linux-mips
[Top] [All Lists]

Re: [PATCH 16/17] MIPS: bpf: Use 32 or 64-bit load instruction to load a

To: Paul Burton <paul.burton@imgtec.com>
Subject: Re: [PATCH 16/17] MIPS: bpf: Use 32 or 64-bit load instruction to load an address to register
From: Markos Chandras <Markos.Chandras@imgtec.com>
Date: Wed, 25 Jun 2014 09:18:48 +0100
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>
In-reply-to: <20140623202437.GD2200@pburton-laptop>
List-archive: <http://www.linux-mips.org/archives/linux-mips/>
List-help: <mailto:ecartis@linux-mips.org?Subject=help>
List-id: linux-mips <linux-mips.eddie.linux-mips.org>
List-owner: <mailto:ralf@linux-mips.org>
List-post: <mailto:linux-mips@linux-mips.org>
List-software: Ecartis version 1.0.0
List-subscribe: <mailto:ecartis@linux-mips.org?subject=subscribe%20linux-mips>
List-unsubscribe: <mailto:ecartis@linux-mips.org?subject=unsubscribe%20linux-mips>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1403516340-22997-1-git-send-email-markos.chandras@imgtec.com> <1403516340-22997-17-git-send-email-markos.chandras@imgtec.com> <20140623202437.GD2200@pburton-laptop>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0
On 06/23/2014 09:24 PM, Paul Burton wrote:
> On Mon, Jun 23, 2014 at 10:38:59AM +0100, Markos Chandras wrote:
>> 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?
> 
Hi Paul,

I suppose I could do that. I will send a v2

>> +{
>> +    /* 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?
> 

Not right now. I use config_enabled(CONFIG_64BIT) everywhere in that
file to emit 32-bit or 64-bit instructions. So I will look into
switching to the USAM_i_* macros when i submit the remaining fixes
probably for 3.17.

-- 
markos

<Prev in Thread] Current Thread [Next in Thread>