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- /* SPDX-License-Identifier: GPL-2.0-only */
- /*
- * User-mode machine state access
- *
- * Copyright (C) 2007 Red Hat, Inc. All rights reserved.
- *
- * 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;
- struct membuf {
- void *p;
- size_t left;
- };
- static inline int membuf_zero(struct membuf *s, size_t size)
- {
- if (s->left) {
- if (size > s->left)
- size = s->left;
- memset(s->p, 0, size);
- s->p += size;
- s->left -= size;
- }
- return s->left;
- }
- static inline int membuf_write(struct membuf *s, const void *v, size_t size)
- {
- if (s->left) {
- if (size > s->left)
- size = s->left;
- memcpy(s->p, v, size);
- s->p += size;
- s->left -= size;
- }
- return s->left;
- }
- static inline struct membuf membuf_at(const struct membuf *s, size_t offs)
- {
- struct membuf n = *s;
- if (offs > n.left)
- offs = n.left;
- n.p += offs;
- n.left -= offs;
- return n;
- }
- /* current s->p must be aligned for v; v must be a scalar */
- #define membuf_store(s, v) \
- ({ \
- struct membuf *__s = (s); \
- if (__s->left) { \
- typeof(v) __v = (v); \
- size_t __size = sizeof(__v); \
- if (unlikely(__size > __s->left)) { \
- __size = __s->left; \
- memcpy(__s->p, &__v, __size); \
- } else { \
- *(typeof(__v + 0) *)__s->p = __v; \
- } \
- __s->p += __size; \
- __s->left -= __size; \
- } \
- __s->left;})
- /**
- * 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);
- typedef int user_regset_get2_fn(struct task_struct *target,
- const struct user_regset *regset,
- struct membuf to);
- /**
- * 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). For dynamically-sized
- * regsets, @n must contain the maximum possible number of slots for the
- * regset.
- *
- * For backward compatibility, the @get and @set methods must pad to, or
- * accept, @n * @size bytes, even if the current regset size is smaller.
- * The precise semantics of these operations depend on the regset being
- * accessed.
- *
- * The functions to which &struct user_regset members point 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_get2_fn *regset_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);
- 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;
- }
- 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;
- }
- extern int regset_get(struct task_struct *target,
- const struct user_regset *regset,
- unsigned int size, void *data);
- extern int regset_get_alloc(struct task_struct *target,
- const struct user_regset *regset,
- unsigned int size,
- void **data);
- extern 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);
- /**
- * 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(data, size))
- return -EFAULT;
- return regset->set(target, regset, offset, size, NULL, data);
- }
- #endif /* <linux/regset.h> */
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