1 // SPDX-License-Identifier: GPL-2.0 2 /* arch/sparc64/kernel/process.c 3 * 4 * Copyright (C) 1995, 1996, 2008 David S. Miller (davem@davemloft.net) 5 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be) 6 * Copyright (C) 1997, 1998 Jakub Jelinek (jj@sunsite.mff.cuni.cz) 7 */ 8 9 /* 10 * This file handles the architecture-dependent parts of process handling.. 11 */ 12 #include <linux/errno.h> 13 #include <linux/export.h> 14 #include <linux/sched.h> 15 #include <linux/sched/debug.h> 16 #include <linux/sched/task.h> 17 #include <linux/sched/task_stack.h> 18 #include <linux/kernel.h> 19 #include <linux/mm.h> 20 #include <linux/fs.h> 21 #include <linux/smp.h> 22 #include <linux/stddef.h> 23 #include <linux/ptrace.h> 24 #include <linux/slab.h> 25 #include <linux/user.h> 26 #include <linux/delay.h> 27 #include <linux/compat.h> 28 #include <linux/tick.h> 29 #include <linux/init.h> 30 #include <linux/cpu.h> 31 #include <linux/perf_event.h> 32 #include <linux/elfcore.h> 33 #include <linux/sysrq.h> 34 #include <linux/nmi.h> 35 #include <linux/context_tracking.h> 36 #include <linux/signal.h> 37 38 #include <linux/uaccess.h> 39 #include <asm/page.h> 40 #include <asm/pgalloc.h> 41 #include <asm/processor.h> 42 #include <asm/pstate.h> 43 #include <asm/elf.h> 44 #include <asm/fpumacro.h> 45 #include <asm/head.h> 46 #include <asm/cpudata.h> 47 #include <asm/mmu_context.h> 48 #include <asm/unistd.h> 49 #include <asm/hypervisor.h> 50 #include <asm/syscalls.h> 51 #include <asm/irq_regs.h> 52 #include <asm/smp.h> 53 #include <asm/pcr.h> 54 55 #include "kstack.h" 56 57 /* Idle loop support on sparc64. */ 58 void arch_cpu_idle(void) 59 { 60 if (tlb_type != hypervisor) { 61 touch_nmi_watchdog(); 62 raw_local_irq_enable(); 63 } else { 64 unsigned long pstate; 65 66 raw_local_irq_enable(); 67 68 /* The sun4v sleeping code requires that we have PSTATE.IE cleared over 69 * the cpu sleep hypervisor call. 70 */ 71 __asm__ __volatile__( 72 "rdpr %%pstate, %0\n\t" 73 "andn %0, %1, %0\n\t" 74 "wrpr %0, %%g0, %%pstate" 75 : "=&r" (pstate) 76 : "i" (PSTATE_IE)); 77 78 if (!need_resched() && !cpu_is_offline(smp_processor_id())) { 79 sun4v_cpu_yield(); 80 /* If resumed by cpu_poke then we need to explicitly 81 * call scheduler_ipi(). 82 */ 83 scheduler_poke(); 84 } 85 86 /* Re-enable interrupts. */ 87 __asm__ __volatile__( 88 "rdpr %%pstate, %0\n\t" 89 "or %0, %1, %0\n\t" 90 "wrpr %0, %%g0, %%pstate" 91 : "=&r" (pstate) 92 : "i" (PSTATE_IE)); 93 } 94 } 95 96 #ifdef CONFIG_HOTPLUG_CPU 97 void arch_cpu_idle_dead(void) 98 { 99 sched_preempt_enable_no_resched(); 100 cpu_play_dead(); 101 } 102 #endif 103 104 #ifdef CONFIG_COMPAT 105 static void show_regwindow32(struct pt_regs *regs) 106 { 107 struct reg_window32 __user *rw; 108 struct reg_window32 r_w; 109 mm_segment_t old_fs; 110 111 __asm__ __volatile__ ("flushw"); 112 rw = compat_ptr((unsigned int)regs->u_regs[14]); 113 old_fs = get_fs(); 114 set_fs (USER_DS); 115 if (copy_from_user (&r_w, rw, sizeof(r_w))) { 116 set_fs (old_fs); 117 return; 118 } 119 120 set_fs (old_fs); 121 printk("l0: %08x l1: %08x l2: %08x l3: %08x " 122 "l4: %08x l5: %08x l6: %08x l7: %08x\n", 123 r_w.locals[0], r_w.locals[1], r_w.locals[2], r_w.locals[3], 124 r_w.locals[4], r_w.locals[5], r_w.locals[6], r_w.locals[7]); 125 printk("i0: %08x i1: %08x i2: %08x i3: %08x " 126 "i4: %08x i5: %08x i6: %08x i7: %08x\n", 127 r_w.ins[0], r_w.ins[1], r_w.ins[2], r_w.ins[3], 128 r_w.ins[4], r_w.ins[5], r_w.ins[6], r_w.ins[7]); 129 } 130 #else 131 #define show_regwindow32(regs) do { } while (0) 132 #endif 133 134 static void show_regwindow(struct pt_regs *regs) 135 { 136 struct reg_window __user *rw; 137 struct reg_window *rwk; 138 struct reg_window r_w; 139 mm_segment_t old_fs; 140 141 if ((regs->tstate & TSTATE_PRIV) || !(test_thread_flag(TIF_32BIT))) { 142 __asm__ __volatile__ ("flushw"); 143 rw = (struct reg_window __user *) 144 (regs->u_regs[14] + STACK_BIAS); 145 rwk = (struct reg_window *) 146 (regs->u_regs[14] + STACK_BIAS); 147 if (!(regs->tstate & TSTATE_PRIV)) { 148 old_fs = get_fs(); 149 set_fs (USER_DS); 150 if (copy_from_user (&r_w, rw, sizeof(r_w))) { 151 set_fs (old_fs); 152 return; 153 } 154 rwk = &r_w; 155 set_fs (old_fs); 156 } 157 } else { 158 show_regwindow32(regs); 159 return; 160 } 161 printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n", 162 rwk->locals[0], rwk->locals[1], rwk->locals[2], rwk->locals[3]); 163 printk("l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n", 164 rwk->locals[4], rwk->locals[5], rwk->locals[6], rwk->locals[7]); 165 printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n", 166 rwk->ins[0], rwk->ins[1], rwk->ins[2], rwk->ins[3]); 167 printk("i4: %016lx i5: %016lx i6: %016lx i7: %016lx\n", 168 rwk->ins[4], rwk->ins[5], rwk->ins[6], rwk->ins[7]); 169 if (regs->tstate & TSTATE_PRIV) 170 printk("I7: <%pS>\n", (void *) rwk->ins[7]); 171 } 172 173 void show_regs(struct pt_regs *regs) 174 { 175 show_regs_print_info(KERN_DEFAULT); 176 177 printk("TSTATE: %016lx TPC: %016lx TNPC: %016lx Y: %08x %s\n", regs->tstate, 178 regs->tpc, regs->tnpc, regs->y, print_tainted()); 179 printk("TPC: <%pS>\n", (void *) regs->tpc); 180 printk("g0: %016lx g1: %016lx g2: %016lx g3: %016lx\n", 181 regs->u_regs[0], regs->u_regs[1], regs->u_regs[2], 182 regs->u_regs[3]); 183 printk("g4: %016lx g5: %016lx g6: %016lx g7: %016lx\n", 184 regs->u_regs[4], regs->u_regs[5], regs->u_regs[6], 185 regs->u_regs[7]); 186 printk("o0: %016lx o1: %016lx o2: %016lx o3: %016lx\n", 187 regs->u_regs[8], regs->u_regs[9], regs->u_regs[10], 188 regs->u_regs[11]); 189 printk("o4: %016lx o5: %016lx sp: %016lx ret_pc: %016lx\n", 190 regs->u_regs[12], regs->u_regs[13], regs->u_regs[14], 191 regs->u_regs[15]); 192 printk("RPC: <%pS>\n", (void *) regs->u_regs[15]); 193 show_regwindow(regs); 194 show_stack(current, (unsigned long *)regs->u_regs[UREG_FP], KERN_DEFAULT); 195 } 196 197 union global_cpu_snapshot global_cpu_snapshot[NR_CPUS]; 198 static DEFINE_SPINLOCK(global_cpu_snapshot_lock); 199 200 static void __global_reg_self(struct thread_info *tp, struct pt_regs *regs, 201 int this_cpu) 202 { 203 struct global_reg_snapshot *rp; 204 205 flushw_all(); 206 207 rp = &global_cpu_snapshot[this_cpu].reg; 208 209 rp->tstate = regs->tstate; 210 rp->tpc = regs->tpc; 211 rp->tnpc = regs->tnpc; 212 rp->o7 = regs->u_regs[UREG_I7]; 213 214 if (regs->tstate & TSTATE_PRIV) { 215 struct reg_window *rw; 216 217 rw = (struct reg_window *) 218 (regs->u_regs[UREG_FP] + STACK_BIAS); 219 if (kstack_valid(tp, (unsigned long) rw)) { 220 rp->i7 = rw->ins[7]; 221 rw = (struct reg_window *) 222 (rw->ins[6] + STACK_BIAS); 223 if (kstack_valid(tp, (unsigned long) rw)) 224 rp->rpc = rw->ins[7]; 225 } 226 } else { 227 rp->i7 = 0; 228 rp->rpc = 0; 229 } 230 rp->thread = tp; 231 } 232 233 /* In order to avoid hangs we do not try to synchronize with the 234 * global register dump client cpus. The last store they make is to 235 * the thread pointer, so do a short poll waiting for that to become 236 * non-NULL. 237 */ 238 static void __global_reg_poll(struct global_reg_snapshot *gp) 239 { 240 int limit = 0; 241 242 while (!gp->thread && ++limit < 100) { 243 barrier(); 244 udelay(1); 245 } 246 } 247 248 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) 249 { 250 struct thread_info *tp = current_thread_info(); 251 struct pt_regs *regs = get_irq_regs(); 252 unsigned long flags; 253 int this_cpu, cpu; 254 255 if (!regs) 256 regs = tp->kregs; 257 258 spin_lock_irqsave(&global_cpu_snapshot_lock, flags); 259 260 this_cpu = raw_smp_processor_id(); 261 262 memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot)); 263 264 if (cpumask_test_cpu(this_cpu, mask) && !exclude_self) 265 __global_reg_self(tp, regs, this_cpu); 266 267 smp_fetch_global_regs(); 268 269 for_each_cpu(cpu, mask) { 270 struct global_reg_snapshot *gp; 271 272 if (exclude_self && cpu == this_cpu) 273 continue; 274 275 gp = &global_cpu_snapshot[cpu].reg; 276 277 __global_reg_poll(gp); 278 279 tp = gp->thread; 280 printk("%c CPU[%3d]: TSTATE[%016lx] TPC[%016lx] TNPC[%016lx] TASK[%s:%d]\n", 281 (cpu == this_cpu ? '*' : ' '), cpu, 282 gp->tstate, gp->tpc, gp->tnpc, 283 ((tp && tp->task) ? tp->task->comm : "NULL"), 284 ((tp && tp->task) ? tp->task->pid : -1)); 285 286 if (gp->tstate & TSTATE_PRIV) { 287 printk(" TPC[%pS] O7[%pS] I7[%pS] RPC[%pS]\n", 288 (void *) gp->tpc, 289 (void *) gp->o7, 290 (void *) gp->i7, 291 (void *) gp->rpc); 292 } else { 293 printk(" TPC[%lx] O7[%lx] I7[%lx] RPC[%lx]\n", 294 gp->tpc, gp->o7, gp->i7, gp->rpc); 295 } 296 297 touch_nmi_watchdog(); 298 } 299 300 memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot)); 301 302 spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags); 303 } 304 305 #ifdef CONFIG_MAGIC_SYSRQ 306 307 static void sysrq_handle_globreg(int key) 308 { 309 trigger_all_cpu_backtrace(); 310 } 311 312 static const struct sysrq_key_op sparc_globalreg_op = { 313 .handler = sysrq_handle_globreg, 314 .help_msg = "global-regs(y)", 315 .action_msg = "Show Global CPU Regs", 316 }; 317 318 static void __global_pmu_self(int this_cpu) 319 { 320 struct global_pmu_snapshot *pp; 321 int i, num; 322 323 if (!pcr_ops) 324 return; 325 326 pp = &global_cpu_snapshot[this_cpu].pmu; 327 328 num = 1; 329 if (tlb_type == hypervisor && 330 sun4v_chip_type >= SUN4V_CHIP_NIAGARA4) 331 num = 4; 332 333 for (i = 0; i < num; i++) { 334 pp->pcr[i] = pcr_ops->read_pcr(i); 335 pp->pic[i] = pcr_ops->read_pic(i); 336 } 337 } 338 339 static void __global_pmu_poll(struct global_pmu_snapshot *pp) 340 { 341 int limit = 0; 342 343 while (!pp->pcr[0] && ++limit < 100) { 344 barrier(); 345 udelay(1); 346 } 347 } 348 349 static void pmu_snapshot_all_cpus(void) 350 { 351 unsigned long flags; 352 int this_cpu, cpu; 353 354 spin_lock_irqsave(&global_cpu_snapshot_lock, flags); 355 356 memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot)); 357 358 this_cpu = raw_smp_processor_id(); 359 360 __global_pmu_self(this_cpu); 361 362 smp_fetch_global_pmu(); 363 364 for_each_online_cpu(cpu) { 365 struct global_pmu_snapshot *pp = &global_cpu_snapshot[cpu].pmu; 366 367 __global_pmu_poll(pp); 368 369 printk("%c CPU[%3d]: PCR[%08lx:%08lx:%08lx:%08lx] PIC[%08lx:%08lx:%08lx:%08lx]\n", 370 (cpu == this_cpu ? '*' : ' '), cpu, 371 pp->pcr[0], pp->pcr[1], pp->pcr[2], pp->pcr[3], 372 pp->pic[0], pp->pic[1], pp->pic[2], pp->pic[3]); 373 374 touch_nmi_watchdog(); 375 } 376 377 memset(global_cpu_snapshot, 0, sizeof(global_cpu_snapshot)); 378 379 spin_unlock_irqrestore(&global_cpu_snapshot_lock, flags); 380 } 381 382 static void sysrq_handle_globpmu(int key) 383 { 384 pmu_snapshot_all_cpus(); 385 } 386 387 static const struct sysrq_key_op sparc_globalpmu_op = { 388 .handler = sysrq_handle_globpmu, 389 .help_msg = "global-pmu(x)", 390 .action_msg = "Show Global PMU Regs", 391 }; 392 393 static int __init sparc_sysrq_init(void) 394 { 395 int ret = register_sysrq_key('y', &sparc_globalreg_op); 396 397 if (!ret) 398 ret = register_sysrq_key('x', &sparc_globalpmu_op); 399 return ret; 400 } 401 402 core_initcall(sparc_sysrq_init); 403 404 #endif 405 406 /* Free current thread data structures etc.. */ 407 void exit_thread(struct task_struct *tsk) 408 { 409 struct thread_info *t = task_thread_info(tsk); 410 411 if (t->utraps) { 412 if (t->utraps[0] < 2) 413 kfree (t->utraps); 414 else 415 t->utraps[0]--; 416 } 417 } 418 419 void flush_thread(void) 420 { 421 struct thread_info *t = current_thread_info(); 422 struct mm_struct *mm; 423 424 mm = t->task->mm; 425 if (mm) 426 tsb_context_switch(mm); 427 428 set_thread_wsaved(0); 429 430 /* Clear FPU register state. */ 431 t->fpsaved[0] = 0; 432 } 433 434 /* It's a bit more tricky when 64-bit tasks are involved... */ 435 static unsigned long clone_stackframe(unsigned long csp, unsigned long psp) 436 { 437 bool stack_64bit = test_thread_64bit_stack(psp); 438 unsigned long fp, distance, rval; 439 440 if (stack_64bit) { 441 csp += STACK_BIAS; 442 psp += STACK_BIAS; 443 __get_user(fp, &(((struct reg_window __user *)psp)->ins[6])); 444 fp += STACK_BIAS; 445 if (test_thread_flag(TIF_32BIT)) 446 fp &= 0xffffffff; 447 } else 448 __get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6])); 449 450 /* Now align the stack as this is mandatory in the Sparc ABI 451 * due to how register windows work. This hides the 452 * restriction from thread libraries etc. 453 */ 454 csp &= ~15UL; 455 456 distance = fp - psp; 457 rval = (csp - distance); 458 if (raw_copy_in_user((void __user *)rval, (void __user *)psp, distance)) 459 rval = 0; 460 else if (!stack_64bit) { 461 if (put_user(((u32)csp), 462 &(((struct reg_window32 __user *)rval)->ins[6]))) 463 rval = 0; 464 } else { 465 if (put_user(((u64)csp - STACK_BIAS), 466 &(((struct reg_window __user *)rval)->ins[6]))) 467 rval = 0; 468 else 469 rval = rval - STACK_BIAS; 470 } 471 472 return rval; 473 } 474 475 /* Standard stuff. */ 476 static inline void shift_window_buffer(int first_win, int last_win, 477 struct thread_info *t) 478 { 479 int i; 480 481 for (i = first_win; i < last_win; i++) { 482 t->rwbuf_stkptrs[i] = t->rwbuf_stkptrs[i+1]; 483 memcpy(&t->reg_window[i], &t->reg_window[i+1], 484 sizeof(struct reg_window)); 485 } 486 } 487 488 void synchronize_user_stack(void) 489 { 490 struct thread_info *t = current_thread_info(); 491 unsigned long window; 492 493 flush_user_windows(); 494 if ((window = get_thread_wsaved()) != 0) { 495 window -= 1; 496 do { 497 struct reg_window *rwin = &t->reg_window[window]; 498 int winsize = sizeof(struct reg_window); 499 unsigned long sp; 500 501 sp = t->rwbuf_stkptrs[window]; 502 503 if (test_thread_64bit_stack(sp)) 504 sp += STACK_BIAS; 505 else 506 winsize = sizeof(struct reg_window32); 507 508 if (!copy_to_user((char __user *)sp, rwin, winsize)) { 509 shift_window_buffer(window, get_thread_wsaved() - 1, t); 510 set_thread_wsaved(get_thread_wsaved() - 1); 511 } 512 } while (window--); 513 } 514 } 515 516 static void stack_unaligned(unsigned long sp) 517 { 518 force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) sp); 519 } 520 521 static const char uwfault32[] = KERN_INFO \ 522 "%s[%d]: bad register window fault: SP %08lx (orig_sp %08lx) TPC %08lx O7 %08lx\n"; 523 static const char uwfault64[] = KERN_INFO \ 524 "%s[%d]: bad register window fault: SP %016lx (orig_sp %016lx) TPC %08lx O7 %016lx\n"; 525 526 void fault_in_user_windows(struct pt_regs *regs) 527 { 528 struct thread_info *t = current_thread_info(); 529 unsigned long window; 530 531 flush_user_windows(); 532 window = get_thread_wsaved(); 533 534 if (likely(window != 0)) { 535 window -= 1; 536 do { 537 struct reg_window *rwin = &t->reg_window[window]; 538 int winsize = sizeof(struct reg_window); 539 unsigned long sp, orig_sp; 540 541 orig_sp = sp = t->rwbuf_stkptrs[window]; 542 543 if (test_thread_64bit_stack(sp)) 544 sp += STACK_BIAS; 545 else 546 winsize = sizeof(struct reg_window32); 547 548 if (unlikely(sp & 0x7UL)) 549 stack_unaligned(sp); 550 551 if (unlikely(copy_to_user((char __user *)sp, 552 rwin, winsize))) { 553 if (show_unhandled_signals) 554 printk_ratelimited(is_compat_task() ? 555 uwfault32 : uwfault64, 556 current->comm, current->pid, 557 sp, orig_sp, 558 regs->tpc, 559 regs->u_regs[UREG_I7]); 560 goto barf; 561 } 562 } while (window--); 563 } 564 set_thread_wsaved(0); 565 return; 566 567 barf: 568 set_thread_wsaved(window + 1); 569 force_sig(SIGSEGV); 570 } 571 572 /* Copy a Sparc thread. The fork() return value conventions 573 * under SunOS are nothing short of bletcherous: 574 * Parent --> %o0 == childs pid, %o1 == 0 575 * Child --> %o0 == parents pid, %o1 == 1 576 */ 577 int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, 578 struct task_struct *p, unsigned long tls) 579 { 580 struct thread_info *t = task_thread_info(p); 581 struct pt_regs *regs = current_pt_regs(); 582 struct sparc_stackf *parent_sf; 583 unsigned long child_stack_sz; 584 char *child_trap_frame; 585 586 /* Calculate offset to stack_frame & pt_regs */ 587 child_stack_sz = (STACKFRAME_SZ + TRACEREG_SZ); 588 child_trap_frame = (task_stack_page(p) + 589 (THREAD_SIZE - child_stack_sz)); 590 591 t->new_child = 1; 592 t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS; 593 t->kregs = (struct pt_regs *) (child_trap_frame + 594 sizeof(struct sparc_stackf)); 595 t->fpsaved[0] = 0; 596 597 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { 598 memset(child_trap_frame, 0, child_stack_sz); 599 __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] = 600 (current_pt_regs()->tstate + 1) & TSTATE_CWP; 601 t->current_ds = ASI_P; 602 t->kregs->u_regs[UREG_G1] = sp; /* function */ 603 t->kregs->u_regs[UREG_G2] = arg; 604 return 0; 605 } 606 607 parent_sf = ((struct sparc_stackf *) regs) - 1; 608 memcpy(child_trap_frame, parent_sf, child_stack_sz); 609 if (t->flags & _TIF_32BIT) { 610 sp &= 0x00000000ffffffffUL; 611 regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL; 612 } 613 t->kregs->u_regs[UREG_FP] = sp; 614 __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] = 615 (regs->tstate + 1) & TSTATE_CWP; 616 t->current_ds = ASI_AIUS; 617 if (sp != regs->u_regs[UREG_FP]) { 618 unsigned long csp; 619 620 csp = clone_stackframe(sp, regs->u_regs[UREG_FP]); 621 if (!csp) 622 return -EFAULT; 623 t->kregs->u_regs[UREG_FP] = csp; 624 } 625 if (t->utraps) 626 t->utraps[0]++; 627 628 /* Set the return value for the child. */ 629 t->kregs->u_regs[UREG_I0] = current->pid; 630 t->kregs->u_regs[UREG_I1] = 1; 631 632 /* Set the second return value for the parent. */ 633 regs->u_regs[UREG_I1] = 0; 634 635 if (clone_flags & CLONE_SETTLS) 636 t->kregs->u_regs[UREG_G7] = tls; 637 638 return 0; 639 } 640 641 /* TIF_MCDPER in thread info flags for current task is updated lazily upon 642 * a context switch. Update this flag in current task's thread flags 643 * before dup so the dup'd task will inherit the current TIF_MCDPER flag. 644 */ 645 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 646 { 647 if (adi_capable()) { 648 register unsigned long tmp_mcdper; 649 650 __asm__ __volatile__( 651 ".word 0x83438000\n\t" /* rd %mcdper, %g1 */ 652 "mov %%g1, %0\n\t" 653 : "=r" (tmp_mcdper) 654 : 655 : "g1"); 656 if (tmp_mcdper) 657 set_thread_flag(TIF_MCDPER); 658 else 659 clear_thread_flag(TIF_MCDPER); 660 } 661 662 *dst = *src; 663 return 0; 664 } 665 666 unsigned long __get_wchan(struct task_struct *task) 667 { 668 unsigned long pc, fp, bias = 0; 669 struct thread_info *tp; 670 struct reg_window *rw; 671 unsigned long ret = 0; 672 int count = 0; 673 674 tp = task_thread_info(task); 675 bias = STACK_BIAS; 676 fp = task_thread_info(task)->ksp + bias; 677 678 do { 679 if (!kstack_valid(tp, fp)) 680 break; 681 rw = (struct reg_window *) fp; 682 pc = rw->ins[7]; 683 if (!in_sched_functions(pc)) { 684 ret = pc; 685 goto out; 686 } 687 fp = rw->ins[6] + bias; 688 } while (++count < 16); 689 690 out: 691 return ret; 692 } 693