x86, xsave: save/restore the extended state context in sigframe
On cpu's supporting xsave/xrstor, fpstate pointer in the sigcontext, will
include the extended state information along with fpstate information. Presence
of extended state information is indicated by the presence
of FP_XSTATE_MAGIC1 at fpstate.sw_reserved.magic1 and FP_XSTATE_MAGIC2
at fpstate + (fpstate.sw_reserved.extended_size - FP_XSTATE_MAGIC2_SIZE).
Extended feature bit mask that is saved in the memory layout is represented
by the fpstate.sw_reserved.xstate_bv
For RT signal frames, UC_FP_XSTATE in the uc_flags also indicate the
presence of extended state information in the sigcontext's fpstate
pointer.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 7daf3a0..cbb9dc4 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -26,6 +26,7 @@
# define _fpstate_ia32 _fpstate
# define _xstate_ia32 _xstate
# define sig_xstate_ia32_size sig_xstate_size
+# define fx_sw_reserved_ia32 fx_sw_reserved
# define user_i387_ia32_struct user_i387_struct
# define user32_fxsr_struct user_fxsr_struct
#endif
@@ -447,12 +448,30 @@
if (err)
return -1;
- if (__copy_to_user(&buf->_fxsr_env[0], fx,
- sizeof(struct i387_fxsave_struct)))
+ if (__copy_to_user(&buf->_fxsr_env[0], fx, xstate_size))
return -1;
return 1;
}
+static int save_i387_xsave(void __user *buf)
+{
+ struct _fpstate_ia32 __user *fx = buf;
+ int err = 0;
+
+ if (save_i387_fxsave(fx) < 0)
+ return -1;
+
+ err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved_ia32,
+ sizeof(struct _fpx_sw_bytes));
+ err |= __put_user(FP_XSTATE_MAGIC2,
+ (__u32 __user *) (buf + sig_xstate_ia32_size
+ - FP_XSTATE_MAGIC2_SIZE));
+ if (err)
+ return -1;
+
+ return 1;
+}
+
int save_i387_xstate_ia32(void __user *buf)
{
struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
@@ -477,6 +496,8 @@
unlazy_fpu(tsk);
+ if (cpu_has_xsave)
+ return save_i387_xsave(fp);
if (cpu_has_fxsr)
return save_i387_fxsave(fp);
else
@@ -491,14 +512,15 @@
sizeof(struct i387_fsave_struct));
}
-static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
+static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf,
+ unsigned int size)
{
struct task_struct *tsk = current;
struct user_i387_ia32_struct env;
int err;
err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0],
- sizeof(struct i387_fxsave_struct));
+ size);
/* mxcsr reserved bits must be masked to zero for security reasons */
tsk->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
if (err || __copy_from_user(&env, buf, sizeof(env)))
@@ -508,6 +530,51 @@
return 0;
}
+static int restore_i387_xsave(void __user *buf)
+{
+ struct _fpx_sw_bytes fx_sw_user;
+ struct _fpstate_ia32 __user *fx_user =
+ ((struct _fpstate_ia32 __user *) buf);
+ struct i387_fxsave_struct __user *fx =
+ (struct i387_fxsave_struct __user *) &fx_user->_fxsr_env[0];
+ struct xsave_hdr_struct *xsave_hdr =
+ ¤t->thread.xstate->xsave.xsave_hdr;
+ unsigned int lmask, hmask;
+ int err;
+
+ if (check_for_xstate(fx, buf, &fx_sw_user))
+ goto fx_only;
+
+ lmask = fx_sw_user.xstate_bv;
+ hmask = fx_sw_user.xstate_bv >> 32;
+
+ err = restore_i387_fxsave(buf, fx_sw_user.xstate_size);
+
+ xsave_hdr->xstate_bv &= (pcntxt_lmask | (((u64) pcntxt_hmask) << 32));
+ /*
+ * These bits must be zero.
+ */
+ xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
+
+ /*
+ * Init the state that is not present in the memory layout
+ * and enabled by the OS.
+ */
+ lmask = ~(pcntxt_lmask & ~lmask);
+ hmask = ~(pcntxt_hmask & ~hmask);
+ xsave_hdr->xstate_bv &= (lmask | (((u64) hmask) << 32));
+
+ return err;
+fx_only:
+ /*
+ * Couldn't find the extended state information in the memory
+ * layout. Restore the FP/SSE and init the other extended state
+ * enabled by the OS.
+ */
+ xsave_hdr->xstate_bv = XSTATE_FPSSE;
+ return restore_i387_fxsave(buf, sizeof(struct i387_fxsave_struct));
+}
+
int restore_i387_xstate_ia32(void __user *buf)
{
int err;
@@ -535,8 +602,11 @@
}
if (HAVE_HWFP) {
- if (cpu_has_fxsr)
- err = restore_i387_fxsave(fp);
+ if (cpu_has_xsave)
+ err = restore_i387_xsave(buf);
+ else if (cpu_has_fxsr)
+ err = restore_i387_fxsave(fp, sizeof(struct
+ i387_fxsave_struct));
else
err = restore_i387_fsave(fp);
} else {