blob: ddf1cc9b1320c356f6bbf551b6b6ec013caf457c [file] [log] [blame]
/*
* 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 <linux/personality.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
/* PSW bits we allow the debugger to modify */
#define USER_PSW_BITS (PSW_N | PSW_V | PSW_CB)
#undef DEBUG_PTRACE
#ifdef DEBUG_PTRACE
#define DBG(x) printk x
#else
#define DBG(x)
#endif
#ifdef __LP64__
#define CHILD_IS_32BIT (child->personality == PER_LINUX_32BIT)
/* This function is needed to translate 32 bit pt_regs offsets in to
* 64 bit pt_regs offsets. For example, a 32 bit gdb under a 64 bit kernel
* will request offset 12 if it wants gr3, but the lower 32 bits of
* the 64 bit kernels view of gr3 will be at offset 28 (3*8 + 4).
* This code relies on a 32 bit pt_regs being comprised of 32 bit values
* except for the fp registers which (a) are 64 bits, and (b) follow
* the gr registers at the start of pt_regs. The 32 bit pt_regs should
* be half the size of the 64 bit pt_regs, plus 32*4 to allow for fr[]
* being 64 bit in both cases.
*/
static long translate_usr_offset(long offset)
{
if (offset < 0)
return -1;
else if (offset <= 32*4) /* gr[0..31] */
return offset * 2 + 4;
else if (offset <= 32*4+32*8) /* gr[0..31] + fr[0..31] */
return offset + 32*4;
else if (offset < sizeof(struct pt_regs)/2 + 32*4)
return offset * 2 + 4 - 32*8;
else
return -1;
}
#endif
/*
* 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;
#ifdef DEBUG_PTRACE
long oaddr=addr, odata=data;
#endif
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: {
int copied;
#ifdef __LP64__
if (CHILD_IS_32BIT) {
unsigned int tmp;
addr &= 0xffffffffL;
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
ret = -EIO;
if (copied != sizeof(tmp))
goto out_tsk;
ret = put_user(tmp,(unsigned int *) data);
DBG(("sys_ptrace(PEEK%s, %d, %lx, %lx) returning %ld, data %x\n",
request == PTRACE_PEEKTEXT ? "TEXT" : "DATA",
pid, oaddr, odata, ret, tmp));
}
else
#endif
{
unsigned long tmp;
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;
#ifdef __LP64__
if (CHILD_IS_32BIT) {
unsigned int tmp = (unsigned int)data;
DBG(("sys_ptrace(POKE%s, %d, %lx, %lx)\n",
request == PTRACE_POKETEXT ? "TEXT" : "DATA",
pid, oaddr, odata));
addr &= 0xffffffffL;
if (access_process_vm(child, addr, &tmp, sizeof(tmp), 1) == sizeof(tmp))
goto out_tsk;
}
else
#endif
{
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. For ptraced
processes, the kernel saves all regs on a syscall. */
case PTRACE_PEEKUSR: {
ret = -EIO;
#ifdef __LP64__
if (CHILD_IS_32BIT) {
unsigned int tmp;
if (addr & (sizeof(int)-1))
goto out_tsk;
if ((addr = translate_usr_offset(addr)) < 0)
goto out_tsk;
tmp = *(unsigned int *) ((char *) task_regs(child) + addr);
ret = put_user(tmp, (unsigned int *) data);
DBG(("sys_ptrace(PEEKUSR, %d, %lx, %lx) returning %ld, addr %lx, data %x\n",
pid, oaddr, odata, ret, addr, tmp));
}
else
#endif
{
unsigned long tmp;
if ((addr & (sizeof(long)-1)) || (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;
/* 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.
*/
/* PT_PSW=0, so this is valid for 32 bit processes under 64
* bit kernels.
*/
if (addr == PT_PSW) {
/* PT_PSW=0, so this is valid for 32 bit processes
* under 64 bit kernels.
*
* Allow writing to Nullify, Divide-step-correction,
* and carry/borrow bits.
* BEWARE, if you set N, and then single step, it wont
* stop on the nullified instruction.
*/
DBG(("sys_ptrace(POKEUSR, %d, %lx, %lx)\n",
pid, oaddr, odata));
data &= USER_PSW_BITS;
task_regs(child)->gr[0] &= ~USER_PSW_BITS;
task_regs(child)->gr[0] |= data;
ret = 0;
goto out_tsk;
}
#ifdef __LP64__
if (CHILD_IS_32BIT) {
if (addr & (sizeof(int)-1))
goto out_tsk;
if ((addr = translate_usr_offset(addr)) < 0)
goto out_tsk;
DBG(("sys_ptrace(POKEUSR, %d, %lx, %lx) addr %lx\n",
pid, oaddr, odata, addr));
if (addr >= PT_FR0 && addr <= PT_FR31) {
/* Special case, fp regs are 64 bits anyway */
*(unsigned int *) ((char *) task_regs(child) + addr) = data;
ret = 0;
}
else if ((addr >= PT_GR1+4 && addr <= PT_GR31+4) ||
addr == PT_IAOQ0+4 || addr == PT_IAOQ1+4 ||
addr == PT_SAR+4) {
/* Zero the top 32 bits */
*(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0;
*(unsigned int *) ((char *) task_regs(child) + addr) = data;
ret = 0;
}
goto out_tsk;
}
else
#endif
{
if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
goto out_tsk;
if ((addr >= PT_GR1 && addr <= PT_GR31) ||
addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
(addr >= PT_FR0 && addr <= PT_FR31) ||
addr == PT_SAR) {
*(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;
DBG(("sys_ptrace(%s)\n",
request == PTRACE_SYSCALL ? "SYSCALL" : "CONT"));
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.
*/
DBG(("sys_ptrace(KILL)\n"));
if (child->state == TASK_ZOMBIE) /* already dead */
goto out_tsk;
child->exit_code = SIGKILL;
goto out_wake_notrap;
case PTRACE_SINGLEBLOCK:
DBG(("sys_ptrace(SINGLEBLOCK)\n"));
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:
DBG(("sys_ptrace(SINGLESTEP)\n"));
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;
ptrace_disable(child);
/* 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:
ptrace_disable(child);
out_wake:
wake_up_process(child);
ret = 0;
out_tsk:
free_task_struct(child);
out:
unlock_kernel();
DBG(("sys_ptrace(%ld, %d, %lx, %lx) returning %ld\n",
request, pid, oaddr, odata, ret));
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;
}
}