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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2014-02-24 15:26:27 +0100
committerMark Brown <broonie@linaro.org>2014-06-19 12:34:05 +0100
commit2c65b0d3682a1b023f59b2ebaa17876298a4bb5b (patch)
tree6cc0ebd8124509ab5fe3d761306e8c07933e3151
parentd7ee1fd79f9677e5ab75215aa696e6ac50352ca9 (diff)
downloadlinux-linaro-stable-2c65b0d3682a1b023f59b2ebaa17876298a4bb5b.tar.gz
arm64: add abstractions for FPSIMD state manipulation
There are two tacit assumptions in the FPSIMD handling code that will no longer hold after the next patch that optimizes away some FPSIMD state restores: . the FPSIMD registers of this CPU contain the userland FPSIMD state of task 'current'; . when switching to a task, its FPSIMD state will always be restored from memory. This patch adds the following functions to abstract away from straight FPSIMD register file saves and restores: - fpsimd_preserve_current_state -> ensure current's FPSIMD state is saved - fpsimd_update_current_state -> replace current's FPSIMD state Where necessary, the signal handling and fork code are updated to use the above wrappers instead of poking into the FPSIMD registers directly. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> (cherry picked from commit c51f92693c35c141cf7d9b7e2fcbb81128324eb4) Signed-off-by: Mark Brown <broonie@linaro.org>
-rw-r--r--arch/arm64/include/asm/fpsimd.h3
-rw-r--r--arch/arm64/kernel/fpsimd.c20
-rw-r--r--arch/arm64/kernel/process.c2
-rw-r--r--arch/arm64/kernel/signal.c9
-rw-r--r--arch/arm64/kernel/signal32.c9
5 files changed, 30 insertions, 13 deletions
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index c43b4ac13008..f4e524b67e91 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -58,6 +58,9 @@ extern void fpsimd_load_state(struct fpsimd_state *state);
extern void fpsimd_thread_switch(struct task_struct *next);
extern void fpsimd_flush_thread(void);
+extern void fpsimd_preserve_current_state(void);
+extern void fpsimd_update_current_state(struct fpsimd_state *state);
+
#endif
#endif
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 4aef42a04bdc..8a97163debc7 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -87,6 +87,26 @@ void fpsimd_flush_thread(void)
preempt_enable();
}
+/*
+ * Save the userland FPSIMD state of 'current' to memory
+ */
+void fpsimd_preserve_current_state(void)
+{
+ preempt_disable();
+ fpsimd_save_state(&current->thread.fpsimd_state);
+ preempt_enable();
+}
+
+/*
+ * Load an updated userland FPSIMD state for 'current' from memory
+ */
+void fpsimd_update_current_state(struct fpsimd_state *state)
+{
+ 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 46f02c3b5015..e2eb9453d3a1 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -184,7 +184,7 @@ 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);
+ fpsimd_preserve_current_state();
*dst = *src;
return 0;
}
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 890a591f75dd..06448a77ff53 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -51,7 +51,7 @@ static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
int err;
/* dump the hardware registers to the fpsimd_state structure */
- fpsimd_save_state(fpsimd);
+ fpsimd_preserve_current_state();
/* copy the FP and status/control registers */
err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
@@ -86,11 +86,8 @@ static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
__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_update_current_state(&fpsimd);
return err ? -EFAULT : 0;
}
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index e393174fe859..31fbeaf4dd62 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -247,7 +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_preserve_current_state();
/* Place structure header on the stack */
__put_user_error(magic, &frame->magic, err);
@@ -310,11 +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_update_current_state(&fpsimd);
return err ? -EFAULT : 0;
}