1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/arch/arm/kernel/ptrace.c
6 * edited by Linus Torvalds
7 * ARM modifications Copyright (C) 2000 Russell King
9 #include <linux/kernel.h>
10 #include <linux/sched/signal.h>
11 #include <linux/sched/task_stack.h>
13 #include <linux/elf.h>
14 #include <linux/smp.h>
15 #include <linux/ptrace.h>
16 #include <linux/user.h>
17 #include <linux/security.h>
18 #include <linux/init.h>
19 #include <linux/signal.h>
20 #include <linux/uaccess.h>
21 #include <linux/perf_event.h>
22 #include <linux/hw_breakpoint.h>
23 #include <linux/regset.h>
24 #include <linux/audit.h>
25 #include <linux/unistd.h>
27 #include <asm/syscall.h>
28 #include <asm/traps.h>
30 #define CREATE_TRACE_POINTS
31 #include <trace/events/syscalls.h>
36 * does not yet catch signals sent when the child dies.
37 * in exit.c or in signal.c.
42 * Breakpoint SWI instruction: SWI &9F0001
44 #define BREAKINST_ARM 0xef9f0001
45 #define BREAKINST_THUMB 0xdf00 /* fill this in later */
48 * New breakpoints - use an undefined instruction. The ARM architecture
49 * reference manual guarantees that the following instruction space
50 * will produce an undefined instruction exception on all CPUs:
52 * ARM: xxxx 0111 1111 xxxx xxxx xxxx 1111 xxxx
53 * Thumb: 1101 1110 xxxx xxxx
55 #define BREAKINST_ARM 0xe7f001f0
56 #define BREAKINST_THUMB 0xde01
59 struct pt_regs_offset {
64 #define REG_OFFSET_NAME(r) \
65 {.name = #r, .offset = offsetof(struct pt_regs, ARM_##r)}
66 #define REG_OFFSET_END {.name = NULL, .offset = 0}
68 static const struct pt_regs_offset regoffset_table[] = {
85 REG_OFFSET_NAME(cpsr),
86 REG_OFFSET_NAME(ORIG_r0),
91 * regs_query_register_offset() - query register offset from its name
92 * @name: the name of a register
94 * regs_query_register_offset() returns the offset of a register in struct
95 * pt_regs from its name. If the name is invalid, this returns -EINVAL;
97 int regs_query_register_offset(const char *name)
99 const struct pt_regs_offset *roff;
100 for (roff = regoffset_table; roff->name != NULL; roff++)
101 if (!strcmp(roff->name, name))
107 * regs_query_register_name() - query register name from its offset
108 * @offset: the offset of a register in struct pt_regs.
110 * regs_query_register_name() returns the name of a register from its
111 * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
113 const char *regs_query_register_name(unsigned int offset)
115 const struct pt_regs_offset *roff;
116 for (roff = regoffset_table; roff->name != NULL; roff++)
117 if (roff->offset == offset)
123 * regs_within_kernel_stack() - check the address in the stack
124 * @regs: pt_regs which contains kernel stack pointer.
125 * @addr: address which is checked.
127 * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
128 * If @addr is within the kernel stack, it returns true. If not, returns false.
130 bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
132 return ((addr & ~(THREAD_SIZE - 1)) ==
133 (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
137 * regs_get_kernel_stack_nth() - get Nth entry of the stack
138 * @regs: pt_regs which contains kernel stack pointer.
139 * @n: stack entry number.
141 * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
142 * is specified by @regs. If the @n th entry is NOT in the kernel stack,
145 unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
147 unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
149 if (regs_within_kernel_stack(regs, (unsigned long)addr))
156 * this routine will get a word off of the processes privileged stack.
157 * the offset is how far from the base addr as stored in the THREAD.
158 * this routine assumes that all the privileged stacks are in our
161 static inline long get_user_reg(struct task_struct *task, int offset)
163 return task_pt_regs(task)->uregs[offset];
167 * this routine will put a word on the processes privileged stack.
168 * the offset is how far from the base addr as stored in the THREAD.
169 * this routine assumes that all the privileged stacks are in our
173 put_user_reg(struct task_struct *task, int offset, long data)
175 struct pt_regs newregs, *regs = task_pt_regs(task);
179 newregs.uregs[offset] = data;
181 if (valid_user_regs(&newregs)) {
182 regs->uregs[offset] = data;
190 * Called by kernel/ptrace.c when detaching..
192 void ptrace_disable(struct task_struct *child)
198 * Handle hitting a breakpoint.
200 void ptrace_break(struct pt_regs *regs)
202 force_sig_fault(SIGTRAP, TRAP_BRKPT,
203 (void __user *)instruction_pointer(regs));
206 static int break_trap(struct pt_regs *regs, unsigned int instr)
212 static struct undef_hook arm_break_hook = {
213 .instr_mask = 0x0fffffff,
214 .instr_val = 0x07f001f0,
215 .cpsr_mask = PSR_T_BIT,
220 static struct undef_hook thumb_break_hook = {
221 .instr_mask = 0xffffffff,
222 .instr_val = 0x0000de01,
223 .cpsr_mask = PSR_T_BIT,
224 .cpsr_val = PSR_T_BIT,
228 static struct undef_hook thumb2_break_hook = {
229 .instr_mask = 0xffffffff,
230 .instr_val = 0xf7f0a000,
231 .cpsr_mask = PSR_T_BIT,
232 .cpsr_val = PSR_T_BIT,
236 static int __init ptrace_break_init(void)
238 register_undef_hook(&arm_break_hook);
239 register_undef_hook(&thumb_break_hook);
240 register_undef_hook(&thumb2_break_hook);
244 core_initcall(ptrace_break_init);
247 * Read the word at offset "off" into the "struct user". We
248 * actually access the pt_regs stored on the kernel stack.
250 static int ptrace_read_user(struct task_struct *tsk, unsigned long off,
251 unsigned long __user *ret)
259 if (off == PT_TEXT_ADDR)
260 tmp = tsk->mm->start_code;
261 else if (off == PT_DATA_ADDR)
262 tmp = tsk->mm->start_data;
263 else if (off == PT_TEXT_END_ADDR)
264 tmp = tsk->mm->end_code;
265 else if (off < sizeof(struct pt_regs))
266 tmp = get_user_reg(tsk, off >> 2);
267 else if (off >= sizeof(struct user))
270 return put_user(tmp, ret);
274 * Write the word at offset "off" into "struct user". We
275 * actually access the pt_regs stored on the kernel stack.
277 static int ptrace_write_user(struct task_struct *tsk, unsigned long off,
280 if (off & 3 || off >= sizeof(struct user))
283 if (off >= sizeof(struct pt_regs))
286 return put_user_reg(tsk, off >> 2, val);
292 * Get the child iWMMXt state.
294 static int ptrace_getwmmxregs(struct task_struct *tsk, void __user *ufp)
296 struct thread_info *thread = task_thread_info(tsk);
298 if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
300 iwmmxt_task_disable(thread); /* force it to ram */
301 return copy_to_user(ufp, &thread->fpstate.iwmmxt, IWMMXT_SIZE)
306 * Set the child iWMMXt state.
308 static int ptrace_setwmmxregs(struct task_struct *tsk, void __user *ufp)
310 struct thread_info *thread = task_thread_info(tsk);
312 if (!test_ti_thread_flag(thread, TIF_USING_IWMMXT))
314 iwmmxt_task_release(thread); /* force a reload */
315 return copy_from_user(&thread->fpstate.iwmmxt, ufp, IWMMXT_SIZE)
321 #ifdef CONFIG_HAVE_HW_BREAKPOINT
323 * Convert a virtual register number into an index for a thread_info
324 * breakpoint array. Breakpoints are identified using positive numbers
325 * whilst watchpoints are negative. The registers are laid out as pairs
326 * of (address, control), each pair mapping to a unique hw_breakpoint struct.
327 * Register 0 is reserved for describing resource information.
329 static int ptrace_hbp_num_to_idx(long num)
332 num = (ARM_MAX_BRP << 1) - num;
333 return (num - 1) >> 1;
337 * Returns the virtual register number for the address of the
338 * breakpoint at index idx.
340 static long ptrace_hbp_idx_to_num(int idx)
342 long mid = ARM_MAX_BRP << 1;
343 long num = (idx << 1) + 1;
344 return num > mid ? mid - num : num;
348 * Handle hitting a HW-breakpoint.
350 static void ptrace_hbptriggered(struct perf_event *bp,
351 struct perf_sample_data *data,
352 struct pt_regs *regs)
354 struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
358 for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i)
359 if (current->thread.debug.hbp[i] == bp)
362 num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i);
364 force_sig_ptrace_errno_trap((int)num, (void __user *)(bkpt->trigger));
368 * Set ptrace breakpoint pointers to zero for this task.
369 * This is required in order to prevent child processes from unregistering
370 * breakpoints held by their parent.
372 void clear_ptrace_hw_breakpoint(struct task_struct *tsk)
374 memset(tsk->thread.debug.hbp, 0, sizeof(tsk->thread.debug.hbp));
378 * Unregister breakpoints from this task and reset the pointers in
381 void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
384 struct thread_struct *t = &tsk->thread;
386 for (i = 0; i < ARM_MAX_HBP_SLOTS; i++) {
387 if (t->debug.hbp[i]) {
388 unregister_hw_breakpoint(t->debug.hbp[i]);
389 t->debug.hbp[i] = NULL;
394 static u32 ptrace_get_hbp_resource_info(void)
396 u8 num_brps, num_wrps, debug_arch, wp_len;
399 num_brps = hw_breakpoint_slots(TYPE_INST);
400 num_wrps = hw_breakpoint_slots(TYPE_DATA);
401 debug_arch = arch_get_debug_arch();
402 wp_len = arch_get_max_wp_len();
415 static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
417 struct perf_event_attr attr;
419 ptrace_breakpoint_init(&attr);
421 /* Initialise fields to sane defaults. */
423 attr.bp_len = HW_BREAKPOINT_LEN_4;
427 return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL,
431 static int ptrace_gethbpregs(struct task_struct *tsk, long num,
432 unsigned long __user *data)
436 struct perf_event *bp;
437 struct arch_hw_breakpoint_ctrl arch_ctrl;
440 reg = ptrace_get_hbp_resource_info();
442 idx = ptrace_hbp_num_to_idx(num);
443 if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) {
448 bp = tsk->thread.debug.hbp[idx];
454 arch_ctrl = counter_arch_bp(bp)->ctrl;
457 * Fix up the len because we may have adjusted it
458 * to compensate for an unaligned address.
460 while (!(arch_ctrl.len & 0x1))
464 reg = bp->attr.bp_addr;
466 reg = encode_ctrl_reg(arch_ctrl);
470 if (put_user(reg, data))
477 static int ptrace_sethbpregs(struct task_struct *tsk, long num,
478 unsigned long __user *data)
480 int idx, gen_len, gen_type, implied_type, ret = 0;
482 struct perf_event *bp;
483 struct arch_hw_breakpoint_ctrl ctrl;
484 struct perf_event_attr attr;
489 implied_type = HW_BREAKPOINT_RW;
491 implied_type = HW_BREAKPOINT_X;
493 idx = ptrace_hbp_num_to_idx(num);
494 if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS) {
499 if (get_user(user_val, data)) {
504 bp = tsk->thread.debug.hbp[idx];
506 bp = ptrace_hbp_create(tsk, implied_type);
511 tsk->thread.debug.hbp[idx] = bp;
518 attr.bp_addr = user_val;
521 decode_ctrl_reg(user_val, &ctrl);
522 ret = arch_bp_generic_fields(ctrl, &gen_len, &gen_type);
526 if ((gen_type & implied_type) != gen_type) {
531 attr.bp_len = gen_len;
532 attr.bp_type = gen_type;
533 attr.disabled = !ctrl.enabled;
536 ret = modify_user_hw_breakpoint(bp, &attr);
542 /* regset get/set implementations */
544 static int gpr_get(struct task_struct *target,
545 const struct user_regset *regset,
548 return membuf_write(&to, task_pt_regs(target), sizeof(struct pt_regs));
551 static int gpr_set(struct task_struct *target,
552 const struct user_regset *regset,
553 unsigned int pos, unsigned int count,
554 const void *kbuf, const void __user *ubuf)
557 struct pt_regs newregs = *task_pt_regs(target);
559 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
565 if (!valid_user_regs(&newregs))
568 *task_pt_regs(target) = newregs;
572 static int fpa_get(struct task_struct *target,
573 const struct user_regset *regset,
576 return membuf_write(&to, &task_thread_info(target)->fpstate,
577 sizeof(struct user_fp));
580 static int fpa_set(struct task_struct *target,
581 const struct user_regset *regset,
582 unsigned int pos, unsigned int count,
583 const void *kbuf, const void __user *ubuf)
585 struct thread_info *thread = task_thread_info(target);
587 thread->used_cp[1] = thread->used_cp[2] = 1;
589 return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
591 0, sizeof(struct user_fp));
596 * VFP register get/set implementations.
598 * With respect to the kernel, struct user_fp is divided into three chunks:
599 * 16 or 32 real VFP registers (d0-d15 or d0-31)
600 * These are transferred to/from the real registers in the task's
601 * vfp_hard_struct. The number of registers depends on the kernel
604 * 16 or 0 fake VFP registers (d16-d31 or empty)
605 * i.e., the user_vfp structure has space for 32 registers even if
606 * the kernel doesn't have them all.
608 * vfp_get() reads this chunk as zero where applicable
609 * vfp_set() ignores this chunk
611 * 1 word for the FPSCR
613 static int vfp_get(struct task_struct *target,
614 const struct user_regset *regset,
617 struct thread_info *thread = task_thread_info(target);
618 struct vfp_hard_struct const *vfp = &thread->vfpstate.hard;
619 const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);
621 vfp_sync_hwstate(thread);
623 membuf_write(&to, vfp->fpregs, sizeof(vfp->fpregs));
624 membuf_zero(&to, user_fpscr_offset - sizeof(vfp->fpregs));
625 return membuf_store(&to, vfp->fpscr);
629 * For vfp_set() a read-modify-write is done on the VFP registers,
630 * in order to avoid writing back a half-modified set of registers on
633 static int vfp_set(struct task_struct *target,
634 const struct user_regset *regset,
635 unsigned int pos, unsigned int count,
636 const void *kbuf, const void __user *ubuf)
639 struct thread_info *thread = task_thread_info(target);
640 struct vfp_hard_struct new_vfp;
641 const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
642 const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);
644 vfp_sync_hwstate(thread);
645 new_vfp = thread->vfpstate.hard;
647 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
650 user_fpregs_offset + sizeof(new_vfp.fpregs));
654 ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
655 user_fpregs_offset + sizeof(new_vfp.fpregs),
660 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
663 user_fpscr_offset + sizeof(new_vfp.fpscr));
667 thread->vfpstate.hard = new_vfp;
668 vfp_flush_hwstate(thread);
672 #endif /* CONFIG_VFP */
682 static const struct user_regset arm_regsets[] = {
684 .core_note_type = NT_PRSTATUS,
687 .align = sizeof(u32),
688 .regset_get = gpr_get,
693 * For the FPA regs in fpstate, the real fields are a mixture
694 * of sizes, so pretend that the registers are word-sized:
696 .core_note_type = NT_PRFPREG,
697 .n = sizeof(struct user_fp) / sizeof(u32),
699 .align = sizeof(u32),
700 .regset_get = fpa_get,
706 * Pretend that the VFP regs are word-sized, since the FPSCR is
707 * a single word dangling at the end of struct user_vfp:
709 .core_note_type = NT_ARM_VFP,
710 .n = ARM_VFPREGS_SIZE / sizeof(u32),
712 .align = sizeof(u32),
713 .regset_get = vfp_get,
716 #endif /* CONFIG_VFP */
719 static const struct user_regset_view user_arm_view = {
720 .name = "arm", .e_machine = ELF_ARCH, .ei_osabi = ELF_OSABI,
721 .regsets = arm_regsets, .n = ARRAY_SIZE(arm_regsets)
724 const struct user_regset_view *task_user_regset_view(struct task_struct *task)
726 return &user_arm_view;
729 long arch_ptrace(struct task_struct *child, long request,
730 unsigned long addr, unsigned long data)
733 unsigned long __user *datap = (unsigned long __user *) data;
737 ret = ptrace_read_user(child, addr, datap);
741 ret = ptrace_write_user(child, addr, data);
745 ret = copy_regset_to_user(child,
746 &user_arm_view, REGSET_GPR,
747 0, sizeof(struct pt_regs),
752 ret = copy_regset_from_user(child,
753 &user_arm_view, REGSET_GPR,
754 0, sizeof(struct pt_regs),
758 case PTRACE_GETFPREGS:
759 ret = copy_regset_to_user(child,
760 &user_arm_view, REGSET_FPR,
761 0, sizeof(union fp_state),
765 case PTRACE_SETFPREGS:
766 ret = copy_regset_from_user(child,
767 &user_arm_view, REGSET_FPR,
768 0, sizeof(union fp_state),
773 case PTRACE_GETWMMXREGS:
774 ret = ptrace_getwmmxregs(child, datap);
777 case PTRACE_SETWMMXREGS:
778 ret = ptrace_setwmmxregs(child, datap);
782 case PTRACE_GET_THREAD_AREA:
783 ret = put_user(task_thread_info(child)->tp_value[0],
787 case PTRACE_SET_SYSCALL:
788 task_thread_info(child)->abi_syscall = data &
794 case PTRACE_GETVFPREGS:
795 ret = copy_regset_to_user(child,
796 &user_arm_view, REGSET_VFP,
801 case PTRACE_SETVFPREGS:
802 ret = copy_regset_from_user(child,
803 &user_arm_view, REGSET_VFP,
809 #ifdef CONFIG_HAVE_HW_BREAKPOINT
810 case PTRACE_GETHBPREGS:
811 ret = ptrace_gethbpregs(child, addr,
812 (unsigned long __user *)data);
814 case PTRACE_SETHBPREGS:
815 ret = ptrace_sethbpregs(child, addr,
816 (unsigned long __user *)data);
821 ret = ptrace_request(child, request, addr, data);
828 enum ptrace_syscall_dir {
829 PTRACE_SYSCALL_ENTER = 0,
833 static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
838 * IP is used to denote syscall entry/exit:
839 * IP = 0 -> entry, =1 -> exit
844 if (dir == PTRACE_SYSCALL_EXIT)
845 ptrace_report_syscall_exit(regs, 0);
846 else if (ptrace_report_syscall_entry(regs))
847 current_thread_info()->abi_syscall = -1;
852 asmlinkage int syscall_trace_enter(struct pt_regs *regs)
856 if (test_thread_flag(TIF_SYSCALL_TRACE))
857 report_syscall(regs, PTRACE_SYSCALL_ENTER);
859 /* Do seccomp after ptrace; syscall may have changed. */
860 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
861 if (secure_computing() == -1)
864 /* XXX: remove this once OABI gets fixed */
865 secure_computing_strict(syscall_get_nr(current, regs));
868 /* Tracer or seccomp may have changed syscall. */
869 scno = syscall_get_nr(current, regs);
871 if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
872 trace_sys_enter(regs, scno);
874 audit_syscall_entry(scno, regs->ARM_r0, regs->ARM_r1, regs->ARM_r2,
880 asmlinkage void syscall_trace_exit(struct pt_regs *regs)
883 * Audit the syscall before anything else, as a debugger may
884 * come in and change the current registers.
886 audit_syscall_exit(regs);
889 * Note that we haven't updated the ->syscall field for the
890 * current thread. This isn't a problem because it will have
891 * been set on syscall entry and there hasn't been an opportunity
892 * for a PTRACE_SET_SYSCALL since then.
894 if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
895 trace_sys_exit(regs, regs_return_value(regs));
897 if (test_thread_flag(TIF_SYSCALL_TRACE))
898 report_syscall(regs, PTRACE_SYSCALL_EXIT);