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
 102 extern unsigned long
 103 convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs);
 104 extern void send_sigtrap(struct pt_regs *regs, int error_code, int si_code);
 105
 106
 107 static inline unsigned long regs_return_value(struct pt_regs *regs)
 108 {
 109         return regs->ax;
 110 }
 111
 112 static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
 113 {
 114         regs->ax = rc;
 115 }
 116
 117 /*
 118  * user_mode(regs) determines whether a register set came from user
 119  * mode.  On x86_32, this is true if V8086 mode was enabled OR if the
 120  * register set was from protected mode with RPL-3 CS value.  This
 121  * tricky test checks that with one comparison.
 122  *
 123  * On x86_64, vm86 mode is mercifully nonexistent, and we don't need
 124  * the extra check.
 125  */
 126 static inline int user_mode(struct pt_regs *regs)
 127 {
 128 #ifdef CONFIG_X86_32
 129         return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL;
 130 #else
 131         return !!(regs->cs & 3);
 132 #endif
 133 }
 134
 135 static inline int v8086_mode(struct pt_regs *regs)
 136 {
 137 #ifdef CONFIG_X86_32
 138         return (regs->flags & X86_VM_MASK);
 139 #else
 140         return 0;       /* No V86 mode support in long mode */
 141 #endif
 142 }
 143
 144 static inline bool user_64bit_mode(struct pt_regs *regs)
 145 {
 146 #ifdef CONFIG_X86_64
 147 #ifndef CONFIG_PARAVIRT_XXL
 148         /*
 149          * On non-paravirt systems, this is the only long mode CPL 3
 150          * selector.  We do not allow long mode selectors in the LDT.
 151          */
 152         return regs->cs == __USER_CS;
 153 #else
 154         /* Headers are too twisted for this to go in paravirt.h. */
 155         return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
 156 #endif
 157 #else /* !CONFIG_X86_64 */
 158         return false;
 159 #endif
 160 }
 161
 162 #ifdef CONFIG_X86_64
 163 #define current_user_stack_pointer()    current_pt_regs()->sp
 164 #define compat_user_stack_pointer()     current_pt_regs()->sp
 165 #endif
 166
 167 static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
 168 {
 169         return regs->sp;
 170 }
 171
 172 static inline unsigned long instruction_pointer(struct pt_regs *regs)
 173 {
 174         return regs->ip;
 175 }
 176
 177 static inline void instruction_pointer_set(struct pt_regs *regs,
 178                 unsigned long val)
 179 {
 180         regs->ip = val;
 181 }
 182
 183 static inline unsigned long frame_pointer(struct pt_regs *regs)
 184 {
 185         return regs->bp;
 186 }
 187
 188 static inline unsigned long user_stack_pointer(struct pt_regs *regs)
 189 {
 190         return regs->sp;
 191 }
 192
 193 static inline void user_stack_pointer_set(struct pt_regs *regs,
 194                 unsigned long val)
 195 {
 196         regs->sp = val;
 197 }
 198
 199 /* Query offset/name of register from its name/offset */
 200 extern int regs_query_register_offset(const char *name);
 201 extern const char *regs_query_register_name(unsigned int offset);
 202 #define MAX_REG_OFFSET (offsetof(struct pt_regs, ss))
 203
 204 /**
 205  * regs_get_register() - get register value from its offset
 206  * @regs:       pt_regs from which register value is gotten.
 207  * @offset:     offset number of the register.
 208  *
 209  * regs_get_register returns the value of a register. The @offset is the
 210  * offset of the register in struct pt_regs address which specified by @regs.
 211  * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
 212  */
 213 static inline unsigned long regs_get_register(struct pt_regs *regs,
 214                                               unsigned int offset)
 215 {
 216         if (unlikely(offset > MAX_REG_OFFSET))
 217                 return 0;
 218 #ifdef CONFIG_X86_32
 219         /* The selector fields are 16-bit. */
 220         if (offset == offsetof(struct pt_regs, cs) ||
 221             offset == offsetof(struct pt_regs, ss) ||
 222             offset == offsetof(struct pt_regs, ds) ||
 223             offset == offsetof(struct pt_regs, es) ||
 224             offset == offsetof(struct pt_regs, fs) ||
 225             offset == offsetof(struct pt_regs, gs)) {
 226                 return *(u16 *)((unsigned long)regs + offset);
 227
 228         }
 229 #endif
 230         return *(unsigned long *)((unsigned long)regs + offset);
 231 }
 232
 233 /**
 234  * regs_within_kernel_stack() - check the address in the stack
 235  * @regs:       pt_regs which contains kernel stack pointer.
 236  * @addr:       address which is checked.
 237  *
 238  * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
 239  * If @addr is within the kernel stack, it returns true. If not, returns false.
 240  */
 241 static inline int regs_within_kernel_stack(struct pt_regs *regs,
 242                                            unsigned long addr)
 243 {
 244         return ((addr & ~(THREAD_SIZE - 1)) == (regs->sp & ~(THREAD_SIZE - 1)));
 245 }
 246
 247 /**
 248  * regs_get_kernel_stack_nth_addr() - get the address of the Nth entry on stack
 249  * @regs:       pt_regs which contains kernel stack pointer.
 250  * @n:          stack entry number.
 251  *
 252  * regs_get_kernel_stack_nth() returns the address of the @n th entry of the
 253  * kernel stack which is specified by @regs. If the @n th entry is NOT in
 254  * the kernel stack, this returns NULL.
 255  */
 256 static inline unsigned long *regs_get_kernel_stack_nth_addr(struct pt_regs *regs, unsigned int n)
 257 {
 258         unsigned long *addr = (unsigned long *)regs->sp;
 259
 260         addr += n;
 261         if (regs_within_kernel_stack(regs, (unsigned long)addr))
 262                 return addr;
 263         else
 264                 return NULL;
 265 }
 266
 267 /* To avoid include hell, we can't include uaccess.h */
 268 extern long probe_kernel_read(void *dst, const void *src, size_t size);
 269
 270 /**
 271  * regs_get_kernel_stack_nth() - get Nth entry of the stack
 272  * @regs:       pt_regs which contains kernel stack pointer.
 273  * @n:          stack entry number.
 274  *
 275  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
 276  * is specified by @regs. If the @n th entry is NOT in the kernel stack
 277  * this returns 0.
 278  */
 279 static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 280                                                       unsigned int n)
 281 {
 282         unsigned long *addr;
 283         unsigned long val;
 284         long ret;
 285
 286         addr = regs_get_kernel_stack_nth_addr(regs, n);
 287         if (addr) {
 288                 ret = probe_kernel_read(&val, addr, sizeof(val));
 289                 if (!ret)
 290                         return val;
 291         }
 292         return 0;
 293 }
 294
 295 /**
 296  * regs_get_kernel_argument() - get Nth function argument in kernel
 297  * @regs:       pt_regs of that context
 298  * @n:          function argument number (start from 0)
 299  *
 300  * regs_get_argument() returns @n th argument of the function call.
 301  * Note that this chooses most probably assignment, in some case
 302  * it can be incorrect.
 303  * This is expected to be called from kprobes or ftrace with regs
 304  * where the top of stack is the return address.
 305  */
 306 static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 307                                                      unsigned int n)
 308 {
 309         static const unsigned int argument_offs[] = {
 310 #ifdef __i386__
 311                 offsetof(struct pt_regs, ax),
 312                 offsetof(struct pt_regs, cx),
 313                 offsetof(struct pt_regs, dx),
 314 #define NR_REG_ARGUMENTS 3
 315 #else
 316                 offsetof(struct pt_regs, di),
 317                 offsetof(struct pt_regs, si),
 318                 offsetof(struct pt_regs, dx),
 319                 offsetof(struct pt_regs, cx),
 320                 offsetof(struct pt_regs, r8),
 321                 offsetof(struct pt_regs, r9),
 322 #define NR_REG_ARGUMENTS 6
 323 #endif
 324         };
 325
 326         if (n >= NR_REG_ARGUMENTS) {
 327                 n -= NR_REG_ARGUMENTS - 1;
 328                 return regs_get_kernel_stack_nth(regs, n);
 329         } else
 330                 return regs_get_register(regs, argument_offs[n]);
 331 }
 332
 333 #define arch_has_single_step()  (1)
 334 #ifdef CONFIG_X86_DEBUGCTLMSR
 335 #define arch_has_block_step()   (1)
 336 #else
 337 #define arch_has_block_step()   (boot_cpu_data.x86 >= 6)
 338 #endif
 339
 340 #define ARCH_HAS_USER_SINGLE_STEP_REPORT
 341
 342 /*
 343  * When hitting ptrace_stop(), we cannot return using SYSRET because
 344  * that does not restore the full CPU state, only a minimal set.  The
 345  * ptracer can change arbitrary register values, which is usually okay
 346  * because the usual ptrace stops run off the signal delivery path which
 347  * forces IRET; however, ptrace_event() stops happen in arbitrary places
 348  * in the kernel and don't force IRET path.
 349  *
 350  * So force IRET path after a ptrace stop.
 351  */
 352 #define arch_ptrace_stop_needed(code, info)                             \
 353 ({                                                                      \
 354         force_iret();                                                   \
 355         false;                                                          \
 356 })
 357
 358 struct user_desc;
 359 extern int do_get_thread_area(struct task_struct *p, int idx,
 360                               struct user_desc __user *info);
 361 extern int do_set_thread_area(struct task_struct *p, int idx,
 362                               struct user_desc __user *info, int can_allocate);
 363
 364 #endif /* !__ASSEMBLY__ */
 365 #endif /* _ASM_X86_PTRACE_H */