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>
diff --git a/arch/um/sys-i386/signal.c b/arch/um/sys-i386/signal.c
index 1eb21a0..0147227 100644
--- a/arch/um/sys-i386/signal.c
+++ b/arch/um/sys-i386/signal.c
@@ -32,25 +32,186 @@
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;
- unsigned long fpregs[HOST_FP_SIZE];
+ struct sigcontext sc;
int err;
err = copy_from_user(&sc, from, sizeof(sc));
- err |= copy_from_user(fpregs, sc.fpstate, sizeof(fpregs));
if (err)
return err;
copy_sc(®s->regs, &sc);
+ if (have_fpx_regs) {
+ struct user_fxsr_struct fpx;
- err = restore_fp_registers(userspace_pid[0], fpregs);
- if (err < 0) {
- printk(KERN_ERR "copy_sc_from_user_skas - PTRACE_SETFPREGS "
- "failed, errno = %d\n", -err);
- return err;
+ 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;
@@ -61,7 +222,6 @@
unsigned long sp)
{
struct sigcontext sc;
- unsigned long fpregs[HOST_FP_SIZE];
struct faultinfo * fi = ¤t->thread.arch.faultinfo;
int err;
@@ -86,20 +246,43 @@
sc.err = fi->error_code;
sc.trapno = fi->trap_no;
- err = save_fp_registers(userspace_pid[0], fpregs);
- if (err < 0) {
- printk(KERN_ERR "copy_sc_to_user_skas - PTRACE_GETFPREGS "
- "failed, errno = %d\n", err);
- return 1;
- }
to_fp = (to_fp ? to_fp : (struct _fpstate __user *) (to + 1));
sc.fpstate = to_fp;
- if (err)
- return err;
+ if (have_fpx_regs) {
+ struct user_fxsr_struct fpx;
- return copy_to_user(to, &sc, sizeof(sc)) ||
- copy_to_user(to_fp, fpregs, sizeof(fpregs));
+ 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,