// SPDX-License-Identifier: GPL-2.0
/*
 * unaligned.c: Unaligned load/store trap handling with special
 *              cases for the kernel to do them more quickly.
 *
 * Copyright (C) 1996,2008 David S. Miller (davem@davemloft.net)
 * Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
 */


#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/extable.h>
#include <asm/asi.h>
#include <asm/ptrace.h>
#include <asm/pstate.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <linux/smp.h>
#include <linux/bitops.h>
#include <linux/perf_event.h>
#include <linux/ratelimit.h>
#include <linux/context_tracking.h>
#include <asm/fpumacro.h>
#include <asm/cacheflush.h>
#include <asm/setup.h>

#include "entry.h"
#include "kernel.h"

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

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(struct pt_regs *regs, 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?!?!", regs);

                /* 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, fp;
        
        if (reg < 16)
                return (!reg ? 0 : regs->u_regs[reg]);

        fp = regs->u_regs[UREG_FP];

        if (regs->tstate & TSTATE_PRIV) {
                struct reg_window *win;
                win = (struct reg_window *)(fp + STACK_BIAS);
                value = win->locals[reg - 16];
        } else if (!test_thread_64bit_stack(fp)) {
                struct reg_window32 __user *win32;
                win32 = (struct reg_window32 __user *)((unsigned long)((u32)fp));
                get_user(value, &win32->locals[reg - 16]);
        } else {
                struct reg_window __user *win;
                win = (struct reg_window __user *)(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)
{
        unsigned long fp;

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

        fp = regs->u_regs[UREG_FP];

        if (regs->tstate & TSTATE_PRIV) {
                struct reg_window *win;
                win = (struct reg_window *)(fp + STACK_BIAS);
                return &win->locals[reg - 16];
        } else if (!test_thread_64bit_stack(fp)) {
                struct reg_window32 *win32;
                win32 = (struct reg_window32 *)((unsigned long)((u32)fp));
                return (unsigned long *)&win32->locals[reg - 16];
        } else {
                struct reg_window *win;
                win = (struct reg_window *)(fp + STACK_BIAS);
                return &win->locals[reg - 16];
        }
}

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

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

        if (!from_kernel && test_thread_flag(TIF_32BIT))
                addr &= 0xffffffff;

        return addr;
}

/* This is just to make gcc think die_if_kernel does return... */
static void __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 int)fetch_reg(reg_num, regs) : 0)) << 32) |
                        (unsigned int)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 DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 5);

        if (__ratelimit(&ratelimit)) {
                printk("Kernel unaligned access at TPC[%lx] %pS\n",
                       regs->tpc, (void *) 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(regs, 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));
                perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
                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);
        }
}

int handle_popc(u32 insn, struct pt_regs *regs)
{
        int from_kernel = (regs->tstate & TSTATE_PRIV) != 0;
        int ret, rd = ((insn >> 25) & 0x1f);
        u64 value;
                                
        perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, 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);
        }
        ret = hweight64(value);
        if (rd < 16) {
                if (rd)
                        regs->u_regs[rd] = ret;
        } else {
                unsigned long fp = regs->u_regs[UREG_FP];

                if (!test_thread_64bit_stack(fp)) {
                        struct reg_window32 __user *win32;
                        win32 = (struct reg_window32 __user *)((unsigned long)((u32)fp));
                        put_user(ret, &win32->locals[rd - 16]);
                } else {
                        struct reg_window __user *win;
                        win = (struct reg_window __user *)(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 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;
        struct fpustate *f = FPUSTATE;
        int asi = decode_asi(insn, regs);
        int flag;

        perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, 0);

        save_and_clear_fpu();
        current_thread_info()->xfsr[0] &= ~0x1c000;
        if (insn & 0x200000) {
                /* STQ */
                u64 first = 0, second = 0;
                
                freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
                flag = (freg < 32) ? FPRS_DL : FPRS_DU;
                if (freg & 3) {
                        current_thread_info()->xfsr[0] |= (6 << 14) /* invalid_fp_register */;
                        do_fpother(regs);
                        return 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;
                }
                if (size == 1)
                        freg = (insn >> 25) & 0x1f;
                else
                        freg = ((insn >> 25) & 0x1e) | ((insn >> 20) & 0x20);
                flag = (freg < 32) ? FPRS_DL : FPRS_DU;

                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;
                                
        perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, 0);

        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_64bit_stack(regs->u_regs[UREG_FP])) {
                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)
{
        enum ctx_state prev_state = exception_enter();
        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("lddfmna from kernel", regs);
        perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, sfar);
        if (test_thread_flag(TIF_32BIT))
                pc = (u32)pc;
        if (get_user(insn, (u32 __user *) pc) != -EFAULT) {
                int asi = decode_asi(insn, regs);
                u32 first, second;
                int err;

                if ((asi > ASI_SNFL) ||
                    (asi < ASI_P))
                        goto daex;
                first = second = 0;
                err = get_user(first, (u32 __user *)sfar);
                if (!err)
                        err = get_user(second, (u32 __user *)(sfar + 4));
                if (err) {
                        if (!(asi & 0x2))
                                goto daex;
                        first = second = 0;
                }
                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);
                goto out;
        }
        advance(regs);
out:
        exception_exit(prev_state);
}

void handle_stdfmna(struct pt_regs *regs, unsigned long sfar, unsigned long sfsr)
{
        enum ctx_state prev_state = exception_enter();
        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);
        perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, sfar);
        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);
                goto out;
        }
        advance(regs);
out:
        exception_exit(prev_state);
}