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/*
* linux/arch/arm/kernel/ptrace.c
*
* By Ross Biro 1/23/92
* edited by Linus Torvalds
* ARM modifications Copyright (C) 2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include "ptrace.h"
#define REG_PC 15
#define REG_PSR 16
/*
* does not yet catch signals sent when the child dies.
* in exit.c or in signal.c.
*/
/*
* Breakpoint SWI instruction: SWI &9F0001
*/
#define BREAKINST 0xef9f0001
/*
* Get the address of the live pt_regs for the specified task.
* These are saved onto the top kernel stack when the process
* is not running.
*/
static inline struct pt_regs *
get_user_regs(struct task_struct *task)
{
return (struct pt_regs *)
((unsigned long)task + 8192 - sizeof(struct pt_regs));
}
/*
* this routine will get a word off of the processes privileged stack.
* the offset is how far from the base addr as stored in the THREAD.
* this routine assumes that all the privileged stacks are in our
* data space.
*/
static inline long get_stack_long(struct task_struct *task, int offset)
{
return get_user_regs(task)->uregs[offset];
}
/*
* this routine will put a word on the processes privileged stack.
* the offset is how far from the base addr as stored in the THREAD.
* this routine assumes that all the privileged stacks are in our
* data space.
*/
static inline int
put_stack_long(struct task_struct *task, int offset, long data)
{
struct pt_regs newregs, *regs = get_user_regs(task);
int ret = -EINVAL;
newregs = *regs;
newregs.uregs[offset] = data;
if (valid_user_regs(&newregs)) {
regs->uregs[offset] = data;
ret = 0;
}
return ret;
}
static inline int
read_tsk_long(struct task_struct *child, unsigned long addr, unsigned long *res)
{
int copied;
copied = access_process_vm(child, addr, res, sizeof(*res), 0);
return copied != sizeof(*res) ? -EIO : 0;
}
static inline int
write_tsk_long(struct task_struct *child, unsigned long addr, unsigned long val)
{
int copied;
copied = access_process_vm(child, addr, &val, sizeof(val), 1);
return copied != sizeof(val) ? -EIO : 0;
}
/*
* Get value of register `rn' (in the instruction)
*/
static unsigned long
ptrace_getrn(struct task_struct *child, unsigned long insn)
{
unsigned int reg = (insn >> 16) & 15;
unsigned long val;
val = get_stack_long(child, reg);
if (reg == 15)
val = pc_pointer(val + 8);
return val;
}
/*
* Get value of operand 2 (in an ALU instruction)
*/
static unsigned long
ptrace_getaluop2(struct task_struct *child, unsigned long insn)
{
unsigned long val;
int shift;
int type;
if (insn & 1 << 25) {
val = insn & 255;
shift = (insn >> 8) & 15;
type = 3;
} else {
val = get_stack_long (child, insn & 15);
if (insn & (1 << 4))
shift = (int)get_stack_long (child, (insn >> 8) & 15);
else
shift = (insn >> 7) & 31;
type = (insn >> 5) & 3;
}
switch (type) {
case 0: val <<= shift; break;
case 1: val >>= shift; break;
case 2:
val = (((signed long)val) >> shift);
break;
case 3:
val = (val >> shift) | (val << (32 - shift));
break;
}
return val;
}
/*
* Get value of operand 2 (in a LDR instruction)
*/
static unsigned long
ptrace_getldrop2(struct task_struct *child, unsigned long insn)
{
unsigned long val;
int shift;
int type;
val = get_stack_long(child, insn & 15);
shift = (insn >> 7) & 31;
type = (insn >> 5) & 3;
switch (type) {
case 0: val <<= shift; break;
case 1: val >>= shift; break;
case 2:
val = (((signed long)val) >> shift);
break;
case 3:
val = (val >> shift) | (val << (32 - shift));
break;
}
return val;
}
static unsigned long
get_branch_address(struct task_struct *child, unsigned long pc, unsigned long insn)
{
unsigned long alt = 0;
switch (insn & 0x0e000000) {
case 0x00000000:
case 0x02000000: {
/*
* data processing
*/
long aluop1, aluop2, ccbit;
if ((insn & 0xf000) != 0xf000)
break;
aluop1 = ptrace_getrn(child, insn);
aluop2 = ptrace_getaluop2(child, insn);
ccbit = get_stack_long(child, REG_PSR) & CC_C_BIT ? 1 : 0;
switch (insn & 0x01e00000) {
case 0x00000000: alt = aluop1 & aluop2; break;
case 0x00200000: alt = aluop1 ^ aluop2; break;
case 0x00400000: alt = aluop1 - aluop2; break;
case 0x00600000: alt = aluop2 - aluop1; break;
case 0x00800000: alt = aluop1 + aluop2; break;
case 0x00a00000: alt = aluop1 + aluop2 + ccbit; break;
case 0x00c00000: alt = aluop1 - aluop2 + ccbit; break;
case 0x00e00000: alt = aluop2 - aluop1 + ccbit; break;
case 0x01800000: alt = aluop1 | aluop2; break;
case 0x01a00000: alt = aluop2; break;
case 0x01c00000: alt = aluop1 & ~aluop2; break;
case 0x01e00000: alt = ~aluop2; break;
}
break;
}
case 0x04000000:
case 0x06000000:
/*
* ldr
*/
if ((insn & 0x0010f000) == 0x0010f000) {
unsigned long base;
base = ptrace_getrn(child, insn);
if (insn & 1 << 24) {
long aluop2;
if (insn & 0x02000000)
aluop2 = ptrace_getldrop2(child, insn);
else
aluop2 = insn & 0xfff;
if (insn & 1 << 23)
base += aluop2;
else
base -= aluop2;
}
if (read_tsk_long(child, base, &alt) == 0)
alt = pc_pointer(alt);
}
break;
case 0x08000000:
/*
* ldm
*/
if ((insn & 0x00108000) == 0x00108000) {
unsigned long base;
unsigned int nr_regs;
if (insn & (1 << 23)) {
nr_regs = insn & 65535;
nr_regs = (nr_regs & 0x5555) + ((nr_regs & 0xaaaa) >> 1);
nr_regs = (nr_regs & 0x3333) + ((nr_regs & 0xcccc) >> 2);
nr_regs = (nr_regs & 0x0707) + ((nr_regs & 0x7070) >> 4);
nr_regs = (nr_regs & 0x000f) + ((nr_regs & 0x0f00) >> 8);
nr_regs <<= 2;
if (!(insn & (1 << 24)))
nr_regs -= 4;
} else {
if (insn & (1 << 24))
nr_regs = -4;
else
nr_regs = 0;
}
base = ptrace_getrn(child, insn);
if (read_tsk_long(child, base + nr_regs, &alt) == 0)
alt = pc_pointer (alt);
break;
}
break;
case 0x0a000000: {
/*
* bl or b
*/
signed long displ;
/* It's a branch/branch link: instead of trying to
* figure out whether the branch will be taken or not,
* we'll put a breakpoint at both locations. This is
* simpler, more reliable, and probably not a whole lot
* slower than the alternative approach of emulating the
* branch.
*/
displ = (insn & 0x00ffffff) << 8;
displ = (displ >> 6) + 8;
if (displ != 0 && displ != 4)
alt = pc + displ;
}
break;
}
return alt;
}
static int
add_breakpoint(struct task_struct *child, struct debug_info *dbg, unsigned long addr)
{
int nr = dbg->nsaved;
int res = -EINVAL;
if (nr < 2) {
res = read_tsk_long(child, addr, &dbg->bp[nr].insn);
if (res == 0)
res = write_tsk_long(child, addr, BREAKINST);
if (res == 0) {
dbg->bp[nr].address = addr;
dbg->nsaved += 1;
}
} else
printk(KERN_ERR "ptrace: too many breakpoints\n");
return res;
}
int ptrace_set_bpt(struct task_struct *child)
{
struct pt_regs *regs;
unsigned long pc, insn;
int res;
regs = get_user_regs(child);
pc = instruction_pointer(regs);
res = read_tsk_long(child, pc, &insn);
if (!res) {
struct debug_info *dbg = &child->thread.debug;
unsigned long alt;
dbg->nsaved = 0;
alt = get_branch_address(child, pc, insn);
if (alt)
res = add_breakpoint(child, dbg, alt);
/*
* Note that we ignore the result of setting the above
* breakpoint since it may fail. When it does, this is
* not so much an error, but a forewarning that we may
* be receiving a prefetch abort shortly.
*
* If we don't set this breakpoint here, then we can
* loose control of the thread during single stepping.
*/
if (!alt || predicate(insn) != PREDICATE_ALWAYS)
res = add_breakpoint(child, dbg, pc + 4);
}
return res;
}
/*
* Ensure no single-step breakpoint is pending. Returns non-zero
* value if child was being single-stepped.
*/
void __ptrace_cancel_bpt(struct task_struct *child)
{
struct debug_info *dbg = &child->thread.debug;
int i, nsaved = dbg->nsaved;
dbg->nsaved = 0;
if (nsaved > 2) {
printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
nsaved = 2;
}
for (i = 0; i < nsaved; i++) {
unsigned long tmp;
read_tsk_long(child, dbg->bp[i].address, &tmp);
write_tsk_long(child, dbg->bp[i].address, dbg->bp[i].insn);
if (tmp != BREAKINST)
printk(KERN_ERR "ptrace_cancel_bpt: weirdness\n");
}
}
/*
* Called by kernel/ptrace.c when detaching..
*
* Make sure the single step bit is not set.
*/
void ptrace_disable(struct task_struct *child)
{
__ptrace_cancel_bpt(child);
}
static int do_ptrace(int request, struct task_struct *child, long addr, long data)
{
unsigned long tmp;
int ret;
switch (request) {
/*
* read word at location "addr" in the child process.
*/
case PTRACE_PEEKTEXT:
case PTRACE_PEEKDATA:
ret = read_tsk_long(child, addr, &tmp);
if (!ret)
ret = put_user(tmp, (unsigned long *) data);
break;
/*
* read the word at location "addr" in the user registers.
*/
case PTRACE_PEEKUSR:
ret = -EIO;
if ((addr & 3) || addr < 0 || addr >= sizeof(struct user))
break;
tmp = 0; /* Default return condition */
if (addr < sizeof(struct pt_regs))
tmp = get_stack_long(child, (int)addr >> 2);
ret = put_user(tmp, (unsigned long *)data);
break;
/*
* write the word at location addr.
*/
case PTRACE_POKETEXT:
case PTRACE_POKEDATA:
ret = write_tsk_long(child, addr, data);
break;
/*
* write the word at location addr in the user registers.
*/
case PTRACE_POKEUSR:
ret = -EIO;
if ((addr & 3) || addr < 0 || addr >= sizeof(struct user))
break;
if (addr < sizeof(struct pt_regs))
ret = put_stack_long(child, (int)addr >> 2, data);
break;
/*
* continue/restart and stop at next (return from) syscall
*/
case PTRACE_SYSCALL:
case PTRACE_CONT:
ret = -EIO;
if ((unsigned long) data > _NSIG)
break;
if (request == PTRACE_SYSCALL)
child->ptrace |= PT_TRACESYS;
else
child->ptrace &= ~PT_TRACESYS;
child->exit_code = data;
/* make sure single-step breakpoint is gone. */
__ptrace_cancel_bpt(child);
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:
/* already dead */
ret = 0;
if (child->state == TASK_ZOMBIE)
break;
child->exit_code = SIGKILL;
/* make sure single-step breakpoint is gone. */
__ptrace_cancel_bpt(child);
wake_up_process(child);
ret = 0;
break;
/*
* execute single instruction.
*/
case PTRACE_SINGLESTEP:
ret = -EIO;
if ((unsigned long) data > _NSIG)
break;
child->thread.debug.nsaved = -1;
child->ptrace &= ~PT_TRACESYS;
child->exit_code = data;
/* give it a chance to run. */
wake_up_process(child);
ret = 0;
break;
/*
* detach a process that was attached.
*/
case PTRACE_DETACH:
ret = ptrace_detach(child, data);
break;
/*
* Get all gp regs from the child.
*/
case PTRACE_GETREGS: {
struct pt_regs *regs = get_user_regs(child);
ret = 0;
if (copy_to_user((void *)data, regs,
sizeof(struct pt_regs)))
ret = -EFAULT;
break;
}
/*
* Set all gp regs in the child.
*/
case PTRACE_SETREGS: {
struct pt_regs newregs;
ret = -EFAULT;
if (copy_from_user(&newregs, (void *)data,
sizeof(struct pt_regs)) == 0) {
struct pt_regs *regs = get_user_regs(child);
ret = -EINVAL;
if (valid_user_regs(&newregs)) {
*regs = newregs;
ret = 0;
}
}
break;
}
/*
* Get the child FPU state.
*/
case PTRACE_GETFPREGS:
ret = -EIO;
if (!access_ok(VERIFY_WRITE, (void *)data, sizeof(struct user_fp)))
break;
/* we should check child->used_math here */
ret = __copy_to_user((void *)data, &child->thread.fpstate,
sizeof(struct user_fp)) ? -EFAULT : 0;
break;
/*
* Set the child FPU state.
*/
case PTRACE_SETFPREGS:
ret = -EIO;
if (!access_ok(VERIFY_READ, (void *)data, sizeof(struct user_fp)))
break;
child->used_math = 1;
ret = __copy_from_user(&child->thread.fpstate, (void *)data,
sizeof(struct user_fp)) ? -EFAULT : 0;
break;
default:
ret = -EIO;
break;
}
return ret;
}
asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
{
struct task_struct *child;
int ret;
lock_kernel();
ret = -EPERM;
if (request == PTRACE_TRACEME) {
/* are we already being traced? */
if (current->ptrace & PT_PTRACED)
goto out;
/* set the ptrace bit in the process flags. */
current->ptrace |= PT_PTRACED;
ret = 0;
goto out;
}
ret = -ESRCH;
read_lock(&tasklist_lock);
child = find_task_by_pid(pid);
if (child)
get_task_struct(child);
read_unlock(&tasklist_lock);
if (!child)
goto out;
ret = -EPERM;
if (pid == 1) /* you may not mess with init */
goto out_tsk;
if (request == PTRACE_ATTACH) {
ret = ptrace_attach(child);
goto out_tsk;
}
ret = -ESRCH;
if (!(child->ptrace & PT_PTRACED))
goto out_tsk;
if (child->state != TASK_STOPPED && request != PTRACE_KILL)
goto out_tsk;
if (child->p_pptr != current)
goto out_tsk;
ret = do_ptrace(request, child, addr, data);
out_tsk:
free_task_struct(child);
out:
unlock_kernel();
return ret;
}
asmlinkage void syscall_trace(int why, struct pt_regs *regs)
{
unsigned long ip;
if ((current->ptrace & (PT_PTRACED|PT_TRACESYS))
!= (PT_PTRACED|PT_TRACESYS))
return;
/*
* Save IP. IP is used to denote syscall entry/exit:
* IP = 0 -> entry, = 1 -> exit
*/
ip = regs->ARM_ip;
regs->ARM_ip = why;
/* the 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
current->exit_code = SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
? 0x80 : 0);
current->state = TASK_STOPPED;
notify_parent(current, SIGCHLD);
schedule();
/*
* 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;
}
regs->ARM_ip = ip;
}
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