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 */ 37 void 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 */ 53 void user_disable_single_step(struct task_struct *task) 54 { 55 ptrace_disable(task); 56 } 57 58 void 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 } 100 101 void 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 } 112 113 long arch_ptrace(struct task_struct *child, long request, 114 unsigned long addr, unsigned long data) 115 { 116 unsigned long tmp; 117 long ret = -EIO; 118 119 switch (request) { 120 121 /* Read the word at location addr in the USER area. For ptraced 122 processes, the kernel saves all regs on a syscall. */ 123 case PTRACE_PEEKUSR: 124 if ((addr & (sizeof(unsigned long)-1)) || 125 addr >= sizeof(struct pt_regs)) 126 break; 127 tmp = *(unsigned long *) ((char *) task_regs(child) + addr); 128 ret = put_user(tmp, (unsigned long __user *) data); 129 break; 130 131 /* Write the word at location addr in the USER area. This will need 132 to change when the kernel no longer saves all regs on a syscall. 133 FIXME. There is a problem at the moment in that r3-r18 are only 134 saved if the process is ptraced on syscall entry, and even then 135 those values are overwritten by actual register values on syscall 136 exit. */ 137 case PTRACE_POKEUSR: 138 /* Some register values written here may be ignored in 139 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 140 * r31/r31+4, and not with the values in pt_regs. 141 */ 142 if (addr == PT_PSW) { 143 /* Allow writing to Nullify, Divide-step-correction, 144 * and carry/borrow bits. 145 * BEWARE, if you set N, and then single step, it won't 146 * stop on the nullified instruction. 147 */ 148 data &= USER_PSW_BITS; 149 task_regs(child)->gr[0] &= ~USER_PSW_BITS; 150 task_regs(child)->gr[0] |= data; 151 ret = 0; 152 break; 153 } 154 155 if ((addr & (sizeof(unsigned long)-1)) || 156 addr >= sizeof(struct pt_regs)) 157 break; 158 if ((addr >= PT_GR1 && addr <= PT_GR31) || 159 addr == PT_IAOQ0 || addr == PT_IAOQ1 || 160 (addr >= PT_FR0 && addr <= PT_FR31 + 4) || 161 addr == PT_SAR) { 162 *(unsigned long *) ((char *) task_regs(child) + addr) = data; 163 ret = 0; 164 } 165 break; 166 167 default: 168 ret = ptrace_request(child, request, addr, data); 169 break; 170 } 171 172 return ret; 173 } 174 175 176 #ifdef CONFIG_COMPAT 177 178 /* This function is needed to translate 32 bit pt_regs offsets in to 179 * 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel 180 * will request offset 12 if it wants gr3, but the lower 32 bits of 181 * the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4). 182 * This code relies on a 32 bit pt_regs being comprised of 32 bit values 183 * except for the fp registers which (a) are 64 bits, and (b) follow 184 * the gr registers at the start of pt_regs. The 32 bit pt_regs should 185 * be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[] 186 * being 64 bit in both cases. 187 */ 188 189 static compat_ulong_t translate_usr_offset(compat_ulong_t offset) 190 { 191 if (offset < 0) 192 return sizeof(struct pt_regs); 193 else if (offset <= 32*4) /* gr[0..31] */ 194 return offset * 2 + 4; 195 else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */ 196 return offset + 32*4; 197 else if (offset < sizeof(struct pt_regs)/2 + 32*4) 198 return offset * 2 + 4 - 32*8; 199 else 200 return sizeof(struct pt_regs); 201 } 202 203 long compat_arch_ptrace(struct task_struct *child, compat_long_t request, 204 compat_ulong_t addr, compat_ulong_t data) 205 { 206 compat_uint_t tmp; 207 long ret = -EIO; 208 209 switch (request) { 210 211 case PTRACE_PEEKUSR: 212 if (addr & (sizeof(compat_uint_t)-1)) 213 break; 214 addr = translate_usr_offset(addr); 215 if (addr >= sizeof(struct pt_regs)) 216 break; 217 218 tmp = *(compat_uint_t *) ((char *) task_regs(child) + addr); 219 ret = put_user(tmp, (compat_uint_t *) (unsigned long) data); 220 break; 221 222 /* Write the word at location addr in the USER area. This will need 223 to change when the kernel no longer saves all regs on a syscall. 224 FIXME. There is a problem at the moment in that r3-r18 are only 225 saved if the process is ptraced on syscall entry, and even then 226 those values are overwritten by actual register values on syscall 227 exit. */ 228 case PTRACE_POKEUSR: 229 /* Some register values written here may be ignored in 230 * entry.S:syscall_restore_rfi; e.g. iaoq is written with 231 * r31/r31+4, and not with the values in pt_regs. 232 */ 233 if (addr == PT_PSW) { 234 /* Since PT_PSW==0, it is valid for 32 bit processes 235 * under 64 bit kernels as well. 236 */ 237 ret = arch_ptrace(child, request, addr, data); 238 } else { 239 if (addr & (sizeof(compat_uint_t)-1)) 240 break; 241 addr = translate_usr_offset(addr); 242 if (addr >= sizeof(struct pt_regs)) 243 break; 244 if (addr >= PT_FR0 && addr <= PT_FR31 + 4) { 245 /* Special case, fp regs are 64 bits anyway */ 246 *(__u64 *) ((char *) task_regs(child) + addr) = data; 247 ret = 0; 248 } 249 else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) || 250 addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 || 251 addr == PT_SAR+4) { 252 /* Zero the top 32 bits */ 253 *(__u32 *) ((char *) task_regs(child) + addr - 4) = 0; 254 *(__u32 *) ((char *) task_regs(child) + addr) = data; 255 ret = 0; 256 } 257 } 258 break; 259 260 default: 261 ret = compat_ptrace_request(child, request, addr, data); 262 break; 263 } 264 265 return ret; 266 } 267 #endif 268 269 long do_syscall_trace_enter(struct pt_regs *regs) 270 { 271 if (test_thread_flag(TIF_SYSCALL_TRACE) && 272 tracehook_report_syscall_entry(regs)) 273 return -1L; 274 275 return regs->gr[20]; 276 } 277 278 void do_syscall_trace_exit(struct pt_regs *regs) 279 { 280 int stepping = test_thread_flag(TIF_SINGLESTEP) || 281 test_thread_flag(TIF_BLOCKSTEP); 282 283 if (stepping || test_thread_flag(TIF_SYSCALL_TRACE)) 284 tracehook_report_syscall_exit(regs, stepping); 285 } 286