/*

   * unaligned.c: Unaligned load/store trap handling with special
   *              cases for the kernel to do them more quickly.
   *
   * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
   * Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   */
  
  
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/module.h>
  #include <asm/ptrace.h>
  #include <asm/processor.h>
  #include <asm/system.h>
  #include <asm/uaccess.h>
  #include <linux/smp.h>

  #include <linux/perf_event.h>

  
  enum direction {
  	load,    /* ld, ldd, ldh, ldsh */
  	store,   /* st, std, sth, stsh */
  	both,    /* Swap, ldstub, etc. */
  	fpload,
  	fpstore,
  	invalid,
  };

  static inline enum direction decode_direction(unsigned int insn)
  {
  	unsigned long tmp = (insn >> 21) & 1;
  
  	if(!tmp)
  		return load;
  	else {
  		if(((insn>>19)&0x3f) == 15)
  			return both;
  		else
  			return store;
  	}
  }
  
  /* 8 = double-word, 4 = word, 2 = half-word */
  static inline int decode_access_size(unsigned int insn)
  {
  	insn = (insn >> 19) & 3;
  
  	if(!insn)
  		return 4;
  	else if(insn == 3)
  		return 8;
  	else if(insn == 2)
  		return 2;
  	else {
  		printk("Impossible unaligned trap. insn=%08x
  ", insn);
  		die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
  		return 4; /* just to keep gcc happy. */
  	}
  }
  
  /* 0x400000 = signed, 0 = unsigned */
  static inline int decode_signedness(unsigned int insn)
  {
  	return (insn & 0x400000);
  }
  
  static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  				       unsigned int rd)
  {
  	if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  		/* Wheee... */
  		__asm__ __volatile__("save %sp, -0x40, %sp
  \t"
  				     "save %sp, -0x40, %sp
  \t"
  				     "save %sp, -0x40, %sp
  \t"
  				     "save %sp, -0x40, %sp
  \t"
  				     "save %sp, -0x40, %sp
  \t"
  				     "save %sp, -0x40, %sp
  \t"
  				     "save %sp, -0x40, %sp
  \t"
  				     "restore; restore; restore; restore;
  \t"
  				     "restore; restore; restore;
  \t");
  	}
  }
  
  static inline int sign_extend_imm13(int imm)
  {
  	return imm << 19 >> 19;
  }
  
  static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
  {

  	struct reg_window32 *win;

  
  	if(reg < 16)
  		return (!reg ? 0 : regs->u_regs[reg]);
  
  	/* Ho hum, the slightly complicated case. */

  	win = (struct reg_window32 *) regs->u_regs[UREG_FP];

  	return win->locals[reg - 16]; /* yes, I know what this does... */
  }
  
  static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
  {

  	struct reg_window32 __user *win;

  	unsigned long ret;
  
  	if (reg < 16)
  		return (!reg ? 0 : regs->u_regs[reg]);
  
  	/* Ho hum, the slightly complicated case. */

  	win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];

  
  	if ((unsigned long)win & 3)
  		return -1;
  
  	if (get_user(ret, &win->locals[reg - 16]))
  		return -1;
  
  	return ret;
  }
  
  static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
  {

  	struct reg_window32 *win;

  
  	if(reg < 16)
  		return &regs->u_regs[reg];

  	win = (struct reg_window32 *) regs->u_regs[UREG_FP];

  	return &win->locals[reg - 16];
  }
  
  static unsigned long compute_effective_address(struct pt_regs *regs,
  					       unsigned int insn)
  {
  	unsigned int rs1 = (insn >> 14) & 0x1f;
  	unsigned int rs2 = insn & 0x1f;
  	unsigned int rd = (insn >> 25) & 0x1f;
  
  	if(insn & 0x2000) {
  		maybe_flush_windows(rs1, 0, rd);
  		return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
  	} else {
  		maybe_flush_windows(rs1, rs2, rd);
  		return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
  	}
  }
  
  unsigned long safe_compute_effective_address(struct pt_regs *regs,
  					     unsigned int insn)
  {
  	unsigned int rs1 = (insn >> 14) & 0x1f;
  	unsigned int rs2 = insn & 0x1f;
  	unsigned int rd = (insn >> 25) & 0x1f;
  
  	if(insn & 0x2000) {
  		maybe_flush_windows(rs1, 0, rd);
  		return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
  	} else {
  		maybe_flush_windows(rs1, rs2, rd);
  		return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
  	}
  }
  
  /* This is just to make gcc think panic does return... */
  static void unaligned_panic(char *str)
  {
  	panic(str);
  }

  /* una_asm.S */
  extern int do_int_load(unsigned long *dest_reg, int size,
  		       unsigned long *saddr, int is_signed);
  extern int __do_int_store(unsigned long *dst_addr, int size,
  			  unsigned long *src_val);
  
  static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
  			struct pt_regs *regs)
  {
  	unsigned long zero[2] = { 0, 0 };
  	unsigned long *src_val;
  
  	if (reg_num)
  		src_val = fetch_reg_addr(reg_num, regs);
  	else {
  		src_val = &zero[0];
  		if (size == 8)
  			zero[1] = fetch_reg(1, regs);
  	}
  	return __do_int_store(dst_addr, size, src_val);
  }

  
  extern void smp_capture(void);
  extern void smp_release(void);

  static inline void advance(struct pt_regs *regs)
  {
  	regs->pc   = regs->npc;
  	regs->npc += 4;
  }
  
  static inline int floating_point_load_or_store_p(unsigned int insn)
  {
  	return (insn >> 24) & 1;
  }
  
  static inline int ok_for_kernel(unsigned int insn)
  {
  	return !floating_point_load_or_store_p(insn);
  }

  static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)

  {
  	unsigned long g2 = regs->u_regs [UREG_G2];
  	unsigned long fixup = search_extables_range(regs->pc, &g2);
  
  	if (!fixup) {
  		unsigned long address = compute_effective_address(regs, insn);
          	if(address < PAGE_SIZE) {
                  	printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
          	} else
                  	printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
  	        printk(KERN_ALERT " at virtual address %08lx
  ",address);
  		printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx
  ",
  			(current->mm ? current->mm->context :
  			current->active_mm->context));
  		printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx
  ",
  			(current->mm ? (unsigned long) current->mm->pgd :
  			(unsigned long) current->active_mm->pgd));
  	        die_if_kernel("Oops", regs);
  		/* Not reached */
  	}
  	regs->pc = fixup;
  	regs->npc = regs->pc + 4;
  	regs->u_regs [UREG_G2] = g2;
  }
  
  asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
  {
  	enum direction dir = decode_direction(insn);
  	int size = decode_access_size(insn);
  
  	if(!ok_for_kernel(insn) || dir == both) {
  		printk("Unsupported unaligned load/store trap for kernel at <%08lx>.
  ",
  		       regs->pc);
  		unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");

  	} else {
  		unsigned long addr = compute_effective_address(regs, insn);

  		int err;

  		perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, 0, regs, addr);

  		switch (dir) {

  		case load:

  			err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
  							 regs),
  					  size, (unsigned long *) addr,
  					  decode_signedness(insn));

  			break;
  
  		case store:

  			err = do_int_store(((insn>>25)&0x1f), size,
  					   (unsigned long *) addr, regs);

  			break;

  		default:
  			panic("Impossible kernel unaligned trap.");
  			/* Not reached... */
  		}

  		if (err)
  			kernel_mna_trap_fault(regs, insn);
  		else
  			advance(regs);

  	}
  }
  
  static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
  			      enum direction dir)
  {
  	unsigned int reg;
  	int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
  	int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
  
  	if ((regs->pc | regs->npc) & 3)
  		return 0;
  
  	/* Must access_ok() in all the necessary places. */
  #define WINREG_ADDR(regnum) \
  	((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
  
  	reg = (insn >> 25) & 0x1f;
  	if (reg >= 16) {
  		if (!access_ok(check, WINREG_ADDR(reg - 16), size))
  			return -EFAULT;
  	}
  	reg = (insn >> 14) & 0x1f;
  	if (reg >= 16) {
  		if (!access_ok(check, WINREG_ADDR(reg - 16), size))
  			return -EFAULT;
  	}
  	if (!(insn & 0x2000)) {
  		reg = (insn & 0x1f);
  		if (reg >= 16) {
  			if (!access_ok(check, WINREG_ADDR(reg - 16), size))
  				return -EFAULT;
  		}
  	}
  #undef WINREG_ADDR
  	return 0;
  }

  static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)

  {
  	siginfo_t info;
  
  	info.si_signo = SIGBUS;
  	info.si_errno = 0;
  	info.si_code = BUS_ADRALN;
  	info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
  	info.si_trapno = 0;
  	send_sig_info(SIGBUS, &info, current);
  }
  
  asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
  {
  	enum direction dir;

  	if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
  	   (((insn >> 30) & 3) != 3))
  		goto kill_user;
  	dir = decode_direction(insn);
  	if(!ok_for_user(regs, insn, dir)) {
  		goto kill_user;
  	} else {

  		int err, size = decode_access_size(insn);

  		unsigned long addr;
  
  		if(floating_point_load_or_store_p(insn)) {
  			printk("User FPU load/store unaligned unsupported.
  ");
  			goto kill_user;
  		}
  
  		addr = compute_effective_address(regs, insn);

  		perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, 0, regs, addr);

  		switch(dir) {
  		case load:

  			err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
  							 regs),
  					  size, (unsigned long *) addr,
  					  decode_signedness(insn));

  			break;
  
  		case store:

  			err = do_int_store(((insn>>25)&0x1f), size,
  					   (unsigned long *) addr, regs);

  			break;
  
  		case both:

  			/*
  			 * This was supported in 2.4. However, we question
  			 * the value of SWAP instruction across word boundaries.
  			 */
  			printk("Unaligned SWAP unsupported.
  ");

  			err = -EFAULT;

  			break;
  
  		default:
  			unaligned_panic("Impossible user unaligned trap.");

  			goto out;
  		}

  		if (err)
  			goto kill_user;
  		else
  			advance(regs);

  		goto out;
  	}
  
  kill_user:
  	user_mna_trap_fault(regs, insn);
  out:

  	;

  }