From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: peterz@infradead.org, lkml <linux-kernel@vger.kernel.org>,
oleg@redhat.com, Paul Mackerras <paulus@samba.org>,
Anton Blanchard <anton@samba.org>, Ingo Molnar <mingo@elte.hu>,
ppcdev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v4 2/2] powerpc: Uprobes port to powerpc
Date: Thu, 23 Aug 2012 20:06:18 +1000 [thread overview]
Message-ID: <1345716378.29170.4.camel@pasglop> (raw)
In-Reply-To: <20120823053234.GE25338@linux.vnet.ibm.com>
On Thu, 2012-08-23 at 11:02 +0530, Srikar Dronamraju wrote:
> >
>
> insn is updated/accessed in the arch independent code. Size of
> uprobe_opcode_t could be different for different archs.
> uprobe_opcode_t
> represents the size of the smallest breakpoint instruction for an
> arch.
>
> Hence u8 works out the best. I know we could still use uprobe_opcode_t
> and achieve the same. In which case, we would have to interpret
> MAX_UINSN_BYTES differently. Do you see any advantages of using
> uprobe_opcode_t instead of u8 across archs?
But don't you actively rely on the fact that on powerpc, unlike x86, you
-can- atomically replace an instruction with a single 32-bit store ?
If you don't you should consider it, and that makes defining this as a
u8 array non-sensical (as is using memcpy)
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Michael Ellerman <michael@ellerman.id.au>,
ananth@in.ibm.com, ppcdev <linuxppc-dev@lists.ozlabs.org>,
lkml <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>,
Anton Blanchard <anton@samba.org>,
peterz@infradead.org, oleg@redhat.com,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH v4 2/2] powerpc: Uprobes port to powerpc
Date: Thu, 23 Aug 2012 20:06:18 +1000 [thread overview]
Message-ID: <1345716378.29170.4.camel@pasglop> (raw)
In-Reply-To: <20120823053234.GE25338@linux.vnet.ibm.com>
On Thu, 2012-08-23 at 11:02 +0530, Srikar Dronamraju wrote:
> >
>
> insn is updated/accessed in the arch independent code. Size of
> uprobe_opcode_t could be different for different archs.
> uprobe_opcode_t
> represents the size of the smallest breakpoint instruction for an
> arch.
>
> Hence u8 works out the best. I know we could still use uprobe_opcode_t
> and achieve the same. In which case, we would have to interpret
> MAX_UINSN_BYTES differently. Do you see any advantages of using
> uprobe_opcode_t instead of u8 across archs?
But don't you actively rely on the fact that on powerpc, unlike x86, you
-can- atomically replace an instruction with a single 32-bit store ?
If you don't you should consider it, and that makes defining this as a
u8 array non-sensical (as is using memcpy)
Ben.
next prev parent reply other threads:[~2012-08-23 10:06 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-22 8:22 [PATCH 1/2] powerpc: Add trap_nr to thread_struct Ananth N Mavinakayanahalli
2012-08-22 8:22 ` Ananth N Mavinakayanahalli
2012-08-22 8:27 ` [PATCH v4 2/2] powerpc: Uprobes port to powerpc Ananth N Mavinakayanahalli
2012-08-22 8:27 ` Ananth N Mavinakayanahalli
2012-08-22 15:55 ` Oleg Nesterov
2012-08-22 15:55 ` Oleg Nesterov
2012-08-23 4:28 ` Michael Ellerman
2012-08-23 4:28 ` Michael Ellerman
2012-08-23 5:32 ` Srikar Dronamraju
2012-08-23 5:32 ` Srikar Dronamraju
2012-08-23 10:06 ` Benjamin Herrenschmidt [this message]
2012-08-23 10:06 ` Benjamin Herrenschmidt
2012-08-23 9:02 ` Oleg Nesterov
2012-08-23 9:02 ` Oleg Nesterov
2012-08-23 16:02 ` Srikar Dronamraju
2012-08-23 16:02 ` Srikar Dronamraju
2012-08-23 16:17 ` Srikar Dronamraju
2012-08-23 16:17 ` Srikar Dronamraju
2012-08-23 21:57 ` Benjamin Herrenschmidt
2012-08-23 21:57 ` Benjamin Herrenschmidt
2012-08-24 1:33 ` Michael Ellerman
2012-08-24 1:33 ` Michael Ellerman
2012-08-23 5:58 ` Ananth N Mavinakayanahalli
2012-08-23 5:58 ` Ananth N Mavinakayanahalli
2012-08-24 1:13 ` Michael Ellerman
2012-08-24 1:13 ` Michael Ellerman
2012-08-24 7:07 ` Benjamin Herrenschmidt
2012-08-24 7:07 ` Benjamin Herrenschmidt
2012-08-24 7:37 ` Ananth N Mavinakayanahalli
2012-08-24 7:37 ` Ananth N Mavinakayanahalli
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