git: ce5a210997da - main - openzfs: arm64: implement kfpu_begin/kfpu_end

The branch main has been updated by kevans:

URL: https://cgit.FreeBSD.org/src/commit/?id=ce5a210997da3c4064cfe162e760379f1fa8b587

commit ce5a210997da3c4064cfe162e760379f1fa8b587
Author:     Kyle Evans <kevans@FreeBSD.org>
AuthorDate: 2023-04-26 17:23:48 +0000
Commit:     Kyle Evans <kevans@FreeBSD.org>
CommitDate: 2023-04-26 17:24:00 +0000

    openzfs: arm64: implement kfpu_begin/kfpu_end
    
    This is part one of a fix for booting with ZFS on arm64 using
    accelerated checksum implementations.  Checksum benchmarking will
    attempt to use the FPU, so we currently panic quickly on boot.  BLAKE3
    is still broken, as it clobbers x18 and we promptly discover that fact
    as soon as we attempt to fetch curthread in kfpu_end().
    
    Note that _STANDALONE is special-cased here, but ideally we wouldn't be
    building the code that uses kfpu_begin()/kfpu_end() at all in the loader
    environment.
    
    Discussed with: imp (a bit)
    Differential Revision:  https://reviews.freebsd.org/D39448
---
 .../include/os/freebsd/spl/sys/simd_aarch64.h      | 28 +++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_aarch64.h b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_aarch64.h
index 7d2e2db28017..9edbc5f40455 100644
--- a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_aarch64.h
+++ b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_aarch64.h
@@ -44,13 +44,39 @@
 #define	_FREEBSD_SIMD_AARCH64_H
 
 #include <sys/types.h>
+#include <sys/ucontext.h>
 #include <machine/elf.h>
+#include <machine/fpu.h>
 #include <machine/md_var.h>
+#include <machine/pcb.h>
+
+#ifdef _STANDALONE
 
 #define	kfpu_allowed()		0
-#define	kfpu_initialize(tsk)	do {} while (0)
 #define	kfpu_begin()		do {} while (0)
 #define	kfpu_end()		do {} while (0)
+
+#else
+
+/*
+ * XXX kfpu_allowed() should be 1, but this is pending a fix to the BLAKE3
+ * generated assembly to avoid clobbering x18.  Turn it back on after that
+ * lands.
+ */
+#define	kfpu_allowed()		0
+#define	kfpu_begin() do {						\
+	if (__predict_false(!is_fpu_kern_thread(0)))			\
+		fpu_kern_enter(curthread, NULL, FPU_KERN_NOCTX);	\
+} while(0)
+
+#define	kfpu_end() do {							\
+	if (__predict_false(curthread->td_pcb->pcb_fpflags & PCB_FP_NOSAVE))	\
+		fpu_kern_leave(curthread, NULL);			\
+} while(0)
+
+#endif
+
+#define	kfpu_initialize(tsk)	do {} while (0)
 #define	kfpu_init()		(0)
 #define	kfpu_fini()		do {} while (0)