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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2014-05-08 11:20:23 +0200
committerMark Brown <broonie@linaro.org>2014-06-19 12:34:14 +0100
commit8ec3883b5accf54406952962e09fd5db0fae8ecc (patch)
tree581f8dfa2894fab7e1e2a0c7ac2f481e3e0332e5 /arch/arm64/kernel/signal.c
parent2c65b0d3682a1b023f59b2ebaa17876298a4bb5b (diff)
downloadlinux-linaro-stable-8ec3883b5accf54406952962e09fd5db0fae8ecc.tar.gz
arm64: defer reloading a task's FPSIMD state to userland resume
If a task gets scheduled out and back in again and nothing has touched its FPSIMD state in the mean time, there is really no reason to reload it from memory. Similarly, repeated calls to kernel_neon_begin() and kernel_neon_end() will preserve and restore the FPSIMD state every time. This patch defers the FPSIMD state restore to the last possible moment, i.e., right before the task returns to userland. If a task does not return to userland at all (for any reason), the existing FPSIMD state is preserved and may be reused by the owning task if it gets scheduled in again on the same CPU. This patch adds two more functions to abstract away from straight FPSIMD register file saves and restores: - fpsimd_restore_current_state -> ensure current's FPSIMD state is loaded - fpsimd_flush_task_state -> invalidate live copies of a task's FPSIMD state Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> (cherry picked from commit 005f78cd88494457ed38ce817f4e3fe5d372f0cb) Signed-off-by: Mark Brown <broonie@linaro.org>
Diffstat (limited to 'arch/arm64/kernel/signal.c')
-rw-r--r--arch/arm64/kernel/signal.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 06448a77ff53..882f01774365 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -413,4 +413,8 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
+
+ if (thread_flags & _TIF_FOREIGN_FPSTATE)
+ fpsimd_restore_current_state();
+
}