On 2023/1/5 2:24, Yonghong Song wrote:
On 1/2/23 5:31 PM, Pu Lehui wrote:
From: Pu Lehui <pulehui@xxxxxxxxxx>
Extra_nregs of structure parameters and nr_args can be
added directly at the beginning, and using a flip flag
to identifiy structure parameters. Meantime, renaming
some variables to make them more sense.
Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
Thanks for refactoring. Using nr_regs instead of nr_args indeed
making things easier to understand. Ack with a few nits below.
Acked-by: Yonghong Song <yhs@xxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 99 +++++++++++++++++--------------------
1 file changed, 46 insertions(+), 53 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index e3e2b57e4e13..e7b72299f5a4 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1839,62 +1839,57 @@ st: if (is_imm8(insn->off))
return proglen;
}
-static void save_regs(const struct btf_func_model *m, u8 **prog, int
nr_args,
+static void save_regs(const struct btf_func_model *m, u8 **prog, int
nr_regs,
int stack_size)
{
- int i, j, arg_size, nr_regs;
+ int i, j, arg_size;
+ bool is_struct = false;
+
/* Store function arguments to stack.
* For a function that accepts two pointers the sequence will be:
* mov QWORD PTR [rbp-0x10],rdi
* mov QWORD PTR [rbp-0x8],rsi
*/
- for (i = 0, j = 0; i < min(nr_args, 6); i++) {
- if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) {
- nr_regs = (m->arg_size[i] + 7) / 8;
+ for (i = 0, j = 0; i < min(nr_regs, 6); i++) {
+ arg_size = m->arg_size[j];
+ if (arg_size > 8) {
arg_size = 8;
- } else {
- nr_regs = 1;
- arg_size = m->arg_size[i];
+ is_struct ^= 1;
}
- while (nr_regs) {
- emit_stx(prog, bytes_to_bpf_size(arg_size),
- BPF_REG_FP,
- j == 5 ? X86_REG_R9 : BPF_REG_1 + j,
- -(stack_size - j * 8));
- nr_regs--;
- j++;
- }
+ emit_stx(prog, bytes_to_bpf_size(arg_size),
+ BPF_REG_FP,
+ i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
+ -(stack_size - i * 8));
+
+ j = is_struct ? j : j + 1;
}
}
-static void restore_regs(const struct btf_func_model *m, u8 **prog,
int nr_args,
+static void restore_regs(const struct btf_func_model *m, u8 **prog,
int nr_regs,
int stack_size)
{
- int i, j, arg_size, nr_regs;
+ int i, j, arg_size;
+ bool is_struct = false;
Maybe
bool next_same_struct = false
to better characterize what it means?
agree, will do as suggested bellow.
/* Restore function arguments from stack.
* For a function that accepts two pointers the sequence will be:
* EMIT4(0x48, 0x8B, 0x7D, 0xF0); mov rdi,QWORD PTR [rbp-0x10]
* EMIT4(0x48, 0x8B, 0x75, 0xF8); mov rsi,QWORD PTR [rbp-0x8]
*/
- for (i = 0, j = 0; i < min(nr_args, 6); i++) {
- if (m->arg_flags[i] & BTF_FMODEL_STRUCT_ARG) {
- nr_regs = (m->arg_size[i] + 7) / 8;
+ for (i = 0, j = 0; i < min(nr_regs, 6); i++) {
Let us put a comment here so the later users can understand the logic
behind 'is_struct ^= 1'.
/* The arg_size is at most 16 bytes, enforced by the verifier. */
+ arg_size = m->arg_size[j];
+ if (arg_size > 8) {
arg_size = 8;
- } else {
- nr_regs = 1;
- arg_size = m->arg_size[i];
+ is_struct ^= 1;
next_same_struct = !next_same_struct;
The same for above save_regs().
}
- while (nr_regs) {
- emit_ldx(prog, bytes_to_bpf_size(arg_size),
- j == 5 ? X86_REG_R9 : BPF_REG_1 + j,
- BPF_REG_FP,
- -(stack_size - j * 8));
- nr_regs--;
- j++;
- }
+ emit_ldx(prog, bytes_to_bpf_size(arg_size),
+ i == 5 ? X86_REG_R9 : BPF_REG_1 + i,
+ BPF_REG_FP,
+ -(stack_size - i * 8));
+
+ j = is_struct ? j : j + 1;
}
}
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