OpenRISC: PTrace

/*

 * OpenRISC Linux

 *

 * Linux architectural port borrowing liberally from similar works of

 * others.  All original copyrights apply as per the original source

 * declaration.

 *

 * OpenRISC implementation:

 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>

 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>

 * et al.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 */

#ifndef __ASM_OPENRISC_PTRACE_H

#define __ASM_OPENRISC_PTRACE_H

#include <asm/spr_defs.h>

#ifndef __ASSEMBLY__

/*

 * This is the layout of the regset returned by the GETREGSET ptrace call

 */

struct user_regs_struct {

	/* GPR R0-R31... */

	unsigned long gpr[32];

	unsigned long pc;

	unsigned long sr;

	unsigned long pad1;

	unsigned long pad2;

};

#endif

#ifdef __KERNEL__

/*

 * Make kernel PTrace/register structures opaque to userspace... userspace can

 * access thread state via the regset mechanism.  This allows us a bit of

 * flexibility in how we order the registers on the stack, permitting some

 * optimizations like packing call-clobbered registers together so that

 * they share a cacheline (not done yet, though... future optimization).

 */

#ifndef __ASSEMBLY__

/*

 * This struct describes how the registers are laid out on the kernel stack

 * during a syscall or other kernel entry.

 *

 * This structure should always be cacheline aligned on the stack.

 * FIXME: I don't think that's the case right now.  The alignment is

 * taken care of elsewhere... head.S, process.c, etc.

 */

struct pt_regs {

	union {

		struct {

			/* Named registers */

			long  sr;	/* Stored in place of r0 */

			long  sp;	/* r1 */

		};

		struct {

			/* Old style */

			long offset[2];

			long gprs[30];

		};

		struct {

			/* New style */

			long gpr[32];

		};

	};

	long  pc;

	long  orig_gpr11;	/* For restarting system calls */

	long  syscallno;	/* Syscall number (used by strace) */

	long dummy;		/* Cheap alignment fix */

};

#endif /* __ASSEMBLY__ */

/* TODO: Rename this to REDZONE because that's what it is */

#define STACK_FRAME_OVERHEAD  128  /* size of minimum stack frame */

#define instruction_pointer(regs)	((regs)->pc)

#define user_mode(regs)			(((regs)->sr & SPR_SR_SM) == 0)

#define user_stack_pointer(regs)	((unsigned long)(regs)->sp)

#define profile_pc(regs)		instruction_pointer(regs)

/*

 * Offsets used by 'ptrace' system call interface.

 */

#define PT_SR         0

#define PT_SP         4

#define PT_GPR2       8

#define PT_GPR3       12

#define PT_GPR4       16

#define PT_GPR5       20

#define PT_GPR6       24

#define PT_GPR7       28

#define PT_GPR8       32

#define PT_GPR9       36

#define PT_GPR10      40

#define PT_GPR11      44

#define PT_GPR12      48

#define PT_GPR13      52

#define PT_GPR14      56

#define PT_GPR15      60

#define PT_GPR16      64

#define PT_GPR17      68

#define PT_GPR18      72

#define PT_GPR19      76

#define PT_GPR20      80

#define PT_GPR21      84

#define PT_GPR22      88

#define PT_GPR23      92

#define PT_GPR24      96

#define PT_GPR25      100

#define PT_GPR26      104

#define PT_GPR27      108

#define PT_GPR28      112

#define PT_GPR29      116

#define PT_GPR30      120

#define PT_GPR31      124

#define PT_PC	      128

#define PT_ORIG_GPR11 132

#define PT_SYSCALLNO  136

#endif /* __KERNEL__ */

#endif /* __ASM_OPENRISC_PTRACE_H */

/*

 * OpenRISC ptrace.c

 *

 * Linux architectural port borrowing liberally from similar works of

 * others.  All original copyrights apply as per the original source

 * declaration.

 *

 * Modifications for the OpenRISC architecture:

 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>

 * Copyright (C) 2005 Gyorgy Jeney <nog@bsemi.com>

 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>

 *

 *      This program is free software; you can redistribute it and/or

 *      modify it under the terms of the GNU General Public License

 *      as published by the Free Software Foundation; either version

 *      2 of the License, or (at your option) any later version.

 */

#include <stddef.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/string.h>

#include <linux/mm.h>

#include <linux/errno.h>

#include <linux/ptrace.h>

#include <linux/audit.h>

#include <linux/regset.h>

#include <linux/tracehook.h>

#include <linux/elf.h>

#include <asm/thread_info.h>

#include <asm/segment.h>

#include <asm/page.h>

#include <asm/pgtable.h>

#include <asm/system.h>

/*

 * Copy the thread state to a regset that can be interpreted by userspace.

 *

 * It doesn't matter what our internal pt_regs structure looks like.  The

 * important thing is that we export a consistent view of the thread state

 * to userspace.  As such, we need to make sure that the regset remains

 * ABI compatible as defined by the struct user_regs_struct:

 *

 * (Each item is a 32-bit word)

 * r0 = 0 (exported for clarity)

 * 31 GPRS r1-r31

 * PC (Program counter)

 * SR (Supervision register)

 */

static int genregs_get(struct task_struct *target,

		       const struct user_regset *regset,

		       unsigned int pos, unsigned int count,

		       void *kbuf, void __user * ubuf)

{

	const struct pt_regs *regs = task_pt_regs(target);

	int ret;

	/* r0 */

	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, 0, 4);

	if (!ret)

		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,

					  regs->gpr+1, 4, 4*32);

	if (!ret)

		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,

				  &regs->pc, 4*32, 4*33);

	if (!ret)

		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,

					  &regs->sr, 4*33, 4*34);

	if (!ret)

		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,

					       4*34, -1);

	return ret;

}

/*

 * Set the thread state from a regset passed in via ptrace

 */

static int genregs_set(struct task_struct *target,

		       const struct user_regset *regset,

		       unsigned int pos, unsigned int count,

		       const void *kbuf, const void __user * ubuf)

{

	struct pt_regs *regs = task_pt_regs(target);

	int ret;

	/* ignore r0 */

	ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, 0, 4);

	/* r1 - r31 */

	if (!ret)

		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,

					 regs->gpr+1, 4, 4*32);

	/* PC */

	if (!ret)

		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,

				 &regs->pc, 4*32, 4*33);

	/*

	 * Skip SR and padding... userspace isn't allowed to changes bits in

	 * the Supervision register

	 */

	if (!ret)

		ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,

						4*33, -1);

	return ret;

}

/*

 * Define the register sets available on OpenRISC under Linux

 */

enum or1k_regset {

	REGSET_GENERAL,

};

static const struct user_regset or1k_regsets[] = {

	[REGSET_GENERAL] = {

			    .core_note_type = NT_PRSTATUS,

			    .n = ELF_NGREG,

			    .size = sizeof(long),

			    .align = sizeof(long),

			    .get = genregs_get,

			    .set = genregs_set,

			    },

};

static const struct user_regset_view user_or1k_native_view = {

	.name = "or1k",

	.e_machine = EM_OPENRISC,

	.regsets = or1k_regsets,

	.n = ARRAY_SIZE(or1k_regsets),

};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)

{

	return &user_or1k_native_view;

}

/*

 * does not yet catch signals sent when the child dies.

 * in exit.c or in signal.c.

 */

/*

 * Called by kernel/ptrace.c when detaching..

 *

 * Make sure the single step bit is not set.

 */

void ptrace_disable(struct task_struct *child)

{

	pr_debug("ptrace_disable(): TODO\n");

	user_disable_single_step(child);

	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

}

long arch_ptrace(struct task_struct *child, long request, unsigned long addr,

		 unsigned long data)

{

	int ret;

	switch (request) {

	default:

		ret = ptrace_request(child, request, addr, data);

		break;

	}

	return ret;

}

/*

 * Notification of system call entry/exit

 * - triggered by current->work.syscall_trace

 */

asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)

{

	long ret = 0;

	if (test_thread_flag(TIF_SYSCALL_TRACE) &&

	    tracehook_report_syscall_entry(regs))

		/*

		 * Tracing decided this syscall should not happen.

		 * We'll return a bogus call number to get an ENOSYS

		 * error, but leave the original number in <something>.

		 */

		ret = -1L;

	/* Are these regs right??? */

	if (unlikely(current->audit_context))

		audit_syscall_entry(audit_arch(), regs->syscallno,

				    regs->gpr[3], regs->gpr[4],

				    regs->gpr[5], regs->gpr[6]);

	return ret ? : regs->syscallno;

}

asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)

{

	int step;

	if (unlikely(current->audit_context))

		audit_syscall_exit(AUDITSC_RESULT(regs->gpr[11]),

				   regs->gpr[11]);

	step = test_thread_flag(TIF_SINGLESTEP);

	if (step || test_thread_flag(TIF_SYSCALL_TRACE))

		tracehook_report_syscall_exit(regs, step);

}