On Tue, Jul 26, 2022 at 10:11:51AM -0700, Yonghong Song wrote:
SNIP
>
> -static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
> - int regs_off)
> +static void __save_struct_arg_regs(u8 **prog, int curr_reg_idx, int nr_regs,
> + int struct_val_off, int stack_start_idx)
> {
> - int i;
> + int i, reg_idx;
> +
> + /* Save struct registers to stack.
> + * For example, argument 1 (second argument) size is 16 which occupies two
> + * registers, these two register values will be saved in stack.
> + * mov QWORD PTR [rbp-0x40],rsi
> + * mov QWORD PTR [rbp-0x38],rdx
> + */
> + for (i = 0; i < nr_regs; i++) {
> + reg_idx = curr_reg_idx + i;
> + emit_stx(prog, bytes_to_bpf_size(8),
> + BPF_REG_FP,
> + reg_idx == 5 ? X86_REG_R9 : BPF_REG_1 + reg_idx,
> + -(struct_val_off - stack_start_idx * 8));
> + stack_start_idx++;
> + }
> +}
> +
> +static void save_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
> + int regs_off, int struct_val_off)
> +{
> + int curr_arg_idx, curr_reg_idx, curr_s_stack_off;
> + int s_size, s_arg_idx, s_arg_nregs;
> +
> + curr_arg_idx = curr_reg_idx = curr_s_stack_off = 0;
> + for (int i = 0; i < MAX_BPF_FUNC_STRUCT_ARGS; i++) {
> + s_size = m->struct_arg_bsize[i];
> + if (!s_size)
> + return __save_normal_arg_regs(m, prog, curr_arg_idx, nr_args - curr_arg_idx,
> + curr_reg_idx, regs_off);
could we just do break in here instead?
SNIP
> +
> +static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args,
> + int regs_off, int struct_val_off)
> +{
> + int curr_arg_idx, curr_reg_idx, curr_s_stack_off;
> + int s_size, s_arg_idx, s_arg_nregs;
> +
> + curr_arg_idx = curr_reg_idx = curr_s_stack_off = 0;
> + for (int i = 0; i < MAX_BPF_FUNC_STRUCT_ARGS; i++) {
> + s_size = m->struct_arg_bsize[i];
> + if (!s_size)
> + return __restore_normal_arg_regs(m, prog, curr_arg_idx,
> + nr_args - curr_arg_idx,
> + curr_reg_idx, regs_off);
same here
jirka
> +
> + s_arg_idx = m->struct_arg_idx[i];
> + s_arg_nregs = (s_size + 7) / 8;
> +
> + __restore_normal_arg_regs(m, prog, curr_arg_idx, s_arg_idx - curr_arg_idx,
> + curr_reg_idx, regs_off);
> + __restore_struct_arg_regs(prog, curr_reg_idx + s_arg_idx - curr_arg_idx,
> + s_arg_nregs, struct_val_off, curr_s_stack_off);
> + curr_reg_idx += s_arg_idx - curr_arg_idx + s_arg_nregs;
> + curr_s_stack_off += s_arg_nregs;
> + curr_arg_idx = s_arg_idx + 1;
> + }
> +
> + __restore_normal_arg_regs(m, prog, curr_arg_idx, nr_args - curr_arg_idx, curr_reg_idx,
> + regs_off);
> }
>
SNIP
