bpf, arm64: Support up to 12 function arguments

Currently ARM64 bpf trampoline supports up to 8 function arguments.
According to the statistics from commit
473e3150e30a ("bpf, x86: allow function arguments up to 12 for TRACING"),
there are about 200 functions accept 9 to 12 arguments, so adding support
for up to 12 function arguments.

Due to bpf only supporting function arguments up to 16 bytes, according to
AAPCS64, starting from the first argument, each argument is first
attempted to be loaded to 1 or 2 smallest registers from x0-x7, if there
are no enough registers to hold the entire argument, then all remaining
arguments starting from this one are pushed to the stack for passing.
There are some non-trivial cases for which it is not possible to
correctly read arguments from/write arguments to the stack: for example
struct variables may have custom packing/alignment attributes that are
invisible in BTF info. Such cases are denied for now to make sure not to
read incorrect values.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Co-developed-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Link: https://lore.kernel.org/r/20250527-many_args_arm64-v3-1-3faf7bb8e4a2@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

0 files changed, 0 insertions, 0 deletions