arch/x86/include/asm/ptrace.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_PTRACE_H
   3 #define _ASM_X86_PTRACE_H
   4
   5 #include <asm/segment.h>
   6 #include <asm/page_types.h>
   7 #include <uapi/asm/ptrace.h>
   8
   9 #ifndef __ASSEMBLY__
  10 #ifdef __i386__
  11
  12 struct pt_regs {
  13         /*
  14          * NB: 32-bit x86 CPUs are inconsistent as what happens in the
  15          * following cases (where %seg represents a segment register):
  16          *
  17          * - pushl %seg: some do a 16-bit write and leave the high
  18          *   bits alone
  19          * - movl %seg, [mem]: some do a 16-bit write despite the movl
  20          * - IDT entry: some (e.g. 486) will leave the high bits of CS
  21          *   and (if applicable) SS undefined.
  22          *
  23          * Fortunately, x86-32 doesn't read the high bits on POP or IRET,
  24          * so we can just treat all of the segment registers as 16-bit
  25          * values.
  26          */
  27         unsigned long bx;
  28         unsigned long cx;
  29         unsigned long dx;
  30         unsigned long si;
  31         unsigned long di;
  32         unsigned long bp;
  33         unsigned long ax;
  34         unsigned short ds;
  35         unsigned short __dsh;
  36         unsigned short es;
  37         unsigned short __esh;
  38         unsigned short fs;
  39         unsigned short __fsh;
  40         /* On interrupt, gs and __gsh store the vector number. */
  41         unsigned short gs;
  42         unsigned short __gsh;
  43         /* On interrupt, this is the error code. */
  44         unsigned long orig_ax;
  45         unsigned long ip;
  46         unsigned short cs;
  47         unsigned short __csh;
  48         unsigned long flags;
  49         unsigned long sp;
  50         unsigned short ss;
  51         unsigned short __ssh;
  52 };
  53
  54 #else /* __i386__ */
  55
  56 struct pt_regs {
  57 /*
  58  * C ABI says these regs are callee-preserved. They aren't saved on kernel entry
  59  * unless syscall needs a complete, fully filled "struct pt_regs".
  60  */
  61         unsigned long r15;
  62         unsigned long r14;
  63         unsigned long r13;
  64         unsigned long r12;
  65         unsigned long bp;
  66         unsigned long bx;
  67 /* These regs are callee-clobbered. Always saved on kernel entry. */
  68         unsigned long r11;
  69         unsigned long r10;
  70         unsigned long r9;
  71         unsigned long r8;
  72         unsigned long ax;
  73         unsigned long cx;
  74         unsigned long dx;
  75         unsigned long si;
  76         unsigned long di;
  77 /*
  78  * On syscall entry, this is syscall#. On CPU exception, this is error code.
  79  * On hw interrupt, it's IRQ number:
  80  */
  81         unsigned long orig_ax;
  82 /* Return frame for iretq */
  83         unsigned long ip;
  84         unsigned long cs;
  85         unsigned long flags;
  86         unsigned long sp;
  87         unsigned long ss;
  88 /* top of stack page */
  89 };
  90
  91 #endif /* !__i386__ */
  92
  93 #ifdef CONFIG_PARAVIRT
  94 #include <asm/paravirt_types.h>
  95 #endif
  96
  97 struct cpuinfo_x86;
  98 struct task_struct;
  99
 100 extern unsigned long profile_pc(struct pt_regs *regs);
 101 #define profile_pc profile_pc
 102
 103 extern unsigned long
 104 convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
 105 extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
 106                          int error_code, int si_code);
 107
 108
 109 static inline unsigned long regs_return_value(struct pt_regs *regs)
 110 {
 111         return regs->ax;
 112 }
 113
 114 static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
 115 {
 116         regs->ax = rc;
 117 }
 118
 119 /*
 120  * user_mode(regs) determines whether a register set came from user
 121  * mode.  On x86_32, this is true if V8086 mode was enabled OR if the
 122  * register set was from protected mode with RPL-3 CS value.  This
 123  * tricky test checks that with one comparison.
 124  *
 125  * On x86_64, vm86 mode is mercifully nonexistent, and we don't need
 126  * the extra check.
 127  */
 128 static inline int user_mode(struct pt_regs *regs)
 129 {
 130 #ifdef CONFIG_X86_32
 131         return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL;
 132 #else
 133         return !!(regs->cs & 3);
 134 #endif
 135 }
 136
 137 static inline int v8086_mode(struct pt_regs *regs)
 138 {
 139 #ifdef CONFIG_X86_32
 140         return (regs->flags & X86_VM_MASK);
 141 #else
 142         return 0;       /* No V86 mode support in long mode */
 143 #endif
 144 }
 145
 146 static inline bool user_64bit_mode(struct pt_regs *regs)
 147 {
 148 #ifdef CONFIG_X86_64
 149 #ifndef CONFIG_PARAVIRT_XXL
 150         /*
 151          * On non-paravirt systems, this is the only long mode CPL 3
 152          * selector.  We do not allow long mode selectors in the LDT.
 153          */
 154         return regs->cs == __USER_CS;
 155 #else
 156         /* Headers are too twisted for this to go in paravirt.h. */
 157         return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
 158 #endif
 159 #else /* !CONFIG_X86_64 */
 160         return false;
 161 #endif
 162 }
 163
 164 #ifdef CONFIG_X86_64
 165 #define current_user_stack_pointer()    current_pt_regs()->sp
 166 #define compat_user_stack_pointer()     current_pt_regs()->sp
 167 #endif
 168
 169 #ifdef CONFIG_X86_32
 170 extern unsigned long kernel_stack_pointer(struct pt_regs *regs);
 171 #else
 172 static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 173 {
 174         return regs->sp;
 175 }
 176 #endif
 177
 178 #define GET_IP(regs) ((regs)->ip)
 179 #define GET_FP(regs) ((regs)->bp)
 180 #define GET_USP(regs) ((regs)->sp)
 181
 182 #include <asm-generic/ptrace.h>
 183
 184 /* Query offset/name of register from its name/offset */
 185 extern int regs_query_register_offset(const char *name);
 186 extern const char *regs_query_register_name(unsigned int offset);
 187 #define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))
 188
 189 /**
 190  * regs_get_register() - get register value from its offset
 191  * @regs:       pt_regs from which register value is gotten.
 192  * @offset:     offset number of the register.
 193  *
 194  * regs_get_register returns the value of a register. The @offset is the
 195  * offset of the register in struct pt_regs address which specified by @regs.
 196  * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
 197  */
 198 static inline unsigned long regs_get_register(struct pt_regs *regs,
 199                                               unsigned int offset)
 200 {
 201         if (unlikely(offset > MAX_REG_OFFSET))
 202                 return 0;
 203 #ifdef CONFIG_X86_32
 204         /*
 205          * Traps from the kernel do not save sp and ss.
 206          * Use the helper function to retrieve sp.
 207          */
 208         if (offset == offsetof(struct pt_regs, sp) &&
 209             regs->cs == __KERNEL_CS)
 210                 return kernel_stack_pointer(regs);
 211
 212         /* The selector fields are 16-bit. */
 213         if (offset == offsetof(struct pt_regs, cs) ||
 214             offset == offsetof(struct pt_regs, ss) ||
 215             offset == offsetof(struct pt_regs, ds) ||
 216             offset == offsetof(struct pt_regs, es) ||
 217             offset == offsetof(struct pt_regs, fs) ||
 218             offset == offsetof(struct pt_regs, gs)) {
 219                 return *(u16 *)((unsigned long)regs + offset);
 220
 221         }
 222 #endif
 223         return *(unsigned long *)((unsigned long)regs + offset);
 224 }
 225
 226 /**
 227  * regs_within_kernel_stack() - check the address in the stack
 228  * @regs:       pt_regs which contains kernel stack pointer.
 229  * @addr:       address which is checked.
 230  *
 231  * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
 232  * If @addr is within the kernel stack, it returns true. If not, returns false.
 233  */
 234 static inline int regs_within_kernel_stack(struct pt_regs *regs,
 235                                            unsigned long addr)
 236 {
 237         return ((addr & ~(THREAD_SIZE - 1))  ==
 238                 (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
 239 }
 240
 241 /**
 242  * regs_get_kernel_stack_nth_addr() - get the address of the Nth entry on stack
 243  * @regs:       pt_regs which contains kernel stack pointer.
 244  * @n:          stack entry number.
 245  *
 246  * regs_get_kernel_stack_nth() returns the address of the @n th entry of the
 247  * kernel stack which is specified by @regs. If the @n th entry is NOT in
 248  * the kernel stack, this returns NULL.
 249  */
 250 static inline unsigned long *regs_get_kernel_stack_nth_addr(struct pt_regs *regs, unsigned int n)
 251 {
 252         unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
 253
 254         addr += n;
 255         if (regs_within_kernel_stack(regs, (unsigned long)addr))
 256                 return addr;
 257         else
 258                 return NULL;
 259 }
 260
 261 /* To avoid include hell, we can't include uaccess.h */
 262 extern long probe_kernel_read(void *dst, const void *src, size_t size);
 263
 264 /**
 265  * regs_get_kernel_stack_nth() - get Nth entry of the stack
 266  * @regs:       pt_regs which contains kernel stack pointer.
 267  * @n:          stack entry number.
 268  *
 269  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
 270  * is specified by @regs. If the @n th entry is NOT in the kernel stack
 271  * this returns 0.
 272  */
 273 static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 274                                                       unsigned int n)
 275 {
 276         unsigned long *addr;
 277         unsigned long val;
 278         long ret;
 279
 280         addr = regs_get_kernel_stack_nth_addr(regs, n);
 281         if (addr) {
 282                 ret = probe_kernel_read(&val, addr, sizeof(val));
 283                 if (!ret)
 284                         return val;
 285         }
 286         return 0;
 287 }
 288
 289 /**
 290  * regs_get_kernel_argument() - get Nth function argument in kernel
 291  * @regs:       pt_regs of that context
 292  * @n:          function argument number (start from 0)
 293  *
 294  * regs_get_argument() returns @n th argument of the function call.
 295  * Note that this chooses most probably assignment, in some case
 296  * it can be incorrect.
 297  * This is expected to be called from kprobes or ftrace with regs
 298  * where the top of stack is the return address.
 299  */
 300 static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 301                                                      unsigned int n)
 302 {
 303         static const unsigned int argument_offs[] = {
 304 #ifdef __i386__
 305                 offsetof(struct pt_regs, ax),
 306                 offsetof(struct pt_regs, cx),
 307                 offsetof(struct pt_regs, dx),
 308 #define NR_REG_ARGUMENTS 3
 309 #else
 310                 offsetof(struct pt_regs, di),
 311                 offsetof(struct pt_regs, si),
 312                 offsetof(struct pt_regs, dx),
 313                 offsetof(struct pt_regs, cx),
 314                 offsetof(struct pt_regs, r8),
 315                 offsetof(struct pt_regs, r9),
 316 #define NR_REG_ARGUMENTS 6
 317 #endif
 318         };
 319
 320         if (n >= NR_REG_ARGUMENTS) {
 321                 n -= NR_REG_ARGUMENTS - 1;
 322                 return regs_get_kernel_stack_nth(regs, n);
 323         } else
 324                 return regs_get_register(regs, argument_offs[n]);
 325 }
 326
 327 #define arch_has_single_step()  (1)
 328 #ifdef CONFIG_X86_DEBUGCTLMSR
 329 #define arch_has_block_step()   (1)
 330 #else
 331 #define arch_has_block_step()   (boot_cpu_data.x86 >= 6)
 332 #endif
 333
 334 #define ARCH_HAS_USER_SINGLE_STEP_REPORT
 335
 336 /*
 337  * When hitting ptrace_stop(), we cannot return using SYSRET because
 338  * that does not restore the full CPU state, only a minimal set.  The
 339  * ptracer can change arbitrary register values, which is usually okay
 340  * because the usual ptrace stops run off the signal delivery path which
 341  * forces IRET; however, ptrace_event() stops happen in arbitrary places
 342  * in the kernel and don't force IRET path.
 343  *
 344  * So force IRET path after a ptrace stop.
 345  */
 346 #define arch_ptrace_stop_needed(code, info)                             \
 347 ({                                                                      \
 348         force_iret();                                                   \
 349         false;                                                          \
 350 })
 351
 352 struct user_desc;
 353 extern int do_get_thread_area(struct task_struct *p, int idx,
 354                               struct user_desc __user *info);
 355 extern int do_set_thread_area(struct task_struct *p, int idx,
 356                               struct user_desc __user *info, int can_allocate);
 357
 358 #endif /* !__ASSEMBLY__ */
 359 #endif /* _ASM_X86_PTRACE_H */