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