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Subject[RFT PATCH v2 3/4] arm64: reduce duplicated code when saving/restoring FPSIMD for signal handling
Date
From: Jiang Liu <jiang.liu@huawei.com>

Reduce duplicated code when saving/restoring FPSIMD for signal
handling, it also helps to concentrate all FPSIMD hardware related
code into fpsimd.c.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
---
arch/arm64/include/asm/fpsimd.h | 18 ++++--------------
arch/arm64/kernel/fpsimd.c | 35 +++++++++++++++++++++++++++++++++++
arch/arm64/kernel/process.c | 3 +--
arch/arm64/kernel/signal.c | 12 +++---------
arch/arm64/kernel/signal32.c | 10 +++-------
5 files changed, 46 insertions(+), 32 deletions(-)

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index b2dc30f..6f034082f 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -54,25 +54,15 @@ struct fpsimd_state {

struct task_struct;

-static inline void fpsimd_init_hw_state(void)
-{
- int val = AARCH64_FPCR_DEFAULT_VAL;
-
- asm ("msr fpcr, %x0\n"
- "msr fpsr, xzr\n"
- : : "r"(val));
-}
-
-static inline void fpsimd_clear_fpsr(void)
-{
- asm ("msr fpsr, xzr\n");
-}
-
extern void fpsimd_save_state(struct fpsimd_state *state);
extern void fpsimd_load_state(struct fpsimd_state *state);

+extern void fpsimd_dup_task_struct(struct task_struct *dst,
+ struct task_struct *src);
extern void fpsimd_thread_switch(struct task_struct *next);
extern void fpsimd_flush_thread(void);
+extern void fpsimd_prepare_sigctx(struct fpsimd_state *state);
+extern void fpsimd_restore_sigctx(struct fpsimd_state *state);

#endif

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 12a25e5..604fe9f 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -33,6 +33,20 @@
#define FPEXC_IXF (1 << 4)
#define FPEXC_IDF (1 << 7)

+static inline void fpsimd_init_hw_state(void)
+{
+ int val = AARCH64_FPCR_DEFAULT_VAL;
+
+ asm ("msr fpcr, %x0\n"
+ "msr fpsr, xzr\n"
+ : : "r"(val));
+}
+
+static inline void fpsimd_clear_fpsr(void)
+{
+ asm ("msr fpsr, xzr\n");
+}
+
/*
* Trapped FP/ASIMD access.
*/
@@ -69,6 +83,12 @@ void do_fpsimd_exc(unsigned int esr, struct pt_regs *regs)
send_sig_info(SIGFPE, &info, current);
}

+void fpsimd_dup_task_struct(struct task_struct *dst, struct task_struct *src)
+{
+ fpsimd_save_state(&src->thread.fpsimd_state);
+ *dst = *src;
+}
+
void fpsimd_thread_switch(struct task_struct *next)
{
/* check if not kernel threads */
@@ -91,6 +111,21 @@ void fpsimd_flush_thread(void)
preempt_enable();
}

+void fpsimd_prepare_sigctx(struct fpsimd_state *state)
+{
+ /* dump the hardware registers to the fpsimd_state structure */
+ fpsimd_save_state(state);
+ fpsimd_clear_fpsr();
+}
+
+void fpsimd_restore_sigctx(struct fpsimd_state *state)
+{
+ /* load the hardware registers from the fpsimd_state structure */
+ preempt_disable();
+ fpsimd_load_state(state);
+ preempt_enable();
+}
+
#ifdef CONFIG_KERNEL_MODE_NEON

/*
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 7ae8a1f..6796080 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -195,8 +195,7 @@ void release_thread(struct task_struct *dead_task)

int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
- fpsimd_save_state(&current->thread.fpsimd_state);
- *dst = *src;
+ fpsimd_dup_task_struct(dst, src);
return 0;
}

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 4ee231e..1597a33 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -50,9 +50,7 @@ static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
struct fpsimd_state *fpsimd = &current->thread.fpsimd_state;
int err;

- /* dump the hardware registers to the fpsimd_state structure */
- fpsimd_save_state(fpsimd);
- fpsimd_clear_fpsr();
+ fpsimd_prepare_sigctx(fpsimd);

/* copy the FP and status/control registers */
err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
@@ -86,12 +84,8 @@ static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
__get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
__get_user_error(fpsimd.fpcr, &ctx->fpcr, err);

- /* load the hardware registers from the fpsimd_state structure */
- if (!err) {
- preempt_disable();
- fpsimd_load_state(&fpsimd);
- preempt_enable();
- }
+ if (!err)
+ fpsimd_restore_sigctx(&fpsimd);

return err ? -EFAULT : 0;
}
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index cf85c36..f910d3b 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -247,8 +247,7 @@ static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
* Note that this also saves V16-31, which aren't visible
* in AArch32.
*/
- fpsimd_save_state(fpsimd);
- fpsimd_clear_fpsr();
+ fpsimd_prepare_sigctx(fpsimd);

/* Place structure header on the stack */
__put_user_error(magic, &frame->magic, err);
@@ -311,11 +310,8 @@ static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
* We don't need to touch the exception register, so
* reload the hardware state.
*/
- if (!err) {
- preempt_disable();
- fpsimd_load_state(&fpsimd);
- preempt_enable();
- }
+ if (!err)
+ fpsimd_restore_sigctx(&fpsimd);

return err ? -EFAULT : 0;
}
--
1.8.1.2


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