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From: Nick Alcock <nick.alcock@oracle.com>
To: Kris Van Hees <kris.van.hees@oracle.com>
Cc: dtrace@lists.linux.dev, dtrace-devel@oss.oracle.com
Subject: Re: [PATCH v5 3/6] cg: add argument mapping in the trampoline
Date: Tue, 05 Nov 2024 19:58:39 +0000	[thread overview]
Message-ID: <877c9hfo5s.fsf@esperi.org.uk> (raw)
In-Reply-To: <ZypV+dU4YHlxmICk@oracle.com> (Kris Van Hees's message of "Tue, 5 Nov 2024 12:29:29 -0500")

On 5 Nov 2024, Kris Van Hees told this:

> On Tue, Nov 05, 2024 at 12:06:05AM +0000, Nick Alcock wrote:
>> +/*
>> + * Move arguments according to the mappings in the array of arguments given.
>> + * The original arguments are obtained from the saved regs, and overwritten, so
>> + * the regs must be saved in advance of this call.  In effect, this changes the
>> + * native arguments: the caller should adjust the mappings array accordingly,
>> + * and shuffle the native arg types to match.
>
> This is confusing...  How about;
>
> "Populate the probe arguments based on the provided dt_argdesc_t array.
>  The caller must save the arguments because argument mapping copies values from
>  the saved arguments to the  current arguments.  After this function returns,
>  the caller should adjust the mapping to reflect that shuffling has been done."
>
> There is no need to talk about shuffling types because the dt_argdesc_t array
> already lists the correct types anyway.

Ah yeah, historical wart -- when that comment was written, it didn't.

Adjusted as you suggest.

-- 
NULL && (void)

  reply	other threads:[~2024-11-05 19:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-05  0:06 [PATCH v5 0/6] usdt typed args, translators and arg mapping Nick Alcock
2024-11-05  0:06 ` [PATCH v5 1/6] usdt: get arg types and xlations into DTrace from the DOF Nick Alcock
2024-11-05 16:56   ` Kris Van Hees
2024-11-05 18:01     ` [DTrace-devel] " Kris Van Hees
2024-11-05 19:53       ` Nick Alcock
2024-11-05  0:06 ` [PATCH v5 2/6] dtprobed: stop skipping zero-tracepoint probes in dof_stash.c Nick Alcock
2024-11-05  0:06 ` [PATCH v5 3/6] cg: add argument mapping in the trampoline Nick Alcock
2024-11-05 17:29   ` Kris Van Hees
2024-11-05 19:58     ` Nick Alcock [this message]
2024-11-05  0:06 ` [PATCH v5 4/6] usdt: typed args and arg mapping Nick Alcock
2024-11-05 18:53   ` Kris Van Hees
2024-11-06 11:16     ` Nick Alcock
2024-11-06 22:18       ` Kris Van Hees
2024-11-05  0:06 ` [PATCH v5 5/6] usdt: new tests for USDT arg sanity with overlapping pid probes Nick Alcock
2024-11-05  0:06 ` [PATCH v5 6/6] usdt: fix create_underlying error path Nick Alcock

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