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linux/arch/um/sys-i386/signal.c
Phil Carmody 497888cf69 treewide: fix potentially dangerous trailing ';' in #defined values/expressions 
All these are instances of
  #define NAME value;
or
  #define NAME(params_opt) value;

These of course fail to build when used in contexts like
  if(foo $OP NAME)
  while(bar $OP NAME)
and may silently generate the wrong code in contexts such as
  foo = NAME + 1;    /* foo = value; + 1; */
  bar = NAME - 1;    /* bar = value; - 1; */
  baz = NAME & quux; /* baz = value; & quux; */

Reported on comp.lang.c,
Message-ID: <ab0d55fe-25e5-482b-811e-c475aa6065c3@c29g2000yqd.googlegroups.com>
Initial analysis of the dangers provided by Keith Thompson in that thread.

There are many more instances of more complicated macros having unnecessary
trailing semicolons, but this pile seems to be all of the cases of simple
values suffering from the problem. (Thus things that are likely to be found
in one of the contexts above, more complicated ones aren't.)

Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-07-21 14:10:00 +02:00

509 lines
13 KiB
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/*
* Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/ptrace.h>
#include <asm/unistd.h>
#include <asm/uaccess.h>
#include <asm/ucontext.h>
#include "frame_kern.h"
#include "skas.h"
void copy_sc(struct uml_pt_regs *regs, void *from)
{
struct sigcontext *sc = from;
REGS_GS(regs->gp) = sc->gs;
REGS_FS(regs->gp) = sc->fs;
REGS_ES(regs->gp) = sc->es;
REGS_DS(regs->gp) = sc->ds;
REGS_EDI(regs->gp) = sc->di;
REGS_ESI(regs->gp) = sc->si;
REGS_EBP(regs->gp) = sc->bp;
REGS_SP(regs->gp) = sc->sp;
REGS_EBX(regs->gp) = sc->bx;
REGS_EDX(regs->gp) = sc->dx;
REGS_ECX(regs->gp) = sc->cx;
REGS_EAX(regs->gp) = sc->ax;
REGS_IP(regs->gp) = sc->ip;
REGS_CS(regs->gp) = sc->cs;
REGS_EFLAGS(regs->gp) = sc->flags;
REGS_SS(regs->gp) = sc->ss;
}
/*
* FPU tag word conversions.
*/
static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
{
unsigned int tmp; /* to avoid 16 bit prefixes in the code */
/* Transform each pair of bits into 01 (valid) or 00 (empty) */
tmp = ~twd;
tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
/* and move the valid bits to the lower byte. */
tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
return tmp;
}
static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
{
struct _fpxreg *st = NULL;
unsigned long twd = (unsigned long) fxsave->twd;
unsigned long tag;
unsigned long ret = 0xffff0000;
int i;
#define FPREG_ADDR(f, n) ((char *)&(f)->st_space + (n) * 16)
for (i = 0; i < 8; i++) {
if (twd & 0x1) {
st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);
switch (st->exponent & 0x7fff) {
case 0x7fff:
tag = 2; /* Special */
break;
case 0x0000:
if ( !st->significand[0] &&
!st->significand[1] &&
!st->significand[2] &&
!st->significand[3] ) {
tag = 1; /* Zero */
} else {
tag = 2; /* Special */
}
break;
default:
if (st->significand[3] & 0x8000) {
tag = 0; /* Valid */
} else {
tag = 2; /* Special */
}
break;
}
} else {
tag = 3; /* Empty */
}
ret |= (tag << (2 * i));
twd = twd >> 1;
}
return ret;
}
static int convert_fxsr_to_user(struct _fpstate __user *buf,
struct user_fxsr_struct *fxsave)
{
unsigned long env[7];
struct _fpreg __user *to;
struct _fpxreg *from;
int i;
env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
env[2] = twd_fxsr_to_i387(fxsave);
env[3] = fxsave->fip;
env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
env[5] = fxsave->foo;
env[6] = fxsave->fos;
if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
return 1;
to = &buf->_st[0];
from = (struct _fpxreg *) &fxsave->st_space[0];
for (i = 0; i < 8; i++, to++, from++) {
unsigned long __user *t = (unsigned long __user *)to;
unsigned long *f = (unsigned long *)from;
if (__put_user(*f, t) ||
__put_user(*(f + 1), t + 1) ||
__put_user(from->exponent, &to->exponent))
return 1;
}
return 0;
}
static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
struct _fpstate __user *buf)
{
unsigned long env[7];
struct _fpxreg *to;
struct _fpreg __user *from;
int i;
if (copy_from_user( env, buf, 7 * sizeof(long)))
return 1;
fxsave->cwd = (unsigned short)(env[0] & 0xffff);
fxsave->swd = (unsigned short)(env[1] & 0xffff);
fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
fxsave->fip = env[3];
fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
fxsave->fcs = (env[4] & 0xffff);
fxsave->foo = env[5];
fxsave->fos = env[6];
to = (struct _fpxreg *) &fxsave->st_space[0];
from = &buf->_st[0];
for (i = 0; i < 8; i++, to++, from++) {
unsigned long *t = (unsigned long *)to;
unsigned long __user *f = (unsigned long __user *)from;
if (__get_user(*t, f) ||
__get_user(*(t + 1), f + 1) ||
__get_user(to->exponent, &from->exponent))
return 1;
}
return 0;
}
extern int have_fpx_regs;
static int copy_sc_from_user(struct pt_regs *regs,
struct sigcontext __user *from)
{
struct sigcontext sc;
int err, pid;
err = copy_from_user(&sc, from, sizeof(sc));
if (err)
return err;
pid = userspace_pid[current_thread_info()->cpu];
copy_sc(&regs->regs, &sc);
if (have_fpx_regs) {
struct user_fxsr_struct fpx;
err = copy_from_user(&fpx,
&((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
sizeof(struct user_fxsr_struct));
if (err)
return 1;
err = convert_fxsr_from_user(&fpx, sc.fpstate);
if (err)
return 1;
err = restore_fpx_registers(pid, (unsigned long *) &fpx);
if (err < 0) {
printk(KERN_ERR "copy_sc_from_user - "
"restore_fpx_registers failed, errno = %d\n",
-err);
return 1;
}
}
else {
struct user_i387_struct fp;
err = copy_from_user(&fp, sc.fpstate,
sizeof(struct user_i387_struct));
if (err)
return 1;
err = restore_fp_registers(pid, (unsigned long *) &fp);
if (err < 0) {
printk(KERN_ERR "copy_sc_from_user - "
"restore_fp_registers failed, errno = %d\n",
-err);
return 1;
}
}
return 0;
}
static int copy_sc_to_user(struct sigcontext __user *to,
struct _fpstate __user *to_fp, struct pt_regs *regs,
unsigned long sp)
{
struct sigcontext sc;
struct faultinfo * fi = &current->thread.arch.faultinfo;
int err, pid;
sc.gs = REGS_GS(regs->regs.gp);
sc.fs = REGS_FS(regs->regs.gp);
sc.es = REGS_ES(regs->regs.gp);
sc.ds = REGS_DS(regs->regs.gp);
sc.di = REGS_EDI(regs->regs.gp);
sc.si = REGS_ESI(regs->regs.gp);
sc.bp = REGS_EBP(regs->regs.gp);
sc.sp = sp;
sc.bx = REGS_EBX(regs->regs.gp);
sc.dx = REGS_EDX(regs->regs.gp);
sc.cx = REGS_ECX(regs->regs.gp);
sc.ax = REGS_EAX(regs->regs.gp);
sc.ip = REGS_IP(regs->regs.gp);
sc.cs = REGS_CS(regs->regs.gp);
sc.flags = REGS_EFLAGS(regs->regs.gp);
sc.sp_at_signal = regs->regs.gp[UESP];
sc.ss = regs->regs.gp[SS];
sc.cr2 = fi->cr2;
sc.err = fi->error_code;
sc.trapno = fi->trap_no;
to_fp = (to_fp ? to_fp : (struct _fpstate __user *) (to + 1));
sc.fpstate = to_fp;
pid = userspace_pid[current_thread_info()->cpu];
if (have_fpx_regs) {
struct user_fxsr_struct fpx;
err = save_fpx_registers(pid, (unsigned long *) &fpx);
if (err < 0){
printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
"failed, errno = %d\n", err);
return 1;
}
err = convert_fxsr_to_user(to_fp, &fpx);
if (err)
return 1;
err |= __put_user(fpx.swd, &to_fp->status);
err |= __put_user(X86_FXSR_MAGIC, &to_fp->magic);
if (err)
return 1;
if (copy_to_user(&to_fp->_fxsr_env[0], &fpx,
sizeof(struct user_fxsr_struct)))
return 1;
}
else {
struct user_i387_struct fp;
err = save_fp_registers(pid, (unsigned long *) &fp);
if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
return 1;
}
return copy_to_user(to, &sc, sizeof(sc));
}
static int copy_ucontext_to_user(struct ucontext __user *uc,
struct _fpstate __user *fp, sigset_t *set,
unsigned long sp)
{
int err = 0;
err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
return err;
}
struct sigframe
{
char __user *pretcode;
int sig;
struct sigcontext sc;
struct _fpstate fpstate;
unsigned long extramask[_NSIG_WORDS-1];
char retcode[8];
};
struct rt_sigframe
{
char __user *pretcode;
int sig;
struct siginfo __user *pinfo;
void __user *puc;
struct siginfo info;
struct ucontext uc;
struct _fpstate fpstate;
char retcode[8];
};
int setup_signal_stack_sc(unsigned long stack_top, int sig,
struct k_sigaction *ka, struct pt_regs *regs,
sigset_t *mask)
{
struct sigframe __user *frame;
void __user *restorer;
unsigned long save_sp = PT_REGS_SP(regs);
int err = 0;
/* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
stack_top = ((stack_top + 4) & -16UL) - 4;
frame = (struct sigframe __user *) stack_top - 1;
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return 1;
restorer = frame->retcode;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
/* Update SP now because the page fault handler refuses to extend
* the stack if the faulting address is too far below the current
* SP, which frame now certainly is. If there's an error, the original
* value is restored on the way out.
* When writing the sigcontext to the stack, we have to write the
* original value, so that's passed to copy_sc_to_user, which does
* the right thing with it.
*/
PT_REGS_SP(regs) = (unsigned long) frame;
err |= __put_user(restorer, &frame->pretcode);
err |= __put_user(sig, &frame->sig);
err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
err |= __put_user(mask->sig[0], &frame->sc.oldmask);
if (_NSIG_WORDS > 1)
err |= __copy_to_user(&frame->extramask, &mask->sig[1],
sizeof(frame->extramask));
/*
* This is popl %eax ; movl $,%eax ; int $0x80
*
* WE DO NOT USE IT ANY MORE! It's only left here for historical
* reasons and because gdb uses it as a signature to notice
* signal handler stack frames.
*/
err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
if (err)
goto err;
PT_REGS_SP(regs) = (unsigned long) frame;
PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
PT_REGS_EAX(regs) = (unsigned long) sig;
PT_REGS_EDX(regs) = (unsigned long) 0;
PT_REGS_ECX(regs) = (unsigned long) 0;
if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
ptrace_notify(SIGTRAP);
return 0;
err:
PT_REGS_SP(regs) = save_sp;
return err;
}
int setup_signal_stack_si(unsigned long stack_top, int sig,
struct k_sigaction *ka, struct pt_regs *regs,
siginfo_t *info, sigset_t *mask)
{
struct rt_sigframe __user *frame;
void __user *restorer;
unsigned long save_sp = PT_REGS_SP(regs);
int err = 0;
stack_top &= -8UL;
frame = (struct rt_sigframe __user *) stack_top - 1;
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
return 1;
restorer = frame->retcode;
if (ka->sa.sa_flags & SA_RESTORER)
restorer = ka->sa.sa_restorer;
/* See comment above about why this is here */
PT_REGS_SP(regs) = (unsigned long) frame;
err |= __put_user(restorer, &frame->pretcode);
err |= __put_user(sig, &frame->sig);
err |= __put_user(&frame->info, &frame->pinfo);
err |= __put_user(&frame->uc, &frame->puc);
err |= copy_siginfo_to_user(&frame->info, info);
err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
save_sp);
/*
* This is movl $,%eax ; int $0x80
*
* WE DO NOT USE IT ANY MORE! It's only left here for historical
* reasons and because gdb uses it as a signature to notice
* signal handler stack frames.
*/
err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
if (err)
goto err;
PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
PT_REGS_EAX(regs) = (unsigned long) sig;
PT_REGS_EDX(regs) = (unsigned long) &frame->info;
PT_REGS_ECX(regs) = (unsigned long) &frame->uc;
if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
ptrace_notify(SIGTRAP);
return 0;
err:
PT_REGS_SP(regs) = save_sp;
return err;
}
long sys_sigreturn(struct pt_regs regs)
{
unsigned long sp = PT_REGS_SP(&current->thread.regs);
struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
sigset_t set;
struct sigcontext __user *sc = &frame->sc;
unsigned long __user *oldmask = &sc->oldmask;
unsigned long __user *extramask = frame->extramask;
int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
if (copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
copy_from_user(&set.sig[1], extramask, sig_size))
goto segfault;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (copy_sc_from_user(&current->thread.regs, sc))
goto segfault;
/* Avoid ERESTART handling */
PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
return PT_REGS_SYSCALL_RET(&current->thread.regs);
segfault:
force_sig(SIGSEGV, current);
return 0;
}
long sys_rt_sigreturn(struct pt_regs regs)
{
unsigned long sp = PT_REGS_SP(&current->thread.regs);
struct rt_sigframe __user *frame =
(struct rt_sigframe __user *) (sp - 4);
sigset_t set;
struct ucontext __user *uc = &frame->uc;
int sig_size = _NSIG_WORDS * sizeof(unsigned long);
if (copy_from_user(&set, &uc->uc_sigmask, sig_size))
goto segfault;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
goto segfault;
/* Avoid ERESTART handling */
PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
return PT_REGS_SYSCALL_RET(&current->thread.regs);
segfault:
force_sig(SIGSEGV, current);
return 0;
}
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