/*      $NetBSD: linux_ptrace.c,v 1.36 2022/09/05 14:14:42 tsutsui Exp $        */

/*-
 * Copyright (c) 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matthias Scheler.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: linux_ptrace.c,v 1.36 2022/09/05 14:14:42 tsutsui Exp $");

#include <sys/param.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/systm.h>
#include <sys/syscall.h>
#include <sys/syscallargs.h>
#include <uvm/uvm_extern.h>

#include <machine/reg.h>

#include <compat/linux/common/linux_types.h>
#include <compat/linux/common/linux_ptrace.h>
#include <compat/linux/common/linux_signal.h>

#include <compat/linux/common/linux_util.h>
#include <compat/linux/common/linux_machdep.h>
#include <compat/linux/common/linux_emuldata.h>
#include <compat/linux/common/linux_exec.h>     /* for emul_linux */

#include <compat/linux/linux_syscallargs.h>

#include <lib/libkern/libkern.h>        /* for offsetof() */

struct linux_reg {
        long ebx;
        long ecx;
        long edx;
        long esi;
        long edi;
        long ebp;
        long eax;
        long xds, xes;          /* unsigned short ds, __ds, es, __es; */
        long __fs, __gs;        /* unsigned short fs, __fs, gs, __gs; */
        long orig_eax;
        long eip;
        long xcs;               /* unsigned short cs, __cs; */
        long eflags;
        long esp;
        long xss;               /* unsigned short ss, __ss; */
};

/* structure used for storing floating point context */
struct linux_fpctx {
        long cwd;
        long swd;
        long twd;
        long fip;
        long fcs;
        long foo;
        long fos;
        long st_space[20];
};

/* user struct for linux process - this is used for Linux ptrace emulation */
/* most of it is junk only used by gdb */
struct linux_user {
        struct linux_reg regs;          /* registers */
        int u_fpvalid;          /* true if math co-processor being used. */
        struct linux_fpctx i387;        /* Math Co-processor registers. */
/* The rest of this junk is to help gdb figure out what goes where */
#define lusr_startgdb   u_tsize
        unsigned long int u_tsize;      /* Text segment size (pages). */
        unsigned long int u_dsize;      /* Data segment size (pages). */
        unsigned long int u_ssize;      /* Stack segment size (pages). */
        unsigned long start_code;       /* Starting virtual address of text. */
        unsigned long start_stack;      /* Starting virtual address of stack
                                           area. This is actually the bottom of
                                           the stack, the top of the stack is
                                           always found in the esp register. */
        long int __signal;              /* Signal that caused the core dump. */
        int __reserved;                 /* unused */
        void *u_ar0;                    /* Used by gdb to help find the values
                                           for the registers. */
        struct linux_fpctx *u_fpstate;  /* Math Co-processor pointer. */
        unsigned long __magic;          /* To uniquely identify a core file */
        char u_comm[32];                /* User command that was responsible */
        int u_debugreg[8];
#define u_debugreg_end  u_debugreg[7]
};

#define LUSR_OFF(member)        offsetof(struct linux_user, member)

int linux_ptrace_disabled = 1;  /* bitrotted */

int
linux_sys_ptrace_arch(struct lwp *l, const struct linux_sys_ptrace_args *uap,
    register_t *retval)
{
        /* {
                syscallarg(int) request;
                syscallarg(int) pid;
                syscallarg(int) addr;
                syscallarg(int) data;
        } */
        struct proc *p = l->l_proc, *t;
        struct lwp *lt;
        struct reg *regs = NULL;
        struct fpreg *fpregs = NULL;
        struct linux_reg *linux_regs = NULL;
        struct linux_fpctx *linux_fpregs = NULL;
        struct linux_emuldata *led;
        int request, error, addr;
        size_t fp_size;

        if (linux_ptrace_disabled)
                return ENOSYS;

        error = 0;
        request = SCARG(uap, request);

        switch (request) {
        case LINUX_PTRACE_PEEKUSR:
        case LINUX_PTRACE_POKEUSR:
                break;
        case LINUX_PTRACE_GETREGS:
        case LINUX_PTRACE_SETREGS:
                regs = kmem_alloc(sizeof(struct reg), KM_SLEEP);
                linux_regs = kmem_alloc(sizeof(struct linux_reg), KM_SLEEP);
                if (request == LINUX_PTRACE_SETREGS) {
                        error = copyin((void *)SCARG(uap, data), linux_regs,
                            sizeof(struct linux_reg));
                        if (error) {
                                goto out;
                        }
                }
                break;
        case LINUX_PTRACE_GETFPREGS:
        case LINUX_PTRACE_SETFPREGS:
                fpregs = kmem_alloc(sizeof(struct fpreg), KM_SLEEP);
                linux_fpregs = kmem_alloc(sizeof(struct linux_fpctx), KM_SLEEP);
                if (request == LINUX_PTRACE_SETFPREGS) {
                        error = copyin((void *)SCARG(uap, data), linux_fpregs,
                            sizeof(struct linux_fpctx));
                        if (error) {
                                goto out;
                        }
                }
                break;
        default:
                error = EIO;
                goto out;
        }

        /* Find the process we are supposed to be operating on. */
        mutex_enter(&proc_lock);
        if ((t = proc_find(SCARG(uap, pid))) == NULL) {
                mutex_exit(&proc_lock);
                error = ESRCH;
                goto out;
        }
        mutex_enter(t->p_lock);

        /*
         * You cannot do what you want to the process if:
         * 1. It is not being traced at all,
         */
        if (!ISSET(t->p_slflag, PSL_TRACED)) {
                mutex_exit(t->p_lock);
                mutex_exit(&proc_lock);
                error = EPERM;
                goto out;
        }
        /*
         * 2. It is not being traced by _you_, or
         * 3. It is not currently stopped.
         */
        if (t->p_pptr != p || t->p_stat != SSTOP || !t->p_waited) {
                mutex_exit(t->p_lock);
                mutex_exit(&proc_lock);
                error = EBUSY;
                goto out;
        }
        mutex_exit(&proc_lock);
        /* XXX: ptrace needs revamp for multi-threading support. */
        if (t->p_nlwps > 1) {
                mutex_exit(t->p_lock);
                error = ENOSYS;
                goto out;
        }
        lt = LIST_FIRST(&t->p_lwps);
        *retval = 0;

        switch (request) {
        case LINUX_PTRACE_GETREGS:
                error = process_read_regs(lt, regs);
                mutex_exit(t->p_lock);
                if (error) {
                        break;
                }
                memset(linux_regs, 0, sizeof(*linux_regs));
                linux_regs->ebx = regs->r_ebx;
                linux_regs->ecx = regs->r_ecx;
                linux_regs->edx = regs->r_edx;
                linux_regs->esi = regs->r_esi;
                linux_regs->edi = regs->r_edi;
                linux_regs->ebp = regs->r_ebp;
                linux_regs->eax = regs->r_eax;
                linux_regs->xds = regs->r_ds;
                linux_regs->xes = regs->r_es;
                linux_regs->orig_eax = regs->r_eax; /* XXX is this correct? */
                linux_regs->eip = regs->r_cs + regs->r_eip;
                linux_regs->xcs = regs->r_cs;
                linux_regs->eflags = regs->r_eflags;
                linux_regs->esp = regs->r_esp;
                linux_regs->xss = regs->r_ss;

                error = copyout(linux_regs, (void *)SCARG(uap, data),
                    sizeof(struct linux_reg));
                break;

        case LINUX_PTRACE_SETREGS:
                regs->r_ebx = linux_regs->ebx;
                regs->r_ecx = linux_regs->ecx;
                regs->r_edx = linux_regs->edx;
                regs->r_esi = linux_regs->esi;
                regs->r_edi = linux_regs->edi;
                regs->r_ebp = linux_regs->ebp;
                regs->r_eax = linux_regs->eax;
                regs->r_ds = linux_regs->xds;
                regs->r_es = linux_regs->xes;
                regs->r_eip = linux_regs->eip - linux_regs->xcs;
                regs->r_cs = linux_regs->xcs;
                regs->r_eflags = linux_regs->eflags;
                regs->r_esp = linux_regs->esp;
                regs->r_ss = linux_regs->xss;

                error = process_write_regs(lt, regs);
                mutex_exit(t->p_lock);
                break;

        case LINUX_PTRACE_GETFPREGS:
                fp_size = sizeof fpregs;
                error = process_read_fpregs(lt, fpregs, &fp_size);
                mutex_exit(t->p_lock);
                if (error) {
                        break;
                }
                /* Zero the contents if NetBSD fpreg structure is smaller */
                if (fp_size < sizeof(struct linux_fpctx)) {
                        memset(linux_fpregs, '\0', sizeof(struct linux_fpctx));
                }
                memcpy(linux_fpregs, fpregs,
                    uimin(sizeof(struct linux_fpctx), fp_size));
                error = copyout(linux_fpregs, (void *)SCARG(uap, data),
                    sizeof(struct linux_fpctx));
                break;

        case LINUX_PTRACE_SETFPREGS:
                memset(fpregs, '\0', sizeof(struct fpreg));
                memcpy(fpregs, linux_fpregs,
                    uimin(sizeof(struct linux_fpctx), sizeof(struct fpreg)));
                error = process_write_regs(lt, regs);
                mutex_exit(t->p_lock);
                break;

        case LINUX_PTRACE_PEEKUSR:
                /* XXX locking */
                addr = SCARG(uap, addr);

                error = 0;
                if (addr < LUSR_OFF(lusr_startgdb)) {
                        /* XXX should provide appropriate register */
                        error = ENOTSUP;
                } else if (addr == LUSR_OFF(u_tsize))
                        *retval = p->p_vmspace->vm_tsize;
                else if (addr == LUSR_OFF(u_dsize))
                        *retval = p->p_vmspace->vm_dsize;
                else if (addr == LUSR_OFF(u_ssize))
                        *retval = p->p_vmspace->vm_ssize;
                else if (addr == LUSR_OFF(start_code))
                        *retval = (register_t) p->p_vmspace->vm_taddr;
                else if (addr == LUSR_OFF(start_stack))
                        *retval = (register_t) p->p_vmspace->vm_minsaddr;
                else if (addr == LUSR_OFF(u_ar0))
                        *retval = LUSR_OFF(regs);
                else if (addr >= LUSR_OFF(u_debugreg)
                           && addr <= LUSR_OFF(u_debugreg_end)) {
                        int off = (addr - LUSR_OFF(u_debugreg)) / sizeof(int);

                        /* only do this for Linux processes */
                        if (t->p_emul != &emul_linux) {
                                mutex_exit(t->p_lock);
                                return EINVAL;
                        }

                        led = lt->l_emuldata;
                        *retval = led->led_debugreg[off];
                } else if (addr == LUSR_OFF(__signal)) {
                        error = ENOTSUP;
                } else if (addr == LUSR_OFF(u_fpstate)) {
                        error = ENOTSUP;
                } else if (addr == LUSR_OFF(__magic)) {
                        error = ENOTSUP;
                } else if (addr == LUSR_OFF(u_comm)) {
                        error = ENOTSUP;
                } else {
#ifdef DEBUG_LINUX
                        printf("linux_ptrace: unsupported address: %d\n", addr);
#endif
                        error = ENOTSUP;
                }
                mutex_exit(t->p_lock);
                break;

        case LINUX_PTRACE_POKEUSR:
                /* we only support setting debugregs for now */
                addr = SCARG(uap, addr);
                if (addr >= LUSR_OFF(u_debugreg) &&
                    addr <= LUSR_OFF(u_debugreg_end)) {
                        int off = (addr - LUSR_OFF(u_debugreg)) / sizeof(int);
                        int data = SCARG(uap, data);

                        /* only do this for Linux processes */
                        if (t->p_emul != &emul_linux) {
                                mutex_exit(t->p_lock);
                                return EINVAL;
                        }
                        led = lt->l_emuldata;
                        led->led_debugreg[off] = data;
                }
                mutex_exit(t->p_lock);
                break;

        default:
                mutex_exit(t->p_lock);
                break;
        }
out:
        if (regs)
                kmem_free(regs, sizeof(*regs));
        if (linux_regs)
                kmem_free(linux_regs, sizeof(*linux_regs));
        if (fpregs)
                kmem_free(fpregs, sizeof(*fpregs));
        if (linux_fpregs)
                kmem_free(linux_fpregs, sizeof(*linux_fpregs));

        return error;
}