On Mon, Jun 23, 2014 at 10:38:59AM +0100, Markos Chandras wrote:
> When loading a pointer to a register we need to use the appropriate
> 32 or 64bit instruction to preserve the pointer's top 32bits.
>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Daniel Borkmann <dborkman@xxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
> ---
> arch/mips/net/bpf_jit.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c
> index 4920e0fd05ee..d8dba7b523a5 100644
> --- a/arch/mips/net/bpf_jit.c
> +++ b/arch/mips/net/bpf_jit.c
> @@ -447,6 +447,17 @@ static inline void emit_wsbh(unsigned int dst, unsigned int src,
> emit_instr(ctx, wsbh, dst, src);
> }
>
> +/* load address to register */
> +static inline void emit_load_addr(unsigned int dst, unsigned int src,
> + int imm, struct jit_ctx *ctx)
(I originally sent this in reply to your internal posting, but assume you
missed it or it got eaten somewhere along the way.)
The name emit_load_addr & comment "load address to register" makes this
sound like an equivalent of the "la" pseudo instruction, but it appears
to really emit a pointer sized load? How about emit_load_ptr or something
instead, and similarly s/address/pointer/ in the comment?
> +{
> + /* src contains the base addr of the 32/64-pointer */
> + if (config_enabled(CONFIG_64BIT))
> + emit_instr(ctx, ld, dst, imm, src);
> + else
> + emit_instr(ctx, lw, dst, imm, src);
Is there some way you could make use of the UASM_i_LW macro (note the
capitalisation) instead of the if statement here?
Thanks,
Paul
> +}
> +
> /* load a function pointer to register */
> static inline void emit_load_func(unsigned int reg, ptr imm,
> struct jit_ctx *ctx)
> @@ -1271,7 +1282,8 @@ jmp_cmp:
> /* A = skb->dev->ifindex */
> ctx->flags |= SEEN_SKB | SEEN_A | SEEN_S0;
> off = offsetof(struct sk_buff, dev);
> - emit_load(r_s0, r_skb, off, ctx);
> + /* Load address of *dev member */
> + emit_load_addr(r_s0, r_skb, off, ctx);
> /* error (0) in the delay slot */
> emit_bcond(MIPS_COND_EQ, r_s0, r_zero,
> b_imm(prog->len, ctx), ctx);
> --
> 2.0.0
>
>
