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linux/arch/powerpc/kernel/ptrace.c
Paul Mackerras 1bd79336a4 powerpc: Fix various syscall/signal/swapcontext bugs 
A careful reading of the recent changes to the system call entry/exit
paths revealed several problems, plus some things that could be
simplified and improved:

* 32-bit wasn't testing the _TIF_NOERROR bit in the syscall fast exit
  path, so it was only doing anything with it once it saw some other
  bit being set.  In other words, the noerror behaviour would apply to
  the next system call where we had to reschedule or deliver a signal,
  which is not necessarily the current system call.

* 32-bit wasn't doing the call to ptrace_notify in the syscall exit
  path when the _TIF_SINGLESTEP bit was set.

* _TIF_RESTOREALL was in both _TIF_USER_WORK_MASK and
  _TIF_PERSYSCALL_MASK, which is odd since _TIF_RESTOREALL is only set
  by system calls.  I took it out of _TIF_USER_WORK_MASK.

* On 64-bit, _TIF_RESTOREALL wasn't causing the non-volatile registers
  to be restored (unless perhaps a signal was delivered or the syscall
  was traced or single-stepped).  Thus the non-volatile registers
  weren't restored on exit from a signal handler.  We probably got
  away with it mostly because signal handlers written in C wouldn't
  alter the non-volatile registers.

* On 32-bit I simplified the code and made it more like 64-bit by
  making the syscall exit path jump to ret_from_except to handle
  preemption and signal delivery.

* 32-bit was calling do_signal unnecessarily when _TIF_RESTOREALL was
  set - but I think because of that 32-bit was actually restoring the
  non-volatile registers on exit from a signal handler.

* I changed the order of enabling interrupts and saving the
  non-volatile registers before calling do_syscall_trace_leave; now we
  enable interrupts first.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-03-08 13:24:22 +11:00

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/*
* PowerPC version
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* Derived from "arch/m68k/kernel/ptrace.c"
* Copyright (C) 1994 by Hamish Macdonald
* Taken from linux/kernel/ptrace.c and modified for M680x0.
* linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
*
* Modified by Cort Dougan (cort@hq.fsmlabs.com)
* and Paul Mackerras (paulus@samba.org).
*
* This file is subject to the terms and conditions of the GNU General
* Public License. See the file README.legal in the main directory of
* this archive for more details.
*/
#include <linux/config.h>
#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/security.h>
#include <linux/signal.h>
#include <linux/seccomp.h>
#include <linux/audit.h>
#ifdef CONFIG_PPC32
#include <linux/module.h>
#endif
#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#ifdef CONFIG_PPC64
#include "ptrace-common.h"
#endif
#ifdef CONFIG_PPC32
/*
* Set of msr bits that gdb can change on behalf of a process.
*/
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
#define MSR_DEBUGCHANGE 0
#else
#define MSR_DEBUGCHANGE (MSR_SE | MSR_BE)
#endif
#endif /* CONFIG_PPC32 */
/*
* does not yet catch signals sent when the child dies.
* in exit.c or in signal.c.
*/
#ifdef CONFIG_PPC32
/*
* Get contents of register REGNO in task TASK.
*/
static inline unsigned long get_reg(struct task_struct *task, int regno)
{
if (regno < sizeof(struct pt_regs) / sizeof(unsigned long)
&& task->thread.regs != NULL)
return ((unsigned long *)task->thread.regs)[regno];
return (0);
}
/*
* Write contents of register REGNO in task TASK.
*/
static inline int put_reg(struct task_struct *task, int regno,
unsigned long data)
{
if (regno <= PT_MQ && task->thread.regs != NULL) {
if (regno == PT_MSR)
data = (data & MSR_DEBUGCHANGE)
| (task->thread.regs->msr & ~MSR_DEBUGCHANGE);
((unsigned long *)task->thread.regs)[regno] = data;
return 0;
}
return -EIO;
}
#ifdef CONFIG_ALTIVEC
/*
* Get contents of AltiVec register state in task TASK
*/
static inline int get_vrregs(unsigned long __user *data, struct task_struct *task)
{
int i, j;
if (!access_ok(VERIFY_WRITE, data, 133 * sizeof(unsigned long)))
return -EFAULT;
/* copy AltiVec registers VR[0] .. VR[31] */
for (i = 0; i < 32; i++)
for (j = 0; j < 4; j++, data++)
if (__put_user(task->thread.vr[i].u[j], data))
return -EFAULT;
/* copy VSCR */
for (i = 0; i < 4; i++, data++)
if (__put_user(task->thread.vscr.u[i], data))
return -EFAULT;
/* copy VRSAVE */
if (__put_user(task->thread.vrsave, data))
return -EFAULT;
return 0;
}
/*
* Write contents of AltiVec register state into task TASK.
*/
static inline int set_vrregs(struct task_struct *task, unsigned long __user *data)
{
int i, j;
if (!access_ok(VERIFY_READ, data, 133 * sizeof(unsigned long)))
return -EFAULT;
/* copy AltiVec registers VR[0] .. VR[31] */
for (i = 0; i < 32; i++)
for (j = 0; j < 4; j++, data++)
if (__get_user(task->thread.vr[i].u[j], data))
return -EFAULT;
/* copy VSCR */
for (i = 0; i < 4; i++, data++)
if (__get_user(task->thread.vscr.u[i], data))
return -EFAULT;
/* copy VRSAVE */
if (__get_user(task->thread.vrsave, data))
return -EFAULT;
return 0;
}
#endif
#ifdef CONFIG_SPE
/*
* For get_evrregs/set_evrregs functions 'data' has the following layout:
*
* struct {
* u32 evr[32];
* u64 acc;
* u32 spefscr;
* }
*/
/*
* Get contents of SPE register state in task TASK.
*/
static inline int get_evrregs(unsigned long *data, struct task_struct *task)
{
int i;
if (!access_ok(VERIFY_WRITE, data, 35 * sizeof(unsigned long)))
return -EFAULT;
/* copy SPEFSCR */
if (__put_user(task->thread.spefscr, &data[34]))
return -EFAULT;
/* copy SPE registers EVR[0] .. EVR[31] */
for (i = 0; i < 32; i++, data++)
if (__put_user(task->thread.evr[i], data))
return -EFAULT;
/* copy ACC */
if (__put_user64(task->thread.acc, (unsigned long long *)data))
return -EFAULT;
return 0;
}
/*
* Write contents of SPE register state into task TASK.
*/
static inline int set_evrregs(struct task_struct *task, unsigned long *data)
{
int i;
if (!access_ok(VERIFY_READ, data, 35 * sizeof(unsigned long)))
return -EFAULT;
/* copy SPEFSCR */
if (__get_user(task->thread.spefscr, &data[34]))
return -EFAULT;
/* copy SPE registers EVR[0] .. EVR[31] */
for (i = 0; i < 32; i++, data++)
if (__get_user(task->thread.evr[i], data))
return -EFAULT;
/* copy ACC */
if (__get_user64(task->thread.acc, (unsigned long long*)data))
return -EFAULT;
return 0;
}
#endif /* CONFIG_SPE */
static inline void
set_single_step(struct task_struct *task)
{
struct pt_regs *regs = task->thread.regs;
if (regs != NULL) {
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
task->thread.dbcr0 = DBCR0_IDM | DBCR0_IC;
regs->msr |= MSR_DE;
#else
regs->msr |= MSR_SE;
#endif
}
}
static inline void
clear_single_step(struct task_struct *task)
{
struct pt_regs *regs = task->thread.regs;
if (regs != NULL) {
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
task->thread.dbcr0 = 0;
regs->msr &= ~MSR_DE;
#else
regs->msr &= ~MSR_SE;
#endif
}
}
#endif /* CONFIG_PPC32 */
/*
* 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 single step bit is not set. */
clear_single_step(child);
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
int ret = -EPERM;
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;
copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
ret = -EIO;
if (copied != sizeof(tmp))
break;
ret = put_user(tmp,(unsigned long __user *) data);
break;
}
/* read the word at location addr in the USER area. */
case PTRACE_PEEKUSR: {
unsigned long index, tmp;
ret = -EIO;
/* convert to index and check */
#ifdef CONFIG_PPC32
index = (unsigned long) addr >> 2;
if ((addr & 3) || (index > PT_FPSCR)
|| (child->thread.regs == NULL))
#else
index = (unsigned long) addr >> 3;
if ((addr & 7) || (index > PT_FPSCR))
#endif
break;
#ifdef CONFIG_PPC32
CHECK_FULL_REGS(child->thread.regs);
#endif
if (index < PT_FPR0) {
tmp = get_reg(child, (int) index);
} else {
flush_fp_to_thread(child);
tmp = ((unsigned long *)child->thread.fpr)[index - PT_FPR0];
}
ret = put_user(tmp,(unsigned long __user *) data);
break;
}
/* If 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))
break;
ret = -EIO;
break;
/* write the word at location addr in the USER area */
case PTRACE_POKEUSR: {
unsigned long index;
ret = -EIO;
/* convert to index and check */
#ifdef CONFIG_PPC32
index = (unsigned long) addr >> 2;
if ((addr & 3) || (index > PT_FPSCR)
|| (child->thread.regs == NULL))
#else
index = (unsigned long) addr >> 3;
if ((addr & 7) || (index > PT_FPSCR))
#endif
break;
#ifdef CONFIG_PPC32
CHECK_FULL_REGS(child->thread.regs);
#endif
if (index == PT_ORIG_R3)
break;
if (index < PT_FPR0) {
ret = put_reg(child, index, data);
} else {
flush_fp_to_thread(child);
((unsigned long *)child->thread.fpr)[index - PT_FPR0] = data;
ret = 0;
}
break;
}
case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
case PTRACE_CONT: { /* restart after signal. */
ret = -EIO;
if (!valid_signal(data))
break;
if (request == PTRACE_SYSCALL)
set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
else
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
child->exit_code = data;
/* make sure the single step bit is not set. */
clear_single_step(child);
wake_up_process(child);
ret = 0;
break;
}
/*
* 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: {
ret = 0;
if (child->exit_state == EXIT_ZOMBIE) /* already dead */
break;
child->exit_code = SIGKILL;
/* make sure the single step bit is not set. */
clear_single_step(child);
wake_up_process(child);
break;
}
case PTRACE_SINGLESTEP: { /* set the trap flag. */
ret = -EIO;
if (!valid_signal(data))
break;
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
set_single_step(child);
child->exit_code = data;
/* give it a chance to run. */
wake_up_process(child);
ret = 0;
break;
}
#ifdef CONFIG_PPC64
case PTRACE_GET_DEBUGREG: {
ret = -EINVAL;
/* We only support one DABR and no IABRS at the moment */
if (addr > 0)
break;
ret = put_user(child->thread.dabr,
(unsigned long __user *)data);
break;
}
case PTRACE_SET_DEBUGREG:
ret = ptrace_set_debugreg(child, addr, data);
break;
#endif
case PTRACE_DETACH:
ret = ptrace_detach(child, data);
break;
#ifdef CONFIG_PPC64
case PPC_PTRACE_GETREGS: { /* Get GPRs 0 - 31. */
int i;
unsigned long *reg = &((unsigned long *)child->thread.regs)[0];
unsigned long __user *tmp = (unsigned long __user *)addr;
for (i = 0; i < 32; i++) {
ret = put_user(*reg, tmp);
if (ret)
break;
reg++;
tmp++;
}
break;
}
case PPC_PTRACE_SETREGS: { /* Set GPRs 0 - 31. */
int i;
unsigned long *reg = &((unsigned long *)child->thread.regs)[0];
unsigned long __user *tmp = (unsigned long __user *)addr;
for (i = 0; i < 32; i++) {
ret = get_user(*reg, tmp);
if (ret)
break;
reg++;
tmp++;
}
break;
}
case PPC_PTRACE_GETFPREGS: { /* Get FPRs 0 - 31. */
int i;
unsigned long *reg = &((unsigned long *)child->thread.fpr)[0];
unsigned long __user *tmp = (unsigned long __user *)addr;
flush_fp_to_thread(child);
for (i = 0; i < 32; i++) {
ret = put_user(*reg, tmp);
if (ret)
break;
reg++;
tmp++;
}
break;
}
case PPC_PTRACE_SETFPREGS: { /* Get FPRs 0 - 31. */
int i;
unsigned long *reg = &((unsigned long *)child->thread.fpr)[0];
unsigned long __user *tmp = (unsigned long __user *)addr;
flush_fp_to_thread(child);
for (i = 0; i < 32; i++) {
ret = get_user(*reg, tmp);
if (ret)
break;
reg++;
tmp++;
}
break;
}
#endif /* CONFIG_PPC64 */
#ifdef CONFIG_ALTIVEC
case PTRACE_GETVRREGS:
/* Get the child altivec register state. */
flush_altivec_to_thread(child);
ret = get_vrregs((unsigned long __user *)data, child);
break;
case PTRACE_SETVRREGS:
/* Set the child altivec register state. */
flush_altivec_to_thread(child);
ret = set_vrregs(child, (unsigned long __user *)data);
break;
#endif
#ifdef CONFIG_SPE
case PTRACE_GETEVRREGS:
/* Get the child spe register state. */
if (child->thread.regs->msr & MSR_SPE)
giveup_spe(child);
ret = get_evrregs((unsigned long __user *)data, child);
break;
case PTRACE_SETEVRREGS:
/* Set the child spe register state. */
/* this is to clear the MSR_SPE bit to force a reload
* of register state from memory */
if (child->thread.regs->msr & MSR_SPE)
giveup_spe(child);
ret = set_evrregs(child, (unsigned long __user *)data);
break;
#endif
default:
ret = ptrace_request(child, request, addr, data);
break;
}
return ret;
}
static void do_syscall_trace(void)
{
/* the 0x80 provides a way for the tracing parent to distinguish
between a syscall stop and SIGTRAP delivery */
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
? 0x80 : 0));
/*
* 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;
}
}
void do_syscall_trace_enter(struct pt_regs *regs)
{
#ifdef CONFIG_PPC64
secure_computing(regs->gpr[0]);
#endif
if (test_thread_flag(TIF_SYSCALL_TRACE)
&& (current->ptrace & PT_PTRACED))
do_syscall_trace();
if (unlikely(current->audit_context))
audit_syscall_entry(current,
#ifdef CONFIG_PPC32
AUDIT_ARCH_PPC,
#else
test_thread_flag(TIF_32BIT)?AUDIT_ARCH_PPC:AUDIT_ARCH_PPC64,
#endif
regs->gpr[0],
regs->gpr[3], regs->gpr[4],
regs->gpr[5], regs->gpr[6]);
}
void do_syscall_trace_leave(struct pt_regs *regs)
{
#ifdef CONFIG_PPC32
secure_computing(regs->gpr[0]);
#endif
if (unlikely(current->audit_context))
audit_syscall_exit(current,
(regs->ccr&0x1000)?AUDITSC_FAILURE:AUDITSC_SUCCESS,
regs->result);
if ((test_thread_flag(TIF_SYSCALL_TRACE)
|| test_thread_flag(TIF_SINGLESTEP))
&& (current->ptrace & PT_PTRACED))
do_syscall_trace();
}
#ifdef CONFIG_PPC32
EXPORT_SYMBOL(do_syscall_trace_enter);
EXPORT_SYMBOL(do_syscall_trace_leave);
#endif
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