[src-draft/trunk]: src/sys/arch/aarch64/aarch64 Add kthread_fpu_enter/exit su...

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src-all/rev/3a9b1ca3581a
branches:  trunk
changeset: 936593:3a9b1ca3581a
user:      Taylor R Campbell <riastradh%NetBSD.org@localhost>
date:      Fri Jul 31 03:10:13 2020 +0000

description:
Add kthread_fpu_enter/exit support to aarch64.

diffstat:

 sys/arch/aarch64/aarch64/fpu.c  |  46 +++++++++++++++++++++++++++++++++++++++-
 sys/arch/aarch64/aarch64/trap.c |   6 +++++
 2 files changed, 50 insertions(+), 2 deletions(-)

diffs (98 lines):

diff -r 9f9b4e466042 -r 3a9b1ca3581a sys/arch/aarch64/aarch64/fpu.c
--- a/sys/arch/aarch64/aarch64/fpu.c    Fri Jul 31 03:06:02 2020 +0000
+++ b/sys/arch/aarch64/aarch64/fpu.c    Fri Jul 31 03:10:13 2020 +0000
@@ -35,6 +35,8 @@
 
 #include <sys/param.h>
 #include <sys/types.h>
+#include <sys/cpu.h>
+#include <sys/kthread.h>
 #include <sys/lwp.h>
 #include <sys/evcnt.h>
 
@@ -176,12 +178,30 @@
        __asm __volatile ("isb");
 }
 
+static const struct fpreg zero_fpreg;
+
+/*
+ * True if this is a system thread with its own private FPU state.
+ */
+static inline bool
+lwp_system_fpu_p(struct lwp *l)
+{
+
+       return (l->l_flag & (LW_SYSTEM|LW_SYSTEM_FPU)) ==
+           (LW_SYSTEM|LW_SYSTEM_FPU);
+}
+
 void
 fpu_kern_enter(void)
 {
        struct cpu_info *ci;
        int s;
 
+       if (lwp_system_fpu_p(curlwp) && !cpu_intr_p()) {
+               KASSERT(!cpu_softintr_p());
+               return;
+       }
+
        /*
         * Block interrupts up to IPL_VM.  We must block preemption
         * since -- if this is a user thread -- there is nowhere to
@@ -209,10 +229,16 @@
 void
 fpu_kern_leave(void)
 {
-       static const struct fpreg zero_fpreg;
-       struct cpu_info *ci = curcpu();
+       struct cpu_info *ci;
        int s;
 
+       if (lwp_system_fpu_p(curlwp) && !cpu_intr_p()) {
+               KASSERT(!cpu_softintr_p());
+               return;
+       }
+
+       ci = curcpu();
+
        KASSERT(ci->ci_cpl == IPL_VM);
        KASSERT(ci->ci_kfpu_spl != -1);
 
@@ -234,3 +260,19 @@
        ci->ci_kfpu_spl = -1;
        splx(s);
 }
+
+void
+kthread_fpu_enter_md(void)
+{
+
+       fpu_load(curlwp);
+}
+
+void
+kthread_fpu_exit_md(void)
+{
+
+       /* XXX Should fpu_state_release zero the registers itself?  */
+       load_fpregs(&zero_fpreg);
+       fpu_discard(curlwp, 0);
+}
diff -r 9f9b4e466042 -r 3a9b1ca3581a sys/arch/aarch64/aarch64/trap.c
--- a/sys/arch/aarch64/aarch64/trap.c   Fri Jul 31 03:06:02 2020 +0000
+++ b/sys/arch/aarch64/aarch64/trap.c   Fri Jul 31 03:10:13 2020 +0000
@@ -242,6 +242,12 @@
                break;
 
        case ESR_EC_FP_ACCESS:
+               if ((curlwp->l_flag & (LW_SYSTEM|LW_SYSTEM_FPU)) ==
+                   (LW_SYSTEM|LW_SYSTEM_FPU)) {
+                       fpu_load(curlwp);
+                       break;
+               }
+               /*FALLTHROUGH*/
        case ESR_EC_FP_TRAP_A64:
        case ESR_EC_PC_ALIGNMENT:
        case ESR_EC_SP_ALIGNMENT: