// SPDX-License-Identifier: GPL-2.0
/* ptrace.c */
/* By Ross Biro 1/23/92 */
/* edited by Linus Torvalds */
/* mangled further by Bob Manson (manson@santafe.edu) */
/* more mutilation by David Mosberger (davidm@azstarnet.com) */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/signal.h>
#include <linux/audit.h>

#include <linux/uaccess.h>
#include <asm/fpu.h>

#include "proto.h"

#define DEBUG   DBG_MEM
#undef DEBUG

#ifdef DEBUG
enum {
        DBG_MEM         = (1<<0),
        DBG_BPT         = (1<<1),
        DBG_MEM_ALL     = (1<<2)
};
#define DBG(fac,args)   {if ((fac) & DEBUG) printk args;}
#else
#define DBG(fac,args)
#endif

#define BREAKINST       0x00000080      /* call_pal bpt */

/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/*
 * Processes always block with the following stack-layout:
 *
 *  +================================+ <---- task + 2*PAGE_SIZE
 *  | PALcode saved frame (ps, pc,   | ^
 *  | gp, a0, a1, a2)                | |
 *  +================================+ | struct pt_regs
 *  |                                | |
 *  | frame generated by SAVE_ALL    | |
 *  |                                | v
 *  +================================+
 *  |                                | ^
 *  | frame saved by do_switch_stack | | struct switch_stack
 *  |                                | v
 *  +================================+
 */

/* 
 * The following table maps a register index into the stack offset at
 * which the register is saved.  Register indices are 0-31 for integer
 * regs, 32-63 for fp regs, and 64 for the pc.  Notice that sp and
 * zero have no stack-slot and need to be treated specially (see
 * get_reg/put_reg below).
 */
enum {
        REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
};

#define PT_REG(reg) \
  (PAGE_SIZE*2 - sizeof(struct pt_regs) + offsetof(struct pt_regs, reg))

#define SW_REG(reg) \
 (PAGE_SIZE*2 - sizeof(struct pt_regs) - sizeof(struct switch_stack) \
  + offsetof(struct switch_stack, reg))

#define FP_REG(reg) (offsetof(struct thread_info, reg))

static int regoff[] = {
        PT_REG(    r0), PT_REG(    r1), PT_REG(    r2), PT_REG(   r3),
        PT_REG(    r4), PT_REG(    r5), PT_REG(    r6), PT_REG(   r7),
        PT_REG(    r8), SW_REG(    r9), SW_REG(   r10), SW_REG(  r11),
        SW_REG(   r12), SW_REG(   r13), SW_REG(   r14), SW_REG(  r15),
        PT_REG(   r16), PT_REG(   r17), PT_REG(   r18), PT_REG(  r19),
        PT_REG(   r20), PT_REG(   r21), PT_REG(   r22), PT_REG(  r23),
        PT_REG(   r24), PT_REG(   r25), PT_REG(   r26), PT_REG(  r27),
        PT_REG(   r28), PT_REG(    gp),            -1,             -1,
        FP_REG(fp[ 0]), FP_REG(fp[ 1]), FP_REG(fp[ 2]), FP_REG(fp[ 3]),
        FP_REG(fp[ 4]), FP_REG(fp[ 5]), FP_REG(fp[ 6]), FP_REG(fp[ 7]),
        FP_REG(fp[ 8]), FP_REG(fp[ 9]), FP_REG(fp[10]), FP_REG(fp[11]),
        FP_REG(fp[12]), FP_REG(fp[13]), FP_REG(fp[14]), FP_REG(fp[15]),
        FP_REG(fp[16]), FP_REG(fp[17]), FP_REG(fp[18]), FP_REG(fp[19]),
        FP_REG(fp[20]), FP_REG(fp[21]), FP_REG(fp[22]), FP_REG(fp[23]),
        FP_REG(fp[24]), FP_REG(fp[25]), FP_REG(fp[26]), FP_REG(fp[27]),
        FP_REG(fp[28]), FP_REG(fp[29]), FP_REG(fp[30]), FP_REG(fp[31]),
        PT_REG(    pc)
};

static unsigned long zero;

/*
 * Get address of register REGNO in task TASK.
 */
static unsigned long *
get_reg_addr(struct task_struct * task, unsigned long regno)
{
        unsigned long *addr;

        if (regno == 30) {
                addr = &task_thread_info(task)->pcb.usp;
        } else if (regno == 65) {
                addr = &task_thread_info(task)->pcb.unique;
        } else if (regno == 31 || regno > 65) {
                zero = 0;
                addr = &zero;
        } else {
                addr = task_stack_page(task) + regoff[regno];
        }
        return addr;
}

/*
 * Get contents of register REGNO in task TASK.
 */
static unsigned long
get_reg(struct task_struct * task, unsigned long regno)
{
        /* Special hack for fpcr -- combine hardware and software bits.  */
        if (regno == 63) {
                unsigned long fpcr = *get_reg_addr(task, regno);
                unsigned long swcr
                  = task_thread_info(task)->ieee_state & IEEE_SW_MASK;
                swcr = swcr_update_status(swcr, fpcr);
                return fpcr | swcr;
        }
        return *get_reg_addr(task, regno);
}

/*
 * Write contents of register REGNO in task TASK.
 */
static int
put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
{
        if (regno == 63) {
                task_thread_info(task)->ieee_state
                  = ((task_thread_info(task)->ieee_state & ~IEEE_SW_MASK)
                     | (data & IEEE_SW_MASK));
                data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
        }
        *get_reg_addr(task, regno) = data;
        return 0;
}

static inline int
read_int(struct task_struct *task, unsigned long addr, int * data)
{
        int copied = access_process_vm(task, addr, data, sizeof(int),
                        FOLL_FORCE);
        return (copied == sizeof(int)) ? 0 : -EIO;
}

static inline int
write_int(struct task_struct *task, unsigned long addr, int data)
{
        int copied = access_process_vm(task, addr, &data, sizeof(int),
                        FOLL_FORCE | FOLL_WRITE);
        return (copied == sizeof(int)) ? 0 : -EIO;
}

/*
 * Set breakpoint.
 */
int
ptrace_set_bpt(struct task_struct * child)
{
        int displ, i, res, reg_b, nsaved = 0;
        unsigned int insn, op_code;
        unsigned long pc;

        pc  = get_reg(child, REG_PC);
        res = read_int(child, pc, (int *) &insn);
        if (res < 0)
                return res;

        op_code = insn >> 26;
        if (op_code >= 0x30) {
                /*
                 * It's a branch: instead of trying to figure out
                 * whether the branch will be taken or not, we'll put
                 * a breakpoint at either location.  This is simpler,
                 * more reliable, and probably not a whole lot slower
                 * than the alternative approach of emulating the
                 * branch (emulation can be tricky for fp branches).
                 */
                displ = ((s32)(insn << 11)) >> 9;
                task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
                if (displ)              /* guard against unoptimized code */
                        task_thread_info(child)->bpt_addr[nsaved++]
                          = pc + 4 + displ;
                DBG(DBG_BPT, ("execing branch\n"));
        } else if (op_code == 0x1a) {
                reg_b = (insn >> 16) & 0x1f;
                task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
                DBG(DBG_BPT, ("execing jump\n"));
        } else {
                task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
                DBG(DBG_BPT, ("execing normal insn\n"));
        }

        /* install breakpoints: */
        for (i = 0; i < nsaved; ++i) {
                res = read_int(child, task_thread_info(child)->bpt_addr[i],
                               (int *) &insn);
                if (res < 0)
                        return res;
                task_thread_info(child)->bpt_insn[i] = insn;
                DBG(DBG_BPT, ("    -> next_pc=%lx\n",
                              task_thread_info(child)->bpt_addr[i]));
                res = write_int(child, task_thread_info(child)->bpt_addr[i],
                                BREAKINST);
                if (res < 0)
                        return res;
        }
        task_thread_info(child)->bpt_nsaved = nsaved;
        return 0;
}

/*
 * Ensure no single-step breakpoint is pending.  Returns non-zero
 * value if child was being single-stepped.
 */
int
ptrace_cancel_bpt(struct task_struct * child)
{
        int i, nsaved = task_thread_info(child)->bpt_nsaved;

        task_thread_info(child)->bpt_nsaved = 0;

        if (nsaved > 2) {
                printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
                nsaved = 2;
        }

        for (i = 0; i < nsaved; ++i) {
                write_int(child, task_thread_info(child)->bpt_addr[i],
                          task_thread_info(child)->bpt_insn[i]);
        }
        return (nsaved != 0);
}

void user_enable_single_step(struct task_struct *child)
{
        /* Mark single stepping.  */
        task_thread_info(child)->bpt_nsaved = -1;
}

void user_disable_single_step(struct task_struct *child)
{
        ptrace_cancel_bpt(child);
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure the single step bit is not set.
 */
void ptrace_disable(struct task_struct *child)
{ 
        user_disable_single_step(child);
}

long arch_ptrace(struct task_struct *child, long request,
                 unsigned long addr, unsigned long data)
{
        unsigned long tmp;
        size_t copied;
        long ret;

        switch (request) {
        /* When I and D space are separate, these will need to be fixed.  */
        case PTRACE_PEEKTEXT: /* read word at location addr. */
        case PTRACE_PEEKDATA:
                copied = ptrace_access_vm(child, addr, &tmp, sizeof(tmp),
                                FOLL_FORCE);
                ret = -EIO;
                if (copied != sizeof(tmp))
                        break;
                
                force_successful_syscall_return();
                ret = tmp;
                break;

        /* Read register number ADDR. */
        case PTRACE_PEEKUSR:
                force_successful_syscall_return();
                ret = get_reg(child, addr);
                DBG(DBG_MEM, ("peek $%lu->%#lx\n", addr, ret));
                break;

        /* When I and D space are separate, this will have to be fixed.  */
        case PTRACE_POKETEXT: /* write the word at location addr. */
        case PTRACE_POKEDATA:
                ret = generic_ptrace_pokedata(child, addr, data);
                break;

        case PTRACE_POKEUSR: /* write the specified register */
                DBG(DBG_MEM, ("poke $%lu<-%#lx\n", addr, data));
                ret = put_reg(child, addr, data);
                break;
        default:
                ret = ptrace_request(child, request, addr, data);
                break;
        }
        return ret;
}

asmlinkage unsigned long syscall_trace_enter(void)
{
        unsigned long ret = 0;
        struct pt_regs *regs = current_pt_regs();
        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
            ptrace_report_syscall_entry(current_pt_regs()))
                ret = -1UL;
        audit_syscall_entry(regs->r0, regs->r16, regs->r17, regs->r18, regs->r19);
        return ret ?: current_pt_regs()->r0;
}

asmlinkage void
syscall_trace_leave(void)
{
        audit_syscall_exit(current_pt_regs());
        if (test_thread_flag(TIF_SYSCALL_TRACE))
                ptrace_report_syscall_exit(current_pt_regs(), 0);
}