/* $NetBSD: linux_ptrace.c,v 1.23 2021/09/07 11:43:04 riastradh Exp $ */

/* $NetBSD: linux_ptrace.c,v 1.23 2021/09/07 11:43:04 riastradh 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 1.23 2021/09/07 11:43:04 riastradh Exp $");

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

#include <machine/reg.h>
#include <machine/pcb.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() */

/*
* On ARMv2, uregs contains R0--R15, orig_R0.
* On ARMv3 and later, it's R0--R15, CPSR, orig_R0.
* As far as I can see, Linux doesn't initialise orig_R0 on ARMv2, so we
* just produce the ARMv3 version.
*/

struct linux_reg {
long uregs[18];
};

#define LINUX_REG_R0 0
#define LINUX_REG_R1 1
#define LINUX_REG_R2 2
#define LINUX_REG_R3 3
#define LINUX_REG_R4 4
#define LINUX_REG_R5 5
#define LINUX_REG_R6 6
#define LINUX_REG_R7 7
#define LINUX_REG_R8 8
#define LINUX_REG_R9 9
#define LINUX_REG_R10 10
#define LINUX_REG_FP 11
#define LINUX_REG_IP 12
#define LINUX_REG_SP 13
#define LINUX_REG_LR 14
#define LINUX_REG_PC 15
#define LINUX_REG_CPSR 16
#define LINUX_REG_ORIG_R0 17

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;
#ifdef _ARM_ARCH_6
struct pcb *pcb;
void *val;
#endif
struct reg *regs = NULL;
struct linux_reg *linux_regs = NULL;
int request, error;

if (linux_ptrace_disabled)
return ENOSYS;

error = 0;
request = SCARG(uap, request);
regs = kmem_alloc(sizeof(struct reg), KM_SLEEP);
linux_regs = kmem_alloc(sizeof(struct linux_reg), KM_SLEEP);

switch (request) {
case LINUX_PTRACE_GETREGS:
break;
case LINUX_PTRACE_SETREGS:
error = copyin((void *)SCARG(uap, data), linux_regs,
sizeof(struct linux_reg));
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 being traced by procfs (which has different signal
* delivery semantics),
* 3. It is not being traced by _you_, or
* 4. 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));
memcpy(linux_regs->uregs, regs->r, 13 * sizeof(register_t));
linux_regs->uregs[LINUX_REG_SP] = regs->r_sp;
linux_regs->uregs[LINUX_REG_LR] = regs->r_lr;
linux_regs->uregs[LINUX_REG_PC] = regs->r_pc;
linux_regs->uregs[LINUX_REG_CPSR] = regs->r_cpsr;
linux_regs->uregs[LINUX_REG_ORIG_R0] = regs->r[0];

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

case LINUX_PTRACE_SETREGS:
memcpy(regs->r, linux_regs->uregs, 13 * sizeof(register_t));
regs->r_sp = linux_regs->uregs[LINUX_REG_SP];
regs->r_lr = linux_regs->uregs[LINUX_REG_LR];
regs->r_pc = linux_regs->uregs[LINUX_REG_PC];
regs->r_cpsr = linux_regs->uregs[LINUX_REG_CPSR];
error = process_write_regs(lt, regs);
mutex_exit(t->p_lock);
break;

#ifdef _ARM_ARCH_6
#define LINUX_PTRACE_GET_THREAD_AREA 22
case LINUX_PTRACE_GET_THREAD_AREA:
mutex_exit(t->p_lock);
pcb = lwp_getpcb(l);
val = (void *)pcb->pcb_user_pid_ro;
error = copyout(&val, (void *)SCARG(uap, data), sizeof(val));
break;
#endif

default:
mutex_exit(t->p_lock);
}
out:
if (regs)
kmem_free(regs, sizeof(*regs));
if (linux_regs)
kmem_free(linux_regs, sizeof(*linux_regs));
return error;

}