/* 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/head.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/debugreg.h>
#include <asm/segment.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#undef DEBUG
#ifdef DEBUG
enum {
DBG_MEM = (1<<0),
DBG_BPT = (1<<1),
DBG_MEM_ALL = (1<<2)
};
int debug_mask = DBG_BPT;
# define DBG(fac,args) {if ((fac) & debug_mask) 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:
*
* +================================+ --------------------------
* | PALcode saved frame (ps, pc, | ^ ^
* | gp, a0, a1, a2) | | |
* +================================+ | struct pt_regs |
* | | | |
* | frame generated by SAVE_ALL | | |
* | | v | P
* +================================+ | A
* | | ^ | G
* | frame saved by do_switch_stack | | struct switch_stack | E
* | | v | _
* +================================+ | S
* | | | I
* | | | Z
* / / | E
* / / |
* | | |
* | | |
* | | v
* +================================+ <-------------------------
* task->kernel_stack_page
*/
#define PT_REG(reg) (PAGE_SIZE - sizeof(struct pt_regs) \
+ (long)&((struct pt_regs *)0)->reg)
#define SW_REG(reg) (PAGE_SIZE - sizeof(struct pt_regs) \
- sizeof(struct switch_stack) \
+ (long)&((struct switch_stack *)0)->reg)
/*
* 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_PC = 64
};
static unsigned short 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;
/* change a pid into a task struct. */
static inline struct task_struct * get_task(int pid)
{
int i;
for (i = 1; i < NR_TASKS; i++) {
if (task[i] != NULL && (task[i]->pid == pid))
return task[i];
}
return NULL;
}
/*
* Get contents of register REGNO in task TASK.
*/
static inline long get_reg(struct task_struct * task, long regno)
{
long *addr;
if (regno == 30) {
addr = &task->tss.usp;
} else if (regno == 31) {
zero = 0;
addr = &zero;
} else {
addr = (long *) (task->kernel_stack_page + regoff[regno]);
}
return *addr;
}
/*
* Write contents of register REGNO in task TASK.
*/
static inline int put_reg(struct task_struct *task, long regno, long data)
{
long *addr, zero;
if (regno == 30) {
addr = &task->tss.usp;
} else if (regno == 31) {
addr = &zero;
} else {
addr = (long *) (task->kernel_stack_page + regoff[regno]);
}
*addr = data;
return 0;
}
/*
* This routine gets a long from any process space by following the page
* tables. NOTE! You should check that the long isn't on a page boundary,
* and that it is in the task area before calling this: this routine does
* no checking.
*/
static unsigned long get_long(struct task_struct * tsk,
struct vm_area_struct * vma, unsigned long addr)
{
pgd_t * pgdir;
pmd_t * pgmiddle;
pte_t * pgtable;
unsigned long page;
DBG(DBG_MEM_ALL, ("getting long at 0x%lx\n", addr));
repeat:
pgdir = pgd_offset(vma->vm_mm, addr);
if (pgd_none(*pgdir)) {
do_no_page(tsk, vma, addr, 0);
goto repeat;
}
if (pgd_bad(*pgdir)) {
printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));
pgd_clear(pgdir);
return 0;
}
pgmiddle = pmd_offset(pgdir, addr);
if (pmd_none(*pgmiddle)) {
do_no_page(tsk, vma, addr, 0);
goto repeat;
}
if (pmd_bad(*pgmiddle)) {
printk("ptrace: bad page middle %08lx\n", pmd_val(*pgmiddle));
pmd_clear(pgmiddle);
return 0;
}
pgtable = pte_offset(pgmiddle, addr);
if (!pte_present(*pgtable)) {
do_no_page(tsk, vma, addr, 0);
goto repeat;
}
page = pte_page(*pgtable);
/* this is a hack for non-kernel-mapped video buffers and similar */
if (page >= high_memory)
return 0;
page += addr & ~PAGE_MASK;
return *(unsigned long *) page;
}
/*
* This routine puts a long into any process space by following the page
* tables. NOTE! You should check that the long isn't on a page boundary,
* and that it is in the task area before calling this: this routine does
* no checking.
*
* Now keeps R/W state of page so that a text page stays readonly
* even if a debugger scribbles breakpoints into it. -M.U-
*/
static void put_long(struct task_struct * tsk, struct vm_area_struct * vma,
unsigned long addr, unsigned long data)
{
pgd_t *pgdir;
pmd_t *pgmiddle;
pte_t *pgtable;
unsigned long page;
repeat:
pgdir = pgd_offset(vma->vm_mm, addr);
if (!pgd_present(*pgdir)) {
do_no_page(tsk, vma, addr, 1);
goto repeat;
}
if (pgd_bad(*pgdir)) {
printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));
pgd_clear(pgdir);
return;
}
pgmiddle = pmd_offset(pgdir, addr);
if (pmd_none(*pgmiddle)) {
do_no_page(tsk, vma, addr, 1);
goto repeat;
}
if (pmd_bad(*pgmiddle)) {
printk("ptrace: bad page middle %08lx\n", pmd_val(*pgmiddle));
pmd_clear(pgmiddle);
return;
}
pgtable = pte_offset(pgmiddle, addr);
if (!pte_present(*pgtable)) {
do_no_page(tsk, vma, addr, 1);
goto repeat;
}
page = pte_page(*pgtable);
if (!pte_write(*pgtable)) {
do_wp_page(tsk, vma, addr, 1);
goto repeat;
}
/* this is a hack for non-kernel-mapped video buffers and similar */
if (page < high_memory)
*(unsigned long *) (page + (addr & ~PAGE_MASK)) = data;
/* we're bypassing pagetables, so we have to set the dirty bit ourselves */
/* this should also re-instate whatever read-only mode there was before */
set_pte(pgtable, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
flush_tlb();
}
static struct vm_area_struct * find_extend_vma(struct task_struct * tsk,
unsigned long addr)
{
struct vm_area_struct * vma;
addr &= PAGE_MASK;
vma = find_vma(tsk->mm,addr);
if (!vma)
return NULL;
if (vma->vm_start <= addr)
return vma;
if (!(vma->vm_flags & VM_GROWSDOWN))
return NULL;
if (vma->vm_end - addr > tsk->rlim[RLIMIT_STACK].rlim_cur)
return NULL;
vma->vm_offset -= vma->vm_start - addr;
vma->vm_start = addr;
return vma;
}
/*
* This routine checks the page boundaries, and that the offset is
* within the task area. It then calls get_long() to read a long.
*/
static int read_long(struct task_struct * tsk, unsigned long addr,
unsigned long * result)
{
struct vm_area_struct * vma = find_extend_vma(tsk, addr);
DBG(DBG_MEM_ALL, ("in read_long\n"));
if (!vma) {
printk("Unable to find vma for addr 0x%lx\n",addr);
return -EIO;
}
if ((addr & ~PAGE_MASK) > (PAGE_SIZE - sizeof(long))) {
struct vm_area_struct * vma_high = vma;
unsigned long low, align;
if (addr + sizeof(long) >= vma->vm_end) {
vma_high = vma->vm_next;
if (!vma_high || vma_high->vm_start != vma->vm_end)
return -EIO;
}
align = addr & (sizeof(long) - 1);
addr -= align;
low = get_long(tsk, vma, addr);
if (align) {
unsigned long high;
high = get_long(tsk, vma_high, addr + sizeof(long));
low >>= align * 8;
low |= high << (64 - align * 8);
}
*result = low;
} else {
long l = get_long(tsk, vma, addr);
DBG(DBG_MEM_ALL, ("value is 0x%lx\n", l));
*result = l;
}
return 0;
}
/*
* This routine checks the page boundaries, and that the offset is
* within the task area. It then calls put_long() to write a long.
*/
static int write_long(struct task_struct * tsk, unsigned long addr,
unsigned long data)
{
struct vm_area_struct * vma = find_extend_vma(tsk, addr);
if (!vma)
return -EIO;
if ((addr & ~PAGE_MASK) > PAGE_SIZE-sizeof(long)) {
unsigned long low, high, align;
struct vm_area_struct * vma_high = vma;
if (addr + sizeof(long) >= vma->vm_end) {
vma_high = vma->vm_next;
if (!vma_high || vma_high->vm_start != vma->vm_end)
return -EIO;
}
align = addr & (sizeof(long) - 1);
addr -= align;
low = get_long(tsk, vma, addr);
high = get_long(tsk, vma_high, addr + sizeof(long));
low &= ~0UL >> (64 - align * 8);
high &= ~0UL << (align * 8);
low |= data << (align * 8);
high |= data >> (64 - align * 8);
put_long(tsk, vma, addr, low);
put_long(tsk, vma_high, addr + sizeof(long), high);
} else
put_long(tsk, vma, addr, data);
return 0;
}
/*
* Read a 32bit int from address space TSK.
*/
static int read_int(struct task_struct * tsk, unsigned long addr,
unsigned int *data)
{
unsigned long l, align;
int res;
align = addr & 0x7;
addr &= ~0x7;
res = read_long(tsk, addr, &l);
if (res < 0)
return res;
if (align == 0) {
*data = l;
} else {
*data = l >> 32;
}
return 0;
}
/*
* Write a 32bit word to address space TSK.
*
* For simplicity, do a read-modify-write of the 64bit word that
* contains the 32bit word that we are about to write.
*/
static int write_int(struct task_struct * tsk, unsigned long addr,
unsigned int data)
{
unsigned long l, align;
int res;
align = addr & 0x7;
addr &= ~0x7;
res = read_long(tsk, addr, &l);
if (res < 0)
return res;
if (align == 0) {
l = (l & 0xffffffff00000000UL) | ((unsigned long) data << 0);
} else {
l = (l & 0x00000000ffffffffUL) | ((unsigned long) data << 32);
}
return write_long(tsk, addr, l);
}
/*
* 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->debugreg[nsaved++] = pc + 4;
if (displ) /* guard against unoptimized code */
child->debugreg[nsaved++] = pc + 4 + displ;
DBG(DBG_BPT, ("execing branch\n"));
} else if (op_code == 0x1a) {
reg_b = (insn >> 16) & 0x1f;
child->debugreg[nsaved++] = get_reg(child, reg_b);
DBG(DBG_BPT, ("execing jump\n"));
} else {
child->debugreg[nsaved++] = pc + 4;
DBG(DBG_BPT, ("execing normal insn\n"));
}
/* install breakpoints: */
for (i = 0; i < nsaved; ++i) {
res = read_int(child, child->debugreg[i], &insn);
if (res < 0)
return res;
child->debugreg[i + 2] = insn;
DBG(DBG_BPT, (" -> next_pc=%lx\n", child->debugreg[i]));
res = write_int(child, child->debugreg[i], BREAKINST);
if (res < 0)
return res;
}
child->debugreg[4] = 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->debugreg[4];
child->debugreg[4] = 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->debugreg[i], child->debugreg[i + 2]);
}
return (nsaved != 0);
}
asmlinkage long sys_ptrace(long request, long pid, long addr, long data,
int a4, int a5, struct pt_regs regs)
{
struct task_struct *child;
struct user * dummy;
dummy = NULL;
DBG(DBG_MEM, ("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",
request, pid, addr, data));
if (request == PTRACE_TRACEME) {
/* are we already being traced? */
if (current->flags & PF_PTRACED)
return -EPERM;
/* set the ptrace bit in the process flags. */
current->flags |= PF_PTRACED;
return 0;
}
if (pid == 1) /* you may not mess with init */
return -EPERM;
if (!(child = get_task(pid)))
return -ESRCH;
if (request == PTRACE_ATTACH) {
if (child == current)
return -EPERM;
if ((!child->dumpable ||
(current->uid != child->euid) ||
(current->uid != child->suid) ||
(current->uid != child->uid) ||
(current->gid != child->egid) ||
(current->gid != child->sgid) ||
(current->gid != child->gid)) && !suser())
return -EPERM;
/* the same process cannot be attached many times */
if (child->flags & PF_PTRACED)
return -EPERM;
child->flags |= PF_PTRACED;
if (child->p_pptr != current) {
REMOVE_LINKS(child);
child->p_pptr = current;
SET_LINKS(child);
}
send_sig(SIGSTOP, child, 1);
return 0;
}
if (!(child->flags & PF_PTRACED)) {
DBG(DBG_MEM, ("child not traced\n"));
return -ESRCH;
}
if (child->state != TASK_STOPPED) {
DBG(DBG_MEM, ("child process not stopped\n"));
if (request != PTRACE_KILL)
return -ESRCH;
}
if (child->p_pptr != current) {
DBG(DBG_MEM, ("child not parent of this process\n"));
return -ESRCH;
}
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 res;
res = read_long(child, addr, &tmp);
DBG(DBG_MEM, ("peek %#lx->%#lx\n", addr, tmp));
if (res < 0)
return res;
regs.r0 = 0; /* special return: no errors */
return tmp;
}
/* read register number ADDR. */
case PTRACE_PEEKUSR:
regs.r0 = 0; /* special return: no errors */
DBG(DBG_MEM, ("peek $%ld=%#lx\n", addr, regs.r0));
return get_reg(child, addr);
/* 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:
DBG(DBG_MEM, ("poke %#lx<-%#lx\n", addr, data));
return write_long(child, addr, data);
case PTRACE_POKEUSR: /* write the specified register */
DBG(DBG_MEM, ("poke $%ld<-%#lx\n", addr, data));
return put_reg(child, addr, data);
case PTRACE_SYSCALL: /* continue and stop at next
(return from) syscall */
case PTRACE_CONT: { /* restart after signal. */
if ((unsigned long) data > NSIG)
return -EIO;
if (request == PTRACE_SYSCALL)
child->flags |= PF_TRACESYS;
else
child->flags &= ~PF_TRACESYS;
child->exit_code = data;
wake_up_process(child);
/* make sure single-step breakpoint is gone. */
ptrace_cancel_bpt(child);
return data;
}
/*
* 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);
return 0;
}
case PTRACE_SINGLESTEP: { /* execute single instruction. */
if ((unsigned long) data > NSIG)
return -EIO;
child->debugreg[4] = -1; /* mark single-stepping */
child->flags &= ~PF_TRACESYS;
wake_up_process(child);
child->exit_code = data;
/* give it a chance to run. */
return 0;
}
case PTRACE_DETACH: { /* detach a process that was attached. */
if ((unsigned long) data > NSIG)
return -EIO;
child->flags &= ~(PF_PTRACED|PF_TRACESYS);
wake_up_process(child);
child->exit_code = data;
REMOVE_LINKS(child);
child->p_pptr = child->p_opptr;
SET_LINKS(child);
/* make sure single-step breakpoint is gone. */
ptrace_cancel_bpt(child);
return 0;
}
default:
return -EIO;
}
}
asmlinkage void syscall_trace(void)
{
if ((current->flags & (PF_PTRACED|PF_TRACESYS))
!= (PF_PTRACED|PF_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)
current->signal |= (1 << (current->exit_code - 1));
current->exit_code = 0;
}
