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, 24 insertions, 0 deletions

diff --git a/arch/powerpc/boot/microwatt.c b/arch/powerpc/boot/microwatt.c
new file mode 100644
index 000000000..ca9d83617
--- /dev/null
+++ b/arch/powerpc/boot/microwatt.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <stddef.h>
+#include "stdio.h"
+#include "types.h"
+#include "io.h"
+#include "ops.h"
+
+BSS_STACK(8192);
+
+void platform_init(unsigned long r3, unsigned long r4, unsigned long r5)
+{
+	unsigned long heapsize = 16*1024*1024 - (unsigned long)_end;
+
+	/*
+	 * Disable interrupts and turn off MSR_RI, since we'll
+	 * shortly be overwriting the interrupt vectors.
+	 */
+	__asm__ volatile("mtmsrd %0,1" : : "r" (0));
+
+	simple_alloc_init(_end, heapsize, 32, 64);
+	fdt_init(_dtb_start);
+	serial_console_init();
+}