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unaligned.c

/* $Id: unaligned.c,v 1.24 2002/02/09 19:49:31 davem Exp $
 * 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) 1996,1997 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/asi.h>
#include <asm/ptrace.h>
#include <asm/pstate.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/smp.h>
#include <linux/bitops.h>
#include <linux/kallsyms.h>
#include <asm/fpumacro.h>

/* #define DEBUG_MNA */

enum direction {
      load,    /* ld, ldd, ldh, ldsh */
      store,   /* st, std, sth, stsh */
      both,    /* Swap, ldstub, cas, ... */
      fpld,
      fpst,
      invalid,
};

#ifdef DEBUG_MNA
static char *dirstrings[] = {
  "load", "store", "both", "fpload", "fpstore", "invalid"
};
#endif

static inline enum direction decode_direction(unsigned int insn)
{
      unsigned long tmp = (insn >> 21) & 1;

      if (!tmp)
            return load;
      else {
            switch ((insn>>19)&0xf) {
            case 15: /* swap* */
                  return both;
            default:
                  return store;
            }
      }
}

/* 16 = double-word, 8 = extra-word, 4 = word, 2 = half-word */
static inline int decode_access_size(unsigned int insn)
{
      unsigned int tmp;

      tmp = ((insn >> 19) & 0xf);
      if (tmp == 11 || tmp == 14) /* ldx/stx */
            return 8;
      tmp &= 3;
      if (!tmp)
            return 4;
      else if (tmp == 3)
            return 16;  /* ldd/std - Although it is actually 8 */
      else if (tmp == 2)
            return 2;
      else {
            printk("Impossible unaligned trap. insn=%08x\n", insn);
            die_if_kernel("Byte sized unaligned access?!?!", current_thread_info()->kregs);

            /* GCC should never warn that control reaches the end
             * of this function without returning a value because
             * die_if_kernel() is marked with attribute 'noreturn'.
             * Alas, some versions do...
             */

            return 0;
      }
}

static inline int decode_asi(unsigned int insn, struct pt_regs *regs)
{
      if (insn & 0x800000) {
            if (insn & 0x2000)
                  return (unsigned char)(regs->tstate >> 24);     /* %asi */
            else
                  return (unsigned char)(insn >> 5);        /* imm_asi */
      } else
            return ASI_P;
}

/* 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, int from_kernel)
{
      if (rs2 >= 16 || rs1 >= 16 || rd >= 16) {
            if (from_kernel != 0)
                  __asm__ __volatile__("flushw");
            else
                  flushw_user();
      }
}

static inline long sign_extend_imm13(long imm)
{
      return imm << 51 >> 51;
}

static unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
{
      unsigned long value;
      
      if (reg < 16)
            return (!reg ? 0 : regs->u_regs[reg]);
      if (regs->tstate & TSTATE_PRIV) {
            struct reg_window *win;
            win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
            value = win->locals[reg - 16];
      } else if (test_thread_flag(TIF_32BIT)) {
            struct reg_window32 __user *win32;
            win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
            get_user(value, &win32->locals[reg - 16]);
      } else {
            struct reg_window __user *win;
            win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
            get_user(value, &win->locals[reg - 16]);
      }
      return value;
}

static unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
{
      if (reg < 16)
            return &regs->u_regs[reg];
      if (regs->tstate & TSTATE_PRIV) {
            struct reg_window *win;
            win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
            return &win->locals[reg - 16];
      } else if (test_thread_flag(TIF_32BIT)) {
            struct reg_window32 *win32;
            win32 = (struct reg_window32 *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
            return (unsigned long *)&win32->locals[reg - 16];
      } else {
            struct reg_window *win;
            win = (struct reg_window *)(regs->u_regs[UREG_FP] + STACK_BIAS);
            return &win->locals[reg - 16];
      }
}

unsigned long compute_effective_address(struct pt_regs *regs,
                              unsigned int insn, unsigned int rd)
{
      unsigned int rs1 = (insn >> 14) & 0x1f;
      unsigned int rs2 = insn & 0x1f;
      int from_kernel = (regs->tstate & TSTATE_PRIV) != 0;

      if (insn & 0x2000) {
            maybe_flush_windows(rs1, 0, rd, from_kernel);
            return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
      } else {
            maybe_flush_windows(rs1, rs2, rd, from_kernel);
            return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
      }
}

/* This is just to make gcc think die_if_kernel does return... */
static void __attribute_used__ unaligned_panic(char *str, struct pt_regs *regs)
{
      die_if_kernel(str, regs);
}

extern int do_int_load(unsigned long *dest_reg, int size,
                   unsigned long *saddr, int is_signed, int asi);
      
extern int __do_int_store(unsigned long *dst_addr, int size,
                    unsigned long src_val, int asi);

static inline int do_int_store(int reg_num, int size, unsigned long *dst_addr,
                         struct pt_regs *regs, int asi, int orig_asi)
{
      unsigned long zero = 0;
      unsigned long *src_val_p = &zero;
      unsigned long src_val;

      if (size == 16) {
            size = 8;
            zero = (((long)(reg_num ?
                    (unsigned)fetch_reg(reg_num, regs) : 0)) << 32) |
                  (unsigned)fetch_reg(reg_num + 1, regs);
      } else if (reg_num) {
            src_val_p = fetch_reg_addr(reg_num, regs);
      }
      src_val = *src_val_p;
      if (unlikely(asi != orig_asi)) {
            switch (size) {
            case 2:
                  src_val = swab16(src_val);
                  break;
            case 4:
                  src_val = swab32(src_val);
                  break;
            case 8:
                  src_val = swab64(src_val);
                  break;
            case 16:
            default:
                  BUG();
                  break;
            };
      }
      return __do_int_store(dst_addr, size, src_val, asi);
}

static inline void advance(struct pt_regs *regs)
{
      regs->tpc   = regs->tnpc;
      regs->tnpc += 4;
      if (test_thread_flag(TIF_32BIT)) {
            regs->tpc &= 0xffffffff;
            regs->tnpc &= 0xffffffff;
      }
}

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(int fixup_tstate_asi)
{
      struct pt_regs *regs = current_thread_info()->kern_una_regs;
      unsigned int insn = current_thread_info()->kern_una_insn;
      const struct exception_table_entry *entry;

      entry = search_exception_tables(regs->tpc);
      if (!entry) {
            unsigned long address;

            address = compute_effective_address(regs, insn,
                                        ((insn >> 25) & 0x1f));
            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 %016lx\n",address);
            printk(KERN_ALERT "current->{active_,}mm->context = %016lx\n",
                  (current->mm ? CTX_HWBITS(current->mm->context) :
                  CTX_HWBITS(current->active_mm->context)));
            printk(KERN_ALERT "current->{active_,}mm->pgd = %016lx\n",
                  (current->mm ? (unsigned long) current->mm->pgd :
                  (unsigned long) current->active_mm->pgd));
              die_if_kernel("Oops", regs);
            /* Not reached */
      }
      regs->tpc = entry->fixup;
      regs->tnpc = regs->tpc + 4;

      if (fixup_tstate_asi) {
            regs->tstate &= ~TSTATE_ASI;
            regs->tstate |= (ASI_AIUS << 24UL);
      }
}

static void log_unaligned(struct pt_regs *regs)
{
      static unsigned long count, last_time;

      if (jiffies - last_time > 5 * HZ)
            count = 0;
      if (count < 5) {
            last_time = jiffies;
            count++;
            printk("Kernel unaligned access at TPC[%lx] ", regs->tpc);
            print_symbol("%s\n", regs->tpc);
      }
}

asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
{
      enum direction dir = decode_direction(insn);
      int size = decode_access_size(insn);
      int orig_asi, asi;

      current_thread_info()->kern_una_regs = regs;
      current_thread_info()->kern_una_insn = insn;

      orig_asi = asi = decode_asi(insn, regs);

      /* If this is a {get,put}_user() on an unaligned userspace pointer,
       * just signal a fault and do not log the event.
       */
      if (asi == ASI_AIUS) {
            kernel_mna_trap_fault(0);
            return;
      }

      log_unaligned(regs);

      if (!ok_for_kernel(insn) || dir == both) {
            printk("Unsupported unaligned load/store trap for kernel "
                   "at <%016lx>.\n", regs->tpc);
            unaligned_panic("Kernel does fpu/atomic "
                        "unaligned load/store.", regs);

            kernel_mna_trap_fault(0);
      } else {
            unsigned long addr, *reg_addr;
            int err;

            addr = compute_effective_address(regs, insn,
                                     ((insn >> 25) & 0x1f));
#ifdef DEBUG_MNA
            printk("KMNA: pc=%016lx [dir=%s addr=%016lx size=%d] "
                   "retpc[%016lx]\n",
                   regs->tpc, dirstrings[dir], addr, size,
                   regs->u_regs[UREG_RETPC]);
#endif
            switch (asi) {
            case ASI_NL:
            case ASI_AIUPL:
            case ASI_AIUSL:
            case ASI_PL:
            case ASI_SL:
            case ASI_PNFL:
            case ASI_SNFL:
                  asi &= ~0x08;
                  break;
            };
            switch (dir) {
            case load:
                  reg_addr = fetch_reg_addr(((insn>>25)&0x1f), regs);
                  err = do_int_load(reg_addr, size,
                                (unsigned long *) addr,
                                decode_signedness(insn), asi);
                  if (likely(!err) && unlikely(asi != orig_asi)) {
                        unsigned long val_in = *reg_addr;
                        switch (size) {
                        case 2:
                              val_in = swab16(val_in);
                              break;
                        case 4:
                              val_in = swab32(val_in);
                              break;
                        case 8:
                              val_in = swab64(val_in);
                              break;
                        case 16:
                        default:
                              BUG();
                              break;
                        };
                        *reg_addr = val_in;
                  }
                  break;

            case store:
                  err = do_int_store(((insn>>25)&0x1f), size,
                                 (unsigned long *) addr, regs,
                                 asi, orig_asi);
                  break;

            default:
                  panic("Impossible kernel unaligned trap.");
                  /* Not reached... */
            }
            if (unlikely(err))
                  kernel_mna_trap_fault(1);
            else
                  advance(regs);
      }
}

static char popc_helper[] = {
0, 1, 1, 2, 1, 2, 2, 3,
1, 2, 2, 3, 2, 3, 3, 4, 
};

int handle_popc(u32 insn, struct pt_regs *regs)
{
      u64 value;
      int ret, i, rd = ((insn >> 25) & 0x1f);
      int from_kernel = (regs->tstate & TSTATE_PRIV) != 0;
                              
      if (insn & 0x2000) {
            maybe_flush_windows(0, 0, rd, from_kernel);
            value = sign_extend_imm13(insn);
      } else {
            maybe_flush_windows(0, insn & 0x1f, rd, from_kernel);
            value = fetch_reg(insn & 0x1f, regs);
      }
      for (ret = 0, i = 0; i < 16; i++) {
            ret += popc_helper[value & 0xf];
            value >>= 4;
      }
      if (rd < 16) {
            if (rd)
                  regs->u_regs[rd] = ret;
      } else {
            if (test_thread_flag(TIF_32BIT)) {
                  struct reg_window32 __user *win32;
                  win32 = (struct reg_window32 __user *)((unsigned long)((u32)regs->u_regs[UREG_FP]));
                  put_user(ret, &win32->locals[rd - 16]);
            } else {
                  struct reg_window __user *win;
                  win = (struct reg_window __user *)(regs->u_regs[UREG_FP] + STACK_BIAS);
                  put_user(ret, &win->locals[rd - 16]);
            }
      }
      advance(regs);
      return 1;
}

extern void do_fpother(struct pt_regs *regs);
extern void do_privact(struct pt_regs *regs);
extern void spitfire_data_access_exception(struct pt_regs *regs,
                                 unsigned long sfsr,
                                 unsigned long sfar);
extern void sun4v_data_access_exception(struct pt_regs *regs,
                              unsigned long addr,
                              unsigned long type_ctx);

int handle_ldf_stq(u32 insn, struct pt_regs *regs)
{
      unsigned long addr = compute_effective_address(regs, insn, 0);
      int freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
      struct fpustate *f = FPUSTATE;
      int asi = decode_asi(insn, regs);
      int flag = (freg < 32) ? FPRS_DL : FPRS_DU;

      save_and_clear_fpu();
      current_thread_info()->xfsr[0] &= ~0x1c000;
      if (freg & 3) {
            current_thread_info()->xfsr[0] |= (6 << 14) /* invalid_fp_register */;
            do_fpother(regs);
            return 0;
      }
      if (insn & 0x200000) {
            /* STQ */
            u64 first = 0, second = 0;
            
            if (current_thread_info()->fpsaved[0] & flag) {
                  first = *(u64 *)&f->regs[freg];
                  second = *(u64 *)&f->regs[freg+2];
            }
            if (asi < 0x80) {
                  do_privact(regs);
                  return 1;
            }
            switch (asi) {
            case ASI_P:
            case ASI_S: break;
            case ASI_PL:
            case ASI_SL: 
                  {
                        /* Need to convert endians */
                        u64 tmp = __swab64p(&first);
                        
                        first = __swab64p(&second);
                        second = tmp;
                        break;
                  }
            default:
                  if (tlb_type == hypervisor)
                        sun4v_data_access_exception(regs, addr, 0);
                  else
                        spitfire_data_access_exception(regs, 0, addr);
                  return 1;
            }
            if (put_user (first >> 32, (u32 __user *)addr) ||
                __put_user ((u32)first, (u32 __user *)(addr + 4)) ||
                __put_user (second >> 32, (u32 __user *)(addr + 8)) ||
                __put_user ((u32)second, (u32 __user *)(addr + 12))) {
                  if (tlb_type == hypervisor)
                        sun4v_data_access_exception(regs, addr, 0);
                  else
                        spitfire_data_access_exception(regs, 0, addr);
                  return 1;
            }
      } else {
            /* LDF, LDDF, LDQF */
            u32 data[4] __attribute__ ((aligned(8)));
            int size, i;
            int err;

            if (asi < 0x80) {
                  do_privact(regs);
                  return 1;
            } else if (asi > ASI_SNFL) {
                  if (tlb_type == hypervisor)
                        sun4v_data_access_exception(regs, addr, 0);
                  else
                        spitfire_data_access_exception(regs, 0, addr);
                  return 1;
            }
            switch (insn & 0x180000) {
            case 0x000000: size = 1; break;
            case 0x100000: size = 4; break;
            default: size = 2; break;
            }
            for (i = 0; i < size; i++)
                  data[i] = 0;
            
            err = get_user (data[0], (u32 __user *) addr);
            if (!err) {
                  for (i = 1; i < size; i++)
                        err |= __get_user (data[i], (u32 __user *)(addr + 4*i));
            }
            if (err && !(asi & 0x2 /* NF */)) {
                  if (tlb_type == hypervisor)
                        sun4v_data_access_exception(regs, addr, 0);
                  else
                        spitfire_data_access_exception(regs, 0, addr);
                  return 1;
            }
            if (asi & 0x8) /* Little */ {
                  u64 tmp;

                  switch (size) {
                  case 1: data[0] = le32_to_cpup(data + 0); break;
                  default:*(u64 *)(data + 0) = le64_to_cpup((u64 *)(data + 0));
                        break;
                  case 4: tmp = le64_to_cpup((u64 *)(data + 0));
                        *(u64 *)(data + 0) = le64_to_cpup((u64 *)(data + 2));
                        *(u64 *)(data + 2) = tmp;
                        break;
                  }
            }
            if (!(current_thread_info()->fpsaved[0] & FPRS_FEF)) {
                  current_thread_info()->fpsaved[0] = FPRS_FEF;
                  current_thread_info()->gsr[0] = 0;
            }
            if (!(current_thread_info()->fpsaved[0] & flag)) {
                  if (freg < 32)
                        memset(f->regs, 0, 32*sizeof(u32));
                  else
                        memset(f->regs+32, 0, 32*sizeof(u32));
            }
            memcpy(f->regs + freg, data, size * 4);
            current_thread_info()->fpsaved[0] |= flag;
      }
      advance(regs);
      return 1;
}

void handle_ld_nf(u32 insn, struct pt_regs *regs)
{
      int rd = ((insn >> 25) & 0x1f);
      int from_kernel = (regs->tstate & TSTATE_PRIV) != 0;
      unsigned long *reg;
                              
      maybe_flush_windows(0, 0, rd, from_kernel);
      reg = fetch_reg_addr(rd, regs);
      if (from_kernel || rd < 16) {
            reg[0] = 0;
            if ((insn & 0x780000) == 0x180000)
                  reg[1] = 0;
      } else if (test_thread_flag(TIF_32BIT)) {
            put_user(0, (int __user *) reg);
            if ((insn & 0x780000) == 0x180000)
                  put_user(0, ((int __user *) reg) + 1);
      } else {
            put_user(0, (unsigned long __user *) reg);
            if ((insn & 0x780000) == 0x180000)
                  put_user(0, (unsigned long __user *) reg + 1);
      }
      advance(regs);
}

void handle_lddfmna(struct pt_regs *regs, unsigned long sfar, unsigned long sfsr)
{
      unsigned long pc = regs->tpc;
      unsigned long tstate = regs->tstate;
      u32 insn;
      u32 first, second;
      u64 value;
      u8 freg;
      int flag;
      struct fpustate *f = FPUSTATE;

      if (tstate & TSTATE_PRIV)
            die_if_kernel("lddfmna from kernel", regs);
      if (test_thread_flag(TIF_32BIT))
            pc = (u32)pc;
      if (get_user(insn, (u32 __user *) pc) != -EFAULT) {
            int asi = decode_asi(insn, regs);
            if ((asi > ASI_SNFL) ||
                (asi < ASI_P))
                  goto daex;
            if (get_user(first, (u32 __user *)sfar) ||
                 get_user(second, (u32 __user *)(sfar + 4))) {
                  if (asi & 0x2) /* NF */ {
                        first = 0; second = 0;
                  } else
                        goto daex;
            }
            save_and_clear_fpu();
            freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
            value = (((u64)first) << 32) | second;
            if (asi & 0x8) /* Little */
                  value = __swab64p(&value);
            flag = (freg < 32) ? FPRS_DL : FPRS_DU;
            if (!(current_thread_info()->fpsaved[0] & FPRS_FEF)) {
                  current_thread_info()->fpsaved[0] = FPRS_FEF;
                  current_thread_info()->gsr[0] = 0;
            }
            if (!(current_thread_info()->fpsaved[0] & flag)) {
                  if (freg < 32)
                        memset(f->regs, 0, 32*sizeof(u32));
                  else
                        memset(f->regs+32, 0, 32*sizeof(u32));
            }
            *(u64 *)(f->regs + freg) = value;
            current_thread_info()->fpsaved[0] |= flag;
      } else {
daex:
            if (tlb_type == hypervisor)
                  sun4v_data_access_exception(regs, sfar, sfsr);
            else
                  spitfire_data_access_exception(regs, sfsr, sfar);
            return;
      }
      advance(regs);
      return;
}

void handle_stdfmna(struct pt_regs *regs, unsigned long sfar, unsigned long sfsr)
{
      unsigned long pc = regs->tpc;
      unsigned long tstate = regs->tstate;
      u32 insn;
      u64 value;
      u8 freg;
      int flag;
      struct fpustate *f = FPUSTATE;

      if (tstate & TSTATE_PRIV)
            die_if_kernel("stdfmna from kernel", regs);
      if (test_thread_flag(TIF_32BIT))
            pc = (u32)pc;
      if (get_user(insn, (u32 __user *) pc) != -EFAULT) {
            int asi = decode_asi(insn, regs);
            freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
            value = 0;
            flag = (freg < 32) ? FPRS_DL : FPRS_DU;
            if ((asi > ASI_SNFL) ||
                (asi < ASI_P))
                  goto daex;
            save_and_clear_fpu();
            if (current_thread_info()->fpsaved[0] & flag)
                  value = *(u64 *)&f->regs[freg];
            switch (asi) {
            case ASI_P:
            case ASI_S: break;
            case ASI_PL:
            case ASI_SL: 
                  value = __swab64p(&value); break;
            default: goto daex;
            }
            if (put_user (value >> 32, (u32 __user *) sfar) ||
                __put_user ((u32)value, (u32 __user *)(sfar + 4)))
                  goto daex;
      } else {
daex:
            if (tlb_type == hypervisor)
                  sun4v_data_access_exception(regs, sfar, sfsr);
            else
                  spitfire_data_access_exception(regs, sfsr, sfar);
            return;
      }
      advance(regs);
      return;
}

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