bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/arch/mips/power/cpu.c b/arch/mips/power/cpu.c
new file mode 100644
index 000000000..d8ef7778e
--- /dev/null
+++ b/arch/mips/power/cpu.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Suspend support specific for mips.
+ *
+ * Copyright (C) 2009 Lemote Inc.
+ * Author: Hu Hongbing <huhb@lemote.com>
+ *	   Wu Zhangjin <wuzhangjin@gmail.com>
+ */
+#include <linux/suspend.h>
+#include <asm/sections.h>
+#include <asm/fpu.h>
+#include <asm/dsp.h>
+
+static u32 saved_status;
+struct pt_regs saved_regs;
+
+void save_processor_state(void)
+{
+	saved_status = read_c0_status();
+
+	if (is_fpu_owner())
+		save_fp(current);
+
+	save_dsp(current);
+}
+
+void restore_processor_state(void)
+{
+	write_c0_status(saved_status);
+
+	if (is_fpu_owner())
+		restore_fp(current);
+
+	restore_dsp(current);
+}
+
+int pfn_is_nosave(unsigned long pfn)
+{
+	unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin));
+	unsigned long nosave_end_pfn = PFN_UP(__pa(&__nosave_end));
+
+	return	(pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
+}