unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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vdso: Add comment about reason for vdso struct ordering

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struct vdso_data is optimized for fast access to the often required struct
members. The optimization is not documented in the struct description but
it should be kept in mind, when working with the vdso_data struct.
                                                                                                                                                                                                                                             
Add a comment to the struct description.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20240701-vdso-cleanup-v1-2-36eb64e7ece2@linutronix.de
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Anna-Maria Behnsen 2024-07-01 16:47:55 +02:00 committed by Thomas Gleixner
parent f48955e038
commit d00106bbdf
1 changed files with 4 additions and 0 deletions
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4
include/vdso/datapage.h
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@ -77,6 +77,10 @@ struct vdso_timestamp {
* vdso_data will be accessed by 64 bit and compat code at the same time
* so we should be careful before modifying this structure.
*
* The ordering of the struct members is optimized to have fast access to the
* often required struct members which are related to CLOCK_REALTIME and
* CLOCK_MONOTONIC. This information is stored in the first cache lines.
*
* @basetime is used to store the base time for the system wide time getter
* VVAR page.
*