	0xc(%esp), %eax
198	movl	0x4(%ebp), %edx
199	subl	$MCOUNT_INSN_SIZE, %eax
200
201	movl	ftrace_trace_function, %ecx
202	CALL_NOSPEC %ecx
203
204	popl	%edx
205	popl	%ecx
206	popl	%eax
207	jmp	ftrace_stub
208END(function_hook)
209#endif /* CONFIG_DYNAMIC_FTRACE */
210
211#ifdef CONFIG_FUNCTION_GRAPH_TRACER
212ENTRY(ftrace_graph_caller)
213	pushl	%eax
214	pushl	%ecx
215	pushl	%edx
216	movl	3*4(%esp), %eax
217	/* Even with frame pointers, fentry doesn't have one here */
218#ifdef CC_USING_FENTRY
219	lea	4*4(%esp), %edx
220	movl	$0, %ecx
221#else
222	lea	0x4(%ebp), %edx
223	movl	(%ebp), %ecx
224#endif
225	subl	$MCOUNT_INSN_SIZE, %eax
226	call	prepare_ftrace_return
227	popl	%edx
228	popl	%ecx
229	popl	%eax
230	ret
231END(ftrace_graph_caller)
232
233.globl return_to_handler
234return_to_handler:
235	pushl	%eax
236	pushl	%edx
237#ifdef CC_USING_FENTRY
238	movl	$0, %eax
239#else
240	movl	%ebp, %eax
241#endif
242	call	ftrace_return_to_handler
243	movl	%eax, %ecx
244	popl	%edx
245	popl	%eax
246	JMP_NOSPEC %ecx
247#endif

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 *  Copyright (C) 2017  Steven Rostedt, VMware Inc.
  4 */
  5
  6#include <linux/linkage.h>
  7#include <asm/page_types.h>
  8#include <asm/segment.h>
  9#include <asm/export.h>
 10#include <asm/ftrace.h>
 11#include <asm/nospec-branch.h>
 12#include <asm/frame.h>
 13#include <asm/asm-offsets.h>
 14
 
 15# define function_hook	__fentry__
 16EXPORT_SYMBOL(__fentry__)
 
 
 
 
 
 
 
 
 
 
 
 17
 18#ifdef CONFIG_FRAME_POINTER
 19# define MCOUNT_FRAME			1	/* using frame = true  */
 20#else
 21# define MCOUNT_FRAME			0	/* using frame = false */
 22#endif
 23
 24ENTRY(function_hook)
 25	ret
 26END(function_hook)
 27
 28ENTRY(ftrace_caller)
 29
 30#ifdef CONFIG_FRAME_POINTER
 
 31	/*
 32	 * Frame pointers are of ip followed by bp.
 33	 * Since fentry is an immediate jump, we are left with
 34	 * parent-ip, function-ip. We need to add a frame with
 35	 * parent-ip followed by ebp.
 36	 */
 37	pushl	4(%esp)				/* parent ip */
 38	pushl	%ebp
 39	movl	%esp, %ebp
 40	pushl	2*4(%esp)			/* function ip */
 41
 42	/* For mcount, the function ip is directly above */
 43	pushl	%ebp
 44	movl	%esp, %ebp
 45#endif
 46	pushl	%eax
 47	pushl	%ecx
 48	pushl	%edx
 49	pushl	$0				/* Pass NULL as regs pointer */
 50
 51#ifdef CONFIG_FRAME_POINTER
 52	/* Load parent ebp into edx */
 53	movl	4*4(%esp), %edx
 54#else
 55	/* There's no frame pointer, load the appropriate stack addr instead */
 56	lea	4*4(%esp), %edx
 57#endif
 58
 59	movl	(MCOUNT_FRAME+4)*4(%esp), %eax	/* load the rip */
 60	/* Get the parent ip */
 61	movl	4(%edx), %edx			/* edx has ebp */
 62
 63	movl	function_trace_op, %ecx
 64	subl	$MCOUNT_INSN_SIZE, %eax
 65
 66.globl ftrace_call
 67ftrace_call:
 68	call	ftrace_stub
 69
 70	addl	$4, %esp			/* skip NULL pointer */
 71	popl	%edx
 72	popl	%ecx
 73	popl	%eax
 74#ifdef CONFIG_FRAME_POINTER
 75	popl	%ebp
 
 76	addl	$4,%esp				/* skip function ip */
 77	popl	%ebp				/* this is the orig bp */
 78	addl	$4, %esp			/* skip parent ip */
 
 79#endif
 80.Lftrace_ret:
 81#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 82.globl ftrace_graph_call
 83ftrace_graph_call:
 84	jmp	ftrace_stub
 85#endif
 86
 87/* This is weak to keep gas from relaxing the jumps */
 88WEAK(ftrace_stub)
 89	ret
 90END(ftrace_caller)
 91
 92ENTRY(ftrace_regs_caller)
 93	/*
 94	 * We're here from an mcount/fentry CALL, and the stack frame looks like:
 95	 *
 96	 *  <previous context>
 97	 *  RET-IP
 98	 *
 99	 * The purpose of this function is to call out in an emulated INT3
100	 * environment with a stack frame like:
101	 *
102	 *  <previous context>
103	 *  gap / RET-IP
104	 *  gap
105	 *  gap
106	 *  gap
107	 *  pt_regs
108	 *
109	 * We do _NOT_ restore: ss, flags, cs, gs, fs, es, ds
110	 */
111	subl	$3*4, %esp	# RET-IP + 3 gaps
112	pushl	%ss		# ss
113	pushl	%esp		# points at ss
114	addl	$5*4, (%esp)	#   make it point at <previous context>
115	pushfl			# flags
116	pushl	$__KERNEL_CS	# cs
117	pushl	7*4(%esp)	# ip <- RET-IP
118	pushl	$0		# orig_eax
119
120	pushl	%gs
121	pushl	%fs
122	pushl	%es
123	pushl	%ds
 
 
 
 
 
 
124
125	pushl	%eax
126	pushl	%ebp
127	pushl	%edi
128	pushl	%esi
129	pushl	%edx
130	pushl	%ecx
131	pushl	%ebx
132
133	ENCODE_FRAME_POINTER
134
135	movl	PT_EIP(%esp), %eax	# 1st argument: IP
136	subl	$MCOUNT_INSN_SIZE, %eax
137	movl	21*4(%esp), %edx	# 2nd argument: parent ip
138	movl	function_trace_op, %ecx	# 3rd argument: ftrace_pos
139	pushl	%esp			# 4th argument: pt_regs
 
 
140
141GLOBAL(ftrace_regs_call)
142	call	ftrace_stub
143
144	addl	$4, %esp		# skip 4th argument
145
146	/* place IP below the new SP */
147	movl	PT_OLDESP(%esp), %eax
148	movl	PT_EIP(%esp), %ecx
149	movl	%ecx, -4(%eax)
150
151	/* place EAX below that */
152	movl	PT_EAX(%esp), %ecx
153	movl	%ecx, -8(%eax)
154
155	popl	%ebx
156	popl	%ecx
157	popl	%edx
158	popl	%esi
159	popl	%edi
160	popl	%ebp
 
 
 
 
 
161
162	lea	-8(%eax), %esp
163	popl	%eax
164
165	jmp	.Lftrace_ret
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
166
167#ifdef CONFIG_FUNCTION_GRAPH_TRACER
168ENTRY(ftrace_graph_caller)
169	pushl	%eax
170	pushl	%ecx
171	pushl	%edx
172	movl	3*4(%esp), %eax
173	/* Even with frame pointers, fentry doesn't have one here */
 
174	lea	4*4(%esp), %edx
175	movl	$0, %ecx
 
 
 
 
176	subl	$MCOUNT_INSN_SIZE, %eax
177	call	prepare_ftrace_return
178	popl	%edx
179	popl	%ecx
180	popl	%eax
181	ret
182END(ftrace_graph_caller)
183
184.globl return_to_handler
185return_to_handler:
186	pushl	%eax
187	pushl	%edx
 
188	movl	$0, %eax
 
 
 
189	call	ftrace_return_to_handler
190	movl	%eax, %ecx
191	popl	%edx
192	popl	%eax
193	JMP_NOSPEC %ecx
194#endif