patch-1.3.9 linux/arch/alpha/kernel/ptrace.c

• Lines: 648
• Date: Tue Jul 11 08:13:58 1995
• Orig file: v1.3.8/linux/arch/alpha/kernel/ptrace.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.8/linux/arch/alpha/kernel/ptrace.c linux/arch/alpha/kernel/ptrace.c
@@ -0,0 +1,647 @@
+/* ptrace.c */
+/* By Ross Biro 1/23/92 */
+/* edited by Linus Torvalds */
+/* mangled further by Bob Manson (manson@santafe.edu) */
+
+#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>
+
+/* This was determined via brute force. */
+#define MAGICNUM 496
+
+/*
+ * does not yet catch signals sent when the child dies.
+ * in exit.c or in signal.c.
+ */
+
+/* determines which flags the user has access to. */
+/* 1 = access 0 = no access */
+#define FLAG_MASK 0x00044dd5
+
+/* set's the trap flag. */
+#define TRAP_FLAG 0x100
+
+/*
+ * this is the number to subtract from the top of the stack. To find
+ * the local frame.
+ */
+
+/* A mapping between register number and its offset on the kernel stack.
+ * You also need to add MAGICNUM to get past the kernel stack frame
+ * to the actual saved user info.
+ * The first portion is the switch_stack, then comes the pt_regs.
+ * 320 is the size of the switch_stack area.
+ */
+
+static int map_reg_to_offset[] = {
+   320+0,320+8,320+16,320+24,320+32,320+40,320+48,320+56,320+64, /* 0-8 */
+   0,8,16,24,32,40,48, /* 9-15 */
+   320+184,320+192,320+200, /* 16-18 */
+   320+72,320+80,320+88,320+96,320+104,320+112,320+120, /* 19-25 */
+   320+128,320+136,320+144,320+176,320+160,-1, /* 26-31*/
+
+   /* fp registers below */
+   64,72,80,88,96,104,112,120,128,136,144,152,160,168,176,184,192,
+   200,208,216,224,232,240,248,256,264,272,280,288,296,304,312,
+
+   /* 64 = pc */
+   320+168
+};
+
+static int offset_of_register(int reg_num) {
+   if(reg_num<0 || reg_num>64) {
+      return -1;
+   }
+   return map_reg_to_offset[reg_num];
+}
+
+static void unset_singlestep(struct task_struct *child) {
+}
+
+static void set_singlestep(struct task_struct *child) {
+}
+
+/* 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;
+}
+
+/*
+ * 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 TSS.  
+ * this routine assumes that all the privileged stacks are in our
+ * data space.
+ * MAGICNUM is the amount to skip to get to the actual user regs. It
+ * was determined by brute force & asking BufElves.
+ */   
+static inline long get_stack_long(struct task_struct *task, unsigned long offset)
+{
+	unsigned char *stack;
+
+	stack = (unsigned char *)task->tss.ksp;
+	stack += offset+MAGICNUM;
+	return (*((long *)stack));
+}
+
+/*
+ * this routine will put a word on the processes privileged stack. 
+ * the offset is how far from the base addr as stored in the TSS.  
+ * this routine assumes that all the privileged stacks are in our
+ * data space.
+ */
+static inline int put_stack_long(struct task_struct *task, unsigned long offset,
+	unsigned long data)
+{
+	unsigned char * stack;
+
+	stack = (unsigned char *) task->tss.ksp;
+	stack += offset+MAGICNUM;
+	*(unsigned long *) stack = 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 vm_area_struct * vma, unsigned long addr)
+{
+	pgd_t * pgdir;
+	pmd_t * pgmiddle;
+	pte_t * pgtable;
+	unsigned long page;
+
+#ifdef DEBUG
+	printk("Getting long at 0x%lx\n",addr);
+#endif
+repeat:
+	pgdir = pgd_offset(vma->vm_task, addr);
+	if (pgd_none(*pgdir)) {
+		do_no_page(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(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(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 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_task, addr);
+	if (!pgd_present(*pgdir)) {
+		do_no_page(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(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(vma, addr, 1);
+		goto repeat;
+	}
+	page = pte_page(*pgtable);
+	if (!pte_write(*pgtable)) {
+		do_wp_page(vma, addr, 1);
+		goto repeat;
+	}
+/* this is a hack for non-kernel-mapped video buffers and similar */
+	if (page < high_memory) {
+		page += addr & ~PAGE_MASK;
+		*(unsigned long *) page = 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 */
+	*pgtable = pte_mkdirty(mk_pte(page, vma->vm_page_prot));
+	invalidate();
+}
+
+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,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);
+
+#ifdef DEBUG
+	printk("in read_long\n");
+#endif
+	if (!vma) {
+	        printk("Unable to find vma for addr 0x%lx\n",addr);
+		return -EIO;
+	}
+	if ((addr & ~PAGE_MASK) > (PAGE_SIZE-sizeof(long))) {
+		unsigned long low,high;
+		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;
+		}
+		low = get_long(vma, addr & ~(sizeof(long)-1));
+		high = get_long(vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1));
+		switch (addr & (sizeof(long)-1)) {
+			case 1:
+				low >>= 8;
+				low |= high << 56;
+				break;
+			case 2:
+				low >>= 16;
+				low |= high << 48;
+				break;
+			case 3:
+				low >>= 24;
+				low |= high << 40;
+				break;
+			case 4:
+				low >>= 32;
+				low |= high << 32;
+				break;
+			case 5:
+				low >>= 40;
+				low |= high << 24;
+				break;
+			case 6:
+				low >>= 48;
+				low |= high << 16;
+				break;
+			case 7:
+				low >>= 56;
+				low |= high << 8;
+				break;
+		}
+		*result = low;
+	} else {
+	        long l =get_long(vma, addr);
+
+#ifdef DEBUG
+		printk("value is 0x%lx\n",l);
+#endif
+		*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;
+		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;
+		}
+		low = get_long(vma, addr & ~(sizeof(long)-1));
+		high = get_long(vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1));
+		switch (addr & (sizeof(long)-1)) {
+			case 0: /* shouldn't happen, but safety first */
+				low = data;
+				break;
+			case 1:
+				low &= 0x00000000000000ffL;
+				low |= data << 8;
+				high &= ~0x000000000000ffL;
+				high |= data >> 56;
+				break;
+			case 2:
+				low &= 0x000000000000ffffL;
+				low |= data << 16;
+				high &= ~0x0000000000ffffL;
+				high |= data >> 48;
+				break;
+			case 3:
+				low &= 0x0000000000ffffffL;
+				low |= data << 24;
+				high &= ~0x00000000ffffffL;
+				high |= data >> 40;
+				break;
+		        case 4:
+				low &= 0x00000000ffffffffL;
+				low |= data << 32;
+				high &= ~0x000000ffffffffL;
+				high |= data >> 32;
+				break;
+
+			case 5:
+				low &= 0x000000ffffffffffL;
+				low |= data << 40;
+				high &= ~0x0000ffffffffffL;
+				high |= data >> 24;
+				break;
+			case 6:
+				low &= 0x0000ffffffffffffL;
+				low |= data << 48;
+				high &= ~0x00ffffffffffffL;
+				high |= data >> 16;
+				break;
+			case 7:
+				low &= 0x00ffffffffffffffL;
+				low |= data << 56;
+				high &= ~0xffffffffffffffL;
+				high |= data >> 8;
+				break;
+		}
+		put_long(vma, addr & ~(sizeof(long)-1),low);
+		put_long(vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1),high);
+	} else
+		put_long(vma, addr, data);
+	return 0;
+}
+
+/* Uh, this does ugly stuff. It stores the specified value in the a3
+ * register. entry.S will swap a3 and the returned value from
+ * sys_ptrace() before returning to the user.
+ */
+
+static inline void set_success(struct pt_regs *regs,long resval) {
+   regs->r19=resval;
+}
+
+/* This doesn't do diddly, actually--if the value returned from 
+ * sys_ptrace() is != 0, it sets things up properly.
+ */
+
+static inline void set_failure(struct pt_regs *regs,long errcode) {
+   regs->r19=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;
+
+#ifdef DEBUG
+	printk("request=%ld pid=%ld addr=0x%lx data=0x%lx\n",request,pid,addr,data);
+#endif
+	set_success(&regs,0);
+	if (request == PTRACE_TRACEME) {
+		/* are we already being traced? */
+	   if (current->flags & PF_PTRACED) {
+	      set_failure(&regs,-EPERM);
+	      return -EPERM;
+	   }
+	   /* set the ptrace bit in the process flags. */
+	   current->flags |= PF_PTRACED;
+	   return 0;
+	}
+	if (pid == 1) {
+	   set_failure(&regs,-EPERM);
+	   return -EPERM;
+	}
+	if (!(child = get_task(pid))) {
+	   set_failure(&regs,-ESRCH);
+	   return -ESRCH;
+	}
+	if (request == PTRACE_ATTACH) {
+	   if (child == current) {
+	      set_failure(&regs,-EPERM);
+	      return -EPERM;
+	   }
+	   if ((!child->dumpable ||
+		(current->uid != child->euid) ||
+		(current->uid != child->uid) ||
+		(current->gid != child->egid) ||
+		(current->gid != child->gid)) && !suser()) {
+	      set_failure(&regs,-EPERM);
+	      return -EPERM;
+	   }
+	   /* the same process cannot be attached many times */
+	   if (child->flags & PF_PTRACED) {
+	      set_failure(&regs,-EPERM);
+	      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)) {
+#ifdef DEBUG
+	   printk("child not traced\n");
+#endif
+	   set_failure(&regs,-ESRCH);
+	   return -ESRCH;
+	}
+	if (child->state != TASK_STOPPED) {
+#ifdef DEBUG
+	   printk("child process not stopped\n");
+#endif
+	   if (request != PTRACE_KILL) {
+	      set_failure(&regs,-ESRCH);
+	      return -ESRCH;
+	   }
+	}
+	if (child->p_pptr != current) {
+#ifdef DEBUG
+	   printk("child not parent of this process\n");
+#endif
+	   set_failure(&regs,-ESRCH);
+	   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;
+
+#ifdef DEBUG
+			printk("doing request at addr 0x%lx\n",addr);
+#endif
+			res = read_long(child, addr, &tmp);
+			if (res < 0) {
+			   set_failure(&regs,res);
+			   return res;
+			}
+			else {
+			   set_success(&regs,tmp);
+			   return 0;
+			}
+		}
+
+	/* read the word at location addr in the USER area. */
+		case PTRACE_PEEKUSR: {
+		        /* We only allow access to registers. */
+			unsigned long tmp;
+
+			tmp = 0;  /* Default return condition */
+			if(addr==30) {
+			   /* stack pointer */
+			   tmp=child->tss.usp;
+			}
+			else {
+			   int reg=addr;
+			   addr = offset_of_register(addr);
+			   if(addr < 0) {
+			      set_failure(&regs,-EIO);
+			      return -EIO;
+			   }
+			   tmp = get_stack_long(child, addr);
+#ifdef DEBUG
+			   printk("%d = reg 0x%lx=tmp\n",reg,tmp);
+#endif
+			}
+			set_success(&regs,tmp);
+			return 0;
+		}
+
+      /* 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: {
+			long res=write_long(child,addr,data);
+			if(res) {
+			   set_failure(&regs,res);
+			}
+			return res;
+		}
+
+		case PTRACE_POKEUSR: /* write the specified register */
+		{
+		   long res;
+		   addr= offset_of_register(addr);
+		   if(addr < 0) {
+		      set_failure(&regs,-EIO);
+		      return -EIO;
+		   }
+		   res=put_stack_long(child,addr,data);
+		   if(res) {
+		      set_failure(&regs,res);
+		   }
+		   return res;
+		}
+
+		case PTRACE_SYSCALL: /* continue and stop at next 
+					(return from) syscall */
+		case PTRACE_CONT: { /* restart after signal. */
+			if ((unsigned long) data > NSIG) {
+			   set_failure(&regs,-EIO);
+			   return -EIO;
+			}
+			if (request == PTRACE_SYSCALL)
+				child->flags |= PF_TRACESYS;
+			else
+				child->flags &= ~PF_TRACESYS;
+			child->exit_code = data;
+			child->state = TASK_RUNNING;
+			unset_singlestep(child);
+			set_success(&regs,data);
+			return 0;
+		}
+
+/*
+ * 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: {
+			child->state = TASK_RUNNING;
+			child->exit_code = SIGKILL;
+			unset_singlestep(child);
+			return 0;
+		}
+
+		case PTRACE_SINGLESTEP: {  /* set the trap flag. */
+			if ((unsigned long) data > NSIG) {
+			   set_failure(&regs,-EIO);
+			   return -EIO;
+			}
+			child->flags &= ~PF_TRACESYS;
+			set_singlestep(child);
+			child->state = TASK_RUNNING;
+			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) {
+			   set_failure(&regs,-EIO);
+			   return -EIO;
+			}
+			child->flags &= ~(PF_PTRACED|PF_TRACESYS);
+			child->state = TASK_RUNNING;
+			child->exit_code = data;
+			REMOVE_LINKS(child);
+			child->p_pptr = child->p_opptr;
+			SET_LINKS(child);
+			/* make sure the single step bit is not set. */
+			unset_singlestep(child);
+			return 0;
+		}
+
+		default:
+		{
+		   set_failure(&regs,-EIO);
+		   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);
+	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;
+}