From: Paul Burton <paul.burton@imgtec.com>
To: Markos Chandras <markos.chandras@imgtec.com>
Cc: <linux-mips@linux-mips.org>,
"David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <dborkman@redhat.com>,
Alexei Starovoitov <ast@plumgrid.com>, <netdev@vger.kernel.org>
Subject: Re: [PATCH 16/17] MIPS: bpf: Use 32 or 64-bit load instruction to load an address to register
Date: Mon, 23 Jun 2014 21:24:37 +0100 [thread overview]
Message-ID: <20140623202437.GD2200@pburton-laptop> (raw)
In-Reply-To: <1403516340-22997-17-git-send-email-markos.chandras@imgtec.com>
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@davemloft.net>
> Cc: Daniel Borkmann <dborkman@redhat.com>
> Cc: Alexei Starovoitov <ast@plumgrid.com>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
> ---
> 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
>
>
next prev parent reply other threads:[~2014-06-23 20:24 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-23 9:38 [PATCH 00/17] Misc MIPS/BPF fixes for 3.16 Markos Chandras
2014-06-23 9:38 ` [PATCH 04/17] MIPS: bpf: Use the LO register to get division's quotient Markos Chandras
2014-06-23 9:38 ` [PATCH 05/17] MIPS: bpf: Return error code if the offset is a negative number Markos Chandras
2014-06-23 22:09 ` Alexei Starovoitov
2014-06-25 8:12 ` Markos Chandras
2014-06-23 9:38 ` [PATCH 06/17] MIPS: bpf: Use 'andi' instead of 'and' for the VLAN cases Markos Chandras
2014-06-23 9:38 ` [PATCH 07/17] MIPS: bpf: Add SEEN_SKB to flags when looking for the PKT_TYPE Markos Chandras
2014-06-23 9:38 ` [PATCH 08/17] MIPS: bpf: Fix branch conditional for BPF_J{GT/GE} cases Markos Chandras
2014-06-23 9:38 ` [PATCH 09/17] MIPS: bpf: Use correct mask for VLAN_TAG case Markos Chandras
2014-06-23 9:38 ` [PATCH 10/17] MIPS: bpf: Fix return values for VLAN_TAG_PRESENT case Markos Chandras
2014-06-23 9:38 ` [PATCH 11/17] MIPS: bpf: Use pr_debug instead of pr_warn for unhandled opcodes Markos Chandras
2014-06-23 9:38 ` [PATCH 12/17] MIPS: bpf: Fix is_range() semantics Markos Chandras
2014-06-23 9:38 ` [PATCH 13/17] MIPS: bpf: Drop update_on_xread and always initialize the X register Markos Chandras
2014-06-23 9:38 ` [PATCH 14/17] MIPS: bpf: Prevent kernel fall over for >=32bit shifts Markos Chandras
2014-06-23 9:44 ` David Laight
2014-06-23 11:06 ` Markos Chandras
2014-06-23 11:08 ` David Laight
2014-06-23 11:39 ` Markos Chandras
2014-06-25 8:37 ` [PATCH v2 " Markos Chandras
2014-06-23 9:38 ` [PATCH 15/17] MIPS: bpf: Fix PKT_TYPE case for big-endian cores Markos Chandras
2014-06-23 9:38 ` [PATCH 16/17] MIPS: bpf: Use 32 or 64-bit load instruction to load an address to register Markos Chandras
2014-06-23 20:24 ` Paul Burton [this message]
2014-06-25 8:18 ` Markos Chandras
2014-06-25 8:39 ` [PATCH v2 " Markos Chandras
2014-06-25 14:28 ` Alexei Starovoitov
2014-06-23 9:39 ` [PATCH 17/17] MIPS: bpf: Fix stack space allocation for BPF memwords on MIPS64 Markos Chandras
2014-06-23 19:49 ` [PATCH 00/17] Misc MIPS/BPF fixes for 3.16 David Miller
2014-06-25 8:12 ` Markos Chandras
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