--- /dev/null
+/*
+ * User-mode machine state access
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License v.2.
+ *
+ * Red Hat Author: Roland McGrath.
+ */
+
+#ifndef _LINUX_REGSET_H
+#define _LINUX_REGSET_H 1
+
+#include <linux/compiler.h>
+#include <linux/types.h>
+#include <linux/bug.h>
+#include <linux/uaccess.h>
+struct task_struct;
+struct user_regset;
+
+
+/**
+ * user_regset_active_fn - type of @active function in &struct user_regset
+ * @target: thread being examined
+ * @regset: regset being examined
+ *
+ * Return -%ENODEV if not available on the hardware found.
+ * Return %0 if no interesting state in this thread.
+ * Return >%0 number of @size units of interesting state.
+ * Any get call fetching state beyond that number will
+ * see the default initialization state for this data,
+ * so a caller that knows what the default state is need
+ * not copy it all out.
+ * This call is optional; the pointer is %NULL if there
+ * is no inexpensive check to yield a value < @n.
+ */
+typedef int user_regset_active_fn(struct task_struct *target,
+ const struct user_regset *regset);
+
+/**
+ * user_regset_get_fn - type of @get function in &struct user_regset
+ * @target: thread being examined
+ * @regset: regset being examined
+ * @pos: offset into the regset data to access, in bytes
+ * @count: amount of data to copy, in bytes
+ * @kbuf: if not %NULL, a kernel-space pointer to copy into
+ * @ubuf: if @kbuf is %NULL, a user-space pointer to copy into
+ *
+ * Fetch register values. Return %0 on success; -%EIO or -%ENODEV
+ * are usual failure returns. The @pos and @count values are in
+ * bytes, but must be properly aligned. If @kbuf is non-null, that
+ * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then
+ * ubuf gives a userland pointer to access directly, and an -%EFAULT
+ * return value is possible.
+ */
+typedef int user_regset_get_fn(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf);
+
+/**
+ * user_regset_set_fn - type of @set function in &struct user_regset
+ * @target: thread being examined
+ * @regset: regset being examined
+ * @pos: offset into the regset data to access, in bytes
+ * @count: amount of data to copy, in bytes
+ * @kbuf: if not %NULL, a kernel-space pointer to copy from
+ * @ubuf: if @kbuf is %NULL, a user-space pointer to copy from
+ *
+ * Store register values. Return %0 on success; -%EIO or -%ENODEV
+ * are usual failure returns. The @pos and @count values are in
+ * bytes, but must be properly aligned. If @kbuf is non-null, that
+ * buffer is used and @ubuf is ignored. If @kbuf is %NULL, then
+ * ubuf gives a userland pointer to access directly, and an -%EFAULT
+ * return value is possible.
+ */
+typedef int user_regset_set_fn(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf);
+
+/**
+ * user_regset_writeback_fn - type of @writeback function in &struct user_regset
+ * @target: thread being examined
+ * @regset: regset being examined
+ * @immediate: zero if writeback at completion of next context switch is OK
+ *
+ * This call is optional; usually the pointer is %NULL. When
+ * provided, there is some user memory associated with this regset's
+ * hardware, such as memory backing cached register data on register
+ * window machines; the regset's data controls what user memory is
+ * used (e.g. via the stack pointer value).
+ *
+ * Write register data back to user memory. If the @immediate flag
+ * is nonzero, it must be written to the user memory so uaccess or
+ * access_process_vm() can see it when this call returns; if zero,
+ * then it must be written back by the time the task completes a
+ * context switch (as synchronized with wait_task_inactive()).
+ * Return %0 on success or if there was nothing to do, -%EFAULT for
+ * a memory problem (bad stack pointer or whatever), or -%EIO for a
+ * hardware problem.
+ */
+typedef int user_regset_writeback_fn(struct task_struct *target,
+ const struct user_regset *regset,
+ int immediate);
+
+/**
+ * struct user_regset - accessible thread CPU state
+ * @n: Number of slots (registers).
+ * @size: Size in bytes of a slot (register).
+ * @align: Required alignment, in bytes.
+ * @bias: Bias from natural indexing.
+ * @core_note_type: ELF note @n_type value used in core dumps.
+ * @get: Function to fetch values.
+ * @set: Function to store values.
+ * @active: Function to report if regset is active, or %NULL.
+ * @writeback: Function to write data back to user memory, or %NULL.
+ *
+ * This data structure describes a machine resource we call a register set.
+ * This is part of the state of an individual thread, not necessarily
+ * actual CPU registers per se. A register set consists of a number of
+ * similar slots, given by @n. Each slot is @size bytes, and aligned to
+ * @align bytes (which is at least @size).
+ *
+ * These functions must be called only on the current thread or on a
+ * thread that is in %TASK_STOPPED or %TASK_TRACED state, that we are
+ * guaranteed will not be woken up and return to user mode, and that we
+ * have called wait_task_inactive() on. (The target thread always might
+ * wake up for SIGKILL while these functions are working, in which case
+ * that thread's user_regset state might be scrambled.)
+ *
+ * The @pos argument must be aligned according to @align; the @count
+ * argument must be a multiple of @size. These functions are not
+ * responsible for checking for invalid arguments.
+ *
+ * When there is a natural value to use as an index, @bias gives the
+ * difference between the natural index and the slot index for the
+ * register set. For example, x86 GDT segment descriptors form a regset;
+ * the segment selector produces a natural index, but only a subset of
+ * that index space is available as a regset (the TLS slots); subtracting
+ * @bias from a segment selector index value computes the regset slot.
+ *
+ * If nonzero, @core_note_type gives the n_type field (NT_* value)
+ * of the core file note in which this regset's data appears.
+ * NT_PRSTATUS is a special case in that the regset data starts at
+ * offsetof(struct elf_prstatus, pr_reg) into the note data; that is
+ * part of the per-machine ELF formats userland knows about. In
+ * other cases, the core file note contains exactly the whole regset
+ * (@n * @size) and nothing else. The core file note is normally
+ * omitted when there is an @active function and it returns zero.
+ */
+struct user_regset {
+ user_regset_get_fn *get;
+ user_regset_set_fn *set;
+ user_regset_active_fn *active;
+ user_regset_writeback_fn *writeback;
+ unsigned int n;
+ unsigned int size;
+ unsigned int align;
+ unsigned int bias;
+ unsigned int core_note_type;
+};
+
+/**
+ * struct user_regset_view - available regsets
+ * @name: Identifier, e.g. UTS_MACHINE string.
+ * @regsets: Array of @n regsets available in this view.
+ * @n: Number of elements in @regsets.
+ * @e_machine: ELF header @e_machine %EM_* value written in core dumps.
+ * @e_flags: ELF header @e_flags value written in core dumps.
+ * @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps.
+ *
+ * A regset view is a collection of regsets (&struct user_regset,
+ * above). This describes all the state of a thread that can be seen
+ * from a given architecture/ABI environment. More than one view might
+ * refer to the same &struct user_regset, or more than one regset
+ * might refer to the same machine-specific state in the thread. For
+ * example, a 32-bit thread's state could be examined from the 32-bit
+ * view or from the 64-bit view. Either method reaches the same thread
+ * register state, doing appropriate widening or truncation.
+ */
+struct user_regset_view {
+ const char *name;
+ const struct user_regset *regsets;
+ unsigned int n;
+ u32 e_flags;
+ u16 e_machine;
+ u8 ei_osabi;
+};
+
+/*
+ * This is documented here rather than at the definition sites because its
+ * implementation is machine-dependent but its interface is universal.
+ */
+/**
+ * task_user_regset_view - Return the process's native regset view.
+ * @tsk: a thread of the process in question
+ *
+ * Return the &struct user_regset_view that is native for the given process.
+ * For example, what it would access when it called ptrace().
+ * Throughout the life of the process, this only changes at exec.
+ */
+const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);
+
+
+/*
+ * These are helpers for writing regset get/set functions in arch code.
+ * Because @start_pos and @end_pos are always compile-time constants,
+ * these are inlined into very little code though they look large.
+ *
+ * Use one or more calls sequentially for each chunk of regset data stored
+ * contiguously in memory. Call with constants for @start_pos and @end_pos,
+ * giving the range of byte positions in the regset that data corresponds
+ * to; @end_pos can be -1 if this chunk is at the end of the regset layout.
+ * Each call updates the arguments to point past its chunk.
+ */
+
+static inline int user_regset_copyout(unsigned int *pos, unsigned int *count,
+ void **kbuf,
+ void __user **ubuf, const void *data,
+ const int start_pos, const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ data += *pos - start_pos;
+ if (*kbuf) {
+ memcpy(*kbuf, data, copy);
+ *kbuf += copy;
+ } else if (__copy_to_user(*ubuf, data, copy))
+ return -EFAULT;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,
+ const void **kbuf,
+ const void __user **ubuf, void *data,
+ const int start_pos, const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ data += *pos - start_pos;
+ if (*kbuf) {
+ memcpy(data, *kbuf, copy);
+ *kbuf += copy;
+ } else if (__copy_from_user(data, *ubuf, copy))
+ return -EFAULT;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+/*
+ * These two parallel the two above, but for portions of a regset layout
+ * that always read as all-zero or for which writes are ignored.
+ */
+static inline int user_regset_copyout_zero(unsigned int *pos,
+ unsigned int *count,
+ void **kbuf, void __user **ubuf,
+ const int start_pos,
+ const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ if (*kbuf) {
+ memset(*kbuf, 0, copy);
+ *kbuf += copy;
+ } else if (__clear_user(*ubuf, copy))
+ return -EFAULT;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+static inline int user_regset_copyin_ignore(unsigned int *pos,
+ unsigned int *count,
+ const void **kbuf,
+ const void __user **ubuf,
+ const int start_pos,
+ const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ if (*kbuf)
+ *kbuf += copy;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+/**
+ * copy_regset_to_user - fetch a thread's user_regset data into user memory
+ * @target: thread to be examined
+ * @view: &struct user_regset_view describing user thread machine state
+ * @setno: index in @view->regsets
+ * @offset: offset into the regset data, in bytes
+ * @size: amount of data to copy, in bytes
+ * @data: user-mode pointer to copy into
+ */
+static inline int copy_regset_to_user(struct task_struct *target,
+ const struct user_regset_view *view,
+ unsigned int setno,
+ unsigned int offset, unsigned int size,
+ void __user *data)
+{
+ const struct user_regset *regset = &view->regsets[setno];
+
+ if (!regset->get)
+ return -EOPNOTSUPP;
+
+ if (!access_ok(VERIFY_WRITE, data, size))
+ return -EFAULT;
+
+ return regset->get(target, regset, offset, size, NULL, data);
+}
+
+/**
+ * copy_regset_from_user - store into thread's user_regset data from user memory
+ * @target: thread to be examined
+ * @view: &struct user_regset_view describing user thread machine state
+ * @setno: index in @view->regsets
+ * @offset: offset into the regset data, in bytes
+ * @size: amount of data to copy, in bytes
+ * @data: user-mode pointer to copy from
+ */
+static inline int copy_regset_from_user(struct task_struct *target,
+ const struct user_regset_view *view,
+ unsigned int setno,
+ unsigned int offset, unsigned int size,
+ const void __user *data)
+{
+ const struct user_regset *regset = &view->regsets[setno];
+
+ if (!regset->set)
+ return -EOPNOTSUPP;
+
+ if (!access_ok(VERIFY_READ, data, size))
+ return -EFAULT;
+
+ return regset->set(target, regset, offset, size, NULL, data);
+}
+
+
+#endif /* <linux/regset.h> */
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