Roland McGrath | bdf8821 | 2008-01-30 13:31:44 +0100 | [diff] [blame^] | 1 | /* |
| 2 | * User-mode machine state access |
| 3 | * |
| 4 | * Copyright (C) 2007 Red Hat, Inc. All rights reserved. |
| 5 | * |
| 6 | * This copyrighted material is made available to anyone wishing to use, |
| 7 | * modify, copy, or redistribute it subject to the terms and conditions |
| 8 | * of the GNU General Public License v.2. |
| 9 | * |
| 10 | * Red Hat Author: Roland McGrath. |
| 11 | */ |
| 12 | |
| 13 | #ifndef _LINUX_REGSET_H |
| 14 | #define _LINUX_REGSET_H 1 |
| 15 | |
| 16 | #include <linux/compiler.h> |
| 17 | #include <linux/types.h> |
| 18 | struct task_struct; |
| 19 | struct user_regset; |
| 20 | |
| 21 | |
| 22 | /** |
| 23 | * user_regset_active_fn - type of @active function in &struct user_regset |
| 24 | * @target: thread being examined |
| 25 | * @regset: regset being examined |
| 26 | * |
| 27 | * Return -%ENODEV if not available on the hardware found. |
| 28 | * Return %0 if no interesting state in this thread. |
| 29 | * Return >%0 number of @size units of interesting state. |
| 30 | * Any get call fetching state beyond that number will |
| 31 | * see the default initialization state for this data, |
| 32 | * so a caller that knows what the default state is need |
| 33 | * not copy it all out. |
| 34 | * This call is optional; the pointer is %NULL if there |
| 35 | * is no inexpensive check to yield a value < @n. |
| 36 | */ |
| 37 | typedef int user_regset_active_fn(struct task_struct *target, |
| 38 | const struct user_regset *regset); |
| 39 | |
| 40 | /** |
| 41 | * user_regset_get_fn - type of @get function in &struct user_regset |
| 42 | * @target: thread being examined |
| 43 | * @regset: regset being examined |
| 44 | * @pos: offset into the regset data to access, in bytes |
| 45 | * @count: amount of data to copy, in bytes |
| 46 | * @kbuf: if not %NULL, a kernel-space pointer to copy into |
| 47 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy into |
| 48 | * |
| 49 | * Fetch register values. Return %0 on success; -%EIO or -%ENODEV |
| 50 | * are usual failure returns. The @pos and @count values are in |
| 51 | * bytes, but must be properly aligned. If @kbuf is non-null, that |
| 52 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then |
| 53 | * ubuf gives a userland pointer to access directly, and an -%EFAULT |
| 54 | * return value is possible. |
| 55 | */ |
| 56 | typedef int user_regset_get_fn(struct task_struct *target, |
| 57 | const struct user_regset *regset, |
| 58 | unsigned int pos, unsigned int count, |
| 59 | void *kbuf, void __user *ubuf); |
| 60 | |
| 61 | /** |
| 62 | * user_regset_set_fn - type of @set function in &struct user_regset |
| 63 | * @target: thread being examined |
| 64 | * @regset: regset being examined |
| 65 | * @pos: offset into the regset data to access, in bytes |
| 66 | * @count: amount of data to copy, in bytes |
| 67 | * @kbuf: if not %NULL, a kernel-space pointer to copy from |
| 68 | * @ubuf: if @kbuf is %NULL, a user-space pointer to copy from |
| 69 | * |
| 70 | * Store register values. Return %0 on success; -%EIO or -%ENODEV |
| 71 | * are usual failure returns. The @pos and @count values are in |
| 72 | * bytes, but must be properly aligned. If @kbuf is non-null, that |
| 73 | * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then |
| 74 | * ubuf gives a userland pointer to access directly, and an -%EFAULT |
| 75 | * return value is possible. |
| 76 | */ |
| 77 | typedef int user_regset_set_fn(struct task_struct *target, |
| 78 | const struct user_regset *regset, |
| 79 | unsigned int pos, unsigned int count, |
| 80 | const void *kbuf, const void __user *ubuf); |
| 81 | |
| 82 | /** |
| 83 | * user_regset_writeback_fn - type of @writeback function in &struct user_regset |
| 84 | * @target: thread being examined |
| 85 | * @regset: regset being examined |
| 86 | * @immediate: zero if writeback at completion of next context switch is OK |
| 87 | * |
| 88 | * This call is optional; usually the pointer is %NULL. When |
| 89 | * provided, there is some user memory associated with this regset's |
| 90 | * hardware, such as memory backing cached register data on register |
| 91 | * window machines; the regset's data controls what user memory is |
| 92 | * used (e.g. via the stack pointer value). |
| 93 | * |
| 94 | * Write register data back to user memory. If the @immediate flag |
| 95 | * is nonzero, it must be written to the user memory so uaccess or |
| 96 | * access_process_vm() can see it when this call returns; if zero, |
| 97 | * then it must be written back by the time the task completes a |
| 98 | * context switch (as synchronized with wait_task_inactive()). |
| 99 | * Return %0 on success or if there was nothing to do, -%EFAULT for |
| 100 | * a memory problem (bad stack pointer or whatever), or -%EIO for a |
| 101 | * hardware problem. |
| 102 | */ |
| 103 | typedef int user_regset_writeback_fn(struct task_struct *target, |
| 104 | const struct user_regset *regset, |
| 105 | int immediate); |
| 106 | |
| 107 | /** |
| 108 | * struct user_regset - accessible thread CPU state |
| 109 | * @n: Number of slots (registers). |
| 110 | * @size: Size in bytes of a slot (register). |
| 111 | * @align: Required alignment, in bytes. |
| 112 | * @bias: Bias from natural indexing. |
| 113 | * @core_note_type: ELF note @n_type value used in core dumps. |
| 114 | * @get: Function to fetch values. |
| 115 | * @set: Function to store values. |
| 116 | * @active: Function to report if regset is active, or %NULL. |
| 117 | * @writeback: Function to write data back to user memory, or %NULL. |
| 118 | * |
| 119 | * This data structure describes a machine resource we call a register set. |
| 120 | * This is part of the state of an individual thread, not necessarily |
| 121 | * actual CPU registers per se. A register set consists of a number of |
| 122 | * similar slots, given by @n. Each slot is @size bytes, and aligned to |
| 123 | * @align bytes (which is at least @size). |
| 124 | * |
| 125 | * These functions must be called only on the current thread or on a |
| 126 | * thread that is in %TASK_STOPPED or %TASK_TRACED state, that we are |
| 127 | * guaranteed will not be woken up and return to user mode, and that we |
| 128 | * have called wait_task_inactive() on. (The target thread always might |
| 129 | * wake up for SIGKILL while these functions are working, in which case |
| 130 | * that thread's user_regset state might be scrambled.) |
| 131 | * |
| 132 | * The @pos argument must be aligned according to @align; the @count |
| 133 | * argument must be a multiple of @size. These functions are not |
| 134 | * responsible for checking for invalid arguments. |
| 135 | * |
| 136 | * When there is a natural value to use as an index, @bias gives the |
| 137 | * difference between the natural index and the slot index for the |
| 138 | * register set. For example, x86 GDT segment descriptors form a regset; |
| 139 | * the segment selector produces a natural index, but only a subset of |
| 140 | * that index space is available as a regset (the TLS slots); subtracting |
| 141 | * @bias from a segment selector index value computes the regset slot. |
| 142 | * |
| 143 | * If nonzero, @core_note_type gives the n_type field (NT_* value) |
| 144 | * of the core file note in which this regset's data appears. |
| 145 | * NT_PRSTATUS is a special case in that the regset data starts at |
| 146 | * offsetof(struct elf_prstatus, pr_reg) into the note data; that is |
| 147 | * part of the per-machine ELF formats userland knows about. In |
| 148 | * other cases, the core file note contains exactly the whole regset |
| 149 | * (@n * @size) and nothing else. The core file note is normally |
| 150 | * omitted when there is an @active function and it returns zero. |
| 151 | */ |
| 152 | struct user_regset { |
| 153 | user_regset_get_fn *get; |
| 154 | user_regset_set_fn *set; |
| 155 | user_regset_active_fn *active; |
| 156 | user_regset_writeback_fn *writeback; |
| 157 | unsigned int n; |
| 158 | unsigned int size; |
| 159 | unsigned int align; |
| 160 | unsigned int bias; |
| 161 | unsigned int core_note_type; |
| 162 | }; |
| 163 | |
| 164 | /** |
| 165 | * struct user_regset_view - available regsets |
| 166 | * @name: Identifier, e.g. UTS_MACHINE string. |
| 167 | * @regsets: Array of @n regsets available in this view. |
| 168 | * @n: Number of elements in @regsets. |
| 169 | * @e_machine: ELF header @e_machine %EM_* value written in core dumps. |
| 170 | * @e_flags: ELF header @e_flags value written in core dumps. |
| 171 | * @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps. |
| 172 | * |
| 173 | * A regset view is a collection of regsets (&struct user_regset, |
| 174 | * above). This describes all the state of a thread that can be seen |
| 175 | * from a given architecture/ABI environment. More than one view might |
| 176 | * refer to the same &struct user_regset, or more than one regset |
| 177 | * might refer to the same machine-specific state in the thread. For |
| 178 | * example, a 32-bit thread's state could be examined from the 32-bit |
| 179 | * view or from the 64-bit view. Either method reaches the same thread |
| 180 | * register state, doing appropriate widening or truncation. |
| 181 | */ |
| 182 | struct user_regset_view { |
| 183 | const char *name; |
| 184 | const struct user_regset *regsets; |
| 185 | unsigned int n; |
| 186 | u32 e_flags; |
| 187 | u16 e_machine; |
| 188 | u8 ei_osabi; |
| 189 | }; |
| 190 | |
| 191 | /* |
| 192 | * This is documented here rather than at the definition sites because its |
| 193 | * implementation is machine-dependent but its interface is universal. |
| 194 | */ |
| 195 | /** |
| 196 | * task_user_regset_view - Return the process's native regset view. |
| 197 | * @tsk: a thread of the process in question |
| 198 | * |
| 199 | * Return the &struct user_regset_view that is native for the given process. |
| 200 | * For example, what it would access when it called ptrace(). |
| 201 | * Throughout the life of the process, this only changes at exec. |
| 202 | */ |
| 203 | const struct user_regset_view *task_user_regset_view(struct task_struct *tsk); |
| 204 | |
| 205 | |
| 206 | #endif /* <linux/regset.h> */ |