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/* ptrace.c */
/* By Ross Biro 1/23/92 */
/* edited by Linus Torvalds */
/* mangled further by Bob Manson (manson@santafe.edu) */
/* more mutilation by David Mosberger (davidm@azstarnet.com) */
#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/slab.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/fpu.h>
#include "proto.h"
#define DEBUG DBG_MEM
#undef DEBUG
#ifdef DEBUG
enum {
DBG_MEM = (1<<0),
DBG_BPT = (1<<1),
DBG_MEM_ALL = (1<<2)
};
#define DBG(fac,args) {if ((fac) & DEBUG) printk args;}
#else
#define DBG(fac,args)
#endif
#define BREAKINST 0x00000080 /* call_pal bpt */
/*
* does not yet catch signals sent when the child dies.
* in exit.c or in signal.c.
*/
/*
* Processes always block with the following stack-layout:
*
* +================================+ <---- task + 2*PAGE_SIZE
* | PALcode saved frame (ps, pc, | ^
* | gp, a0, a1, a2) | |
* +================================+ | struct pt_regs
* | | |
* | frame generated by SAVE_ALL | |
* | | v
* +================================+
* | | ^
* | frame saved by do_switch_stack | | struct switch_stack
* | | v
* +================================+
*/
/*
* The following table maps a register index into the stack offset at
* which the register is saved. Register indices are 0-31 for integer
* regs, 32-63 for fp regs, and 64 for the pc. Notice that sp and
* zero have no stack-slot and need to be treated specially (see
* get_reg/put_reg below).
*/
enum {
REG_R0 = 0, REG_F0 = 32, REG_FPCR = 63, REG_PC = 64
};
static int regoff[] = {
PT_REG( r0), PT_REG( r1), PT_REG( r2), PT_REG( r3),
PT_REG( r4), PT_REG( r5), PT_REG( r6), PT_REG( r7),
PT_REG( r8), SW_REG( r9), SW_REG( r10), SW_REG( r11),
SW_REG( r12), SW_REG( r13), SW_REG( r14), SW_REG( r15),
PT_REG( r16), PT_REG( r17), PT_REG( r18), PT_REG( r19),
PT_REG( r20), PT_REG( r21), PT_REG( r22), PT_REG( r23),
PT_REG( r24), PT_REG( r25), PT_REG( r26), PT_REG( r27),
PT_REG( r28), PT_REG( gp), -1, -1,
SW_REG(fp[ 0]), SW_REG(fp[ 1]), SW_REG(fp[ 2]), SW_REG(fp[ 3]),
SW_REG(fp[ 4]), SW_REG(fp[ 5]), SW_REG(fp[ 6]), SW_REG(fp[ 7]),
SW_REG(fp[ 8]), SW_REG(fp[ 9]), SW_REG(fp[10]), SW_REG(fp[11]),
SW_REG(fp[12]), SW_REG(fp[13]), SW_REG(fp[14]), SW_REG(fp[15]),
SW_REG(fp[16]), SW_REG(fp[17]), SW_REG(fp[18]), SW_REG(fp[19]),
SW_REG(fp[20]), SW_REG(fp[21]), SW_REG(fp[22]), SW_REG(fp[23]),
SW_REG(fp[24]), SW_REG(fp[25]), SW_REG(fp[26]), SW_REG(fp[27]),
SW_REG(fp[28]), SW_REG(fp[29]), SW_REG(fp[30]), SW_REG(fp[31]),
PT_REG( pc)
};
static long zero;
/*
* Get address of register REGNO in task TASK.
*/
static long *
get_reg_addr(struct task_struct * task, unsigned long regno)
{
long *addr;
if (regno == 30) {
addr = &task->thread.usp;
} else if (regno == 31 || regno > 64) {
zero = 0;
addr = &zero;
} else {
addr = (long *)((long)task + regoff[regno]);
}
return addr;
}
/*
* Get contents of register REGNO in task TASK.
*/
static long
get_reg(struct task_struct * task, unsigned long regno)
{
/* Special hack for fpcr -- combine hardware and software bits. */
if (regno == 63) {
unsigned long fpcr = *get_reg_addr(task, regno);
unsigned long swcr = task->thread.flags & IEEE_SW_MASK;
swcr = swcr_update_status(swcr, fpcr);
return fpcr | swcr;
}
return *get_reg_addr(task, regno);
}
/*
* Write contents of register REGNO in task TASK.
*/
static int
put_reg(struct task_struct *task, unsigned long regno, long data)
{
if (regno == 63) {
task->thread.flags = ((task->thread.flags & ~IEEE_SW_MASK)
| (data & IEEE_SW_MASK));
data = (data & FPCR_DYN_MASK) | ieee_swcr_to_fpcr(data);
}
*get_reg_addr(task, regno) = data;
return 0;
}
static inline int
read_int(struct task_struct *task, unsigned long addr, int * data)
{
int copied = access_process_vm(task, addr, data, sizeof(int), 0);
return (copied == sizeof(int)) ? 0 : -EIO;
}
static inline int
write_int(struct task_struct *task, unsigned long addr, int data)
{
int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
return (copied == sizeof(int)) ? 0 : -EIO;
}
/*
* Set breakpoint.
*/
int
ptrace_set_bpt(struct task_struct * child)
{
int displ, i, res, reg_b, nsaved = 0;
u32 insn, op_code;
unsigned long pc;
pc = get_reg(child, REG_PC);
res = read_int(child, pc, &insn);
if (res < 0)
return res;
op_code = insn >> 26;
if (op_code >= 0x30) {
/*
* It's a branch: instead of trying to figure out
* whether the branch will be taken or not, we'll put
* a breakpoint at either location. This is simpler,
* more reliable, and probably not a whole lot slower
* than the alternative approach of emulating the
* branch (emulation can be tricky for fp branches).
*/
displ = ((s32)(insn << 11)) >> 9;
child->thread.bpt_addr[nsaved++] = pc + 4;
if (displ) /* guard against unoptimized code */
child->thread.bpt_addr[nsaved++] = pc + 4 + displ;
DBG(DBG_BPT, ("execing branch\n"));
} else if (op_code == 0x1a) {
reg_b = (insn >> 16) & 0x1f;
child->thread.bpt_addr[nsaved++] = get_reg(child, reg_b);
DBG(DBG_BPT, ("execing jump\n"));
} else {
child->thread.bpt_addr[nsaved++] = pc + 4;
DBG(DBG_BPT, ("execing normal insn\n"));
}
/* install breakpoints: */
for (i = 0; i < nsaved; ++i) {
res = read_int(child, child->thread.bpt_addr[i], &insn);
if (res < 0)
return res;
child->thread.bpt_insn[i] = insn;
DBG(DBG_BPT, (" -> next_pc=%lx\n", child->thread.bpt_addr[i]));
res = write_int(child, child->thread.bpt_addr[i], BREAKINST);
if (res < 0)
return res;
}
child->thread.bpt_nsaved = nsaved;
return 0;
}
/*
* Ensure no single-step breakpoint is pending. Returns non-zero
* value if child was being single-stepped.
*/
int
ptrace_cancel_bpt(struct task_struct * child)
{
int i, nsaved = child->thread.bpt_nsaved;
child->thread.bpt_nsaved = 0;
if (nsaved > 2) {
printk("ptrace_cancel_bpt: bogus nsaved: %d!\n", nsaved);
nsaved = 2;
}
for (i = 0; i < nsaved; ++i) {
write_int(child, child->thread.bpt_addr[i],
child->thread.bpt_insn[i]);
}
return (nsaved != 0);
}
/*
* 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);
}
asmlinkage long
sys_ptrace(long request, long pid, long addr, long data,
int a4, int a5, struct pt_regs regs)
{
struct task_struct *child;
long ret;
lock_kernel();
DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",
request, pid, addr, data));
ret = -EPERM;
if (request == PTRACE_TRACEME) {
/* are we already being traced? */
if (current->ptrace & PT_PTRACED)
goto out_notsk;
/* set the ptrace bit in the process ptrace flags. */
current->ptrace |= PT_PTRACED;
ret = 0;
goto out_notsk;
}
if (pid == 1) /* you may not mess with init */
goto out_notsk;
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_notsk;
if (request == PTRACE_ATTACH) {
ret = ptrace_attach(child);
goto out;
}
ret = -ESRCH;
if (!(child->ptrace & PT_PTRACED)) {
DBG(DBG_MEM, ("child not traced\n"));
goto out;
}
if (child->state != TASK_STOPPED) {
DBG(DBG_MEM, ("child process not stopped\n"));
if (request != PTRACE_KILL)
goto out;
}
if (child->p_pptr != current) {
DBG(DBG_MEM, ("child not parent of this process\n"));
goto out;
}
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: {
unsigned long tmp;
int copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
ret = -EIO;
if (copied != sizeof(tmp))
goto out;
regs.r0 = 0; /* special return: no errors */
ret = tmp;
goto out;
}
/* Read register number ADDR. */
case PTRACE_PEEKUSR:
regs.r0 = 0; /* special return: no errors */
ret = get_reg(child, addr);
DBG(DBG_MEM, ("peek $%ld->%#lx\n", addr, ret));
goto out;
/* 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: {
unsigned long tmp = data;
int copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 1);
ret = (copied == sizeof(tmp)) ? 0 : -EIO;
goto out;
}
case PTRACE_POKEUSR: /* write the specified register */
DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
ret = put_reg(child, addr, data);
goto out;
case PTRACE_SYSCALL: /* continue and stop at next
(return from) syscall */
case PTRACE_CONT: /* restart after signal. */
ret = -EIO;
if ((unsigned long) data > _NSIG)
goto out;
if (request == PTRACE_SYSCALL)
child->ptrace |= PT_TRACESYS;
else
child->ptrace &= ~PT_TRACESYS;
child->exit_code = data;
wake_up_process(child);
/* make sure single-step breakpoint is gone. */
ptrace_cancel_bpt(child);
ret = data;
goto out;
/*
* 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:
if (child->state != TASK_ZOMBIE) {
wake_up_process(child);
child->exit_code = SIGKILL;
}
/* make sure single-step breakpoint is gone. */
ptrace_cancel_bpt(child);
ret = 0;
goto out;
case PTRACE_SINGLESTEP: /* execute single instruction. */
ret = -EIO;
if ((unsigned long) data > _NSIG)
goto out;
child->thread.bpt_nsaved = -1; /* mark single-stepping */
child->ptrace &= ~PT_TRACESYS;
wake_up_process(child);
child->exit_code = data;
/* give it a chance to run. */
ret = 0;
goto out;
case PTRACE_DETACH: /* detach a process that was attached. */
ret = ptrace_detach(child, data);
goto out;
default:
ret = -EIO;
goto out;
}
out:
free_task_struct(child);
out_notsk:
unlock_kernel();
return ret;
}
asmlinkage 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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