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, 27 insertions, 0 deletions

diff --git a/arch/mips/bmips/dma.c b/arch/mips/bmips/dma.c
new file mode 100644
index 000000000..2bc9c0d44
--- /dev/null
+++ b/arch/mips/bmips/dma.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/types.h>
+#include <linux/dma-map-ops.h>
+#include <asm/bmips.h>
+#include <asm/io.h>
+
+bool bmips_rac_flush_disable;
+
+void arch_sync_dma_for_cpu_all(void)
+{
+	void __iomem *cbr = bmips_cbr_addr;
+	u32 cfg;
+
+	if (boot_cpu_type() != CPU_BMIPS3300 &&
+	    boot_cpu_type() != CPU_BMIPS4350 &&
+	    boot_cpu_type() != CPU_BMIPS4380)
+		return;
+
+	if (unlikely(bmips_rac_flush_disable))
+		return;
+
+	/* Flush stale data out of the readahead cache */
+	cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
+	__raw_writel(cfg | 0x100, cbr + BMIPS_RAC_CONFIG);
+	__raw_readl(cbr + BMIPS_RAC_CONFIG);
+}