[PATCH 2/8] x86/fpu: Clean up and rename variables in signal frame handling

Clean up signal frame handling code by renaming several variables for
clarity and consistency, and moving masking logic closer to its usage.

- Rename 'fxbuf' to 'buf_fx' in check_xstate_in_sigframe() for consistency.
- Rename label 'setfx' to 'err_setfx' in check_xstate_in_sigframe() to
  indicate it is an error path.
- In __restore_fpregs_from_user(), rename 'ufeatures' to 'task_xfeatures'
  and 'xrestore' to 'xrestore_mask'.
- Move the masking logic 'xrestore_mask &= task_xfeatures' from
  restore_fpregs_from_user() into __restore_fpregs_from_user().
- Rename 'xrestore' to 'xrestore_mask' in restore_fpregs_from_user() to
  match the name in __restore_fpregs_from_user() and __fpu_restore_sig().
- In __fpu_restore_sig(), rename 'buf' to 'buf_f' to distinguish it from
  'buf_fx', and 'user_xfeatures' to 'xrestore_mask'.

No functional changes.

Suggested-by: Ingo Molnar <[email protected]>
Reviewed-by: Alexander Mikhalitsyn <[email protected]>
Signed-off-by: Andrei Vagin <[email protected]>
---
 arch/x86/kernel/fpu/signal.c | 40 ++++++++++++++++++------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 20b638c507ca..42c3d78bd849 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -24,15 +24,15 @@
  * Check for the presence of extended state information in the
  * user fpstate pointer in the sigcontext.
  */
-static inline bool check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
+static inline bool check_xstate_in_sigframe(struct fxregs_state __user *buf_fx,
 					    struct _fpx_sw_bytes *fx_sw)
 {
 	int min_xstate_size = sizeof(struct fxregs_state) +
 			      sizeof(struct xstate_header);
-	void __user *fpstate = fxbuf;
+	void __user *fpstate = buf_fx;
 	unsigned int magic2;
 
-	if (__copy_from_user(fx_sw, &fxbuf->sw_reserved[0], sizeof(*fx_sw)))
+	if (__copy_from_user(fx_sw, &buf_fx->sw_reserved[0], sizeof(*fx_sw)))
 		return false;
 
 	/* Check for the first magic field and other error scenarios. */
@@ -40,7 +40,7 @@ static inline bool check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
 	    fx_sw->xstate_size < min_xstate_size ||
 	    fx_sw->xstate_size > x86_task_fpu(current)->fpstate->user_size ||
 	    fx_sw->xstate_size > fx_sw->extended_size)
-		goto setfx;
+		goto err_setfx;
 
 	/*
 	 * Check for the presence of second magic word at the end of memory
@@ -53,7 +53,7 @@ static inline bool check_xstate_in_sigframe(struct fxregs_state __user *fxbuf,
 
 	if (likely(magic2 == FP_XSTATE_MAGIC2))
 		return true;
-setfx:
+err_setfx:
 	trace_x86_fpu_xstate_check_failed(x86_task_fpu(current));
 
 	/* Set the parameters for fx only state */
@@ -240,15 +240,17 @@ bool copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size, u
 	return true;
 }
 
-static int __restore_fpregs_from_user(void __user *buf, u64 ufeatures,
-				      u64 xrestore, bool fx_only)
+static int __restore_fpregs_from_user(void __user *buf, u64 task_xfeatures,
+				      u64 xrestore_mask, bool fx_only)
 {
 	if (use_xsave()) {
-		u64 init_bv = ufeatures & ~xrestore;
+		u64 init_bv = task_xfeatures & ~xrestore_mask;
 		int ret;
 
+		/* Restore enabled features only. */
+		xrestore_mask &= task_xfeatures;
 		if (likely(!fx_only))
-			ret = xrstor_from_user_sigframe(buf, xrestore);
+			ret = xrstor_from_user_sigframe(buf, xrestore_mask);
 		else
 			ret = fxrstor_from_user_sigframe(buf);
 
@@ -266,20 +268,18 @@ static int __restore_fpregs_from_user(void __user *buf, u64 ufeatures,
  * Attempt to restore the FPU registers directly from user memory.
  * Pagefaults are handled and any errors returned are fatal.
  */
-static bool restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only)
+static bool restore_fpregs_from_user(void __user *buf, u64 xrestore_mask, bool fx_only)
 {
 	struct fpu *fpu = x86_task_fpu(current);
 	int ret;
 
-	/* Restore enabled features only. */
-	xrestore &= fpu->fpstate->user_xfeatures;
 retry:
 	fpregs_lock();
 	/* Ensure that XFD is up to date */
 	xfd_update_state(fpu->fpstate);
 	pagefault_disable();
 	ret = __restore_fpregs_from_user(buf, fpu->fpstate->user_xfeatures,
-					 xrestore, fx_only);
+					 xrestore_mask, fx_only);
 	pagefault_enable();
 
 	if (unlikely(ret)) {
@@ -324,7 +324,7 @@ static bool restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_onl
 	return true;
 }
 
-static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
+static bool __fpu_restore_sig(void __user *buf_f, void __user *buf_fx,
 			      bool ia32_fxstate)
 {
 	struct task_struct *tsk = current;
@@ -332,7 +332,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 	struct user_i387_ia32_struct env;
 	bool success, fx_only = false;
 	union fpregs_state *fpregs;
-	u64 user_xfeatures = 0;
+	u64 xrestore_mask = 0;
 
 	if (use_xsave()) {
 		struct _fpx_sw_bytes fx_sw_user;
@@ -341,14 +341,14 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 			return false;
 
 		fx_only = !fx_sw_user.magic1;
-		user_xfeatures = fx_sw_user.xfeatures;
+		xrestore_mask = fx_sw_user.xfeatures;
 	} else {
-		user_xfeatures = XFEATURE_MASK_FPSSE;
+		xrestore_mask = XFEATURE_MASK_FPSSE;
 	}
 
 	if (likely(!ia32_fxstate)) {
 		/* Restore the FPU registers directly from user memory. */
-		return restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only);
+		return restore_fpregs_from_user(buf_fx, xrestore_mask, fx_only);
 	}
 
 	/*
@@ -356,7 +356,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 	 * to be ignored for histerical raisins. The legacy state is folded
 	 * in once the larger state has been copied.
 	 */
-	if (__copy_from_user(&env, buf, sizeof(env)))
+	if (__copy_from_user(&env, buf_f, sizeof(env)))
 		return false;
 
 	/*
@@ -420,7 +420,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx,
 		 *
 		 * Preserve supervisor states!
 		 */
-		u64 mask = user_xfeatures | xfeatures_mask_supervisor();
+		u64 mask = xrestore_mask | xfeatures_mask_supervisor();
 
 		fpregs->xsave.header.xfeatures &= mask;
 		success = !os_xrstor_safe(fpu->fpstate,
-- 
2.55.0.691.gc56d675ccc-goog