2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * Copyright (C) 1992 Ross Biro
7 * Copyright (C) Linus Torvalds
8 * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
9 * Copyright (C) 1996 David S. Miller
10 * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
11 * Copyright (C) 1999 MIPS Technologies, Inc.
12 * Copyright (C) 2000 Ulf Carlsson
14 * At this time Linux/MIPS64 only supports syscall tracing, even for 32-bit
17 #include <linux/compiler.h>
18 #include <linux/context_tracking.h>
19 #include <linux/elf.h>
20 #include <linux/kernel.h>
21 #include <linux/sched.h>
23 #include <linux/errno.h>
24 #include <linux/ptrace.h>
25 #include <linux/regset.h>
26 #include <linux/smp.h>
27 #include <linux/security.h>
28 #include <linux/stddef.h>
29 #include <linux/tracehook.h>
30 #include <linux/audit.h>
31 #include <linux/seccomp.h>
32 #include <linux/ftrace.h>
34 #include <asm/byteorder.h>
36 #include <asm/cpu-info.h>
39 #include <asm/mipsregs.h>
40 #include <asm/mipsmtregs.h>
41 #include <asm/pgtable.h>
43 #include <asm/syscall.h>
44 #include <asm/uaccess.h>
45 #include <asm/bootinfo.h>
48 #define CREATE_TRACE_POINTS
49 #include <trace/events/syscalls.h>
51 static void init_fp_ctx(struct task_struct *target)
53 /* If FP has been used then the target already has context */
54 if (tsk_used_math(target))
57 /* Begin with data registers set to all 1s... */
58 memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
60 /* ...and FCSR zeroed */
61 target->thread.fpu.fcr31 = 0;
64 * Record that the target has "used" math, such that the context
65 * just initialised, and any modifications made by the caller,
68 set_stopped_child_used_math(target);
72 * Called by kernel/ptrace.c when detaching..
74 * Make sure single step bits etc are not set.
76 void ptrace_disable(struct task_struct *child)
78 /* Don't load the watchpoint registers for the ex-child. */
79 clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
83 * Read a general register set. We always use the 64-bit format, even
84 * for 32-bit kernels and for 32-bit processes on a 64-bit kernel.
85 * Registers are sign extended to fill the available space.
87 int ptrace_getregs(struct task_struct *child, struct user_pt_regs __user *data)
92 if (!access_ok(VERIFY_WRITE, data, 38 * 8))
95 regs = task_pt_regs(child);
97 for (i = 0; i < 32; i++)
98 __put_user((long)regs->regs[i], (__s64 __user *)&data->regs[i]);
99 __put_user((long)regs->lo, (__s64 __user *)&data->lo);
100 __put_user((long)regs->hi, (__s64 __user *)&data->hi);
101 __put_user((long)regs->cp0_epc, (__s64 __user *)&data->cp0_epc);
102 __put_user((long)regs->cp0_badvaddr, (__s64 __user *)&data->cp0_badvaddr);
103 __put_user((long)regs->cp0_status, (__s64 __user *)&data->cp0_status);
104 __put_user((long)regs->cp0_cause, (__s64 __user *)&data->cp0_cause);
110 * Write a general register set. As for PTRACE_GETREGS, we always use
111 * the 64-bit format. On a 32-bit kernel only the lower order half
112 * (according to endianness) will be used.
114 int ptrace_setregs(struct task_struct *child, struct user_pt_regs __user *data)
116 struct pt_regs *regs;
119 if (!access_ok(VERIFY_READ, data, 38 * 8))
122 regs = task_pt_regs(child);
124 for (i = 0; i < 32; i++)
125 __get_user(regs->regs[i], (__s64 __user *)&data->regs[i]);
126 __get_user(regs->lo, (__s64 __user *)&data->lo);
127 __get_user(regs->hi, (__s64 __user *)&data->hi);
128 __get_user(regs->cp0_epc, (__s64 __user *)&data->cp0_epc);
130 /* badvaddr, status, and cause may not be written. */
135 int ptrace_getfpregs(struct task_struct *child, __u32 __user *data)
139 if (!access_ok(VERIFY_WRITE, data, 33 * 8))
142 if (tsk_used_math(child)) {
143 union fpureg *fregs = get_fpu_regs(child);
144 for (i = 0; i < 32; i++)
145 __put_user(get_fpr64(&fregs[i], 0),
146 i + (__u64 __user *)data);
148 for (i = 0; i < 32; i++)
149 __put_user((__u64) -1, i + (__u64 __user *) data);
152 __put_user(child->thread.fpu.fcr31, data + 64);
153 __put_user(boot_cpu_data.fpu_id, data + 65);
158 int ptrace_setfpregs(struct task_struct *child, __u32 __user *data)
167 if (!access_ok(VERIFY_READ, data, 33 * 8))
171 fregs = get_fpu_regs(child);
173 for (i = 0; i < 32; i++) {
174 __get_user(fpr_val, i + (__u64 __user *)data);
175 set_fpr64(&fregs[i], 0, fpr_val);
178 __get_user(value, data + 64);
179 value &= ~FPU_CSR_ALL_X;
180 fcr31 = child->thread.fpu.fcr31;
181 mask = boot_cpu_data.fpu_msk31;
182 child->thread.fpu.fcr31 = (value & ~mask) | (fcr31 & mask);
184 /* FIR may not be written. */
189 int ptrace_get_watch_regs(struct task_struct *child,
190 struct pt_watch_regs __user *addr)
192 enum pt_watch_style style;
195 if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0)
197 if (!access_ok(VERIFY_WRITE, addr, sizeof(struct pt_watch_regs)))
201 style = pt_watch_style_mips32;
202 #define WATCH_STYLE mips32
204 style = pt_watch_style_mips64;
205 #define WATCH_STYLE mips64
208 __put_user(style, &addr->style);
209 __put_user(boot_cpu_data.watch_reg_use_cnt,
210 &addr->WATCH_STYLE.num_valid);
211 for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
212 __put_user(child->thread.watch.mips3264.watchlo[i],
213 &addr->WATCH_STYLE.watchlo[i]);
214 __put_user(child->thread.watch.mips3264.watchhi[i] &
215 (MIPS_WATCHHI_MASK | MIPS_WATCHHI_IRW),
216 &addr->WATCH_STYLE.watchhi[i]);
217 __put_user(boot_cpu_data.watch_reg_masks[i],
218 &addr->WATCH_STYLE.watch_masks[i]);
221 __put_user(0, &addr->WATCH_STYLE.watchlo[i]);
222 __put_user(0, &addr->WATCH_STYLE.watchhi[i]);
223 __put_user(0, &addr->WATCH_STYLE.watch_masks[i]);
229 int ptrace_set_watch_regs(struct task_struct *child,
230 struct pt_watch_regs __user *addr)
233 int watch_active = 0;
234 unsigned long lt[NUM_WATCH_REGS];
235 u16 ht[NUM_WATCH_REGS];
237 if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0)
239 if (!access_ok(VERIFY_READ, addr, sizeof(struct pt_watch_regs)))
241 /* Check the values. */
242 for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
243 __get_user(lt[i], &addr->WATCH_STYLE.watchlo[i]);
245 if (lt[i] & __UA_LIMIT)
248 if (test_tsk_thread_flag(child, TIF_32BIT_ADDR)) {
249 if (lt[i] & 0xffffffff80000000UL)
252 if (lt[i] & __UA_LIMIT)
256 __get_user(ht[i], &addr->WATCH_STYLE.watchhi[i]);
257 if (ht[i] & ~MIPS_WATCHHI_MASK)
261 for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
262 if (lt[i] & MIPS_WATCHLO_IRW)
264 child->thread.watch.mips3264.watchlo[i] = lt[i];
266 child->thread.watch.mips3264.watchhi[i] = ht[i];
270 set_tsk_thread_flag(child, TIF_LOAD_WATCH);
272 clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
277 /* regset get/set implementations */
279 #if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
281 static int gpr32_get(struct task_struct *target,
282 const struct user_regset *regset,
283 unsigned int pos, unsigned int count,
284 void *kbuf, void __user *ubuf)
286 struct pt_regs *regs = task_pt_regs(target);
287 u32 uregs[ELF_NGREG] = {};
290 for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) {
291 /* k0/k1 are copied as zero. */
292 if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27)
295 uregs[i] = regs->regs[i - MIPS32_EF_R0];
298 uregs[MIPS32_EF_LO] = regs->lo;
299 uregs[MIPS32_EF_HI] = regs->hi;
300 uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc;
301 uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
302 uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status;
303 uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause;
305 return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0,
309 static int gpr32_set(struct task_struct *target,
310 const struct user_regset *regset,
311 unsigned int pos, unsigned int count,
312 const void *kbuf, const void __user *ubuf)
314 struct pt_regs *regs = task_pt_regs(target);
315 u32 uregs[ELF_NGREG];
316 unsigned start, num_regs, i;
319 start = pos / sizeof(u32);
320 num_regs = count / sizeof(u32);
322 if (start + num_regs > ELF_NGREG)
325 err = user_regset_copyin(&pos, &count, &kbuf, &ubuf, uregs, 0,
330 for (i = start; i < num_regs; i++) {
332 * Cast all values to signed here so that if this is a 64-bit
333 * kernel, the supplied 32-bit values will be sign extended.
336 case MIPS32_EF_R1 ... MIPS32_EF_R25:
337 /* k0/k1 are ignored. */
338 case MIPS32_EF_R28 ... MIPS32_EF_R31:
339 regs->regs[i - MIPS32_EF_R0] = (s32)uregs[i];
342 regs->lo = (s32)uregs[i];
345 regs->hi = (s32)uregs[i];
347 case MIPS32_EF_CP0_EPC:
348 regs->cp0_epc = (s32)uregs[i];
356 #endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
360 static int gpr64_get(struct task_struct *target,
361 const struct user_regset *regset,
362 unsigned int pos, unsigned int count,
363 void *kbuf, void __user *ubuf)
365 struct pt_regs *regs = task_pt_regs(target);
366 u64 uregs[ELF_NGREG] = {};
369 for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) {
370 /* k0/k1 are copied as zero. */
371 if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27)
374 uregs[i] = regs->regs[i - MIPS64_EF_R0];
377 uregs[MIPS64_EF_LO] = regs->lo;
378 uregs[MIPS64_EF_HI] = regs->hi;
379 uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc;
380 uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
381 uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status;
382 uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause;
384 return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0,
388 static int gpr64_set(struct task_struct *target,
389 const struct user_regset *regset,
390 unsigned int pos, unsigned int count,
391 const void *kbuf, const void __user *ubuf)
393 struct pt_regs *regs = task_pt_regs(target);
394 u64 uregs[ELF_NGREG];
395 unsigned start, num_regs, i;
398 start = pos / sizeof(u64);
399 num_regs = count / sizeof(u64);
401 if (start + num_regs > ELF_NGREG)
404 err = user_regset_copyin(&pos, &count, &kbuf, &ubuf, uregs, 0,
409 for (i = start; i < num_regs; i++) {
411 case MIPS64_EF_R1 ... MIPS64_EF_R25:
412 /* k0/k1 are ignored. */
413 case MIPS64_EF_R28 ... MIPS64_EF_R31:
414 regs->regs[i - MIPS64_EF_R0] = uregs[i];
422 case MIPS64_EF_CP0_EPC:
423 regs->cp0_epc = uregs[i];
431 #endif /* CONFIG_64BIT */
433 static int fpr_get(struct task_struct *target,
434 const struct user_regset *regset,
435 unsigned int pos, unsigned int count,
436 void *kbuf, void __user *ubuf)
444 if (sizeof(target->thread.fpu.fpr[i]) == sizeof(elf_fpreg_t))
445 return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
447 0, sizeof(elf_fpregset_t));
449 for (i = 0; i < NUM_FPU_REGS; i++) {
450 fpr_val = get_fpr64(&target->thread.fpu.fpr[i], 0);
451 err = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
452 &fpr_val, i * sizeof(elf_fpreg_t),
453 (i + 1) * sizeof(elf_fpreg_t));
461 static int fpr_set(struct task_struct *target,
462 const struct user_regset *regset,
463 unsigned int pos, unsigned int count,
464 const void *kbuf, const void __user *ubuf)
474 if (sizeof(target->thread.fpu.fpr[i]) == sizeof(elf_fpreg_t))
475 return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
477 0, sizeof(elf_fpregset_t));
479 for (i = 0; i < NUM_FPU_REGS; i++) {
480 err = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
481 &fpr_val, i * sizeof(elf_fpreg_t),
482 (i + 1) * sizeof(elf_fpreg_t));
485 set_fpr64(&target->thread.fpu.fpr[i], 0, fpr_val);
496 struct pt_regs_offset {
501 #define REG_OFFSET_NAME(reg, r) { \
503 .offset = offsetof(struct pt_regs, r) \
506 #define REG_OFFSET_END { \
511 static const struct pt_regs_offset regoffset_table[] = {
512 REG_OFFSET_NAME(r0, regs[0]),
513 REG_OFFSET_NAME(r1, regs[1]),
514 REG_OFFSET_NAME(r2, regs[2]),
515 REG_OFFSET_NAME(r3, regs[3]),
516 REG_OFFSET_NAME(r4, regs[4]),
517 REG_OFFSET_NAME(r5, regs[5]),
518 REG_OFFSET_NAME(r6, regs[6]),
519 REG_OFFSET_NAME(r7, regs[7]),
520 REG_OFFSET_NAME(r8, regs[8]),
521 REG_OFFSET_NAME(r9, regs[9]),
522 REG_OFFSET_NAME(r10, regs[10]),
523 REG_OFFSET_NAME(r11, regs[11]),
524 REG_OFFSET_NAME(r12, regs[12]),
525 REG_OFFSET_NAME(r13, regs[13]),
526 REG_OFFSET_NAME(r14, regs[14]),
527 REG_OFFSET_NAME(r15, regs[15]),
528 REG_OFFSET_NAME(r16, regs[16]),
529 REG_OFFSET_NAME(r17, regs[17]),
530 REG_OFFSET_NAME(r18, regs[18]),
531 REG_OFFSET_NAME(r19, regs[19]),
532 REG_OFFSET_NAME(r20, regs[20]),
533 REG_OFFSET_NAME(r21, regs[21]),
534 REG_OFFSET_NAME(r22, regs[22]),
535 REG_OFFSET_NAME(r23, regs[23]),
536 REG_OFFSET_NAME(r24, regs[24]),
537 REG_OFFSET_NAME(r25, regs[25]),
538 REG_OFFSET_NAME(r26, regs[26]),
539 REG_OFFSET_NAME(r27, regs[27]),
540 REG_OFFSET_NAME(r28, regs[28]),
541 REG_OFFSET_NAME(r29, regs[29]),
542 REG_OFFSET_NAME(r30, regs[30]),
543 REG_OFFSET_NAME(r31, regs[31]),
544 REG_OFFSET_NAME(c0_status, cp0_status),
545 REG_OFFSET_NAME(hi, hi),
546 REG_OFFSET_NAME(lo, lo),
547 #ifdef CONFIG_CPU_HAS_SMARTMIPS
548 REG_OFFSET_NAME(acx, acx),
550 REG_OFFSET_NAME(c0_badvaddr, cp0_badvaddr),
551 REG_OFFSET_NAME(c0_cause, cp0_cause),
552 REG_OFFSET_NAME(c0_epc, cp0_epc),
553 #ifdef CONFIG_CPU_CAVIUM_OCTEON
554 REG_OFFSET_NAME(mpl0, mpl[0]),
555 REG_OFFSET_NAME(mpl1, mpl[1]),
556 REG_OFFSET_NAME(mpl2, mpl[2]),
557 REG_OFFSET_NAME(mtp0, mtp[0]),
558 REG_OFFSET_NAME(mtp1, mtp[1]),
559 REG_OFFSET_NAME(mtp2, mtp[2]),
565 * regs_query_register_offset() - query register offset from its name
566 * @name: the name of a register
568 * regs_query_register_offset() returns the offset of a register in struct
569 * pt_regs from its name. If the name is invalid, this returns -EINVAL;
571 int regs_query_register_offset(const char *name)
573 const struct pt_regs_offset *roff;
574 for (roff = regoffset_table; roff->name != NULL; roff++)
575 if (!strcmp(roff->name, name))
580 #if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
582 static const struct user_regset mips_regsets[] = {
584 .core_note_type = NT_PRSTATUS,
586 .size = sizeof(unsigned int),
587 .align = sizeof(unsigned int),
592 .core_note_type = NT_PRFPREG,
594 .size = sizeof(elf_fpreg_t),
595 .align = sizeof(elf_fpreg_t),
601 static const struct user_regset_view user_mips_view = {
603 .e_machine = ELF_ARCH,
604 .ei_osabi = ELF_OSABI,
605 .regsets = mips_regsets,
606 .n = ARRAY_SIZE(mips_regsets),
609 #endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
613 static const struct user_regset mips64_regsets[] = {
615 .core_note_type = NT_PRSTATUS,
617 .size = sizeof(unsigned long),
618 .align = sizeof(unsigned long),
623 .core_note_type = NT_PRFPREG,
625 .size = sizeof(elf_fpreg_t),
626 .align = sizeof(elf_fpreg_t),
632 static const struct user_regset_view user_mips64_view = {
634 .e_machine = ELF_ARCH,
635 .ei_osabi = ELF_OSABI,
636 .regsets = mips64_regsets,
637 .n = ARRAY_SIZE(mips64_regsets),
640 #endif /* CONFIG_64BIT */
642 const struct user_regset_view *task_user_regset_view(struct task_struct *task)
645 return &user_mips_view;
647 #ifdef CONFIG_MIPS32_O32
648 if (test_tsk_thread_flag(task, TIF_32BIT_REGS))
649 return &user_mips_view;
651 return &user_mips64_view;
655 long arch_ptrace(struct task_struct *child, long request,
656 unsigned long addr, unsigned long data)
659 void __user *addrp = (void __user *) addr;
660 void __user *datavp = (void __user *) data;
661 unsigned long __user *datalp = (void __user *) data;
664 /* when I and D space are separate, these will need to be fixed. */
665 case PTRACE_PEEKTEXT: /* read word at location addr. */
666 case PTRACE_PEEKDATA:
667 ret = generic_ptrace_peekdata(child, addr, data);
670 /* Read the word at location addr in the USER area. */
671 case PTRACE_PEEKUSR: {
672 struct pt_regs *regs;
674 unsigned long tmp = 0;
676 regs = task_pt_regs(child);
677 ret = 0; /* Default return value. */
681 tmp = regs->regs[addr];
683 case FPR_BASE ... FPR_BASE + 31:
684 if (!tsk_used_math(child)) {
685 /* FP not yet used */
689 fregs = get_fpu_regs(child);
692 if (test_thread_flag(TIF_32BIT_FPREGS)) {
694 * The odd registers are actually the high
695 * order bits of the values stored in the even
696 * registers - unless we're using r2k_switch.S.
698 tmp = get_fpr32(&fregs[(addr & ~1) - FPR_BASE],
703 tmp = get_fpr32(&fregs[addr - FPR_BASE], 0);
709 tmp = regs->cp0_cause;
712 tmp = regs->cp0_badvaddr;
720 #ifdef CONFIG_CPU_HAS_SMARTMIPS
726 tmp = child->thread.fpu.fcr31;
729 /* implementation / version register */
730 tmp = boot_cpu_data.fpu_id;
732 case DSP_BASE ... DSP_BASE + 5: {
740 dregs = __get_dsp_regs(child);
741 tmp = (unsigned long) (dregs[addr - DSP_BASE]);
750 tmp = child->thread.dsp.dspcontrol;
757 ret = put_user(tmp, datalp);
761 /* when I and D space are separate, this will have to be fixed. */
762 case PTRACE_POKETEXT: /* write the word at location addr. */
763 case PTRACE_POKEDATA:
764 ret = generic_ptrace_pokedata(child, addr, data);
767 case PTRACE_POKEUSR: {
768 struct pt_regs *regs;
770 regs = task_pt_regs(child);
774 regs->regs[addr] = data;
776 case FPR_BASE ... FPR_BASE + 31: {
777 union fpureg *fregs = get_fpu_regs(child);
781 if (test_thread_flag(TIF_32BIT_FPREGS)) {
783 * The odd registers are actually the high
784 * order bits of the values stored in the even
785 * registers - unless we're using r2k_switch.S.
787 set_fpr32(&fregs[(addr & ~1) - FPR_BASE],
792 set_fpr64(&fregs[addr - FPR_BASE], 0, data);
796 regs->cp0_epc = data;
804 #ifdef CONFIG_CPU_HAS_SMARTMIPS
810 child->thread.fpu.fcr31 = data & ~FPU_CSR_ALL_X;
812 case DSP_BASE ... DSP_BASE + 5: {
820 dregs = __get_dsp_regs(child);
821 dregs[addr - DSP_BASE] = data;
829 child->thread.dsp.dspcontrol = data;
832 /* The rest are not allowed. */
840 ret = ptrace_getregs(child, datavp);
844 ret = ptrace_setregs(child, datavp);
847 case PTRACE_GETFPREGS:
848 ret = ptrace_getfpregs(child, datavp);
851 case PTRACE_SETFPREGS:
852 ret = ptrace_setfpregs(child, datavp);
855 case PTRACE_GET_THREAD_AREA:
856 ret = put_user(task_thread_info(child)->tp_value, datalp);
859 case PTRACE_GET_WATCH_REGS:
860 ret = ptrace_get_watch_regs(child, addrp);
863 case PTRACE_SET_WATCH_REGS:
864 ret = ptrace_set_watch_regs(child, addrp);
868 ret = ptrace_request(child, request, addr, data);
876 * Notification of system call entry/exit
877 * - triggered by current->work.syscall_trace
879 asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)
884 current_thread_info()->syscall = syscall;
886 if (secure_computing() == -1)
889 if (test_thread_flag(TIF_SYSCALL_TRACE) &&
890 tracehook_report_syscall_entry(regs))
893 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
894 trace_sys_enter(regs, regs->regs[2]);
896 audit_syscall_entry(syscall, regs->regs[4], regs->regs[5],
897 regs->regs[6], regs->regs[7]);
902 * Notification of system call entry/exit
903 * - triggered by current->work.syscall_trace
905 asmlinkage void syscall_trace_leave(struct pt_regs *regs)
908 * We may come here right after calling schedule_user()
909 * or do_notify_resume(), in which case we can be in RCU
914 audit_syscall_exit(regs);
916 if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
917 trace_sys_exit(regs, regs->regs[2]);
919 if (test_thread_flag(TIF_SYSCALL_TRACE))
920 tracehook_report_syscall_exit(regs, 0);