ptrace.c

  1/*
  2 * `ptrace' system call
  3 *
  4 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
  5 * Copyright (C) 2007-2009 PetaLogix
  6 * Copyright (C) 2004-2007 John Williams <john.williams@petalogix.com>
  7 *
  8 * derived from arch/v850/kernel/ptrace.c
  9 *
 10 * Copyright (C) 2002,03 NEC Electronics Corporation
 11 * Copyright (C) 2002,03 Miles Bader <miles@gnu.org>
 12 *
 13 * Derived from arch/mips/kernel/ptrace.c:
 14 *
 15 * Copyright (C) 1992 Ross Biro
 16 * Copyright (C) Linus Torvalds
 17 * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
 18 * Copyright (C) 1996 David S. Miller
 19 * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
 20 * Copyright (C) 1999 MIPS Technologies, Inc.
 21 *
 22 * This file is subject to the terms and conditions of the GNU General
 23 * Public License. See the file COPYING in the main directory of this
 24 * archive for more details.
 25 */
 26
 27#include <linux/kernel.h>
 28#include <linux/mm.h>
 29#include <linux/sched.h>
 30#include <linux/sched/task_stack.h>
 31#include <linux/ptrace.h>
 32#include <linux/signal.h>
 33#include <linux/elf.h>
 34#include <linux/audit.h>
 35#include <linux/seccomp.h>
 36
 37#include <linux/errno.h>
 38#include <asm/processor.h>
 39#include <linux/uaccess.h>
 40#include <asm/asm-offsets.h>
 41#include <asm/cacheflush.h>
 42#include <asm/syscall.h>
 43#include <linux/io.h>
 44
 45/* Returns the address where the register at REG_OFFS in P is stashed away. */
 46static microblaze_reg_t *reg_save_addr(unsigned reg_offs,
 47					struct task_struct *t)
 48{
 49	struct pt_regs *regs;
 50
 51	/*
 52	 * Three basic cases:
 53	 *
 54	 * (1)	A register normally saved before calling the scheduler, is
 55	 *	available in the kernel entry pt_regs structure at the top
 56	 *	of the kernel stack. The kernel trap/irq exit path takes
 57	 *	care to save/restore almost all registers for ptrace'd
 58	 *	processes.
 59	 *
 60	 * (2)	A call-clobbered register, where the process P entered the
 61	 *	kernel via [syscall] trap, is not stored anywhere; that's
 62	 *	OK, because such registers are not expected to be preserved
 63	 *	when the trap returns anyway (so we don't actually bother to
 64	 *	test for this case).
 65	 *
 66	 * (3)	A few registers not used at all by the kernel, and so
 67	 *	normally never saved except by context-switches, are in the
 68	 *	context switch state.
 69	 */
 70
 71	/* Register saved during kernel entry (or not available). */
 72	regs = task_pt_regs(t);
 73
 74	return (microblaze_reg_t *)((char *)regs + reg_offs);
 75}
 76
 77long arch_ptrace(struct task_struct *child, long request,
 78		 unsigned long addr, unsigned long data)
 79{
 80	int rval;
 81	unsigned long val = 0;
 82
 83	switch (request) {
 84	/* Read/write the word at location ADDR in the registers. */
 85	case PTRACE_PEEKUSR:
 86	case PTRACE_POKEUSR:
 87		pr_debug("PEEKUSR/POKEUSR : 0x%08lx\n", addr);
 88		rval = 0;
 89		if (addr >= PT_SIZE && request == PTRACE_PEEKUSR) {
 90			/*
 91			 * Special requests that don't actually correspond
 92			 * to offsets in struct pt_regs.
 93			 */
 94			if (addr == PT_TEXT_ADDR) {
 95				val = child->mm->start_code;
 96			} else if (addr == PT_DATA_ADDR) {
 97				val = child->mm->start_data;
 98			} else if (addr == PT_TEXT_LEN) {
 99				val = child->mm->end_code
100					- child->mm->start_code;
101			} else {
102				rval = -EIO;
103			}
104		} else if (addr < PT_SIZE && (addr & 0x3) == 0) {
105			microblaze_reg_t *reg_addr = reg_save_addr(addr, child);
106			if (request == PTRACE_PEEKUSR)
107				val = *reg_addr;
108			else {
109#if 1
110				*reg_addr = data;
111#else
112				/* MS potential problem on WB system
113				 * Be aware that reg_addr is virtual address
114				 * virt_to_phys conversion is necessary.
115				 * This could be sensible solution.
116				 */
117				u32 paddr = virt_to_phys((u32)reg_addr);
118				invalidate_icache_range(paddr, paddr + 4);
119				*reg_addr = data;
120				flush_dcache_range(paddr, paddr + 4);
121#endif
122			}
123		} else
124			rval = -EIO;
125
126		if (rval == 0 && request == PTRACE_PEEKUSR)
127			rval = put_user(val, (unsigned long __user *)data);
128		break;
129	default:
130		rval = ptrace_request(child, request, addr, data);
131	}
132	return rval;
133}
134
135asmlinkage unsigned long do_syscall_trace_enter(struct pt_regs *regs)
136{
137	unsigned long ret = 0;
138
139	secure_computing_strict(regs->r12);
140
141	if (test_thread_flag(TIF_SYSCALL_TRACE) &&
142	    ptrace_report_syscall_entry(regs))
143		/*
144		 * Tracing decided this syscall should not happen.
145		 * We'll return a bogus call number to get an ENOSYS
146		 * error, but leave the original number in regs->regs[0].
147		 */
148		ret = -1L;
149
150	audit_syscall_entry(regs->r12, regs->r5, regs->r6, regs->r7, regs->r8);
151
152	return ret ?: regs->r12;
153}
154
155asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
156{
157	int step;
158
159	audit_syscall_exit(regs);
160
161	step = test_thread_flag(TIF_SINGLESTEP);
162	if (step || test_thread_flag(TIF_SYSCALL_TRACE))
163		ptrace_report_syscall_exit(regs, step);
164}
165
166void ptrace_disable(struct task_struct *child)
167{
168	/* nothing to do */
169}