ptrace.c

/*
 * 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) 1992 Ross Biro
 * Copyright (C) Linus Torvalds
 * Copyright (C) 1994, 95, 96, 97, 98, 2000 Ralf Baechle
 * Copyright (C) 1996 David S. Miller
 * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 1999 MIPS Technologies, Inc.
 * Copyright (C) 2000 Ulf Carlsson
 *
 * At this time Linux/MIPS64 only supports syscall tracing, even for 32-bit
 * binaries.
 */
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/smp.h>
#include <linux/user.h>
#include <linux/security.h>
#include <linux/audit.h>
#include <linux/seccomp.h>

#include <asm/byteorder.h>
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/bootinfo.h>
#include <asm/reg.h>

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
	/* Nothing to do.. */
}

/*
 * Read a general register set.  We always use the 64-bit format, even
 * for 32-bit kernels and for 32-bit processes on a 64-bit kernel.
 * Registers are sign extended to fill the available space.
 */
int ptrace_getregs (struct task_struct *child, __s64 __user *data)
{
	struct pt_regs *regs;
	int i;

	if (!access_ok(VERIFY_WRITE, data, 38 * 8))
		return -EIO;

	regs = task_pt_regs(child);

	for (i = 0; i < 32; i++)
		__put_user (regs->regs[i], data + i);
	__put_user (regs->lo, data + EF_LO - EF_R0);
	__put_user (regs->hi, data + EF_HI - EF_R0);
	__put_user (regs->cp0_epc, data + EF_CP0_EPC - EF_R0);
	__put_user (regs->cp0_badvaddr, data + EF_CP0_BADVADDR - EF_R0);
	__put_user (regs->cp0_status, data + EF_CP0_STATUS - EF_R0);
	__put_user (regs->cp0_cause, data + EF_CP0_CAUSE - EF_R0);

	return 0;
}

/*
 * Write a general register set.  As for PTRACE_GETREGS, we always use
 * the 64-bit format.  On a 32-bit kernel only the lower order half
 * (according to endianness) will be used.
 */
int ptrace_setregs (struct task_struct *child, __s64 __user *data)
{
	struct pt_regs *regs;
	int i;

	if (!access_ok(VERIFY_READ, data, 38 * 8))
		return -EIO;

	regs = task_pt_regs(child);

	for (i = 0; i < 32; i++)
		__get_user (regs->regs[i], data + i);
	__get_user (regs->lo, data + EF_LO - EF_R0);
	__get_user (regs->hi, data + EF_HI - EF_R0);
	__get_user (regs->cp0_epc, data + EF_CP0_EPC - EF_R0);

	/* badvaddr, status, and cause may not be written.  */

	return 0;
}

int ptrace_getfpregs (struct task_struct *child, __u32 __user *data)
{
	int i;
	unsigned int tmp;

	if (!access_ok(VERIFY_WRITE, data, 33 * 8))
		return -EIO;

	if (tsk_used_math(child)) {
		fpureg_t *fregs = get_fpu_regs(child);
		for (i = 0; i < 32; i++)
			__put_user (fregs[i], i + (__u64 __user *) data);
	} else {
		for (i = 0; i < 32; i++)
			__put_user ((__u64) -1, i + (__u64 __user *) data);
	}

	__put_user (child->thread.fpu.fcr31, data + 64);

	preempt_disable();
	if (cpu_has_fpu) {
		unsigned int flags;

		if (cpu_has_mipsmt) {
			unsigned int vpflags = dvpe();
			flags = read_c0_status();
			__enable_fpu();
			__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
			write_c0_status(flags);
			evpe(vpflags);
		} else {
			flags = read_c0_status();
			__enable_fpu();
			__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
			write_c0_status(flags);
		}
	} else {
		tmp = 0;
	}
	preempt_enable();
	__put_user (tmp, data + 65);

	return 0;
}

int ptrace_setfpregs (struct task_struct *child, __u32 __user *data)
{
	fpureg_t *fregs;
	int i;

	if (!access_ok(VERIFY_READ, data, 33 * 8))
		return -EIO;

	fregs = get_fpu_regs(child);

	for (i = 0; i < 32; i++)
		__get_user (fregs[i], i + (__u64 __user *) data);

	__get_user (child->thread.fpu.fcr31, data + 64);

	/* FIR may not be written.  */

	return 0;
}

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
	int 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:
		ret = generic_ptrace_peekdata(child, addr, data);
		break;

	/* Read the word at location addr in the USER area. */
	case PTRACE_PEEKUSR: {
		struct pt_regs *regs;
		unsigned long tmp = 0;

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

		switch (addr) {
		case 0 ... 31:
			tmp = regs->regs[addr];
			break;
		case FPR_BASE ... FPR_BASE + 31:
			if (tsk_used_math(child)) {
				fpureg_t *fregs = get_fpu_regs(child);

#ifdef CONFIG_32BIT
				/*
				 * The odd registers are actually the high
				 * order bits of the values stored in the even
				 * registers - unless we're using r2k_switch.S.
				 */
				if (addr & 1)
					tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
				else
					tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
#endif
#ifdef CONFIG_64BIT
				tmp = fregs[addr - FPR_BASE];
#endif
			} else {
				tmp = -1;	/* FP not yet used  */
			}
			break;
		case PC:
			tmp = regs->cp0_epc;
			break;
		case CAUSE:
			tmp = regs->cp0_cause;
			break;
		case BADVADDR:
			tmp = regs->cp0_badvaddr;
			break;
		case MMHI:
			tmp = regs->hi;
			break;
		case MMLO:
			tmp = regs->lo;
			break;
#ifdef CONFIG_CPU_HAS_SMARTMIPS
		case ACX:
			tmp = regs->acx;
			break;
#endif
		case FPC_CSR:
			tmp = child->thread.fpu.fcr31;
			break;
		case FPC_EIR: {	/* implementation / version register */
			unsigned int flags;
#ifdef CONFIG_MIPS_MT_SMTC
			unsigned int irqflags;
			unsigned int mtflags;
#endif /* CONFIG_MIPS_MT_SMTC */

			preempt_disable();
			if (!cpu_has_fpu) {
				preempt_enable();
				break;
			}

#ifdef CONFIG_MIPS_MT_SMTC
			/* Read-modify-write of Status must be atomic */
			local_irq_save(irqflags);
			mtflags = dmt();
#endif /* CONFIG_MIPS_MT_SMTC */
			if (cpu_has_mipsmt) {
				unsigned int vpflags = dvpe();
				flags = read_c0_status();
				__enable_fpu();
				__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
				write_c0_status(flags);
				evpe(vpflags);
			} else {
				flags = read_c0_status();
				__enable_fpu();
				__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
				write_c0_status(flags);
			}
#ifdef CONFIG_MIPS_MT_SMTC
			emt(mtflags);
			local_irq_restore(irqflags);
#endif /* CONFIG_MIPS_MT_SMTC */
			preempt_enable();
			break;
		}
		case DSP_BASE ... DSP_BASE + 5: {
			dspreg_t *dregs;

			if (!cpu_has_dsp) {
				tmp = 0;
				ret = -EIO;
				goto out;
			}
			dregs = __get_dsp_regs(child);
			tmp = (unsigned long) (dregs[addr - DSP_BASE]);
			break;
		}
		case DSP_CONTROL:
			if (!cpu_has_dsp) {
				tmp = 0;
				ret = -EIO;
				goto out;
			}
			tmp = child->thread.dsp.dspcontrol;
			break;
		default:
			tmp = 0;
			ret = -EIO;
			goto out;
		}
		ret = put_user(tmp, (unsigned long __user *) data);
		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: {
		struct pt_regs *regs;
		ret = 0;
		regs = task_pt_regs(child);

		switch (addr) {
		case 0 ... 31:
			regs->regs[addr] = data;
			break;
		case FPR_BASE ... FPR_BASE + 31: {
			fpureg_t *fregs = get_fpu_regs(child);

			if (!tsk_used_math(child)) {
				/* FP not yet used  */
				memset(&child->thread.fpu, ~0,
				       sizeof(child->thread.fpu));
				child->thread.fpu.fcr31 = 0;
			}
#ifdef CONFIG_32BIT
			/*
			 * The odd registers are actually the high order bits
			 * of the values stored in the even registers - unless
			 * we're using r2k_switch.S.
			 */
			if (addr & 1) {
				fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
				fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
			} else {
				fregs[addr - FPR_BASE] &= ~0xffffffffLL;
				fregs[addr - FPR_BASE] |= data;
			}
#endif
#ifdef CONFIG_64BIT
			fregs[addr - FPR_BASE] = data;
#endif
			break;
		}
		case PC:
			regs->cp0_epc = data;
			break;
		case MMHI:
			regs->hi = data;
			break;
		case MMLO:
			regs->lo = data;
			break;
#ifdef CONFIG_CPU_HAS_SMARTMIPS
		case ACX:
			regs->acx = data;
			break;
#endif
		case FPC_CSR:
			child->thread.fpu.fcr31 = data;
			break;
		case DSP_BASE ... DSP_BASE + 5: {
			dspreg_t *dregs;

			if (!cpu_has_dsp) {
				ret = -EIO;
				break;
			}

			dregs = __get_dsp_regs(child);
			dregs[addr - DSP_BASE] = data;
			break;
		}
		case DSP_CONTROL:
			if (!cpu_has_dsp) {
				ret = -EIO;
				break;
			}
			child->thread.dsp.dspcontrol = data;
			break;
		default:
			/* The rest are not allowed. */
			ret = -EIO;
			break;
		}
		break;
		}

	case PTRACE_GETREGS:
		ret = ptrace_getregs (child, (__u64 __user *) data);
		break;

	case PTRACE_SETREGS:
		ret = ptrace_setregs (child, (__u64 __user *) data);
		break;

	case PTRACE_GETFPREGS:
		ret = ptrace_getfpregs (child, (__u32 __user *) data);
		break;

	case PTRACE_SETFPREGS:
		ret = ptrace_setfpregs (child, (__u32 __user *) data);
		break;

	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
	case PTRACE_CONT: { /* restart after signal. */
		ret = -EIO;
		if (!valid_signal(data))
			break;
		if (request == PTRACE_SYSCALL) {
			set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		}
		else {
			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		}
		child->exit_code = data;
		wake_up_process(child);
		ret = 0;
		break;
	}

	/*
	 * make the child exit.  Best I can do is send it a sigkill.
	 * perhaps it should be put in the status that it wants to
	 * exit.
	 */
	case PTRACE_KILL:
		ret = 0;
		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
			break;
		child->exit_code = SIGKILL;
		wake_up_process(child);
		break;

	case PTRACE_DETACH: /* detach a process that was attached. */
		ret = ptrace_detach(child, data);
		break;

	case PTRACE_GET_THREAD_AREA:
		ret = put_user(task_thread_info(child)->tp_value,
				(unsigned long __user *) data);
		break;

	default:
		ret = ptrace_request(child, request, addr, data);
		break;
	}
 out:
	return ret;
}

static inline int audit_arch(void)
{
	int arch = EM_MIPS;
#ifdef CONFIG_64BIT
	arch |=  __AUDIT_ARCH_64BIT;
#endif
#if defined(__LITTLE_ENDIAN)
	arch |=  __AUDIT_ARCH_LE;
#endif
	return arch;
}

/*
 * Notification of system call entry/exit
 * - triggered by current->work.syscall_trace
 */
asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
{
	/* do the secure computing check first */
	if (!entryexit)
		secure_computing(regs->regs[0]);

	if (unlikely(current->audit_context) && entryexit)
		audit_syscall_exit(AUDITSC_RESULT(regs->regs[2]),
		                   regs->regs[2]);

	if (!(current->ptrace & PT_PTRACED))
		goto out;

	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		goto out;

	/* The 0x80 provides a way for the tracing parent to distinguish
	   between a syscall stop and SIGTRAP delivery */
	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ?
	                         0x80 : 0));

	/*
	 * this isn't the same as continuing with a signal, but it will do
	 * for normal use.  strace only continues with a signal if the
	 * stopping signal is not SIGTRAP.  -brl
	 */
	if (current->exit_code) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}

out:
	if (unlikely(current->audit_context) && !entryexit)
		audit_syscall_entry(audit_arch(), regs->regs[0],
				    regs->regs[4], regs->regs[5],
				    regs->regs[6], regs->regs[7]);
}