426 lines
15 KiB
C
426 lines
15 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* User-mode machine state access
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*
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* Copyright (C) 2007 Red Hat, Inc. All rights reserved.
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*
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* Red Hat Author: Roland McGrath.
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*/
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#ifndef _LINUX_REGSET_H
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#define _LINUX_REGSET_H 1
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <linux/bug.h>
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#include <linux/uaccess.h>
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struct task_struct;
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struct user_regset;
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/**
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* user_regset_active_fn - type of @active function in &struct user_regset
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* @target: thread being examined
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* @regset: regset being examined
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*
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* Return -%ENODEV if not available on the hardware found.
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* Return %0 if no interesting state in this thread.
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* Return >%0 number of @size units of interesting state.
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* Any get call fetching state beyond that number will
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* see the default initialization state for this data,
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* so a caller that knows what the default state is need
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* not copy it all out.
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* This call is optional; the pointer is %NULL if there
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* is no inexpensive check to yield a value < @n.
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*/
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typedef int user_regset_active_fn(struct task_struct *target,
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const struct user_regset *regset);
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/**
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* user_regset_get_fn - type of @get function in &struct user_regset
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* @target: thread being examined
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* @regset: regset being examined
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* @pos: offset into the regset data to access, in bytes
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* @count: amount of data to copy, in bytes
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* @kbuf: if not %NULL, a kernel-space pointer to copy into
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* @ubuf: if @kbuf is %NULL, a user-space pointer to copy into
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*
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* Fetch register values. Return %0 on success; -%EIO or -%ENODEV
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* are usual failure returns. The @pos and @count values are in
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* bytes, but must be properly aligned. If @kbuf is non-null, that
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* buffer is used and @ubuf is ignored. If @kbuf is %NULL, then
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* ubuf gives a userland pointer to access directly, and an -%EFAULT
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* return value is possible.
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*/
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typedef int user_regset_get_fn(struct task_struct *target,
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const struct user_regset *regset,
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unsigned int pos, unsigned int count,
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void *kbuf, void __user *ubuf);
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/**
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* user_regset_set_fn - type of @set function in &struct user_regset
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* @target: thread being examined
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* @regset: regset being examined
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* @pos: offset into the regset data to access, in bytes
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* @count: amount of data to copy, in bytes
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* @kbuf: if not %NULL, a kernel-space pointer to copy from
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* @ubuf: if @kbuf is %NULL, a user-space pointer to copy from
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*
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* Store register values. Return %0 on success; -%EIO or -%ENODEV
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* are usual failure returns. The @pos and @count values are in
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* bytes, but must be properly aligned. If @kbuf is non-null, that
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* buffer is used and @ubuf is ignored. If @kbuf is %NULL, then
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* ubuf gives a userland pointer to access directly, and an -%EFAULT
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* return value is possible.
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*/
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typedef int user_regset_set_fn(struct task_struct *target,
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const struct user_regset *regset,
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unsigned int pos, unsigned int count,
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const void *kbuf, const void __user *ubuf);
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/**
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* user_regset_writeback_fn - type of @writeback function in &struct user_regset
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* @target: thread being examined
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* @regset: regset being examined
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* @immediate: zero if writeback at completion of next context switch is OK
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*
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* This call is optional; usually the pointer is %NULL. When
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* provided, there is some user memory associated with this regset's
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* hardware, such as memory backing cached register data on register
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* window machines; the regset's data controls what user memory is
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* used (e.g. via the stack pointer value).
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*
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* Write register data back to user memory. If the @immediate flag
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* is nonzero, it must be written to the user memory so uaccess or
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* access_process_vm() can see it when this call returns; if zero,
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* then it must be written back by the time the task completes a
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* context switch (as synchronized with wait_task_inactive()).
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* Return %0 on success or if there was nothing to do, -%EFAULT for
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* a memory problem (bad stack pointer or whatever), or -%EIO for a
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* hardware problem.
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*/
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typedef int user_regset_writeback_fn(struct task_struct *target,
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const struct user_regset *regset,
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int immediate);
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/**
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* user_regset_get_size_fn - type of @get_size function in &struct user_regset
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* @target: thread being examined
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* @regset: regset being examined
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*
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* This call is optional; usually the pointer is %NULL.
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*
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* When provided, this function must return the current size of regset
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* data, as observed by the @get function in &struct user_regset. The
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* value returned must be a multiple of @size. The returned size is
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* required to be valid only until the next time (if any) @regset is
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* modified for @target.
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*
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* This function is intended for dynamically sized regsets. A regset
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* that is statically sized does not need to implement it.
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*
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* This function should not be called directly: instead, callers should
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* call regset_size() to determine the current size of a regset.
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*/
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typedef unsigned int user_regset_get_size_fn(struct task_struct *target,
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const struct user_regset *regset);
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/**
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* struct user_regset - accessible thread CPU state
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* @n: Number of slots (registers).
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* @size: Size in bytes of a slot (register).
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* @align: Required alignment, in bytes.
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* @bias: Bias from natural indexing.
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* @core_note_type: ELF note @n_type value used in core dumps.
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* @get: Function to fetch values.
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* @set: Function to store values.
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* @active: Function to report if regset is active, or %NULL.
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* @writeback: Function to write data back to user memory, or %NULL.
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* @get_size: Function to return the regset's size, or %NULL.
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*
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* This data structure describes a machine resource we call a register set.
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* This is part of the state of an individual thread, not necessarily
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* actual CPU registers per se. A register set consists of a number of
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* similar slots, given by @n. Each slot is @size bytes, and aligned to
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* @align bytes (which is at least @size). For dynamically-sized
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* regsets, @n must contain the maximum possible number of slots for the
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* regset, and @get_size must point to a function that returns the
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* current regset size.
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*
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* Callers that need to know only the current size of the regset and do
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* not care about its internal structure should call regset_size()
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* instead of inspecting @n or calling @get_size.
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*
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* For backward compatibility, the @get and @set methods must pad to, or
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* accept, @n * @size bytes, even if the current regset size is smaller.
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* The precise semantics of these operations depend on the regset being
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* accessed.
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*
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* The functions to which &struct user_regset members point must be
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* called only on the current thread or on a thread that is in
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* %TASK_STOPPED or %TASK_TRACED state, that we are guaranteed will not
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* be woken up and return to user mode, and that we have called
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* wait_task_inactive() on. (The target thread always might wake up for
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* SIGKILL while these functions are working, in which case that
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* thread's user_regset state might be scrambled.)
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*
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* The @pos argument must be aligned according to @align; the @count
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* argument must be a multiple of @size. These functions are not
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* responsible for checking for invalid arguments.
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*
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* When there is a natural value to use as an index, @bias gives the
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* difference between the natural index and the slot index for the
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* register set. For example, x86 GDT segment descriptors form a regset;
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* the segment selector produces a natural index, but only a subset of
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* that index space is available as a regset (the TLS slots); subtracting
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* @bias from a segment selector index value computes the regset slot.
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*
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* If nonzero, @core_note_type gives the n_type field (NT_* value)
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* of the core file note in which this regset's data appears.
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* NT_PRSTATUS is a special case in that the regset data starts at
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* offsetof(struct elf_prstatus, pr_reg) into the note data; that is
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* part of the per-machine ELF formats userland knows about. In
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* other cases, the core file note contains exactly the whole regset
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* (@n * @size) and nothing else. The core file note is normally
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* omitted when there is an @active function and it returns zero.
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*/
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struct user_regset {
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user_regset_get_fn *get;
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user_regset_set_fn *set;
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user_regset_active_fn *active;
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user_regset_writeback_fn *writeback;
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user_regset_get_size_fn *get_size;
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unsigned int n;
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unsigned int size;
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unsigned int align;
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unsigned int bias;
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unsigned int core_note_type;
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};
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/**
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* struct user_regset_view - available regsets
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* @name: Identifier, e.g. UTS_MACHINE string.
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* @regsets: Array of @n regsets available in this view.
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* @n: Number of elements in @regsets.
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* @e_machine: ELF header @e_machine %EM_* value written in core dumps.
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* @e_flags: ELF header @e_flags value written in core dumps.
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* @ei_osabi: ELF header @e_ident[%EI_OSABI] value written in core dumps.
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*
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* A regset view is a collection of regsets (&struct user_regset,
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* above). This describes all the state of a thread that can be seen
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* from a given architecture/ABI environment. More than one view might
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* refer to the same &struct user_regset, or more than one regset
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* might refer to the same machine-specific state in the thread. For
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* example, a 32-bit thread's state could be examined from the 32-bit
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* view or from the 64-bit view. Either method reaches the same thread
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* register state, doing appropriate widening or truncation.
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*/
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struct user_regset_view {
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const char *name;
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const struct user_regset *regsets;
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unsigned int n;
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u32 e_flags;
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u16 e_machine;
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u8 ei_osabi;
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};
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/*
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* This is documented here rather than at the definition sites because its
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* implementation is machine-dependent but its interface is universal.
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*/
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/**
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* task_user_regset_view - Return the process's native regset view.
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* @tsk: a thread of the process in question
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*
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* Return the &struct user_regset_view that is native for the given process.
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* For example, what it would access when it called ptrace().
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* Throughout the life of the process, this only changes at exec.
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*/
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const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);
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/*
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* These are helpers for writing regset get/set functions in arch code.
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* Because @start_pos and @end_pos are always compile-time constants,
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* these are inlined into very little code though they look large.
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*
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* Use one or more calls sequentially for each chunk of regset data stored
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* contiguously in memory. Call with constants for @start_pos and @end_pos,
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* giving the range of byte positions in the regset that data corresponds
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* to; @end_pos can be -1 if this chunk is at the end of the regset layout.
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* Each call updates the arguments to point past its chunk.
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*/
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static inline int user_regset_copyout(unsigned int *pos, unsigned int *count,
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void **kbuf,
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void __user **ubuf, const void *data,
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const int start_pos, const int end_pos)
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{
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if (*count == 0)
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return 0;
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BUG_ON(*pos < start_pos);
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if (end_pos < 0 || *pos < end_pos) {
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unsigned int copy = (end_pos < 0 ? *count
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: min(*count, end_pos - *pos));
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data += *pos - start_pos;
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if (*kbuf) {
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memcpy(*kbuf, data, copy);
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*kbuf += copy;
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} else if (__copy_to_user(*ubuf, data, copy))
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return -EFAULT;
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else
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*ubuf += copy;
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*pos += copy;
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*count -= copy;
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}
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return 0;
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}
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static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,
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const void **kbuf,
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const void __user **ubuf, void *data,
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const int start_pos, const int end_pos)
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{
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if (*count == 0)
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return 0;
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BUG_ON(*pos < start_pos);
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if (end_pos < 0 || *pos < end_pos) {
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unsigned int copy = (end_pos < 0 ? *count
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: min(*count, end_pos - *pos));
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data += *pos - start_pos;
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if (*kbuf) {
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memcpy(data, *kbuf, copy);
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*kbuf += copy;
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} else if (__copy_from_user(data, *ubuf, copy))
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return -EFAULT;
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else
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*ubuf += copy;
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*pos += copy;
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*count -= copy;
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}
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return 0;
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}
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/*
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* These two parallel the two above, but for portions of a regset layout
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* that always read as all-zero or for which writes are ignored.
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*/
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static inline int user_regset_copyout_zero(unsigned int *pos,
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unsigned int *count,
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void **kbuf, void __user **ubuf,
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const int start_pos,
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const int end_pos)
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{
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if (*count == 0)
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return 0;
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BUG_ON(*pos < start_pos);
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if (end_pos < 0 || *pos < end_pos) {
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unsigned int copy = (end_pos < 0 ? *count
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: min(*count, end_pos - *pos));
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if (*kbuf) {
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memset(*kbuf, 0, copy);
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*kbuf += copy;
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} else if (__clear_user(*ubuf, copy))
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return -EFAULT;
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else
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*ubuf += copy;
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*pos += copy;
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*count -= copy;
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}
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return 0;
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}
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static inline int user_regset_copyin_ignore(unsigned int *pos,
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unsigned int *count,
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const void **kbuf,
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const void __user **ubuf,
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const int start_pos,
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const int end_pos)
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{
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if (*count == 0)
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return 0;
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BUG_ON(*pos < start_pos);
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if (end_pos < 0 || *pos < end_pos) {
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unsigned int copy = (end_pos < 0 ? *count
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: min(*count, end_pos - *pos));
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if (*kbuf)
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*kbuf += copy;
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else
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*ubuf += copy;
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*pos += copy;
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*count -= copy;
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}
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return 0;
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}
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/**
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* copy_regset_to_user - fetch a thread's user_regset data into user memory
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* @target: thread to be examined
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* @view: &struct user_regset_view describing user thread machine state
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* @setno: index in @view->regsets
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* @offset: offset into the regset data, in bytes
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* @size: amount of data to copy, in bytes
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* @data: user-mode pointer to copy into
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*/
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static inline int copy_regset_to_user(struct task_struct *target,
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const struct user_regset_view *view,
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unsigned int setno,
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unsigned int offset, unsigned int size,
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void __user *data)
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{
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const struct user_regset *regset = &view->regsets[setno];
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if (!regset->get)
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return -EOPNOTSUPP;
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if (!access_ok(data, size))
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return -EFAULT;
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return regset->get(target, regset, offset, size, NULL, data);
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}
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/**
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* copy_regset_from_user - store into thread's user_regset data from user memory
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* @target: thread to be examined
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* @view: &struct user_regset_view describing user thread machine state
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* @setno: index in @view->regsets
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* @offset: offset into the regset data, in bytes
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* @size: amount of data to copy, in bytes
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* @data: user-mode pointer to copy from
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*/
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static inline int copy_regset_from_user(struct task_struct *target,
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const struct user_regset_view *view,
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unsigned int setno,
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unsigned int offset, unsigned int size,
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const void __user *data)
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{
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const struct user_regset *regset = &view->regsets[setno];
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if (!regset->set)
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return -EOPNOTSUPP;
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if (!access_ok(data, size))
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return -EFAULT;
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return regset->set(target, regset, offset, size, NULL, data);
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}
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/**
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* regset_size - determine the current size of a regset
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* @target: thread to be examined
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* @regset: regset to be examined
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*
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* Note that the returned size is valid only until the next time
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* (if any) @regset is modified for @target.
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*/
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static inline unsigned int regset_size(struct task_struct *target,
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const struct user_regset *regset)
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{
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if (!regset->get_size)
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return regset->n * regset->size;
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else
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return regset->get_size(target, regset);
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}
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#endif /* <linux/regset.h> */
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