text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *  PowerPC version 
   *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   *
   *  Derived from "arch/i386/kernel/signal.c"
   *    Copyright (C) 1991, 1992 Linus Torvalds
   *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   */
  
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/smp.h>
  #include <linux/kernel.h>
  #include <linux/signal.h>
  #include <linux/errno.h>
  #include <linux/wait.h>
  #include <linux/unistd.h>
  #include <linux/stddef.h>
  #include <linux/elf.h>
  #include <linux/ptrace.h>
  #include <linux/ratelimit.h>
  #include <linux/syscalls.h>
  #include <linux/pagemap.h>
  
  #include <asm/sigcontext.h>
  #include <asm/ucontext.h>
  #include <linux/uaccess.h>
  #include <asm/unistd.h>
  #include <asm/cacheflush.h>
  #include <asm/syscalls.h>
  #include <asm/vdso.h>
  #include <asm/switch_to.h>
  #include <asm/tm.h>
  #include <asm/asm-prototypes.h>
  
  #include "signal.h"
  
  
  #define GP_REGS_SIZE	min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
  #define FP_REGS_SIZE	sizeof(elf_fpregset_t)
  
  #define TRAMP_TRACEBACK	4
  #define TRAMP_SIZE	7
  
  /*
   * When we have signals to deliver, we set up on the user stack,
   * going down from the original stack pointer:
   *	1) a rt_sigframe struct which contains the ucontext	
   *	2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
   *	   frame for the signal handler.
   */
  
  struct rt_sigframe {
  	/* sys_rt_sigreturn requires the ucontext be the first field */
  	struct ucontext uc;
  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
  	struct ucontext uc_transact;
  #endif
  	unsigned long _unused[2];
  	unsigned int tramp[TRAMP_SIZE];
  	struct siginfo __user *pinfo;
  	void __user *puc;
  	struct siginfo info;
  	/* New 64 bit little-endian ABI allows redzone of 512 bytes below sp */
  	char abigap[USER_REDZONE_SIZE];
  } __attribute__ ((aligned (16)));
  
  /*
   * This computes a quad word aligned pointer inside the vmx_reserve array
   * element. For historical reasons sigcontext might not be quad word aligned,
   * but the location we write the VMX regs to must be. See the comment in
   * sigcontext for more detail.
   */
  #ifdef CONFIG_ALTIVEC
  static elf_vrreg_t __user *sigcontext_vmx_regs(struct sigcontext __user *sc)
  {
  	return (elf_vrreg_t __user *) (((unsigned long)sc->vmx_reserve + 15) & ~0xful);
  }
  #endif
  
  static void prepare_setup_sigcontext(struct task_struct *tsk)
  {
  #ifdef CONFIG_ALTIVEC
  	/* save altivec registers */
  	if (tsk->thread.used_vr)
  		flush_altivec_to_thread(tsk);
  	if (cpu_has_feature(CPU_FTR_ALTIVEC))
  		tsk->thread.vrsave = mfspr(SPRN_VRSAVE);
  #endif /* CONFIG_ALTIVEC */
  
  	flush_fp_to_thread(tsk);
  
  #ifdef CONFIG_VSX
  	if (tsk->thread.used_vsr)
  		flush_vsx_to_thread(tsk);
  #endif /* CONFIG_VSX */
  }
  
  /*
   * Set up the sigcontext for the signal frame.
   */
  
  #define unsafe_setup_sigcontext(sc, tsk, signr, set, handler, ctx_has_vsx_region, label)\
  do {											\
  	if (__unsafe_setup_sigcontext(sc, tsk, signr, set, handler, ctx_has_vsx_region))\
  		goto label;								\
  } while (0)
  static long notrace __unsafe_setup_sigcontext(struct sigcontext __user *sc,
  					struct task_struct *tsk, int signr, sigset_t *set,
  					unsigned long handler, int ctx_has_vsx_region)
  {
  	/* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
  	 * process never used altivec yet (MSR_VEC is zero in pt_regs of
  	 * the context). This is very important because we must ensure we
  	 * don't lose the VRSAVE content that may have been set prior to
  	 * the process doing its first vector operation
  	 * Userland shall check AT_HWCAP to know whether it can rely on the
  	 * v_regs pointer or not
  	 */
  #ifdef CONFIG_ALTIVEC
  	elf_vrreg_t __user *v_regs = sigcontext_vmx_regs(sc);
  #endif
  	struct pt_regs *regs = tsk->thread.regs;
  	unsigned long msr = regs->msr;
  	/* Force usr to alway see softe as 1 (interrupts enabled) */
  	unsigned long softe = 0x1;
  
  	BUG_ON(tsk != current);
  
  #ifdef CONFIG_ALTIVEC
  	unsafe_put_user(v_regs, &sc->v_regs, efault_out);
  
  	/* save altivec registers */
  	if (tsk->thread.used_vr) {
  		/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
  		unsafe_copy_to_user(v_regs, &tsk->thread.vr_state,
  				    33 * sizeof(vector128), efault_out);
  		/* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
  		 * contains valid data.
  		 */
  		msr |= MSR_VEC;
  	}
  	/* We always copy to/from vrsave, it's 0 if we don't have or don't
  	 * use altivec.
  	 */
  	unsafe_put_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], efault_out);
  #else /* CONFIG_ALTIVEC */
  	unsafe_put_user(0, &sc->v_regs, efault_out);
  #endif /* CONFIG_ALTIVEC */
  	/* copy fpr regs and fpscr */
  	unsafe_copy_fpr_to_user(&sc->fp_regs, tsk, efault_out);
  
  	/*
  	 * Clear the MSR VSX bit to indicate there is no valid state attached
  	 * to this context, except in the specific case below where we set it.
  	 */
  	msr &= ~MSR_VSX;
  #ifdef CONFIG_VSX
  	/*
  	 * Copy VSX low doubleword to local buffer for formatting,
  	 * then out to userspace.  Update v_regs to point after the
  	 * VMX data.
  	 */
  	if (tsk->thread.used_vsr && ctx_has_vsx_region) {
  		v_regs += ELF_NVRREG;
  		unsafe_copy_vsx_to_user(v_regs, tsk, efault_out);
  		/* set MSR_VSX in the MSR value in the frame to
  		 * indicate that sc->vs_reg) contains valid data.
  		 */
  		msr |= MSR_VSX;
  	}
  #endif /* CONFIG_VSX */
  	unsafe_put_user(&sc->gp_regs, &sc->regs, efault_out);
  	unsafe_copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE, efault_out);
  	unsafe_put_user(msr, &sc->gp_regs[PT_MSR], efault_out);
  	unsafe_put_user(softe, &sc->gp_regs[PT_SOFTE], efault_out);
  	unsafe_put_user(signr, &sc->signal, efault_out);
  	unsafe_put_user(handler, &sc->handler, efault_out);
  	if (set != NULL)
  		unsafe_put_user(set->sig[0], &sc->oldmask, efault_out);
  
  	return 0;
  
  efault_out:
  	return -EFAULT;
  }
  
  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
  /*
   * As above, but Transactional Memory is in use, so deliver sigcontexts
   * containing checkpointed and transactional register states.
   *
   * To do this, we treclaim (done before entering here) to gather both sets of
   * registers and set up the 'normal' sigcontext registers with rolled-back
   * register values such that a simple signal handler sees a correct
   * checkpointed register state.  If interested, a TM-aware sighandler can
   * examine the transactional registers in the 2nd sigcontext to determine the
   * real origin of the signal.
   */
  static long setup_tm_sigcontexts(struct sigcontext __user *sc,
  				 struct sigcontext __user *tm_sc,
  				 struct task_struct *tsk,
  				 int signr, sigset_t *set, unsigned long handler,
  				 unsigned long msr)
  {
  	/* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
  	 * process never used altivec yet (MSR_VEC is zero in pt_regs of
  	 * the context). This is very important because we must ensure we
  	 * don't lose the VRSAVE content that may have been set prior to
  	 * the process doing its first vector operation
  	 * Userland shall check AT_HWCAP to know wether it can rely on the
  	 * v_regs pointer or not.
  	 */
  #ifdef CONFIG_ALTIVEC
  	elf_vrreg_t __user *v_regs = sigcontext_vmx_regs(sc);
  	elf_vrreg_t __user *tm_v_regs = sigcontext_vmx_regs(tm_sc);
  #endif
  	struct pt_regs *regs = tsk->thread.regs;
  	long err = 0;
  
  	BUG_ON(tsk != current);
  
  	BUG_ON(!MSR_TM_ACTIVE(msr));
  
  	WARN_ON(tm_suspend_disabled);
  
  	/* Restore checkpointed FP, VEC, and VSX bits from ckpt_regs as
  	 * it contains the correct FP, VEC, VSX state after we treclaimed
  	 * the transaction and giveup_all() was called on reclaiming.
  	 */
  	msr |= tsk->thread.ckpt_regs.msr & (MSR_FP | MSR_VEC | MSR_VSX);
  
  #ifdef CONFIG_ALTIVEC
  	err |= __put_user(v_regs, &sc->v_regs);
  	err |= __put_user(tm_v_regs, &tm_sc->v_regs);
  
  	/* save altivec registers */
  	if (tsk->thread.used_vr) {
  		/* Copy 33 vec registers (vr0..31 and vscr) to the stack */
  		err |= __copy_to_user(v_regs, &tsk->thread.ckvr_state,
  				      33 * sizeof(vector128));
  		/* If VEC was enabled there are transactional VRs valid too,
  		 * else they're a copy of the checkpointed VRs.
  		 */
  		if (msr & MSR_VEC)
  			err |= __copy_to_user(tm_v_regs,
  					      &tsk->thread.vr_state,
  					      33 * sizeof(vector128));
  		else
  			err |= __copy_to_user(tm_v_regs,
  					      &tsk->thread.ckvr_state,
  					      33 * sizeof(vector128));
  
  		/* set MSR_VEC in the MSR value in the frame to indicate
  		 * that sc->v_reg contains valid data.
  		 */
  		msr |= MSR_VEC;
  	}
  	/* We always copy to/from vrsave, it's 0 if we don't have or don't
  	 * use altivec.
  	 */
  	if (cpu_has_feature(CPU_FTR_ALTIVEC))
  		tsk->thread.ckvrsave = mfspr(SPRN_VRSAVE);
  	err |= __put_user(tsk->thread.ckvrsave, (u32 __user *)&v_regs[33]);
  	if (msr & MSR_VEC)
  		err |= __put_user(tsk->thread.vrsave,
  				  (u32 __user *)&tm_v_regs[33]);
  	else
  		err |= __put_user(tsk->thread.ckvrsave,
  				  (u32 __user *)&tm_v_regs[33]);
  
  #else /* CONFIG_ALTIVEC */
  	err |= __put_user(0, &sc->v_regs);
  	err |= __put_user(0, &tm_sc->v_regs);
  #endif /* CONFIG_ALTIVEC */
  
  	/* copy fpr regs and fpscr */
  	err |= copy_ckfpr_to_user(&sc->fp_regs, tsk);
  	if (msr & MSR_FP)
  		err |= copy_fpr_to_user(&tm_sc->fp_regs, tsk);
  	else
  		err |= copy_ckfpr_to_user(&tm_sc->fp_regs, tsk);
  
  #ifdef CONFIG_VSX
  	/*
  	 * Copy VSX low doubleword to local buffer for formatting,
  	 * then out to userspace.  Update v_regs to point after the
  	 * VMX data.
  	 */
  	if (tsk->thread.used_vsr) {
  		v_regs += ELF_NVRREG;
  		tm_v_regs += ELF_NVRREG;
  
  		err |= copy_ckvsx_to_user(v_regs, tsk);
  
  		if (msr & MSR_VSX)
  			err |= copy_vsx_to_user(tm_v_regs, tsk);
  		else
  			err |= copy_ckvsx_to_user(tm_v_regs, tsk);
  
  		/* set MSR_VSX in the MSR value in the frame to
  		 * indicate that sc->vs_reg) contains valid data.
  		 */
  		msr |= MSR_VSX;
  	}
  #endif /* CONFIG_VSX */
  
  	err |= __put_user(&sc->gp_regs, &sc->regs);
  	err |= __put_user(&tm_sc->gp_regs, &tm_sc->regs);
  	err |= __copy_to_user(&tm_sc->gp_regs, regs, GP_REGS_SIZE);
  	err |= __copy_to_user(&sc->gp_regs,
  			      &tsk->thread.ckpt_regs, GP_REGS_SIZE);
  	err |= __put_user(msr, &tm_sc->gp_regs[PT_MSR]);
  	err |= __put_user(msr, &sc->gp_regs[PT_MSR]);
  	err |= __put_user(signr, &sc->signal);
  	err |= __put_user(handler, &sc->handler);
  	if (set != NULL)
  		err |=  __put_user(set->sig[0], &sc->oldmask);
  
  	return err;
  }
  #endif
  
  /*
   * Restore the sigcontext from the signal frame.
   */
  #define unsafe_restore_sigcontext(tsk, set, sig, sc, label) do {	\
  	if (__unsafe_restore_sigcontext(tsk, set, sig, sc))		\
  		goto label;						\
  } while (0)
  static long notrace __unsafe_restore_sigcontext(struct task_struct *tsk, sigset_t *set,
  						int sig, struct sigcontext __user *sc)
  {
  #ifdef CONFIG_ALTIVEC
  	elf_vrreg_t __user *v_regs;
  #endif
  	unsigned long save_r13 = 0;
  	unsigned long msr;
  	struct pt_regs *regs = tsk->thread.regs;
  #ifdef CONFIG_VSX
  	int i;
  #endif
  
  	BUG_ON(tsk != current);
  
  	/* If this is not a signal return, we preserve the TLS in r13 */
  	if (!sig)
  		save_r13 = regs->gpr[13];
  
  	/* copy the GPRs */
  	unsafe_copy_from_user(regs->gpr, sc->gp_regs, sizeof(regs->gpr), efault_out);
  	unsafe_get_user(regs->nip, &sc->gp_regs[PT_NIP], efault_out);
  	/* get MSR separately, transfer the LE bit if doing signal return */
  	unsafe_get_user(msr, &sc->gp_regs[PT_MSR], efault_out);
  	if (sig)
  		regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (msr & MSR_LE));
  	unsafe_get_user(regs->orig_gpr3, &sc->gp_regs[PT_ORIG_R3], efault_out);
  	unsafe_get_user(regs->ctr, &sc->gp_regs[PT_CTR], efault_out);
  	unsafe_get_user(regs->link, &sc->gp_regs[PT_LNK], efault_out);
  	unsafe_get_user(regs->xer, &sc->gp_regs[PT_XER], efault_out);
  	unsafe_get_user(regs->ccr, &sc->gp_regs[PT_CCR], efault_out);
  	/* Don't allow userspace to set SOFTE */
  	set_trap_norestart(regs);
  	unsafe_get_user(regs->dar, &sc->gp_regs[PT_DAR], efault_out);
  	unsafe_get_user(regs->dsisr, &sc->gp_regs[PT_DSISR], efault_out);
  	unsafe_get_user(regs->result, &sc->gp_regs[PT_RESULT], efault_out);
  
  	if (!sig)
  		regs->gpr[13] = save_r13;
  	if (set != NULL)
  		unsafe_get_user(set->sig[0], &sc->oldmask, efault_out);
  
  	/*
  	 * Force reload of FP/VEC.
  	 * This has to be done before copying stuff into tsk->thread.fpr/vr
  	 * for the reasons explained in the previous comment.
  	 */
  	regs_set_return_msr(regs, regs->msr & ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX));
  
  #ifdef CONFIG_ALTIVEC
  	unsafe_get_user(v_regs, &sc->v_regs, efault_out);
  	if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128)))
  		return -EFAULT;
  	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
  	if (v_regs != NULL && (msr & MSR_VEC) != 0) {
  		unsafe_copy_from_user(&tsk->thread.vr_state, v_regs,
  				      33 * sizeof(vector128), efault_out);
  		tsk->thread.used_vr = true;
  	} else if (tsk->thread.used_vr) {
  		memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
  	}
  	/* Always get VRSAVE back */
  	if (v_regs != NULL)
  		unsafe_get_user(tsk->thread.vrsave, (u32 __user *)&v_regs[33], efault_out);
  	else
  		tsk->thread.vrsave = 0;
  	if (cpu_has_feature(CPU_FTR_ALTIVEC))
  		mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
  #endif /* CONFIG_ALTIVEC */
  	/* restore floating point */
  	unsafe_copy_fpr_from_user(tsk, &sc->fp_regs, efault_out);
  #ifdef CONFIG_VSX
  	/*
  	 * Get additional VSX data. Update v_regs to point after the
  	 * VMX data.  Copy VSX low doubleword from userspace to local
  	 * buffer for formatting, then into the taskstruct.
  	 */
  	v_regs += ELF_NVRREG;
  	if ((msr & MSR_VSX) != 0) {
  		unsafe_copy_vsx_from_user(tsk, v_regs, efault_out);
  		tsk->thread.used_vsr = true;
  	} else {
  		for (i = 0; i < 32 ; i++)
  			tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
  	}
  #endif
  	return 0;
  
  efault_out:
  	return -EFAULT;
  }
  
  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
  /*
   * Restore the two sigcontexts from the frame of a transactional processes.
   */
  
  static long restore_tm_sigcontexts(struct task_struct *tsk,
  				   struct sigcontext __user *sc,
  				   struct sigcontext __user *tm_sc)
  {
  #ifdef CONFIG_ALTIVEC
  	elf_vrreg_t __user *v_regs, *tm_v_regs;
  #endif
  	unsigned long err = 0;
  	unsigned long msr;
  	struct pt_regs *regs = tsk->thread.regs;
  #ifdef CONFIG_VSX
  	int i;
  #endif
  
  	BUG_ON(tsk != current);
  
  	if (tm_suspend_disabled)
  		return -EINVAL;
  
  	/* copy the GPRs */
  	err |= __copy_from_user(regs->gpr, tm_sc->gp_regs, sizeof(regs->gpr));
  	err |= __copy_from_user(&tsk->thread.ckpt_regs, sc->gp_regs,
  				sizeof(regs->gpr));
  
  	/*
  	 * TFHAR is restored from the checkpointed 'wound-back' ucontext's NIP.
  	 * TEXASR was set by the signal delivery reclaim, as was TFIAR.
  	 * Users doing anything abhorrent like thread-switching w/ signals for
  	 * TM-Suspended code will have to back TEXASR/TFIAR up themselves.
  	 * For the case of getting a signal and simply returning from it,
  	 * we don't need to re-copy them here.
  	 */
  	err |= __get_user(regs->nip, &tm_sc->gp_regs[PT_NIP]);
  	err |= __get_user(tsk->thread.tm_tfhar, &sc->gp_regs[PT_NIP]);
  
  	/* get MSR separately, transfer the LE bit if doing signal return */
  	err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
  	/* Don't allow reserved mode. */
  	if (MSR_TM_RESV(msr))
  		return -EINVAL;
  
  	/* pull in MSR LE from user context */
  	regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (msr & MSR_LE));
  
  	/* The following non-GPR non-FPR non-VR state is also checkpointed: */
  	err |= __get_user(regs->ctr, &tm_sc->gp_regs[PT_CTR]);
  	err |= __get_user(regs->link, &tm_sc->gp_regs[PT_LNK]);
  	err |= __get_user(regs->xer, &tm_sc->gp_regs[PT_XER]);
  	err |= __get_user(regs->ccr, &tm_sc->gp_regs[PT_CCR]);
  	err |= __get_user(tsk->thread.ckpt_regs.ctr,
  			  &sc->gp_regs[PT_CTR]);
  	err |= __get_user(tsk->thread.ckpt_regs.link,
  			  &sc->gp_regs[PT_LNK]);
  	err |= __get_user(tsk->thread.ckpt_regs.xer,
  			  &sc->gp_regs[PT_XER]);
  	err |= __get_user(tsk->thread.ckpt_regs.ccr,
  			  &sc->gp_regs[PT_CCR]);
  	/* Don't allow userspace to set SOFTE */
  	set_trap_norestart(regs);
  	/* These regs are not checkpointed; they can go in 'regs'. */
  	err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
  	err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
  	err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
  
  	/*
  	 * Force reload of FP/VEC.
  	 * This has to be done before copying stuff into tsk->thread.fpr/vr
  	 * for the reasons explained in the previous comment.
  	 */
  	regs_set_return_msr(regs, regs->msr & ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX));
  
  #ifdef CONFIG_ALTIVEC
  	err |= __get_user(v_regs, &sc->v_regs);
  	err |= __get_user(tm_v_regs, &tm_sc->v_regs);
  	if (err)
  		return err;
  	if (v_regs && !access_ok(v_regs, 34 * sizeof(vector128)))
  		return -EFAULT;
  	if (tm_v_regs && !access_ok(tm_v_regs, 34 * sizeof(vector128)))
  		return -EFAULT;
  	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
  	if (v_regs != NULL && tm_v_regs != NULL && (msr & MSR_VEC) != 0) {
  		err |= __copy_from_user(&tsk->thread.ckvr_state, v_regs,
  					33 * sizeof(vector128));
  		err |= __copy_from_user(&tsk->thread.vr_state, tm_v_regs,
  					33 * sizeof(vector128));
  		current->thread.used_vr = true;
  	}
  	else if (tsk->thread.used_vr) {
  		memset(&tsk->thread.vr_state, 0, 33 * sizeof(vector128));
  		memset(&tsk->thread.ckvr_state, 0, 33 * sizeof(vector128));
  	}
  	/* Always get VRSAVE back */
  	if (v_regs != NULL && tm_v_regs != NULL) {
  		err |= __get_user(tsk->thread.ckvrsave,
  				  (u32 __user *)&v_regs[33]);
  		err |= __get_user(tsk->thread.vrsave,
  				  (u32 __user *)&tm_v_regs[33]);
  	}
  	else {
  		tsk->thread.vrsave = 0;
  		tsk->thread.ckvrsave = 0;
  	}
  	if (cpu_has_feature(CPU_FTR_ALTIVEC))
  		mtspr(SPRN_VRSAVE, tsk->thread.vrsave);
  #endif /* CONFIG_ALTIVEC */
  	/* restore floating point */
  	err |= copy_fpr_from_user(tsk, &tm_sc->fp_regs);
  	err |= copy_ckfpr_from_user(tsk, &sc->fp_regs);
  #ifdef CONFIG_VSX
  	/*
  	 * Get additional VSX data. Update v_regs to point after the
  	 * VMX data.  Copy VSX low doubleword from userspace to local
  	 * buffer for formatting, then into the taskstruct.
  	 */
  	if (v_regs && ((msr & MSR_VSX) != 0)) {
  		v_regs += ELF_NVRREG;
  		tm_v_regs += ELF_NVRREG;
  		err |= copy_vsx_from_user(tsk, tm_v_regs);
  		err |= copy_ckvsx_from_user(tsk, v_regs);
  		tsk->thread.used_vsr = true;
  	} else {
  		for (i = 0; i < 32 ; i++) {
  			tsk->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
  			tsk->thread.ckfp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
  		}
  	}
  #endif
  	tm_enable();
  	/* Make sure the transaction is marked as failed */
  	tsk->thread.tm_texasr |= TEXASR_FS;
  
  	/*
  	 * Disabling preemption, since it is unsafe to be preempted
  	 * with MSR[TS] set without recheckpointing.
  	 */
  	preempt_disable();
  
  	/* pull in MSR TS bits from user context */
  	regs_set_return_msr(regs, regs->msr | (msr & MSR_TS_MASK));
  
  	/*
  	 * Ensure that TM is enabled in regs->msr before we leave the signal
  	 * handler. It could be the case that (a) user disabled the TM bit
  	 * through the manipulation of the MSR bits in uc_mcontext or (b) the
  	 * TM bit was disabled because a sufficient number of context switches
  	 * happened whilst in the signal handler and load_tm overflowed,
  	 * disabling the TM bit. In either case we can end up with an illegal
  	 * TM state leading to a TM Bad Thing when we return to userspace.
  	 *
  	 * CAUTION:
  	 * After regs->MSR[TS] being updated, make sure that get_user(),
  	 * put_user() or similar functions are *not* called. These
  	 * functions can generate page faults which will cause the process
  	 * to be de-scheduled with MSR[TS] set but without calling
  	 * tm_recheckpoint(). This can cause a bug.
  	 */
  	regs_set_return_msr(regs, regs->msr | MSR_TM);
  
  	/* This loads the checkpointed FP/VEC state, if used */
  	tm_recheckpoint(&tsk->thread);
  
  	msr_check_and_set(msr & (MSR_FP | MSR_VEC));
  	if (msr & MSR_FP) {
  		load_fp_state(&tsk->thread.fp_state);
  		regs_set_return_msr(regs, regs->msr | (MSR_FP | tsk->thread.fpexc_mode));
  	}
  	if (msr & MSR_VEC) {
  		load_vr_state(&tsk->thread.vr_state);
  		regs_set_return_msr(regs, regs->msr | MSR_VEC);
  	}
  
  	preempt_enable();
  
  	return err;
  }
  #else /* !CONFIG_PPC_TRANSACTIONAL_MEM */
  static long restore_tm_sigcontexts(struct task_struct *tsk, struct sigcontext __user *sc,
  				   struct sigcontext __user *tm_sc)
  {
  	return -EINVAL;
  }
  #endif
  
  /*
   * Setup the trampoline code on the stack
   */
  static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
  {
  	int i;
  	long err = 0;
  
  	/* Call the handler and pop the dummy stackframe*/
  	err |= __put_user(PPC_RAW_BCTRL(), &tramp[0]);
  	err |= __put_user(PPC_RAW_ADDI(_R1, _R1, __SIGNAL_FRAMESIZE), &tramp[1]);
  
  	err |= __put_user(PPC_RAW_LI(_R0, syscall), &tramp[2]);
  	err |= __put_user(PPC_RAW_SC(), &tramp[3]);
  
  	/* Minimal traceback info */
  	for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
  		err |= __put_user(0, &tramp[i]);
  
  	if (!err)
  		flush_icache_range((unsigned long) &tramp[0],
  			   (unsigned long) &tramp[TRAMP_SIZE]);
  
  	return err;
  }
  
  /*
   * Userspace code may pass a ucontext which doesn't include VSX added
   * at the end.  We need to check for this case.
   */
  #define UCONTEXTSIZEWITHOUTVSX \
  		(sizeof(struct ucontext) - 32*sizeof(long))
  
  /*
   * Handle {get,set,swap}_context operations
   */
  SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
  		struct ucontext __user *, new_ctx, long, ctx_size)
  {
  	sigset_t set;
  	unsigned long new_msr = 0;
  	int ctx_has_vsx_region = 0;
  
  	if (new_ctx &&
  	    get_user(new_msr, &new_ctx->uc_mcontext.gp_regs[PT_MSR]))
  		return -EFAULT;
  	/*
  	 * Check that the context is not smaller than the original
  	 * size (with VMX but without VSX)
  	 */
  	if (ctx_size < UCONTEXTSIZEWITHOUTVSX)
  		return -EINVAL;
  	/*
  	 * If the new context state sets the MSR VSX bits but
  	 * it doesn't provide VSX state.
  	 */
  	if ((ctx_size < sizeof(struct ucontext)) &&
  	    (new_msr & MSR_VSX))
  		return -EINVAL;
  	/* Does the context have enough room to store VSX data? */
  	if (ctx_size >= sizeof(struct ucontext))
  		ctx_has_vsx_region = 1;
  
  	if (old_ctx != NULL) {
  		prepare_setup_sigcontext(current);
  		if (!user_write_access_begin(old_ctx, ctx_size))
  			return -EFAULT;
  
  		unsafe_setup_sigcontext(&old_ctx->uc_mcontext, current, 0, NULL,
  					0, ctx_has_vsx_region, efault_out);
  		unsafe_copy_to_user(&old_ctx->uc_sigmask, &current->blocked,
  				    sizeof(sigset_t), efault_out);
  
  		user_write_access_end();
  	}
  	if (new_ctx == NULL)
  		return 0;
  	if (!access_ok(new_ctx, ctx_size) ||
  	    fault_in_readable((char __user *)new_ctx, ctx_size))
  		return -EFAULT;
  
  	/*
  	 * If we get a fault copying the context into the kernel's
  	 * image of the user's registers, we can't just return -EFAULT
  	 * because the user's registers will be corrupted.  For instance
  	 * the NIP value may have been updated but not some of the
  	 * other registers.  Given that we have done the access_ok
  	 * and successfully read the first and last bytes of the region
  	 * above, this should only happen in an out-of-memory situation
  	 * or if another thread unmaps the region containing the context.
  	 * We kill the task with a SIGSEGV in this situation.
  	 */
  
  	if (__get_user_sigset(&set, &new_ctx->uc_sigmask)) {
  		force_exit_sig(SIGSEGV);
  		return -EFAULT;
  	}
  	set_current_blocked(&set);
  
  	if (!user_read_access_begin(new_ctx, ctx_size))
  		return -EFAULT;
  	if (__unsafe_restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) {
  		user_read_access_end();
  		force_exit_sig(SIGSEGV);
  		return -EFAULT;
  	}
  	user_read_access_end();
  
  	/* This returns like rt_sigreturn */
  	set_thread_flag(TIF_RESTOREALL);
  
  	return 0;
  
  efault_out:
  	user_write_access_end();
  	return -EFAULT;
  }
  
  
  /*
   * Do a signal return; undo the signal stack.
   */
  
  SYSCALL_DEFINE0(rt_sigreturn)
  {
  	struct pt_regs *regs = current_pt_regs();
  	struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
  	sigset_t set;
  	unsigned long msr;
  
  	/* Always make any pending restarted system calls return -EINTR */
  	current->restart_block.fn = do_no_restart_syscall;
  
  	if (!access_ok(uc, sizeof(*uc)))
  		goto badframe;
  
  	if (__get_user_sigset(&set, &uc->uc_sigmask))
  		goto badframe;
  	set_current_blocked(&set);
  
  	if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM)) {
  		/*
  		 * If there is a transactional state then throw it away.
  		 * The purpose of a sigreturn is to destroy all traces of the
  		 * signal frame, this includes any transactional state created
  		 * within in. We only check for suspended as we can never be
  		 * active in the kernel, we are active, there is nothing better to
  		 * do than go ahead and Bad Thing later.
  		 * The cause is not important as there will never be a
  		 * recheckpoint so it's not user visible.
  		 */
  		if (MSR_TM_SUSPENDED(mfmsr()))
  			tm_reclaim_current(0);
  
  		/*
  		 * Disable MSR[TS] bit also, so, if there is an exception in the
  		 * code below (as a page fault in copy_ckvsx_to_user()), it does
  		 * not recheckpoint this task if there was a context switch inside
  		 * the exception.
  		 *
  		 * A major page fault can indirectly call schedule(). A reschedule
  		 * process in the middle of an exception can have a side effect
  		 * (Changing the CPU MSR[TS] state), since schedule() is called
  		 * with the CPU MSR[TS] disable and returns with MSR[TS]=Suspended
  		 * (switch_to() calls tm_recheckpoint() for the 'new' process). In
  		 * this case, the process continues to be the same in the CPU, but
  		 * the CPU state just changed.
  		 *
  		 * This can cause a TM Bad Thing, since the MSR in the stack will
  		 * have the MSR[TS]=0, and this is what will be used to RFID.
  		 *
  		 * Clearing MSR[TS] state here will avoid a recheckpoint if there
  		 * is any process reschedule in kernel space. The MSR[TS] state
  		 * does not need to be saved also, since it will be replaced with
  		 * the MSR[TS] that came from user context later, at
  		 * restore_tm_sigcontexts.
  		 */
  		regs_set_return_msr(regs, regs->msr & ~MSR_TS_MASK);
  
  		if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
  			goto badframe;
  	}
  
  	if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && MSR_TM_ACTIVE(msr)) {
  		/* We recheckpoint on return. */
  		struct ucontext __user *uc_transact;
  
  		/* Trying to start TM on non TM system */
  		if (!cpu_has_feature(CPU_FTR_TM))
  			goto badframe;
  
  		if (__get_user(uc_transact, &uc->uc_link))
  			goto badframe;
  		if (restore_tm_sigcontexts(current, &uc->uc_mcontext,
  					   &uc_transact->uc_mcontext))
  			goto badframe;
  	} else {
  		/*
  		 * Fall through, for non-TM restore
  		 *
  		 * Unset MSR[TS] on the thread regs since MSR from user
  		 * context does not have MSR active, and recheckpoint was
  		 * not called since restore_tm_sigcontexts() was not called
  		 * also.
  		 *
  		 * If not unsetting it, the code can RFID to userspace with
  		 * MSR[TS] set, but without CPU in the proper state,
  		 * causing a TM bad thing.
  		 */
  		regs_set_return_msr(current->thread.regs,
  				current->thread.regs->msr & ~MSR_TS_MASK);
  		if (!user_read_access_begin(&uc->uc_mcontext, sizeof(uc->uc_mcontext)))
  			goto badframe;
  
  		unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext,
  					  badframe_block);
  
  		user_read_access_end();
  	}
  
  	if (restore_altstack(&uc->uc_stack))
  		goto badframe;
  
  	set_thread_flag(TIF_RESTOREALL);
  
  	return 0;
  
  badframe_block:
  	user_read_access_end();
  badframe:
  	signal_fault(current, regs, "rt_sigreturn", uc);
  
  	force_sig(SIGSEGV);
  	return 0;
  }
  
  int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
  		struct task_struct *tsk)
  {
  	struct rt_sigframe __user *frame;
  	unsigned long newsp = 0;
  	long err = 0;
  	struct pt_regs *regs = tsk->thread.regs;
  	/* Save the thread's msr before get_tm_stackpointer() changes it */
  	unsigned long msr = regs->msr;
  
  	frame = get_sigframe(ksig, tsk, sizeof(*frame), 0);
  
  	/*
  	 * This only applies when calling unsafe_setup_sigcontext() and must be
  	 * called before opening the uaccess window.
  	 */
  	if (!MSR_TM_ACTIVE(msr))
  		prepare_setup_sigcontext(tsk);
  
  	if (!user_write_access_begin(frame, sizeof(*frame)))
  		goto badframe;
  
  	unsafe_put_user(&frame->info, &frame->pinfo, badframe_block);
  	unsafe_put_user(&frame->uc, &frame->puc, badframe_block);
  
  	/* Create the ucontext.  */
  	unsafe_put_user(0, &frame->uc.uc_flags, badframe_block);
  	unsafe_save_altstack(&frame->uc.uc_stack, regs->gpr[1], badframe_block);
  
  	if (MSR_TM_ACTIVE(msr)) {
  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
  		/* The ucontext_t passed to userland points to the second
  		 * ucontext_t (for transactional state) with its uc_link ptr.
  		 */
  		unsafe_put_user(&frame->uc_transact, &frame->uc.uc_link, badframe_block);
  
  		user_write_access_end();
  
  		err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext,
  					    &frame->uc_transact.uc_mcontext,
  					    tsk, ksig->sig, NULL,
  					    (unsigned long)ksig->ka.sa.sa_handler,
  					    msr);
  
  		if (!user_write_access_begin(&frame->uc.uc_sigmask,
  					     sizeof(frame->uc.uc_sigmask)))
  			goto badframe;
  
  #endif
  	} else {
  		unsafe_put_user(0, &frame->uc.uc_link, badframe_block);
  		unsafe_setup_sigcontext(&frame->uc.uc_mcontext, tsk, ksig->sig,
  					NULL, (unsigned long)ksig->ka.sa.sa_handler,
  					1, badframe_block);
  	}
  
  	unsafe_copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set), badframe_block);
  	user_write_access_end();
  
  	/* Save the siginfo outside of the unsafe block. */
  	if (copy_siginfo_to_user(&frame->info, &ksig->info))
  		goto badframe;
  
  	/* Make sure signal handler doesn't get spurious FP exceptions */
  	tsk->thread.fp_state.fpscr = 0;
  
  	/* Set up to return from userspace. */
  	if (tsk->mm->context.vdso) {
  		regs_set_return_ip(regs, VDSO64_SYMBOL(tsk->mm->context.vdso, sigtramp_rt64));
  	} else {
  		err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
  		if (err)
  			goto badframe;
  		regs_set_return_ip(regs, (unsigned long) &frame->tramp[0]);
  	}
  
  	/* Allocate a dummy caller frame for the signal handler. */
  	newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
  	err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
  
  	/* Set up "regs" so we "return" to the signal handler. */
  	if (is_elf2_task()) {
  		regs->ctr = (unsigned long) ksig->ka.sa.sa_handler;
  		regs->gpr[12] = regs->ctr;
  	} else {
  		/* Handler is *really* a pointer to the function descriptor for
  		 * the signal routine.  The first entry in the function
  		 * descriptor is the entry address of signal and the second
  		 * entry is the TOC value we need to use.
  		 */
  		func_descr_t __user *funct_desc_ptr =
  			(func_descr_t __user *) ksig->ka.sa.sa_handler;
  
  		err |= get_user(regs->ctr, &funct_desc_ptr->entry);
  		err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
  	}
  
  	/* enter the signal handler in native-endian mode */
  	regs_set_return_msr(regs, (regs->msr & ~MSR_LE) | (MSR_KERNEL & MSR_LE));
  	regs->gpr[1] = newsp;
  	regs->gpr[3] = ksig->sig;
  	regs->result = 0;
  	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
  		regs->gpr[4] = (unsigned long)&frame->info;
  		regs->gpr[5] = (unsigned long)&frame->uc;
  		regs->gpr[6] = (unsigned long) frame;
  	} else {
  		regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
  	}
  	if (err)
  		goto badframe;
  
  	return 0;
  
  badframe_block:
  	user_write_access_end();
  badframe:
  	signal_fault(current, regs, "handle_rt_signal64", frame);
  
  	return 1;
  }
  