linux-kernel - [PATCH 20/27] x86/fpu: Inline copy_user_to_fpregs

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Message-Id: <20190403164156.19645-21-bigeasy@linutronix.de>
Date:   Wed,  3 Apr 2019 18:41:49 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, Andy Lutomirski <luto@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        kvm@...r.kernel.org, "Jason A. Donenfeld" <Jason@...c4.com>,
        Rik van Riel <riel@...riel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 20/27] x86/fpu: Inline copy_user_to_fpregs_zeroing()

Start refactoring __fpu__restore_sig() by inlining
copy_user_to_fpregs_zeroing(). The orignal function remains and will be
used to restore from userland memory if possible.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 arch/x86/kernel/fpu/signal.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index c98c7bca13bc0..f733425c66d8d 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -337,11 +337,29 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 		kfree(tmp);
 		return err;
 	} else {
+		int ret;
+
 		/*
 		 * For 64-bit frames and 32-bit fsave frames, restore the user
 		 * state to the registers directly (with exceptions handled).
 		 */
-		if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
+		if (use_xsave()) {
+			if ((unsigned long)buf_fx % 64 || fx_only) {
+				u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
+				copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
+				ret = copy_user_to_fxregs(buf_fx);
+			} else {
+				u64 init_bv = xfeatures_mask & ~xfeatures;
+				if (unlikely(init_bv))
+					copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
+				ret = copy_user_to_xregs(buf_fx, xfeatures);
+			}
+		} else if (use_fxsr()) {
+			ret = copy_user_to_fxregs(buf_fx);
+		} else
+			ret = copy_user_to_fregs(buf_fx);
+
+		if (ret) {
 			fpu__clear(fpu);
 			return -1;
 		}
-- 
2.20.1