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Date: Wed, 24 Apr 2013 19:41:34 +0200
From: Daniel Borkmann <dborkman@...hat.com>
To: Nicolas Schichan <nschichan@...ebox.fr>
CC: Will Drewry <wad@...omium.org>,
Mircea Gherzan <mgherzan@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Russell King <linux@....linux.org.uk>,
"David S. Miller" <davem@...emloft.net>,
Daniel Borkmann <daniel.borkmann@....ee.ethz.ch>,
netdev@...r.kernel.org
Subject: Re: [PATCH V3 2/3] ARM: net: bpf_jit: make code generation less dependent
on struct sk_filter.
On 04/24/2013 07:27 PM, Nicolas Schichan wrote:
> This is in preparation of bpf_jit support for seccomp filters.
Please also CC the netdev list for BPF related patches.
Just to give you a heads-up, this might likely lead to a merge
conflict with the net-next tree (commit 79617801ea0c0e66, "filter:
bpf_jit_comp: refactor and unify BPF JIT image dump output").
> Signed-off-by: Nicolas Schichan <nschichan@...ebox.fr>
> ---
> arch/arm/net/bpf_jit_32.c | 46 ++++++++++++++++++++++++++++-----------------
> 1 file changed, 29 insertions(+), 17 deletions(-)
>
> diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
> index a0bd8a7..bb66a2b 100644
> --- a/arch/arm/net/bpf_jit_32.c
> +++ b/arch/arm/net/bpf_jit_32.c
> @@ -55,7 +55,8 @@
> #define FLAG_NEED_X_RESET (1 << 0)
>
> struct jit_ctx {
> - const struct sk_filter *skf;
> + unsigned short prog_len;
> + struct sock_filter *prog_insns;
> unsigned idx;
> unsigned prologue_bytes;
> int ret0_fp_idx;
> @@ -131,8 +132,8 @@ static u16 saved_regs(struct jit_ctx *ctx)
> {
> u16 ret = 0;
>
> - if ((ctx->skf->len > 1) ||
> - (ctx->skf->insns[0].code == BPF_S_RET_A))
> + if ((ctx->prog_len > 1) ||
> + (ctx->prog_insns[0].code == BPF_S_RET_A))
> ret |= 1 << r_A;
>
> #ifdef CONFIG_FRAME_POINTER
> @@ -181,7 +182,7 @@ static inline bool is_load_to_a(u16 inst)
> static void build_prologue(struct jit_ctx *ctx)
> {
> u16 reg_set = saved_regs(ctx);
> - u16 first_inst = ctx->skf->insns[0].code;
> + u16 first_inst = ctx->prog_insns[0].code;
> u16 off;
>
> #ifdef CONFIG_FRAME_POINTER
> @@ -279,7 +280,7 @@ static u16 imm_offset(u32 k, struct jit_ctx *ctx)
> ctx->imms[i] = k;
>
> /* constants go just after the epilogue */
> - offset = ctx->offsets[ctx->skf->len];
> + offset = ctx->offsets[ctx->prog_len];
> offset += ctx->prologue_bytes;
> offset += ctx->epilogue_bytes;
> offset += i * 4;
> @@ -419,7 +420,7 @@ static inline void emit_err_ret(u8 cond, struct jit_ctx *ctx)
> emit(ARM_MOV_R(ARM_R0, ARM_R0), ctx);
> } else {
> _emit(cond, ARM_MOV_I(ARM_R0, 0), ctx);
> - _emit(cond, ARM_B(b_imm(ctx->skf->len, ctx)), ctx);
> + _emit(cond, ARM_B(b_imm(ctx->prog_len, ctx)), ctx);
> }
> }
>
> @@ -469,14 +470,13 @@ static inline void update_on_xread(struct jit_ctx *ctx)
> static int build_body(struct jit_ctx *ctx)
> {
> void *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w};
> - const struct sk_filter *prog = ctx->skf;
> const struct sock_filter *inst;
> unsigned i, load_order, off, condt;
> int imm12;
> u32 k;
>
> - for (i = 0; i < prog->len; i++) {
> - inst = &(prog->insns[i]);
> + for (i = 0; i < ctx->prog_len; i++) {
> + inst = &(ctx->prog_insns[i]);
> /* K as an immediate value operand */
> k = inst->k;
>
> @@ -769,8 +769,8 @@ cmp_x:
> ctx->ret0_fp_idx = i;
> emit_mov_i(ARM_R0, k, ctx);
> b_epilogue:
> - if (i != ctx->skf->len - 1)
> - emit(ARM_B(b_imm(prog->len, ctx)), ctx);
> + if (i != ctx->prog_len - 1)
> + emit(ARM_B(b_imm(ctx->prog_len, ctx)), ctx);
> break;
> case BPF_S_MISC_TAX:
> /* X = A */
> @@ -858,7 +858,7 @@ b_epilogue:
> }
>
>
> -void bpf_jit_compile(struct sk_filter *fp)
> +static void __bpf_jit_compile(struct jit_ctx *out_ctx)
> {
> struct jit_ctx ctx;
> unsigned tmp_idx;
> @@ -867,11 +867,10 @@ void bpf_jit_compile(struct sk_filter *fp)
> if (!bpf_jit_enable)
> return;
>
> - memset(&ctx, 0, sizeof(ctx));
> - ctx.skf = fp;
> + ctx = *out_ctx;
> ctx.ret0_fp_idx = -1;
>
> - ctx.offsets = kzalloc(4 * (ctx.skf->len + 1), GFP_KERNEL);
> + ctx.offsets = kzalloc(4 * (ctx.prog_len + 1), GFP_KERNEL);
> if (ctx.offsets == NULL)
> return;
>
> @@ -921,13 +920,26 @@ void bpf_jit_compile(struct sk_filter *fp)
> print_hex_dump(KERN_INFO, "BPF JIT code: ",
> DUMP_PREFIX_ADDRESS, 16, 4, ctx.target,
> alloc_size, false);
> -
> - fp->bpf_func = (void *)ctx.target;
> out:
> kfree(ctx.offsets);
> +
> + *out_ctx = ctx;
> return;
> }
>
> +void bpf_jit_compile(struct sk_filter *fp)
> +{
> + struct jit_ctx ctx;
> +
> + memset(&ctx, 0, sizeof(ctx));
> + ctx.prog_len = fp->len;
> + ctx.prog_insns = fp->insns;
> +
> + __bpf_jit_compile(&ctx);
> + if (ctx.target)
> + fp->bpf_func = (void *)ctx.target;
> +}
> +
> static void bpf_jit_free_worker(struct work_struct *work)
> {
> module_free(NULL, work);
>
--
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