[patch V2 21/21] x86/fpu/signal: Use fpstate for size and features

[Thomas Gleixner <tglx@linutronix.de>]

For dynamically enabled features it's required to get the features which
are enabled for that context when restoring from sigframe.

The same applies for all signal frame size calculations.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V2: Added a missing conversion and folded back a conversion which
    was hidden in part 3
---
 arch/x86/kernel/fpu/signal.c |   44 ++++++++++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 17 deletions(-)

--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -41,7 +41,7 @@ static inline bool check_xstate_in_sigfr
 	/* Check for the first magic field and other error scenarios. */
 	if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
 	    fx_sw->xstate_size < min_xstate_size ||
-	    fx_sw->xstate_size > fpu_user_xstate_size ||
+	    fx_sw->xstate_size > current->thread.fpu.fpstate->user_size ||
 	    fx_sw->xstate_size > fx_sw->extended_size)
 		goto setfx;
 
@@ -98,7 +98,8 @@ static inline bool save_fsave_header(str
 	return true;
 }
 
-static inline bool save_xstate_epilog(void __user *buf, int ia32_frame)
+static inline bool save_xstate_epilog(void __user *buf, int ia32_frame,
+				      unsigned int usize)
 {
 	struct xregs_state __user *x = buf;
 	struct _fpx_sw_bytes *sw_bytes;
@@ -113,7 +114,7 @@ static inline bool save_xstate_epilog(vo
 		return !err;
 
 	err |= __put_user(FP_XSTATE_MAGIC2,
-			  (__u32 __user *)(buf + fpu_user_xstate_size));
+			  (__u32 __user *)(buf + usize));
 
 	/*
 	 * Read the xfeatures which we copied (directly from the cpu or
@@ -171,6 +172,7 @@ static inline int copy_fpregs_to_sigfram
 bool copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
 {
 	struct task_struct *tsk = current;
+	struct fpstate *fpstate = tsk->thread.fpu.fpstate;
 	int ia32_fxstate = (buf != buf_fx);
 	int ret;
 
@@ -215,7 +217,7 @@ bool copy_fpstate_to_sigframe(void __use
 	fpregs_unlock();
 
 	if (ret) {
-		if (!__clear_user(buf_fx, fpu_user_xstate_size))
+		if (!__clear_user(buf_fx, fpstate->user_size))
 			goto retry;
 		return false;
 	}
@@ -224,17 +226,18 @@ bool copy_fpstate_to_sigframe(void __use
 	if ((ia32_fxstate || !use_fxsr()) && !save_fsave_header(tsk, buf))
 		return false;
 
-	if (use_fxsr() && !save_xstate_epilog(buf_fx, ia32_fxstate))
+	if (use_fxsr() &&
+	    !save_xstate_epilog(buf_fx, ia32_fxstate, fpstate->user_size))
 		return false;
 
 	return true;
 }
 
-static int __restore_fpregs_from_user(void __user *buf, u64 xrestore,
-				      bool fx_only)
+static int __restore_fpregs_from_user(void __user *buf, u64 ufeatures,
+				      u64 xrestore, bool fx_only)
 {
 	if (use_xsave()) {
-		u64 init_bv = xfeatures_mask_uabi() & ~xrestore;
+		u64 init_bv = ufeatures & ~xrestore;
 		int ret;
 
 		if (likely(!fx_only))
@@ -265,7 +268,8 @@ static bool restore_fpregs_from_user(voi
 retry:
 	fpregs_lock();
 	pagefault_disable();
-	ret = __restore_fpregs_from_user(buf, xrestore, fx_only);
+	ret = __restore_fpregs_from_user(buf, fpu->fpstate->user_xfeatures,
+					 xrestore, fx_only);
 	pagefault_enable();
 
 	if (unlikely(ret)) {
@@ -332,7 +336,7 @@ static bool __fpu_restore_sig(void __use
 		user_xfeatures = fx_sw_user.xfeatures;
 	} else {
 		user_xfeatures = XFEATURE_MASK_FPSSE;
-		state_size = fpu->fpstate->size;
+		state_size = fpu->fpstate->user_size;
 	}
 
 	if (likely(!ia32_fxstate)) {
@@ -425,10 +429,11 @@ static bool __fpu_restore_sig(void __use
 	return success;
 }
 
-static inline int xstate_sigframe_size(void)
+static inline unsigned int xstate_sigframe_size(struct fpstate *fpstate)
 {
-	return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
-			fpu_user_xstate_size;
+	unsigned int size = fpstate->user_size;
+
+	return use_xsave() ? size + FP_XSTATE_MAGIC2_SIZE : size;
 }
 
 /*
@@ -436,17 +441,19 @@ static inline int xstate_sigframe_size(v
  */
 bool fpu__restore_sig(void __user *buf, int ia32_frame)
 {
-	unsigned int size = xstate_sigframe_size();
 	struct fpu *fpu = &current->thread.fpu;
 	void __user *buf_fx = buf;
 	bool ia32_fxstate = false;
 	bool success = false;
+	unsigned int size;
 
 	if (unlikely(!buf)) {
 		fpu__clear_user_states(fpu);
 		return true;
 	}
 
+	size = xstate_sigframe_size(fpu->fpstate);
+
 	ia32_frame &= (IS_ENABLED(CONFIG_X86_32) ||
 		       IS_ENABLED(CONFIG_IA32_EMULATION));
 
@@ -481,7 +488,7 @@ unsigned long
 fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
 		     unsigned long *buf_fx, unsigned long *size)
 {
-	unsigned long frame_size = xstate_sigframe_size();
+	unsigned long frame_size = xstate_sigframe_size(current->thread.fpu.fpstate);
 
 	*buf_fx = sp = round_down(sp - frame_size, 64);
 	if (ia32_frame && use_fxsr()) {
@@ -494,9 +501,12 @@ fpu__alloc_mathframe(unsigned long sp, i
 	return sp;
 }
 
-unsigned long fpu__get_fpstate_size(void)
+unsigned long __init fpu__get_fpstate_size(void)
 {
-	unsigned long ret = xstate_sigframe_size();
+	unsigned long ret = fpu_user_xstate_size;
+
+	if (use_xsave())
+		ret += FP_XSTATE_MAGIC2_SIZE;
 
 	/*
 	 * This space is needed on (most) 32-bit kernels, or when a 32-bit