1/* 2 * Kernel support for the ptrace() and syscall tracing interfaces. 3 * 4 * Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc. 5 * Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx> 6 * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org> 7 * Copyright (C) 2008 Helge Deller <deller@gmx.de> 8 */ 9 10#include <linux/kernel.h> 11#include <linux/sched.h> 12#include <linux/mm.h> 13#include <linux/smp.h> 14#include <linux/errno.h> 15#include <linux/ptrace.h> 16#include <linux/tracehook.h> 17#include <linux/user.h> 18#include <linux/personality.h> 19#include <linux/security.h> 20#include <linux/compat.h> 21#include <linux/signal.h> 22 23#include <asm/uaccess.h> 24#include <asm/pgtable.h> 25#include <asm/system.h> 26#include <asm/processor.h> 27#include <asm/asm-offsets.h> 28 29/* PSW bits we allow the debugger to modify */ 30#define USER_PSW_BITS (PSW_N | PSW_V | PSW_CB) 31 32/* 33 * Called by kernel/ptrace.c when detaching.. 34 * 35 * Make sure single step bits etc are not set. 36 */ 37void ptrace_disable(struct task_struct *task) 38{ 39 clear_tsk_thread_flag(task, TIF_SINGLESTEP); 40 clear_tsk_thread_flag(task, TIF_BLOCKSTEP); 41 42 /* make sure the trap bits are not set */ 43 pa_psw(task)->r = 0; 44 pa_psw(task)->t = 0; 45 pa_psw(task)->h = 0; 46 pa_psw(task)->l = 0; 47} 48 49/* 50 * The following functions are called by ptrace_resume() when 51 * enabling or disabling single/block tracing. 52 */ 53void user_disable_single_step(struct task_struct *task) 54{ 55 ptrace_disable(task); 56} 57 58void user_enable_single_step(struct task_struct *task) 59{ 60 clear_tsk_thread_flag(task, TIF_BLOCKSTEP); 61 set_tsk_thread_flag(task, TIF_SINGLESTEP); 62 63 if (pa_psw(task)->n) { 64 struct siginfo si; 65 66 /* Nullified, just crank over the queue. */ 67 task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1]; 68 task_regs(task)->iasq[0] = task_regs(task)->iasq[1]; 69 task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4; 70 pa_psw(task)->n = 0; 71 pa_psw(task)->x = 0; 72 pa_psw(task)->y = 0; 73 pa_psw(task)->z = 0; 74 pa_psw(task)->b = 0; 75 ptrace_disable(task); 76 /* Don't wake up the task, but let the 77 parent know something happened. */ 78 si.si_code = TRAP_TRACE; 79 si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3); 80 si.si_signo = SIGTRAP; 81 si.si_errno = 0; 82 force_sig_info(SIGTRAP, &si, task); 83 /* notify_parent(task, SIGCHLD); */ 84 return; 85 } 86 87 /* Enable recovery counter traps. The recovery counter 88 * itself will be set to zero on a task switch. If the 89 * task is suspended on a syscall then the syscall return 90 * path will overwrite the recovery counter with a suitable 91 * value such that it traps once back in user space. We 92 * disable interrupts in the tasks PSW here also, to avoid 93 * interrupts while the recovery counter is decrementing. 94 */ 95 pa_psw(task)->r = 1; 96 pa_psw(task)->t = 0; 97 pa_psw(task)->h = 0; 98 pa_psw(task)->l = 0; 99} 100 101void user_enable_block_step(struct task_struct *task) 102{ 103 clear_tsk_thread_flag(task, TIF_SINGLESTEP); 104 set_tsk_thread_flag(task, TIF_BLOCKSTEP); 105 106 /* Enable taken branch trap. */ 107 pa_psw(task)->r = 0; 108 pa_psw(task)->t = 1; 109 pa_psw(task)->h = 0; 110 pa_psw(task)->l = 0; 111} 112 113long arch_ptrace(struct task_struct *child, long request, long addr, long data) 114{ 115 unsigned long tmp; 116 long ret = -EIO; 117 118 switch (request) { 119 120 /* Read the word at location addr in the USER area. For ptraced 121 processes, the kernel saves all regs on a syscall. */ 122 case PTRACE_PEEKUSR: 123 if ((addr & (sizeof(long)-1)) || 124 (unsigned long) addr >= sizeof(struct pt_regs)) 125 break; 126 tmp = *(unsigned long *) ((char *) task_regs(child) + addr); 127 ret = put_user(tmp, (unsigned long *) data); 128 break; 129 130 case PTRACE_POKEUSR: 131 /* Some register values written here may be ignored in 132 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 133 * r31/r31+4, and not with the values in pt_regs. 134 */ 135 if (addr == PT_PSW) { 136 /* Allow writing to Nullify, Divide-step-correction, 137 * and carry/borrow bits. 138 * BEWARE, if you set N, and then single step, it won't 139 * stop on the nullified instruction. 140 */ 141 data &= USER_PSW_BITS; 142 task_regs(child)->gr[0] &= ~USER_PSW_BITS; 143 task_regs(child)->gr[0] |= data; 144 ret = 0; 145 break; 146 } 147 148 if ((addr & (sizeof(long)-1)) || 149 (unsigned long) addr >= sizeof(struct pt_regs)) 150 break; 151 if ((addr >= PT_GR1 && addr <= PT_GR31) || 152 addr == PT_IAOQ0 || addr == PT_IAOQ1 || 153 (addr >= PT_FR0 && addr <= PT_FR31 + 4) || 154 addr == PT_SAR) { 155 *(unsigned long *) ((char *) task_regs(child) + addr) = data; 156 ret = 0; 157 } 158 break; 159 160 default: 161 ret = ptrace_request(child, request, addr, data); 162 break; 163 } 164 165 return ret; 166} 167 168 169#ifdef CONFIG_COMPAT 170 171/* This function is needed to translate 32 bit pt_regs offsets in to 172 * 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel 173 * will request offset 12 if it wants gr3, but the lower 32 bits of 174 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4). 175 * This code relies on a 32 bit pt_regs being comprised of 32 bit values 176 * except for the fp registers which (a) are 64 bits, and (b) follow 177 * the gr registers at the start of pt_regs. The 32 bit pt_regs should 178 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[] 179 * being 64 bit in both cases. 180 */ 181 182static compat_ulong_t translate_usr_offset(compat_ulong_t offset) 183{ 184 if (offset < 0) 185 return sizeof(struct pt_regs); 186 else if (offset <= 32*4) /* gr[0..31] */ 187 return offset * 2 + 4; 188 else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */ 189 return offset + 32*4; 190 else if (offset < sizeof(struct pt_regs)/2 + 32*4) 191 return offset * 2 + 4 - 32*8; 192 else 193 return sizeof(struct pt_regs); 194} 195 196long compat_arch_ptrace(struct task_struct *child, compat_long_t request, 197 compat_ulong_t addr, compat_ulong_t data) 198{ 199 compat_uint_t tmp; 200 long ret = -EIO; 201 202 switch (request) { 203 204 case PTRACE_PEEKUSR: 205 if (addr & (sizeof(compat_uint_t)-1)) 206 break; 207 addr = translate_usr_offset(addr); 208 if (addr >= sizeof(struct pt_regs)) 209 break; 210 211 tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr); 212 ret = put_user(tmp, (compat_uint_t *) (unsigned long) data); 213 break; 214 215 case PTRACE_POKEUSR: 216 /* Some register values written here may be ignored in 217 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 218 * r31/r31+4, and not with the values in pt_regs. 219 */ 220 if (addr == PT_PSW) { 221 /* Since PT_PSW==0, it is valid for 32 bit processes 222 * under 64 bit kernels as well. 223 */ 224 ret = arch_ptrace(child, request, addr, data); 225 } else { 226 if (addr & (sizeof(compat_uint_t)-1)) 227 break; 228 addr = translate_usr_offset(addr); 229 if (addr >= sizeof(struct pt_regs)) 230 break; 231 if (addr >= PT_FR0 && addr <= PT_FR31 + 4) { 232 /* Special case, fp regs are 64 bits anyway */ 233 *(__u64 *) ((char *) task_regs(child) + addr) = data; 234 ret = 0; 235 } 236 else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) || 237 addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 || 238 addr == PT_SAR+4) { 239 /* Zero the top 32 bits */ 240 *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0; 241 *(__u32 *) ((char *) task_regs(child) + addr) = data; 242 ret = 0; 243 } 244 } 245 break; 246 247 default: 248 ret = compat_ptrace_request(child, request, addr, data); 249 break; 250 } 251 252 return ret; 253} 254#endif 255 256long do_syscall_trace_enter(struct pt_regs *regs) 257{ 258 if (test_thread_flag(TIF_SYSCALL_TRACE) && 259 tracehook_report_syscall_entry(regs)) 260 return -1L; 261 262 return regs->gr[20]; 263} 264 265void do_syscall_trace_exit(struct pt_regs *regs) 266{ 267 int stepping = test_thread_flag(TIF_SINGLESTEP) || 268 test_thread_flag(TIF_BLOCKSTEP); 269 270 if (stepping || test_thread_flag(TIF_SYSCALL_TRACE)) 271 tracehook_report_syscall_exit(regs, stepping); 272} 273