/* 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. * @core_note_name: ELF note name to qualify the note type. * @regset_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. * @core_note_name specifies the note name. The preferred way to * specify these two fields is to use the @USER_REGSET_NOTE_TYPE() * macro. * * 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; const char *core_note_name; }; #define USER_REGSET_NOTE_TYPE(type) \ .core_note_type = (NT_ ## type), \ .core_note_name = (NN_ ## 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 void 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; 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; } } 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> */
