/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001 - 2007  Tensilica Inc.
 *
 * Joe Taylor   <joe@tensilica.com, joetylr@yahoo.com>
 * Chris Zankel <chris@zankel.net>
 * Scott Foehner<sfoehner@yahoo.com>,
 * Kevin Chea
 * Marc Gauthier<marc@tensilica.com> <marc@alumni.uwaterloo.ca>
 */

#include <linux/audit.h>
#include <linux/errno.h>
#include <linux/hw_breakpoint.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/perf_event.h>
#include <linux/ptrace.h>
#include <linux/regset.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/seccomp.h>
#include <linux/security.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/uaccess.h>

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

#include <asm/coprocessor.h>
#include <asm/elf.h>
#include <asm/page.h>
#include <asm/ptrace.h>

static int gpr_get(struct task_struct *target,
                   const struct user_regset *regset,
                   struct membuf to)
{
        struct pt_regs *regs = task_pt_regs(target);
        struct user_pt_regs newregs = {
                .pc = regs->pc,
                .ps = regs->ps & ~(1 << PS_EXCM_BIT),
                .lbeg = regs->lbeg,
                .lend = regs->lend,
                .lcount = regs->lcount,
                .sar = regs->sar,
                .threadptr = regs->threadptr,
                .windowbase = regs->windowbase,
                .windowstart = regs->windowstart,
                .syscall = regs->syscall,
        };

        memcpy(newregs.a,
               regs->areg + XCHAL_NUM_AREGS - regs->windowbase * 4,
               regs->windowbase * 16);
        memcpy(newregs.a + regs->windowbase * 4,
               regs->areg,
               (WSBITS - regs->windowbase) * 16);

        return membuf_write(&to, &newregs, sizeof(newregs));
}

static int gpr_set(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   const void *kbuf, const void __user *ubuf)
{
        int ret;
        struct user_pt_regs newregs = {0};
        struct pt_regs *regs;
        const u32 ps_mask = PS_CALLINC_MASK | PS_OWB_MASK;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newregs, 0, -1);
        if (ret)
                return ret;

        if (newregs.windowbase >= XCHAL_NUM_AREGS / 4)
                return -EINVAL;

        regs = task_pt_regs(target);
        regs->pc = newregs.pc;
        regs->ps = (regs->ps & ~ps_mask) | (newregs.ps & ps_mask);
        regs->lbeg = newregs.lbeg;
        regs->lend = newregs.lend;
        regs->lcount = newregs.lcount;
        regs->sar = newregs.sar;
        regs->threadptr = newregs.threadptr;

        if (newregs.syscall)
                regs->syscall = newregs.syscall;

        if (newregs.windowbase != regs->windowbase ||
            newregs.windowstart != regs->windowstart) {
                u32 rotws, wmask;

                rotws = (((newregs.windowstart |
                           (newregs.windowstart << WSBITS)) >>
                          newregs.windowbase) &
                         ((1 << WSBITS) - 1)) & ~1;
                wmask = ((rotws ? WSBITS + 1 - ffs(rotws) : 0) << 4) |
                        (rotws & 0xF) | 1;
                regs->windowbase = newregs.windowbase;
                regs->windowstart = newregs.windowstart;
                regs->wmask = wmask;
        }

        memcpy(regs->areg + XCHAL_NUM_AREGS - newregs.windowbase * 4,
               newregs.a, newregs.windowbase * 16);
        memcpy(regs->areg, newregs.a + newregs.windowbase * 4,
               (WSBITS - newregs.windowbase) * 16);

        return 0;
}

static int tie_get(struct task_struct *target,
                   const struct user_regset *regset,
                   struct membuf to)
{
        int ret;
        struct pt_regs *regs = task_pt_regs(target);
        struct thread_info *ti = task_thread_info(target);
        elf_xtregs_t *newregs = kzalloc_obj(elf_xtregs_t);

        if (!newregs)
                return -ENOMEM;

        newregs->opt = regs->xtregs_opt;
        newregs->user = ti->xtregs_user;

#if XTENSA_HAVE_COPROCESSORS
        /* Flush all coprocessor registers to memory. */
        coprocessor_flush_all(ti);
        newregs->cp0 = ti->xtregs_cp.cp0;
        newregs->cp1 = ti->xtregs_cp.cp1;
        newregs->cp2 = ti->xtregs_cp.cp2;
        newregs->cp3 = ti->xtregs_cp.cp3;
        newregs->cp4 = ti->xtregs_cp.cp4;
        newregs->cp5 = ti->xtregs_cp.cp5;
        newregs->cp6 = ti->xtregs_cp.cp6;
        newregs->cp7 = ti->xtregs_cp.cp7;
#endif
        ret = membuf_write(&to, newregs, sizeof(*newregs));
        kfree(newregs);
        return ret;
}

static int tie_set(struct task_struct *target,
                   const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   const void *kbuf, const void __user *ubuf)
{
        int ret;
        struct pt_regs *regs = task_pt_regs(target);
        struct thread_info *ti = task_thread_info(target);
        elf_xtregs_t *newregs = kzalloc_obj(elf_xtregs_t);

        if (!newregs)
                return -ENOMEM;

        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
                                 newregs, 0, -1);

        if (ret)
                goto exit;
        regs->xtregs_opt = newregs->opt;
        ti->xtregs_user = newregs->user;

#if XTENSA_HAVE_COPROCESSORS
        /* Flush all coprocessors before we overwrite them. */
        coprocessor_flush_release_all(ti);
        ti->xtregs_cp.cp0 = newregs->cp0;
        ti->xtregs_cp.cp1 = newregs->cp1;
        ti->xtregs_cp.cp2 = newregs->cp2;
        ti->xtregs_cp.cp3 = newregs->cp3;
        ti->xtregs_cp.cp4 = newregs->cp4;
        ti->xtregs_cp.cp5 = newregs->cp5;
        ti->xtregs_cp.cp6 = newregs->cp6;
        ti->xtregs_cp.cp7 = newregs->cp7;
#endif
exit:
        kfree(newregs);
        return ret;
}

enum xtensa_regset {
        REGSET_GPR,
        REGSET_TIE,
};

static const struct user_regset xtensa_regsets[] = {
        [REGSET_GPR] = {
                USER_REGSET_NOTE_TYPE(PRSTATUS),
                .n = sizeof(struct user_pt_regs) / sizeof(u32),
                .size = sizeof(u32),
                .align = sizeof(u32),
                .regset_get = gpr_get,
                .set = gpr_set,
        },
        [REGSET_TIE] = {
                USER_REGSET_NOTE_TYPE(PRFPREG),
                .n = sizeof(elf_xtregs_t) / sizeof(u32),
                .size = sizeof(u32),
                .align = sizeof(u32),
                .regset_get = tie_get,
                .set = tie_set,
        },
};

static const struct user_regset_view user_xtensa_view = {
        .name = "xtensa",
        .e_machine = EM_XTENSA,
        .regsets = xtensa_regsets,
        .n = ARRAY_SIZE(xtensa_regsets)
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
        return &user_xtensa_view;
}

void user_enable_single_step(struct task_struct *child)
{
        set_tsk_thread_flag(child, TIF_SINGLESTEP);
}

void user_disable_single_step(struct task_struct *child)
{
        clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}

/*
 * Called by kernel/ptrace.c when detaching to disable single stepping.
 */

void ptrace_disable(struct task_struct *child)
{
        /* Nothing to do.. */
}

static int ptrace_getregs(struct task_struct *child, void __user *uregs)
{
        return copy_regset_to_user(child, &user_xtensa_view, REGSET_GPR,
                                   0, sizeof(xtensa_gregset_t), uregs);
}

static int ptrace_setregs(struct task_struct *child, void __user *uregs)
{
        return copy_regset_from_user(child, &user_xtensa_view, REGSET_GPR,
                                     0, sizeof(xtensa_gregset_t), uregs);
}

static int ptrace_getxregs(struct task_struct *child, void __user *uregs)
{
        return copy_regset_to_user(child, &user_xtensa_view, REGSET_TIE,
                                   0, sizeof(elf_xtregs_t), uregs);
}

static int ptrace_setxregs(struct task_struct *child, void __user *uregs)
{
        return copy_regset_from_user(child, &user_xtensa_view, REGSET_TIE,
                                     0, sizeof(elf_xtregs_t), uregs);
}

static int ptrace_peekusr(struct task_struct *child, long regno,
                          long __user *ret)
{
        struct pt_regs *regs;
        unsigned long tmp;

        regs = task_pt_regs(child);
        tmp = 0;  /* Default return value. */

        switch(regno) {
        case REG_AR_BASE ... REG_AR_BASE + XCHAL_NUM_AREGS - 1:
                tmp = regs->areg[regno - REG_AR_BASE];
                break;

        case REG_A_BASE ... REG_A_BASE + 15:
                tmp = regs->areg[regno - REG_A_BASE];
                break;

        case REG_PC:
                tmp = regs->pc;
                break;

        case REG_PS:
                /* Note: PS.EXCM is not set while user task is running;
                 * its being set in regs is for exception handling
                 * convenience.
                 */
                tmp = (regs->ps & ~(1 << PS_EXCM_BIT));
                break;

        case REG_WB:
                break;          /* tmp = 0 */

        case REG_WS:
                {
                        unsigned long wb = regs->windowbase;
                        unsigned long ws = regs->windowstart;
                        tmp = ((ws >> wb) | (ws << (WSBITS - wb))) &
                                ((1 << WSBITS) - 1);
                        break;
                }
        case REG_LBEG:
                tmp = regs->lbeg;
                break;

        case REG_LEND:
                tmp = regs->lend;
                break;

        case REG_LCOUNT:
                tmp = regs->lcount;
                break;

        case REG_SAR:
                tmp = regs->sar;
                break;

        case SYSCALL_NR:
                tmp = regs->syscall;
                break;

        default:
                return -EIO;
        }
        return put_user(tmp, ret);
}

static int ptrace_pokeusr(struct task_struct *child, long regno, long val)
{
        struct pt_regs *regs;
        regs = task_pt_regs(child);

        switch (regno) {
        case REG_AR_BASE ... REG_AR_BASE + XCHAL_NUM_AREGS - 1:
                regs->areg[regno - REG_AR_BASE] = val;
                break;

        case REG_A_BASE ... REG_A_BASE + 15:
                regs->areg[regno - REG_A_BASE] = val;
                break;

        case REG_PC:
                regs->pc = val;
                break;

        case SYSCALL_NR:
                regs->syscall = val;
                break;

        default:
                return -EIO;
        }
        return 0;
}

#ifdef CONFIG_HAVE_HW_BREAKPOINT
static void ptrace_hbptriggered(struct perf_event *bp,
                                struct perf_sample_data *data,
                                struct pt_regs *regs)
{
        int i;
        struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);

        if (bp->attr.bp_type & HW_BREAKPOINT_X) {
                for (i = 0; i < XCHAL_NUM_IBREAK; ++i)
                        if (current->thread.ptrace_bp[i] == bp)
                                break;
                i <<= 1;
        } else {
                for (i = 0; i < XCHAL_NUM_DBREAK; ++i)
                        if (current->thread.ptrace_wp[i] == bp)
                                break;
                i = (i << 1) | 1;
        }

        force_sig_ptrace_errno_trap(i, (void __user *)bkpt->address);
}

static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
{
        struct perf_event_attr attr;

        ptrace_breakpoint_init(&attr);

        /* Initialise fields to sane defaults. */
        attr.bp_addr    = 0;
        attr.bp_len     = 1;
        attr.bp_type    = type;
        attr.disabled   = 1;

        return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL,
                                           tsk);
}

/*
 * Address bit 0 choose instruction (0) or data (1) break register, bits
 * 31..1 are the register number.
 * Both PTRACE_GETHBPREGS and PTRACE_SETHBPREGS transfer two 32-bit words:
 * address (0) and control (1).
 * Instruction breakpoint contorl word is 0 to clear breakpoint, 1 to set.
 * Data breakpoint control word bit 31 is 'trigger on store', bit 30 is
 * 'trigger on load, bits 29..0 are length. Length 0 is used to clear a
 * breakpoint. To set a breakpoint length must be a power of 2 in the range
 * 1..64 and the address must be length-aligned.
 */

static long ptrace_gethbpregs(struct task_struct *child, long addr,
                              long __user *datap)
{
        struct perf_event *bp;
        u32 user_data[2] = {0};
        bool dbreak = addr & 1;
        unsigned idx = addr >> 1;

        if ((!dbreak && idx >= XCHAL_NUM_IBREAK) ||
            (dbreak && idx >= XCHAL_NUM_DBREAK))
                return -EINVAL;

        if (dbreak)
                bp = child->thread.ptrace_wp[idx];
        else
                bp = child->thread.ptrace_bp[idx];

        if (bp) {
                user_data[0] = bp->attr.bp_addr;
                user_data[1] = bp->attr.disabled ? 0 : bp->attr.bp_len;
                if (dbreak) {
                        if (bp->attr.bp_type & HW_BREAKPOINT_R)
                                user_data[1] |= DBREAKC_LOAD_MASK;
                        if (bp->attr.bp_type & HW_BREAKPOINT_W)
                                user_data[1] |= DBREAKC_STOR_MASK;
                }
        }

        if (copy_to_user(datap, user_data, sizeof(user_data)))
                return -EFAULT;

        return 0;
}

static long ptrace_sethbpregs(struct task_struct *child, long addr,
                              long __user *datap)
{
        struct perf_event *bp;
        struct perf_event_attr attr;
        u32 user_data[2];
        bool dbreak = addr & 1;
        unsigned idx = addr >> 1;
        int bp_type = 0;

        if ((!dbreak && idx >= XCHAL_NUM_IBREAK) ||
            (dbreak && idx >= XCHAL_NUM_DBREAK))
                return -EINVAL;

        if (copy_from_user(user_data, datap, sizeof(user_data)))
                return -EFAULT;

        if (dbreak) {
                bp = child->thread.ptrace_wp[idx];
                if (user_data[1] & DBREAKC_LOAD_MASK)
                        bp_type |= HW_BREAKPOINT_R;
                if (user_data[1] & DBREAKC_STOR_MASK)
                        bp_type |= HW_BREAKPOINT_W;
        } else {
                bp = child->thread.ptrace_bp[idx];
                bp_type = HW_BREAKPOINT_X;
        }

        if (!bp) {
                bp = ptrace_hbp_create(child,
                                       bp_type ? bp_type : HW_BREAKPOINT_RW);
                if (IS_ERR(bp))
                        return PTR_ERR(bp);
                if (dbreak)
                        child->thread.ptrace_wp[idx] = bp;
                else
                        child->thread.ptrace_bp[idx] = bp;
        }

        attr = bp->attr;
        attr.bp_addr = user_data[0];
        attr.bp_len = user_data[1] & ~(DBREAKC_LOAD_MASK | DBREAKC_STOR_MASK);
        attr.bp_type = bp_type;
        attr.disabled = !attr.bp_len;

        return modify_user_hw_breakpoint(bp, &attr);
}
#endif

long arch_ptrace(struct task_struct *child, long request,
                 unsigned long addr, unsigned long data)
{
        int ret = -EPERM;
        void __user *datap = (void __user *) data;

        switch (request) {
        case PTRACE_PEEKUSR:    /* read register specified by addr. */
                ret = ptrace_peekusr(child, addr, datap);
                break;

        case PTRACE_POKEUSR:    /* write register specified by addr. */
                ret = ptrace_pokeusr(child, addr, data);
                break;

        case PTRACE_GETREGS:
                ret = ptrace_getregs(child, datap);
                break;

        case PTRACE_SETREGS:
                ret = ptrace_setregs(child, datap);
                break;

        case PTRACE_GETXTREGS:
                ret = ptrace_getxregs(child, datap);
                break;

        case PTRACE_SETXTREGS:
                ret = ptrace_setxregs(child, datap);
                break;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
        case PTRACE_GETHBPREGS:
                ret = ptrace_gethbpregs(child, addr, datap);
                break;

        case PTRACE_SETHBPREGS:
                ret = ptrace_sethbpregs(child, addr, datap);
                break;
#endif
        default:
                ret = ptrace_request(child, request, addr, data);
                break;
        }

        return ret;
}

int do_syscall_trace_enter(struct pt_regs *regs)
{
        if (regs->syscall == NO_SYSCALL)
                regs->areg[2] = -ENOSYS;

        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
            ptrace_report_syscall_entry(regs)) {
                regs->areg[2] = -ENOSYS;
                regs->syscall = NO_SYSCALL;
                return 0;
        }

        if (regs->syscall == NO_SYSCALL ||
            secure_computing() == -1) {
                do_syscall_trace_leave(regs);
                return 0;
        }

        if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
                trace_sys_enter(regs, syscall_get_nr(current, regs));

        audit_syscall_entry(regs->syscall, regs->areg[6],
                            regs->areg[3], regs->areg[4],
                            regs->areg[5]);
        return 1;
}

void do_syscall_trace_leave(struct pt_regs *regs)
{
        int step;

        audit_syscall_exit(regs);

        if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
                trace_sys_exit(regs, regs_return_value(regs));

        step = test_thread_flag(TIF_SINGLESTEP);

        if (step || test_thread_flag(TIF_SYSCALL_TRACE))
                ptrace_report_syscall_exit(regs, step);
}