diff options
Diffstat (limited to 'include/linux/regset.h')
| -rw-r--r-- | include/linux/regset.h | 340 |
1 files changed, 340 insertions, 0 deletions
diff --git a/include/linux/regset.h b/include/linux/regset.h new file mode 100644 index 000000000..9061266dd --- /dev/null +++ b/include/linux/regset.h @@ -0,0 +1,340 @@ +/* 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 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> */ |