linux-kernel - [PATCHv4 05/19] arm64: move sve_user_{enable,disable} to <asm/fpsimd.h>

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Date:   Mon,  2 Jul 2018 12:04:01 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     linux-arm-kernel@...ts.infradead.org, will.deacon@....com
Cc:     linux-kernel@...r.kernel.org, catalin.marinas@....com,
        dave.martin@....com, hch@...radead.org, james.morse@....com,
        linux@...inikbrodowski.net, linux-fsdevel@...r.kernel.org,
        marc.zyngier@....com, mark.rutland@....com, viro@...iv.linux.org.uk
Subject: [PATCHv4 05/19] arm64: move sve_user_{enable,disable} to <asm/fpsimd.h>

In subsequent patches, we'll want to make use of sve_user_enable() and
sve_user_disable() outside of kernel/fpsimd.c. Let's move these to
<asm/fpsimd.h> where we can make use of them.

To avoid ifdeffery in sequences like:

if (system_supports_sve() && some_condition)
	sve_user_disable();

... empty stubs are provided when support for SVE is not enabled. Note
that system_supports_sve() contains as IS_ENABLED(CONFIG_ARM64_SVE), so
the sve_user_disable() call should be optimized away entirely when
CONFIG_ARM64_SVE is not selected.

To ensure that this is the case, the stub definitions contain a
BUILD_BUG(), as we do for other stubs for which calls should always be
optimized away when the relevant config option is not selected.

At the same time, the include list of <asm/fpsimd.h> is sorted while
adding <asm/sysreg.h>.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Acked-by: Catalin Marinas <catalin.marinas@....com>
Reviewed-by: Dave Martin <dave.martin@....com>
Cc: Will Deacon <will.deacon@....com>
---
 arch/arm64/include/asm/fpsimd.h | 17 ++++++++++++++++-
 arch/arm64/kernel/fpsimd.c      | 10 ----------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index fa92747a49c8..dd1ad3950ef5 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -16,13 +16,15 @@
 #ifndef __ASM_FP_H
 #define __ASM_FP_H
 
-#include <asm/ptrace.h>
 #include <asm/errno.h>
+#include <asm/ptrace.h>
 #include <asm/processor.h>
 #include <asm/sigcontext.h>
+#include <asm/sysreg.h>
 
 #ifndef __ASSEMBLY__
 
+#include <linux/build_bug.h>
 #include <linux/cache.h>
 #include <linux/init.h>
 #include <linux/stddef.h>
@@ -102,6 +104,16 @@ extern int sve_set_vector_length(struct task_struct *task,
 extern int sve_set_current_vl(unsigned long arg);
 extern int sve_get_current_vl(void);
 
+static inline void sve_user_disable(void)
+{
+	sysreg_clear_set(cpacr_el1, CPACR_EL1_ZEN_EL0EN, 0);
+}
+
+static inline void sve_user_enable(void)
+{
+	sysreg_clear_set(cpacr_el1, 0, CPACR_EL1_ZEN_EL0EN);
+}
+
 /*
  * Probing and setup functions.
  * Calls to these functions must be serialised with one another.
@@ -128,6 +140,9 @@ static inline int sve_get_current_vl(void)
 	return -EINVAL;
 }
 
+static inline void sve_user_disable(void) { BUILD_BUG(); }
+static inline void sve_user_enable(void) { BUILD_BUG(); }
+
 static inline void sve_init_vq_map(void) { }
 static inline void sve_update_vq_map(void) { }
 static inline int sve_verify_vq_map(void) { return 0; }
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index a98a7f96aff1..58c53bc96928 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -159,16 +159,6 @@ static void sve_free(struct task_struct *task)
 	__sve_free(task);
 }
 
-static void sve_user_disable(void)
-{
-	sysreg_clear_set(cpacr_el1, CPACR_EL1_ZEN_EL0EN, 0);
-}
-
-static void sve_user_enable(void)
-{
-	sysreg_clear_set(cpacr_el1, 0, CPACR_EL1_ZEN_EL0EN);
-}
-
 /*
  * TIF_SVE controls whether a task can use SVE without trapping while
  * in userspace, and also the way a task's FPSIMD/SVE state is stored
-- 
2.11.0