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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /arch/powerpc/lib/vmx-helper.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/powerpc/lib/vmx-helper.c')
-rw-r--r--arch/powerpc/lib/vmx-helper.c75
1 files changed, 75 insertions, 0 deletions
diff --git a/arch/powerpc/lib/vmx-helper.c b/arch/powerpc/lib/vmx-helper.c
new file mode 100644
index 000000000..d491da8d1
--- /dev/null
+++ b/arch/powerpc/lib/vmx-helper.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ * Copyright (C) IBM Corporation, 2011
+ *
+ * Authors: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
+ * Anton Blanchard <anton@au.ibm.com>
+ */
+#include <linux/uaccess.h>
+#include <linux/hardirq.h>
+#include <asm/switch_to.h>
+
+int enter_vmx_usercopy(void)
+{
+ if (in_interrupt())
+ return 0;
+
+ preempt_disable();
+ /*
+ * We need to disable page faults as they can call schedule and
+ * thus make us lose the VMX context. So on page faults, we just
+ * fail which will cause a fallback to the normal non-vmx copy.
+ */
+ pagefault_disable();
+
+ enable_kernel_altivec();
+
+ return 1;
+}
+
+/*
+ * This function must return 0 because we tail call optimise when calling
+ * from __copy_tofrom_user_power7 which returns 0 on success.
+ */
+int exit_vmx_usercopy(void)
+{
+ disable_kernel_altivec();
+ pagefault_enable();
+ preempt_enable_no_resched();
+ /*
+ * Must never explicitly call schedule (including preempt_enable())
+ * while in a kuap-unlocked user copy, because the AMR register will
+ * not be saved and restored across context switch. However preempt
+ * kernels need to be preempted as soon as possible if need_resched is
+ * set and we are preemptible. The hack here is to schedule a
+ * decrementer to fire here and reschedule for us if necessary.
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT) && need_resched())
+ set_dec(1);
+ return 0;
+}
+
+int enter_vmx_ops(void)
+{
+ if (in_interrupt())
+ return 0;
+
+ preempt_disable();
+
+ enable_kernel_altivec();
+
+ return 1;
+}
+
+/*
+ * All calls to this function will be optimised into tail calls. We are
+ * passed a pointer to the destination which we return as required by a
+ * memcpy implementation.
+ */
+void *exit_vmx_ops(void *dest)
+{
+ disable_kernel_altivec();
+ preempt_enable();
+ return dest;
+}