On Wed, Nov 6, 2019 at 9:48 PM Alexei Starovoitov <ast@xxxxxxxxxx> wrote:
>
> BPF trampoline can be made to work with existing 5 bytes of BPF program
> prologue, but let's add 5 bytes of NOPs to the beginning of every JITed BPF
> program to make BPF trampoline job easier. They can be removed in the future.
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> arch/x86/net/bpf_jit_comp.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> index 44169e8bffc0..260f61276f18 100644
> --- a/arch/x86/net/bpf_jit_comp.c
> +++ b/arch/x86/net/bpf_jit_comp.c
> @@ -206,7 +206,7 @@ struct jit_context {
> /* number of bytes emit_call() needs to generate call instruction */
> #define X86_CALL_SIZE 5
>
> -#define PROLOGUE_SIZE 20
> +#define PROLOGUE_SIZE 25
nit: define as 20 + X86_CALL_SIZE ?
[...]
