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, 59 insertions, 0 deletions

diff --git a/drivers/gpib/include/amccs5933.h b/drivers/gpib/include/amccs5933.h
new file mode 100644
index 000000000..d7f63c795
--- /dev/null
+++ b/drivers/gpib/include/amccs5933.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/***************************************************************************
+ * Registers and bits for amccs5933 pci chip
+ *    copyright            : (C) 2002 by Frank Mori Hess
+ ***************************************************************************/
+
+// register offsets
+enum {
+	MBEF_REG = 0x34,	// mailbux empty/full
+	INTCSR_REG = 0x38,	// interrupt control and status
+	BMCSR_REG = 0x3c,	// bus master control and status
+};
+
+// incoming mailbox 0-3  register offsets
+extern inline int INCOMING_MAILBOX_REG(unsigned int mailbox)
+{
+	return (0x10 + 4 * mailbox);
+};
+
+// bit definitions
+
+// INTCSR bits
+enum {
+	OUTBOX_EMPTY_INTR_BIT = 0x10,	// enable outbox empty interrupt
+	INBOX_FULL_INTR_BIT = 0x1000,	// enable inbox full interrupt
+	INBOX_INTR_CS_BIT = 0x20000,	// read, or write clear inbox full interrupt
+	INTR_ASSERTED_BIT = 0x800000,	// read only, interrupt asserted
+};
+
+// select byte 0 to 3 of incoming mailbox
+extern inline int INBOX_BYTE_BITS(unsigned int byte)
+{
+	return (byte & 0x3) << 8;
+};
+
+// select incoming mailbox 0 to 3
+extern inline int INBOX_SELECT_BITS(unsigned int mailbox)
+{
+	return (mailbox & 0x3) << 10;
+};
+
+// select byte 0 to 3 of outgoing mailbox
+extern inline int OUTBOX_BYTE_BITS(unsigned int byte)
+{
+	return (byte & 0x3);
+};
+
+// select outgoing mailbox 0 to 3
+extern inline int OUTBOX_SELECT_BITS(unsigned int mailbox)
+{
+	return (mailbox & 0x3) << 2;
+};
+
+// BMCSR bits
+enum {
+	MBOX_FLAGS_RESET_BIT = 0x08000000,	// resets mailbox empty/full flags
+};
+