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("$FreeBSD$"); 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 } 272