linux/arch/x86/kernel/fpu/signal.c

// SPDX-License-Identifier: GPL-2.0
/*
 * FPU signal frame handling routines.
 */

#include <linux/compat.h>
#include <linux/cpu.h>
#include <linux/pagemap.h>

#include <asm/fpu/signal.h>
#include <asm/fpu/regset.h>
#include <asm/fpu/xstate.h>

#include <asm/sigframe.h>
#include <asm/trapnr.h>
#include <asm/trace/fpu.h>

#include "context.h"
#include "internal.h"
#include "legacy.h"
#include "xstate.h"

/*
 * Check for the presence of extended state information in the
 * user fpstate pointer in the sigcontext.
 */
static inline bool check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
					    struct _fpx_sw_bytes *fx_sw)
{ … }

/*
 * Update the value of PKRU register that was already pushed onto the signal frame.
 */
static inline int update_pkru_in_sigframe(struct xregs_state __user *buf, u32 pkru)
{ … }

/*
 * Signal frame handlers.
 */
static inline bool save_fsave_header(struct task_struct *tsk, void __user *buf)
{ … }

/*
 * Prepare the SW reserved portion of the fxsave memory layout, indicating
 * the presence of the extended state information in the memory layout
 * pointed to by the fpstate pointer in the sigcontext.
 * This is saved when ever the FP and extended state context is
 * saved on the user stack during the signal handler delivery to the user.
 */
static inline void save_sw_bytes(struct _fpx_sw_bytes *sw_bytes, bool ia32_frame,
				 struct fpstate *fpstate)
{ … }

static inline bool save_xstate_epilog(void __user *buf, int ia32_frame,
				      struct fpstate *fpstate)
{ … }

static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf, u32 pkru)
{ … }

/*
 * Save the fpu, extended register state to the user signal frame.
 *
 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
 *  state is copied.
 *  'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
 *
 *	buf == buf_fx for 64-bit frames and 32-bit fsave frame.
 *	buf != buf_fx for 32-bit frames with fxstate.
 *
 * Save it directly to the user frame with disabled page fault handler. If
 * that faults, try to clear the frame which handles the page fault.
 *
 * If this is a 32-bit frame with fxstate, put a fsave header before
 * the aligned state at 'buf_fx'.
 *
 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
 * indicating the absence/presence of the extended state to the user.
 */
bool copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size, u32 pkru)
{ … }

static int __restore_fpregs_from_user(void __user *buf, u64 ufeatures,
				      u64 xrestore, bool fx_only)
{ … }

/*
 * Attempt to restore the FPU registers directly from user memory.
 * Pagefaults are handled and any errors returned are fatal.
 */
static bool restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only)
{ … }

static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
			      bool ia32_fxstate)
{ … }

static inline unsigned int xstate_sigframe_size(struct fpstate *fpstate)
{ … }

/*
 * Restore FPU state from a sigframe:
 */
bool fpu__restore_sig(void __user *buf, int ia32_frame)
{ … }

unsigned long
fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
		     unsigned long *buf_fx, unsigned long *size)
{ … }

unsigned long __init fpu__get_fpstate_size(void)
{ … }