On 7/29/22 4:10 AM, Jiri Olsa wrote:
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?
Thanks for pointing out. Yes, we can just do break and later call
__save_normal_arg_regs(...) will handle this automatically.
The same for another place you pointed below.
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
