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/*
* Kernel support for the ptrace() and syscall tracing interfaces.
*
* Copyright (C) 2000 Hewlett-Packard Co, Linuxcare Inc.
* Copyright (C) 2000 Matthew Wilcox <matthew@wil.cx>
* Copyright (C) 2000 David Huggins-Daines <dhd@debian.org>
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/offset.h>
/* These are used in entry.S, syscall_restore_rfi. We need to record the
* current stepping mode somewhere other than in PSW, because there is no
* concept of saving and restoring the users PSW over a syscall. We choose
* to use these two bits in task->ptrace. These bits must not clash with
* any PT_* defined in include/linux/sched.h, and must match with the bit
* tests in entry.S
*/
#define PT_SINGLESTEP 0x10000
#define PT_BLOCKSTEP 0x20000
/*
* Called by kernel/ptrace.c when detaching..
*
* Make sure single step bits etc are not set.
*/
void ptrace_disable(struct task_struct *child)
{
/* make sure the trap bits are not set */
pa_psw(child)->r = 0;
pa_psw(child)->t = 0;
pa_psw(child)->h = 0;
pa_psw(child)->l = 0;
}
long sys_ptrace(long request, pid_t pid, long addr, long data)
{
struct task_struct *child;
long 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) /* no messing around 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) {
if (request != PTRACE_KILL)
goto out_tsk;
}
if (child->p_pptr != current)
goto out_tsk;
switch (request) {
case PTRACE_PEEKTEXT: /* read word at location addr. */
case PTRACE_PEEKDATA: {
unsigned long tmp;
int copied;
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
ret = -EIO;
if (copied != sizeof(tmp))
goto out_tsk;
ret = put_user(tmp,(unsigned long *) data);
goto out_tsk;
}
/* 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 = 0;
if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
goto out_tsk;
ret = -EIO;
goto out_tsk;
/* Read the word at location addr in the USER area. This will need
to change when the kernel no longer saves all regs on a syscall. */
case PTRACE_PEEKUSR: {
unsigned long tmp;
ret = -EIO;
if ((addr & 3) || (unsigned long) addr >= sizeof(struct pt_regs))
goto out_tsk;
tmp = *(unsigned long *) ((char *) task_regs(child) + addr);
ret = put_user(tmp, (unsigned long *) data);
goto out_tsk;
}
/* Write the word at location addr in the USER area. This will need
to change when the kernel no longer saves all regs on a syscall.
FIXME. There is a problem at the moment in that r3-r18 are only
saved if the process is ptraced on syscall entry, and even then
those values are overwritten by actual register values on syscall
exit. */
case PTRACE_POKEUSR:
ret = -EIO;
if ((addr & 3) || (unsigned long) addr >= sizeof(struct pt_regs))
goto out_tsk;
/* XXX This test probably needs adjusting. We probably want to
* allow writes to some bits of PSW, and may want to block writes
* to (some) space registers. Some register values written here
* may be ignored in entry.S:syscall_restore_rfi; e.g. iaoq is
* written with r31/r31+4, and not with the values in pt_regs.
*/
/* Allow writing of gr1-gr31, fr*, sr*, iasq*, iaoq*, sar */
if (addr == PT_PSW || (addr > PT_IAOQ1 && addr != PT_SAR))
goto out_tsk;
*(unsigned long *) ((char *) task_regs(child) + addr) = data;
ret = 0;
goto out_tsk;
case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
case PTRACE_CONT:
ret = -EIO;
if ((unsigned long) data > _NSIG)
goto out_tsk;
child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
if (request == PTRACE_SYSCALL)
child->ptrace |= PT_TRACESYS;
else
child->ptrace &= ~PT_TRACESYS;
child->exit_code = data;
goto out_wake_notrap;
case PTRACE_KILL:
/*
* 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.
*/
if (child->state == TASK_ZOMBIE) /* already dead */
goto out_tsk;
child->exit_code = SIGKILL;
goto out_wake_notrap;
case PTRACE_SINGLEBLOCK:
ret = -EIO;
if ((unsigned long) data > _NSIG)
goto out_tsk;
child->ptrace &= ~(PT_TRACESYS|PT_SINGLESTEP);
child->ptrace |= PT_BLOCKSTEP;
child->exit_code = data;
/* Enable taken branch trap. */
pa_psw(child)->r = 0;
pa_psw(child)->t = 1;
pa_psw(child)->h = 0;
pa_psw(child)->l = 0;
goto out_wake;
case PTRACE_SINGLESTEP:
ret = -EIO;
if ((unsigned long) data > _NSIG)
goto out_tsk;
child->ptrace &= ~(PT_TRACESYS|PT_BLOCKSTEP);
child->ptrace |= PT_SINGLESTEP;
child->exit_code = data;
if (pa_psw(child)->n) {
struct siginfo si;
/* Nullified, just crank over the queue. */
task_regs(child)->iaoq[0] = task_regs(child)->iaoq[1];
task_regs(child)->iasq[0] = task_regs(child)->iasq[1];
task_regs(child)->iaoq[1] = task_regs(child)->iaoq[0] + 4;
pa_psw(child)->n = 0;
pa_psw(child)->x = 0;
pa_psw(child)->y = 0;
pa_psw(child)->z = 0;
pa_psw(child)->b = 0;
pa_psw(child)->r = 0;
pa_psw(child)->t = 0;
pa_psw(child)->h = 0;
pa_psw(child)->l = 0;
/* Don't wake up the child, but let the
parent know something happened. */
si.si_code = TRAP_TRACE;
si.si_addr = (void *) (task_regs(child)->iaoq[0] & ~3);
si.si_signo = SIGTRAP;
si.si_errno = 0;
force_sig_info(SIGTRAP, &si, child);
//notify_parent(child, SIGCHLD);
//ret = 0;
goto out_wake;
}
/* Enable recovery counter traps. The recovery counter
* itself will be set to zero on a task switch. If the
* task is suspended on a syscall then the syscall return
* path will overwrite the recovery counter with a suitable
* value such that it traps once back in user space. We
* disable interrupts in the childs PSW here also, to avoid
* interrupts while the recovery counter is decrementing.
*/
pa_psw(child)->r = 1;
pa_psw(child)->t = 0;
pa_psw(child)->h = 0;
pa_psw(child)->l = 0;
/* give it a chance to run. */
goto out_wake;
case PTRACE_DETACH:
ret = ptrace_detach(child, data);
goto out_tsk;
default:
ret = -EIO;
goto out_tsk;
}
out_wake_notrap:
/* make sure the trap bits are not set */
pa_psw(child)->r = 0;
pa_psw(child)->t = 0;
pa_psw(child)->h = 0;
pa_psw(child)->l = 0;
out_wake:
wake_up_process(child);
ret = 0;
out_tsk:
free_task_struct(child);
out:
unlock_kernel();
return ret;
}
void syscall_trace(void)
{
if ((current->ptrace & (PT_PTRACED|PT_TRACESYS)) !=
(PT_PTRACED|PT_TRACESYS))
return;
current->exit_code = SIGTRAP;
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;
}
}
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