kernel-ark/arch/um/sys-i386/signal.c
Jeff Dike a5f6096c80 uml: floating point signal delivery fixes
Handle floating point state in across signals correctly.  UML/i386 needs to
know whether the host does PTRACE_[GS]ETFPXREGS, so an arch_init_registers
hook is added, which on x86_64 does nothing.

UML doesn't save and restore floating point registers on kernel entry and
exit, so they need to be copied between the host process and the sigcontext.
save_fpx_registers and restore_fpx_registers are added for this purpose.
save_fp_registers and restore_fp_registers already exist.

There was a bunch of floating point state conversion code in
arch/um/sys-i386/ptrace.c which isn't needed there, but is needed in signal.c,
so it is moved over.

The i386 code now distinguishes between fp and fpx state and handles them
correctly.  The x86_64 code just needs to copy state as-is between the host
process and the stack.  There are also some fixes there to pass the correct
address of the floating point state around.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 09:43:07 -07:00

510 lines
13 KiB
C

/*
* 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->edi;
REGS_ESI(regs->gp) = sc->esi;
REGS_EBP(regs->gp) = sc->ebp;
REGS_SP(regs->gp) = sc->esp;
REGS_EBX(regs->gp) = sc->ebx;
REGS_EDX(regs->gp) = sc->edx;
REGS_ECX(regs->gp) = sc->ecx;
REGS_EAX(regs->gp) = sc->eax;
REGS_IP(regs->gp) = sc->eip;
REGS_CS(regs->gp) = sc->cs;
REGS_EFLAGS(regs->gp) = sc->eflags;
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;
err = copy_from_user(&sc, from, sizeof(sc));
if (err)
return err;
copy_sc(&regs->regs, &sc);
if (have_fpx_regs) {
struct user_fxsr_struct fpx;
err = copy_from_user(&fpx, &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(userspace_pid[current_thread->cpu],
(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(userspace_pid[current_thread->cpu],
(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;
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.edi = REGS_EDI(regs->regs.gp);
sc.esi = REGS_ESI(regs->regs.gp);
sc.ebp = REGS_EBP(regs->regs.gp);
sc.esp = sp;
sc.ebx = REGS_EBX(regs->regs.gp);
sc.edx = REGS_EDX(regs->regs.gp);
sc.ecx = REGS_ECX(regs->regs.gp);
sc.eax = REGS_EAX(regs->regs.gp);
sc.eip = REGS_IP(regs->regs.gp);
sc.cs = REGS_CS(regs->regs.gp);
sc.eflags = REGS_EFLAGS(regs->regs.gp);
sc.esp_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;
if (have_fpx_regs) {
struct user_fxsr_struct fpx;
err = save_fpx_registers(userspace_pid[current_thread->cpu],
(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(userspace_pid[current_thread->cpu],
(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;
}