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kernel-fxtec-pro1x/arch/sparc/kernel/ptrace.c
David S. Miller 28e6103665 sparc: Fix debugger syscall restart interactions. 
So, forever, we've had this ptrace_signal_deliver implementation
which tries to handle all of the nasties that can occur when the
debugger looks at a process about to take a signal.  It's meant
to address all of these issues inside of the kernel so that the
debugger need not be mindful of such things.

Problem is, this doesn't work.

The idea was that we should do the syscall restart business first, so
that the debugger captures that state.  Otherwise, if the debugger for
example saves the child's state, makes the child execute something
else, then restores the saved state, we won't handle the syscall
restart properly because we lose the "we're in a syscall" state.

The code here worked for most cases, but if the debugger actually
passes the signal through to the child unaltered, it's possible that
we would do a syscall restart when we shouldn't have.

In particular this breaks the case of debugging a process under a gdb
which is being debugged by yet another gdb.  gdb uses sigsuspend
to wait for SIGCHLD of the inferior, but if gdb itself is being
debugged by a top-level gdb we get a ptrace_stop().  The top-level gdb
does a PTRACE_CONT with SIGCHLD to let the inferior gdb see the
signal.  But ptrace_signal_deliver() assumed the debugger would cancel
out the signal and therefore did a syscall restart, because the return
error was ERESTARTNOHAND.

Fix this by simply making ptrace_signal_deliver() a nop, and providing
a way for the debugger to control system call restarting properly:

1) Report a "in syscall" software bit in regs->{tstate,psr}.
   It is set early on in trap entry to a system call and is fully
   visible to the debugger via ptrace() and regsets.

2) Test this bit right before doing a syscall restart.  We have
   to do a final recheck right after get_signal_to_deliver() in
   case the debugger cleared the bit during ptrace_stop().

3) Clear the bit in trap return so we don't accidently try to set
   that bit in the real register.

As a result we also get a ptrace_{is,clear}_syscall() for sparc32 just
like sparc64 has.

M68K has this same exact bug, and is now the only other user of the
ptrace_signal_deliver hook.  It needs to be fixed in the same exact
way as sparc.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-05-11 02:07:19 -07:00

470 lines
10 KiB
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/* ptrace.c: Sparc process tracing support.
*
* Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
*
* Based upon code written by Ross Biro, Linus Torvalds, Bob Manson,
* and David Mosberger.
*
* Added Linux support -miguel (weird, eh?, the original code was meant
* to emulate SunOS).
*/
#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/smp.h>
#include <linux/smp_lock.h>
#include <linux/security.h>
#include <linux/signal.h>
#include <linux/regset.h>
#include <linux/elf.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/uaccess.h>
/* #define ALLOW_INIT_TRACING */
/*
* Called by kernel/ptrace.c when detaching..
*
* Make sure single step bits etc are not set.
*/
void ptrace_disable(struct task_struct *child)
{
/* nothing to do */
}
enum sparc_regset {
REGSET_GENERAL,
REGSET_FP,
};
static int genregs32_get(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
const struct pt_regs *regs = target->thread.kregs;
unsigned long __user *reg_window;
unsigned long *k = kbuf;
unsigned long __user *u = ubuf;
unsigned long reg;
if (target == current)
flush_user_windows();
pos /= sizeof(reg);
count /= sizeof(reg);
if (kbuf) {
for (; count > 0 && pos < 16; count--)
*k++ = regs->u_regs[pos++];
reg_window = (unsigned long __user *) regs->u_regs[UREG_I6];
for (; count > 0 && pos < 32; count--) {
if (get_user(*k++, &reg_window[pos++]))
return -EFAULT;
}
} else {
for (; count > 0 && pos < 16; count--) {
if (put_user(regs->u_regs[pos++], u++))
return -EFAULT;
}
reg_window = (unsigned long __user *) regs->u_regs[UREG_I6];
for (; count > 0 && pos < 32; count--) {
if (get_user(reg, &reg_window[pos++]) ||
put_user(reg, u++))
return -EFAULT;
}
}
while (count > 0) {
switch (pos) {
case 32: /* PSR */
reg = regs->psr;
break;
case 33: /* PC */
reg = regs->pc;
break;
case 34: /* NPC */
reg = regs->npc;
break;
case 35: /* Y */
reg = regs->y;
break;
case 36: /* WIM */
case 37: /* TBR */
reg = 0;
break;
default:
goto finish;
}
if (kbuf)
*k++ = reg;
else if (put_user(reg, u++))
return -EFAULT;
pos++;
count--;
}
finish:
pos *= sizeof(reg);
count *= sizeof(reg);
return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
38 * sizeof(reg), -1);
}
static int genregs32_set(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
struct pt_regs *regs = target->thread.kregs;
unsigned long __user *reg_window;
const unsigned long *k = kbuf;
const unsigned long __user *u = ubuf;
unsigned long reg;
if (target == current)
flush_user_windows();
pos /= sizeof(reg);
count /= sizeof(reg);
if (kbuf) {
for (; count > 0 && pos < 16; count--)
regs->u_regs[pos++] = *k++;
reg_window = (unsigned long __user *) regs->u_regs[UREG_I6];
for (; count > 0 && pos < 32; count--) {
if (put_user(*k++, &reg_window[pos++]))
return -EFAULT;
}
} else {
for (; count > 0 && pos < 16; count--) {
if (get_user(reg, u++))
return -EFAULT;
regs->u_regs[pos++] = reg;
}
reg_window = (unsigned long __user *) regs->u_regs[UREG_I6];
for (; count > 0 && pos < 32; count--) {
if (get_user(reg, u++) ||
put_user(reg, &reg_window[pos++]))
return -EFAULT;
}
}
while (count > 0) {
unsigned long psr;
if (kbuf)
reg = *k++;
else if (get_user(reg, u++))
return -EFAULT;
switch (pos) {
case 32: /* PSR */
psr = regs->psr;
psr &= ~(PSR_ICC | PSR_SYSCALL);
psr |= (reg & (PSR_ICC | PSR_SYSCALL));
regs->psr = psr;
break;
case 33: /* PC */
regs->pc = reg;
break;
case 34: /* NPC */
regs->npc = reg;
break;
case 35: /* Y */
regs->y = reg;
break;
case 36: /* WIM */
case 37: /* TBR */
break;
default:
goto finish;
}
pos++;
count--;
}
finish:
pos *= sizeof(reg);
count *= sizeof(reg);
return user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
38 * sizeof(reg), -1);
}
static int fpregs32_get(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
const unsigned long *fpregs = target->thread.float_regs;
int ret = 0;
#if 0
if (target == current)
save_and_clear_fpu();
#endif
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
fpregs,
0, 32 * sizeof(u32));
if (!ret)
ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
32 * sizeof(u32),
33 * sizeof(u32));
if (!ret)
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.fsr,
33 * sizeof(u32),
34 * sizeof(u32));
if (!ret) {
unsigned long val;
val = (1 << 8) | (8 << 16);
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&val,
34 * sizeof(u32),
35 * sizeof(u32));
}
if (!ret)
ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
35 * sizeof(u32), -1);
return ret;
}
static int fpregs32_set(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
unsigned long *fpregs = target->thread.float_regs;
int ret;
#if 0
if (target == current)
save_and_clear_fpu();
#endif
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
fpregs,
0, 32 * sizeof(u32));
if (!ret)
user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
32 * sizeof(u32),
33 * sizeof(u32));
if (!ret && count > 0) {
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.fsr,
33 * sizeof(u32),
34 * sizeof(u32));
}
if (!ret)
ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
34 * sizeof(u32), -1);
return ret;
}
static const struct user_regset sparc32_regsets[] = {
/* Format is:
* G0 --> G7
* O0 --> O7
* L0 --> L7
* I0 --> I7
* PSR, PC, nPC, Y, WIM, TBR
*/
[REGSET_GENERAL] = {
.core_note_type = NT_PRSTATUS,
.n = 38 * sizeof(u32),
.size = sizeof(u32), .align = sizeof(u32),
.get = genregs32_get, .set = genregs32_set
},
/* Format is:
* F0 --> F31
* empty 32-bit word
* FSR (32--bit word)
* FPU QUEUE COUNT (8-bit char)
* FPU QUEUE ENTRYSIZE (8-bit char)
* FPU ENABLED (8-bit char)
* empty 8-bit char
* FPU QUEUE (64 32-bit ints)
*/
[REGSET_FP] = {
.core_note_type = NT_PRFPREG,
.n = 99 * sizeof(u32),
.size = sizeof(u32), .align = sizeof(u32),
.get = fpregs32_get, .set = fpregs32_set
},
};
static const struct user_regset_view user_sparc32_view = {
.name = "sparc", .e_machine = EM_SPARC,
.regsets = sparc32_regsets, .n = ARRAY_SIZE(sparc32_regsets)
};
const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
return &user_sparc32_view;
}
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
unsigned long addr2 = current->thread.kregs->u_regs[UREG_I4];
const struct user_regset_view *view;
int ret;
view = task_user_regset_view(current);
switch(request) {
case PTRACE_GETREGS: {
struct pt_regs __user *pregs = (struct pt_regs __user *) addr;
ret = copy_regset_to_user(child, view, REGSET_GENERAL,
32 * sizeof(u32),
4 * sizeof(u32),
&pregs->psr);
if (!ret)
copy_regset_to_user(child, view, REGSET_GENERAL,
1 * sizeof(u32),
15 * sizeof(u32),
&pregs->u_regs[0]);
break;
}
case PTRACE_SETREGS: {
struct pt_regs __user *pregs = (struct pt_regs __user *) addr;
ret = copy_regset_from_user(child, view, REGSET_GENERAL,
32 * sizeof(u32),
4 * sizeof(u32),
&pregs->psr);
if (!ret)
copy_regset_from_user(child, view, REGSET_GENERAL,
1 * sizeof(u32),
15 * sizeof(u32),
&pregs->u_regs[0]);
break;
}
case PTRACE_GETFPREGS: {
struct fps {
unsigned long regs[32];
unsigned long fsr;
unsigned long flags;
unsigned long extra;
unsigned long fpqd;
struct fq {
unsigned long *insnaddr;
unsigned long insn;
} fpq[16];
};
struct fps __user *fps = (struct fps __user *) addr;
ret = copy_regset_to_user(child, view, REGSET_FP,
0 * sizeof(u32),
32 * sizeof(u32),
&fps->regs[0]);
if (!ret)
ret = copy_regset_to_user(child, view, REGSET_FP,
33 * sizeof(u32),
1 * sizeof(u32),
&fps->fsr);
if (!ret) {
if (__put_user(0, &fps->fpqd) ||
__put_user(0, &fps->flags) ||
__put_user(0, &fps->extra) ||
clear_user(fps->fpq, sizeof(fps->fpq)))
ret = -EFAULT;
}
break;
}
case PTRACE_SETFPREGS: {
struct fps {
unsigned long regs[32];
unsigned long fsr;
unsigned long flags;
unsigned long extra;
unsigned long fpqd;
struct fq {
unsigned long *insnaddr;
unsigned long insn;
} fpq[16];
};
struct fps __user *fps = (struct fps __user *) addr;
ret = copy_regset_from_user(child, view, REGSET_FP,
0 * sizeof(u32),
32 * sizeof(u32),
&fps->regs[0]);
if (!ret)
ret = copy_regset_from_user(child, view, REGSET_FP,
33 * sizeof(u32),
1 * sizeof(u32),
&fps->fsr);
break;
}
case PTRACE_READTEXT:
case PTRACE_READDATA:
ret = ptrace_readdata(child, addr,
(void __user *) addr2, data);
if (ret == data)
ret = 0;
else if (ret >= 0)
ret = -EIO;
break;
case PTRACE_WRITETEXT:
case PTRACE_WRITEDATA:
ret = ptrace_writedata(child, (void __user *) addr2,
addr, data);
if (ret == data)
ret = 0;
else if (ret >= 0)
ret = -EIO;
break;
default:
if (request == PTRACE_SPARC_DETACH)
request = PTRACE_DETACH;
ret = ptrace_request(child, request, addr, data);
break;
}
return ret;
}
asmlinkage void syscall_trace(void)
{
if (!test_thread_flag(TIF_SYSCALL_TRACE))
return;
if (!(current->ptrace & PT_PTRACED))
return;
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;
}
}
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