diff options
| author |   Daniel Borkmann <daniel@iogearbox.net> | 2018-05-14 23:22:33 +0200 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2018-05-14 19:11:45 -0700 |
| commit | 56ea6a8b4949c66d550d05e92da8ef4351b90027 (patch) | |
| tree | 21af064891911296afea5e9193c902f848cc03fe /arch | |
| parent | bpf, arm64: optimize 32/64 immediate emission (diff) | |
| download | linux-dev-56ea6a8b4949c66d550d05e92da8ef4351b90027.tar.xz linux-dev-56ea6a8b4949c66d550d05e92da8ef4351b90027.zip | |
bpf, arm64: save 4 bytes in prologue when ebpf insns came from cbpf
We can trivially save 4 bytes in prologue for cBPF since tail calls
can never be used from there. The register push/pop is pairwise,
here, x25 (fp) and x26 (tcc), so no point in changing that, only
reset to zero is not needed.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/net/bpf_jit_comp.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c8a2620312c0..a6fdaea07c63 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -185,7 +185,7 @@ static inline int epilogue_offset(const struct jit_ctx *ctx) /* Tail call offset to jump into */ #define PROLOGUE_OFFSET 7 -static int build_prologue(struct jit_ctx *ctx) +static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf) { const struct bpf_prog *prog = ctx->prog; const u8 r6 = bpf2a64[BPF_REG_6]; @@ -232,14 +232,16 @@ static int build_prologue(struct jit_ctx *ctx) /* Set up BPF prog stack base register */ emit(A64_MOV(1, fp, A64_SP), ctx); - /* Initialize tail_call_cnt */ - emit(A64_MOVZ(1, tcc, 0, 0), ctx); + if (!ebpf_from_cbpf) { + /* Initialize tail_call_cnt */ + emit(A64_MOVZ(1, tcc, 0, 0), ctx); - cur_offset = ctx->idx - idx0; - if (cur_offset != PROLOGUE_OFFSET) { - pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n", - cur_offset, PROLOGUE_OFFSET); - return -1; + cur_offset = ctx->idx - idx0; + if (cur_offset != PROLOGUE_OFFSET) { + pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n", + cur_offset, PROLOGUE_OFFSET); + return -1; + } } ctx->stack_size = STACK_ALIGN(prog->aux->stack_depth); @@ -806,6 +808,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) struct bpf_prog *tmp, *orig_prog = prog; struct bpf_binary_header *header; struct arm64_jit_data *jit_data; + bool was_classic = bpf_prog_was_classic(prog); bool tmp_blinded = false; bool extra_pass = false; struct jit_ctx ctx; @@ -860,7 +863,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) goto out_off; } - if (build_prologue(&ctx)) { + if (build_prologue(&ctx, was_classic)) { prog = orig_prog; goto out_off; } @@ -883,7 +886,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) skip_init_ctx: ctx.idx = 0; - build_prologue(&ctx); + build_prologue(&ctx, was_classic); if (build_body(&ctx)) { bpf_jit_binary_free(header); |