linux-kernel - [PATCH] x86/fpu: allow kernel_fpu_{begin,end} to be used by non-GPL modules

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Message-Id: <20190522044204.24207-1-cyphar@cyphar.com>
Date:   Wed, 22 May 2019 14:42:04 +1000
From:   Aleksa Sarai <cyphar@...har.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Aleksa Sarai <cyphar@...har.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Rik van Riel <riel@...riel.com>,
        Nicolai Stange <nstange@...e.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        zfs-devel@...t.zfsonlinux.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86/fpu: allow kernel_fpu_{begin,end} to be used by non-GPL modules

Prior to [1], all non-GPL modules were able to make use of SIMD on x86
by making use of the __kernel_fpu_* API. Given that __kernel_fpu_* were
both EXPORT_SYMBOL'd and kernel_fpu_* are such trivial wrappers around
the now-static __kernel_fpu_*, it seems to me that there is no reason to
have different licensing rules for them.

In the case of OpenZFS, the lack of SIMD on newer Linux kernels has
caused significant performance problems (since ZFS uses SIMD for
calculation of blkptr checksums as well as raidz calculations).

[1]: commit 12209993e98c ("x86/fpu: Don't export __kernel_fpu_{begin,end}()")

Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Signed-off-by: Aleksa Sarai <cyphar@...har.com>
---
 arch/x86/kernel/fpu/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 2e5003fef51a..8de5687a470d 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -127,14 +127,14 @@ void kernel_fpu_begin(void)
 	preempt_disable();
 	__kernel_fpu_begin();
 }
-EXPORT_SYMBOL_GPL(kernel_fpu_begin);
+EXPORT_SYMBOL(kernel_fpu_begin);
 
 void kernel_fpu_end(void)
 {
 	__kernel_fpu_end();
 	preempt_enable();
 }
-EXPORT_SYMBOL_GPL(kernel_fpu_end);
+EXPORT_SYMBOL(kernel_fpu_end);
 
 /*
  * Save the FPU state (mark it for reload if necessary):
-- 
2.21.0