On 2024/7/5 20:51, Puranjay Mohan wrote:
Pu Lehui <pulehui@xxxxxxxxxxxxxxx> writes:
From: Pu Lehui <pulehui@xxxxxxxxxx>
This patch adds 12 function arguments support for riscv64 bpf
trampoline. The current bpf trampoline supports <= sizeof(u64) bytes
scalar arguments [0] and <= 16 bytes struct arguments [1]. Therefore, we
focus on the situation where scalars are at most XLEN bits and
aggregates whose total size does not exceed 2×XLEN bits in the riscv
calling convention [2].
[SNIP]
@@ -854,7 +875,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
retval_off = stack_size;
}
- stack_size += nregs * 8;
+ stack_size += nr_arg_slots * 8;
args_off = stack_size;
stack_size += 8;
@@ -871,8 +892,14 @@ 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)
+ stack_size += (nr_arg_slots - RV_MAX_REG_ARGS) * 8;
Hi Pu,
Although this is merged now, while working on this for arm64 I realised
that the above doesn't check for BPF_TRAMP_F_CALL_ORIG and can waste
some stack space, we should change this to:
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;
It will save some stack space when BPF_TRAMP_F_CALL_ORIG is not set?
Nice catch. It will be better. Feel free to patch it. Thanks!
I can send a patch if you think this is worth fixing.
Thanks,
Puranjay
