selftests/bpf: Add a test for objects stuck in free_by_rcu_ttracegrafted

Delete all elements of BPF_F_NO_PREALLOC hash map in one batch. The first
free_bulk() starts RCU tasks trace GP and the rest of the elements are
freed while it's in flight. Wait for call_rcu_ttrace_in_progress to clear
in bpf_mem_cache of every cpu and check that free_by_rcu_ttrace and
waiting_for_gp_ttrace lists are empty.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260930095920.601738-4-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/include/vdso/math64.h b/include/vdso/math64.h
new file mode 100644
index 000000000..22ae212f8
--- /dev/null
+++ b/include/vdso/math64.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_MATH64_H
+#define __VDSO_MATH64_H
+
+static __always_inline u32
+__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
+{
+	u32 ret = 0;
+
+	while (dividend >= divisor) {
+		/* The following asm() prevents the compiler from
+		   optimising this loop into a modulo operation.  */
+		asm("" : "+rm"(dividend));
+
+		dividend -= divisor;
+		ret++;
+	}
+
+	*remainder = dividend;
+
+	return ret;
+}
+
+#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
+
+#ifndef mul_u64_u32_add_u64_shr
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	return (u64)((((unsigned __int128)a * mul) + b) >> shift);
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#else
+
+#ifndef mul_u64_u32_add_u64_shr
+#ifndef mul_u32_u32
+static inline u64 mul_u32_u32(u32 a, u32 b)
+{
+	return (u64)a * b;
+}
+#define mul_u32_u32 mul_u32_u32
+#endif
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	u32 ah = a >> 32, al = a;
+	bool ovf;
+	u64 ret;
+
+	ovf = __builtin_add_overflow(mul_u32_u32(al, mul), b, &ret);
+	ret >>= shift;
+	if (ovf && shift)
+		ret += 1ULL << (64 - shift);
+	if (ah)
+		ret += mul_u32_u32(ah, mul) << (32 - shift);
+
+	return ret;
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#endif
+
+#endif /* __VDSO_MATH64_H */