[PATCH bpf-next] riscv, bpf: Optimize stack usage of trampoline

Puranjay Mohan
2024-07-08T11:48:13Z

When BPF_TRAMP_F_CALL_ORIG is not set, stack space for passing arguments
on stack doesn't need to be reserved because the original function is
not called.

Only reserve space for stacked arguments when BPF_TRAMP_F_CALL_ORIG is
set.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
---
arch/riscv/net/bpf_jit_comp64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 685c7389ae7e..0795efdd3519 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -892,7 +892,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
stack_size += 8;
sreg_off = stack_size;

- if (nr_arg_slots - RV_MAX_REG_ARGS > 0)
+ if ((flags & BPF_TRAMP_F_CALL_ORIG) && (nr_arg_slots - RV_MAX_REG_ARGS > 0))
stack_size += (nr_arg_slots - RV_MAX_REG_ARGS) * 8;

stack_size = round_up(stack_size, STACK_ALIGN);
--
2.40.1