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/user.h> 17 #include <linux/personality.h> 18 #include <linux/security.h> 19 #include <linux/compat.h> 20 #include <linux/signal.h> 21 22 #include <asm/uaccess.h> 23 #include <asm/pgtable.h> 24 #include <asm/system.h> 25 #include <asm/processor.h> 26 #include <asm/asm-offsets.h> 27 28 /* PSW bits we allow the debugger to modify */ 29 #define USER_PSW_BITS (PSW_N | PSW_V | PSW_CB) 30 31 /* 32 * Called by kernel/ptrace.c when detaching.. 33 * 34 * Make sure single step bits etc are not set. 35 */ 36 void ptrace_disable(struct task_struct *task) 37 { 38 task->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP); 39 40 /* make sure the trap bits are not set */ 41 pa_psw(task)->r = 0; 42 pa_psw(task)->t = 0; 43 pa_psw(task)->h = 0; 44 pa_psw(task)->l = 0; 45 } 46 47 /* 48 * The following functions are called by ptrace_resume() when 49 * enabling or disabling single/block tracing. 50 */ 51 void user_disable_single_step(struct task_struct *task) 52 { 53 ptrace_disable(task); 54 } 55 56 void user_enable_single_step(struct task_struct *task) 57 { 58 task->ptrace &= ~PT_BLOCKSTEP; 59 task->ptrace |= PT_SINGLESTEP; 60 61 if (pa_psw(task)->n) { 62 struct siginfo si; 63 64 /* Nullified, just crank over the queue. */ 65 task_regs(task)->iaoq[0] = task_regs(task)->iaoq[1]; 66 task_regs(task)->iasq[0] = task_regs(task)->iasq[1]; 67 task_regs(task)->iaoq[1] = task_regs(task)->iaoq[0] + 4; 68 pa_psw(task)->n = 0; 69 pa_psw(task)->x = 0; 70 pa_psw(task)->y = 0; 71 pa_psw(task)->z = 0; 72 pa_psw(task)->b = 0; 73 ptrace_disable(task); 74 /* Don't wake up the task, but let the 75 parent know something happened. */ 76 si.si_code = TRAP_TRACE; 77 si.si_addr = (void __user *) (task_regs(task)->iaoq[0] & ~3); 78 si.si_signo = SIGTRAP; 79 si.si_errno = 0; 80 force_sig_info(SIGTRAP, &si, task); 81 /* notify_parent(task, SIGCHLD); */ 82 return; 83 } 84 85 /* Enable recovery counter traps. The recovery counter 86 * itself will be set to zero on a task switch. If the 87 * task is suspended on a syscall then the syscall return 88 * path will overwrite the recovery counter with a suitable 89 * value such that it traps once back in user space. We 90 * disable interrupts in the tasks PSW here also, to avoid 91 * interrupts while the recovery counter is decrementing. 92 */ 93 pa_psw(task)->r = 1; 94 pa_psw(task)->t = 0; 95 pa_psw(task)->h = 0; 96 pa_psw(task)->l = 0; 97 } 98 99 void user_enable_block_step(struct task_struct *task) 100 { 101 task->ptrace &= ~PT_SINGLESTEP; 102 task->ptrace |= PT_BLOCKSTEP; 103 104 /* Enable taken branch trap. */ 105 pa_psw(task)->r = 0; 106 pa_psw(task)->t = 1; 107 pa_psw(task)->h = 0; 108 pa_psw(task)->l = 0; 109 } 110 111 long arch_ptrace(struct task_struct *child, long request, long addr, long data) 112 { 113 unsigned long tmp; 114 long ret = -EIO; 115 116 switch (request) { 117 118 /* Read the word at location addr in the USER area. For ptraced 119 processes, the kernel saves all regs on a syscall. */ 120 case PTRACE_PEEKUSR: 121 if ((addr & (sizeof(long)-1)) || 122 (unsigned long) addr >= sizeof(struct pt_regs)) 123 break; 124 tmp = *(unsigned long *) ((char *) task_regs(child) + addr); 125 ret = put_user(tmp, (unsigned long *) data); 126 break; 127 128 /* Write the word at location addr in the USER area. This will need 129 to change when the kernel no longer saves all regs on a syscall. 130 FIXME. There is a problem at the moment in that r3-r18 are only 131 saved if the process is ptraced on syscall entry, and even then 132 those values are overwritten by actual register values on syscall 133 exit. */ 134 case PTRACE_POKEUSR: 135 /* Some register values written here may be ignored in 136 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 137 * r31/r31+4, and not with the values in pt_regs. 138 */ 139 if (addr == PT_PSW) { 140 /* Allow writing to Nullify, Divide-step-correction, 141 * and carry/borrow bits. 142 * BEWARE, if you set N, and then single step, it won't 143 * stop on the nullified instruction. 144 */ 145 data &= USER_PSW_BITS; 146 task_regs(child)->gr[0] &= ~USER_PSW_BITS; 147 task_regs(child)->gr[0] |= data; 148 ret = 0; 149 break; 150 } 151 152 if ((addr & (sizeof(long)-1)) || 153 (unsigned long) addr >= sizeof(struct pt_regs)) 154 break; 155 if ((addr >= PT_GR1 && addr <= PT_GR31) || 156 addr == PT_IAOQ0 || addr == PT_IAOQ1 || 157 (addr >= PT_FR0 && addr <= PT_FR31 + 4) || 158 addr == PT_SAR) { 159 *(unsigned long *) ((char *) task_regs(child) + addr) = data; 160 ret = 0; 161 } 162 break; 163 164 default: 165 ret = ptrace_request(child, request, addr, data); 166 break; 167 } 168 169 return ret; 170 } 171 172 173 #ifdef CONFIG_COMPAT 174 175 /* This function is needed to translate 32 bit pt_regs offsets in to 176 * 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel 177 * will request offset 12 if it wants gr3, but the lower 32 bits of 178 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4). 179 * This code relies on a 32 bit pt_regs being comprised of 32 bit values 180 * except for the fp registers which (a) are 64 bits, and (b) follow 181 * the gr registers at the start of pt_regs. The 32 bit pt_regs should 182 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[] 183 * being 64 bit in both cases. 184 */ 185 186 static compat_ulong_t translate_usr_offset(compat_ulong_t offset) 187 { 188 if (offset < 0) 189 return sizeof(struct pt_regs); 190 else if (offset <= 32*4) /* gr[0..31] */ 191 return offset * 2 + 4; 192 else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */ 193 return offset + 32*4; 194 else if (offset < sizeof(struct pt_regs)/2 + 32*4) 195 return offset * 2 + 4 - 32*8; 196 else 197 return sizeof(struct pt_regs); 198 } 199 200 long compat_arch_ptrace(struct task_struct *child, compat_long_t request, 201 compat_ulong_t addr, compat_ulong_t data) 202 { 203 compat_uint_t tmp; 204 long ret = -EIO; 205 206 switch (request) { 207 208 case PTRACE_PEEKUSR: 209 if (addr & (sizeof(compat_uint_t)-1)) 210 break; 211 addr = translate_usr_offset(addr); 212 if (addr >= sizeof(struct pt_regs)) 213 break; 214 215 tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr); 216 ret = put_user(tmp, (compat_uint_t *) (unsigned long) data); 217 break; 218 219 /* Write the word at location addr in the USER area. This will need 220 to change when the kernel no longer saves all regs on a syscall. 221 FIXME. There is a problem at the moment in that r3-r18 are only 222 saved if the process is ptraced on syscall entry, and even then 223 those values are overwritten by actual register values on syscall 224 exit. */ 225 case PTRACE_POKEUSR: 226 /* Some register values written here may be ignored in 227 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 228 * r31/r31+4, and not with the values in pt_regs. 229 */ 230 if (addr == PT_PSW) { 231 /* Since PT_PSW==0, it is valid for 32 bit processes 232 * under 64 bit kernels as well. 233 */ 234 ret = arch_ptrace(child, request, addr, data); 235 } else { 236 if (addr & (sizeof(compat_uint_t)-1)) 237 break; 238 addr = translate_usr_offset(addr); 239 if (addr >= sizeof(struct pt_regs)) 240 break; 241 if (addr >= PT_FR0 && addr <= PT_FR31 + 4) { 242 /* Special case, fp regs are 64 bits anyway */ 243 *(__u64 *) ((char *) task_regs(child) + addr) = data; 244 ret = 0; 245 } 246 else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) || 247 addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 || 248 addr == PT_SAR+4) { 249 /* Zero the top 32 bits */ 250 *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0; 251 *(__u32 *) ((char *) task_regs(child) + addr) = data; 252 ret = 0; 253 } 254 } 255 break; 256 257 default: 258 ret = compat_ptrace_request(child, request, addr, data); 259 break; 260 } 261 262 return ret; 263 } 264 #endif 265 266 267 void syscall_trace(void) 268 { 269 if (!test_thread_flag(TIF_SYSCALL_TRACE)) 270 return; 271 if (!(current->ptrace & PT_PTRACED)) 272 return; 273 ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) 274 ? 0x80 : 0)); 275 /* 276 * this isn't the same as continuing with a signal, but it will do 277 * for normal use. strace only continues with a signal if the 278 * stopping signal is not SIGTRAP. -brl 279 */ 280 if (current->exit_code) { 281 send_sig(current->exit_code, current, 1); 282 current->exit_code = 0; 283 } 284 } 285