[PATCH 02/10] x86/fpu: Clean up and rename variables in signal frame handling

[Andrei Vagin <avagin@google.com>]

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 <mingo@kernel.org>
Signed-off-by: Andrei Vagin <avagin@google.com>
---
 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,
-- 
2.54.0.1189.g8c84645362-goog