1 /*-
2 * Copyright (c) 2005,2008 Joseph Koshy
3 * Copyright (c) 2007 The FreeBSD Foundation
4 * All rights reserved.
5 *
6 * Portions of this software were developed by A. Joseph Koshy under
7 * sponsorship from the FreeBSD Foundation and Google, Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD: releng/7.3/sys/dev/hwpmc/hwpmc_x86.c 200237 2009-12-07 20:51:19Z fabient $");
33
34 #include <sys/param.h>
35 #include <sys/bus.h>
36 #include <sys/pmc.h>
37 #include <sys/proc.h>
38 #include <sys/systm.h>
39
40 #include <machine/cpu.h>
41 #include <machine/cputypes.h>
42 #include <machine/intr_machdep.h>
43 #include <machine/apicvar.h>
44 #include <machine/pmc_mdep.h>
45 #include <machine/md_var.h>
46
47 #include <vm/vm.h>
48 #include <vm/vm_param.h>
49 #include <vm/pmap.h>
50
51 /*
52 * Attempt to walk a user call stack using a too-simple algorithm.
53 * In the general case we need unwind information associated with
54 * the executable to be able to walk the user stack.
55 *
56 * We are handed a trap frame laid down at the time the PMC interrupt
57 * was taken. If the application is using frame pointers, the saved
58 * PC value could be:
59 * a. at the beginning of a function before the stack frame is laid
60 * down,
61 * b. just before a 'ret', after the stack frame has been taken off,
62 * c. somewhere else in the function with a valid stack frame being
63 * present,
64 *
65 * If the application is not using frame pointers, this algorithm will
66 * fail to yield an interesting call chain.
67 *
68 * TODO: figure out a way to use unwind information.
69 */
70
71 int
72 pmc_save_user_callchain(uintptr_t *cc, int nframes, struct trapframe *tf)
73 {
74 int n;
75 uint32_t instr;
76 uintptr_t fp, oldfp, pc, r, sp;
77
78 KASSERT(TRAPF_USERMODE(tf), ("[x86,%d] Not a user trap frame tf=%p",
79 __LINE__, (void *) tf));
80
81 pc = PMC_TRAPFRAME_TO_PC(tf);
82 oldfp = fp = PMC_TRAPFRAME_TO_FP(tf);
83 sp = PMC_TRAPFRAME_TO_USER_SP(tf);
84
85 *cc++ = pc; n = 1;
86
87 r = fp + sizeof(uintptr_t); /* points to return address */
88
89 if (!PMC_IN_USERSPACE(pc))
90 return (n);
91
92 if (copyin((void *) pc, &instr, sizeof(instr)) != 0)
93 return (n);
94
95 if (PMC_AT_FUNCTION_PROLOGUE_PUSH_BP(instr) ||
96 PMC_AT_FUNCTION_EPILOGUE_RET(instr)) { /* ret */
97 if (copyin((void *) sp, &pc, sizeof(pc)) != 0)
98 return (n);
99 } else if (PMC_AT_FUNCTION_PROLOGUE_MOV_SP_BP(instr)) {
100 sp += sizeof(uintptr_t);
101 if (copyin((void *) sp, &pc, sizeof(pc)) != 0)
102 return (n);
103 } else if (copyin((void *) r, &pc, sizeof(pc)) != 0 ||
104 copyin((void *) fp, &fp, sizeof(fp)) != 0)
105 return (n);
106
107 for (; n < nframes;) {
108 if (pc == 0 || !PMC_IN_USERSPACE(pc))
109 break;
110
111 *cc++ = pc; n++;
112
113 if (fp < oldfp)
114 break;
115
116 r = fp + sizeof(uintptr_t); /* address of return address */
117 oldfp = fp;
118
119 if (copyin((void *) r, &pc, sizeof(pc)) != 0 ||
120 copyin((void *) fp, &fp, sizeof(fp)) != 0)
121 break;
122 }
123
124 return (n);
125 }
126
127 /*
128 * Walking the kernel call stack.
129 *
130 * We are handed the trap frame laid down at the time the PMC
131 * interrupt was taken. The saved PC could be:
132 * a. in the lowlevel trap handler, meaning that there isn't a C stack
133 * to traverse,
134 * b. at the beginning of a function before the stack frame is laid
135 * down,
136 * c. just before a 'ret', after the stack frame has been taken off,
137 * d. somewhere else in a function with a valid stack frame being
138 * present.
139 *
140 * In case (d), the previous frame pointer is at [%ebp]/[%rbp] and
141 * the return address is at [%ebp+4]/[%rbp+8].
142 *
143 * For cases (b) and (c), the return address is at [%esp]/[%rsp] and
144 * the frame pointer doesn't need to be changed when going up one
145 * level in the stack.
146 *
147 * For case (a), we check if the PC lies in low-level trap handling
148 * code, and if so we terminate our trace.
149 */
150
151 int
152 pmc_save_kernel_callchain(uintptr_t *cc, int nframes, struct trapframe *tf)
153 {
154 int n;
155 uint32_t instr;
156 uintptr_t fp, pc, r, sp, stackstart, stackend;
157 struct thread *td;
158
159 KASSERT(TRAPF_USERMODE(tf) == 0,("[x86,%d] not a kernel backtrace",
160 __LINE__));
161
162 pc = PMC_TRAPFRAME_TO_PC(tf);
163 fp = PMC_TRAPFRAME_TO_FP(tf);
164 sp = PMC_TRAPFRAME_TO_KERNEL_SP(tf);
165
166 *cc++ = pc;
167 r = fp + sizeof(uintptr_t); /* points to return address */
168
169 if ((td = curthread) == NULL)
170 return (1);
171
172 if (nframes <= 1)
173 return (1);
174
175 stackstart = (uintptr_t) td->td_kstack;
176 stackend = (uintptr_t) td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
177
178 if (PMC_IN_TRAP_HANDLER(pc) ||
179 !PMC_IN_KERNEL(pc) ||
180 !PMC_IN_KERNEL_STACK(r, stackstart, stackend) ||
181 !PMC_IN_KERNEL_STACK(sp, stackstart, stackend) ||
182 !PMC_IN_KERNEL_STACK(fp, stackstart, stackend))
183 return (1);
184
185 instr = *(uint32_t *) pc;
186
187 /*
188 * Determine whether the interrupted function was in the
189 * processing of either laying down its stack frame or taking
190 * it off.
191 *
192 * If we haven't started laying down a stack frame, or are
193 * just about to return, then our caller's address is at
194 * *sp, and we don't have a frame to unwind.
195 */
196 if (PMC_AT_FUNCTION_PROLOGUE_PUSH_BP(instr) ||
197 PMC_AT_FUNCTION_EPILOGUE_RET(instr))
198 pc = *(uintptr_t *) sp;
199 else if (PMC_AT_FUNCTION_PROLOGUE_MOV_SP_BP(instr)) {
200 /*
201 * The code was midway through laying down a frame.
202 * At this point sp[0] has a frame back pointer,
203 * and the caller's address is therefore at sp[1].
204 */
205 sp += sizeof(uintptr_t);
206 if (!PMC_IN_KERNEL_STACK(sp, stackstart, stackend))
207 return (1);
208 pc = *(uintptr_t *) sp;
209 } else {
210 /*
211 * Not in the function prologue or epilogue.
212 */
213 pc = *(uintptr_t *) r;
214 fp = *(uintptr_t *) fp;
215 }
216
217 for (n = 1; n < nframes; n++) {
218 *cc++ = pc;
219
220 if (PMC_IN_TRAP_HANDLER(pc))
221 break;
222
223 r = fp + sizeof(uintptr_t);
224 if (!PMC_IN_KERNEL_STACK(fp, stackstart, stackend) ||
225 !PMC_IN_KERNEL_STACK(r, stackstart, stackend))
226 break;
227 pc = *(uintptr_t *) r;
228 fp = *(uintptr_t *) fp;
229 }
230
231 return (n);
232 }
233
234 /*
235 * Machine dependent initialization for x86 class platforms.
236 */
237
238 struct pmc_mdep *
239 pmc_md_initialize()
240 {
241 int i;
242 struct pmc_mdep *md;
243
244 /* determine the CPU kind */
245 if (cpu_vendor_id == CPU_VENDOR_AMD)
246 md = pmc_amd_initialize();
247 else if (cpu_vendor_id == CPU_VENDOR_INTEL)
248 md = pmc_intel_initialize();
249 else
250 return (NULL);
251
252 /* disallow sampling if we do not have an LAPIC */
253 if (!lapic_enable_pmc())
254 for (i = 1; i < md->pmd_nclass; i++)
255 md->pmd_classdep[i].pcd_caps &= ~PMC_CAP_INTERRUPT;
256
257 return (md);
258 }
259
260 void
261 pmc_md_finalize(struct pmc_mdep *md)
262 {
263
264 lapic_disable_pmc();
265 if (cpu_vendor_id == CPU_VENDOR_AMD)
266 pmc_amd_finalize(md);
267 else if (cpu_vendor_id == CPU_VENDOR_INTEL)
268 pmc_intel_finalize(md);
269 else
270 KASSERT(0, ("[x86,%d] Unknown vendor", __LINE__));
271 }
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