linux-kernel - [PATCH 02/41] x86: copy_fpstate_to_sigframe(): have fpregs_soft

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Date:   Mon, 29 Jun 2020 19:25:49 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        David Miller <davem@...emloft.net>,
        Tony Luck <tony.luck@...el.com>, Will Deacon <will@...nel.org>
Subject: [PATCH 02/41] x86: copy_fpstate_to_sigframe(): have fpregs_soft_get() use kernel buffer

From: Al Viro <viro@...iv.linux.org.uk>

... then copy_to_user() the results

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 arch/x86/kernel/fpu/signal.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index 9393a445d73c..e0b832df7404 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -170,14 +170,14 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
 	ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
 			 IS_ENABLED(CONFIG_IA32_EMULATION));
 
+	if (!static_cpu_has(X86_FEATURE_FPU)) {
+		struct user_i387_ia32_struct fp;
+		fpregs_soft_get(current, NULL, 0, sizeof(fp), &fp, NULL);
+		return copy_to_user(buf, &fp, sizeof(fp)) ? -EFAULT : 0;
+	}
+
 	if (!access_ok(buf, size))
 		return -EACCES;
-
-	if (!static_cpu_has(X86_FEATURE_FPU))
-		return fpregs_soft_get(current, NULL, 0,
-			sizeof(struct user_i387_ia32_struct), NULL,
-			(struct _fpstate_32 __user *) buf) ? -1 : 1;
-
 retry:
 	/*
 	 * Load the FPU registers if they are not valid for the current task.
-- 
2.11.0