Messages in this thread | | | From | Jeremy Fitzhardinge <> | Subject | [PATCH RFC V3 0/8] jump-label: allow early jump_label_enable() | Date | Tue, 4 Oct 2011 12:18:01 -0700 |
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From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
[ Change from V2: add arch_jump_label_transform_static() for use on code which can't possibly be currently executing (ie, a freshly loaded module), which can avoid heavyweight things like stop_machine. The default implementation is simply arch_jump_label_transform(), so only architectures which would particularly benefit need implement it (x86 and s390 in this series). ]
While trying to use the jump-label stuff for my PV ticketlock changes, I had some problems using jump labels early in the kernel's lifetime (pre-SMP).
The basic problem is that even if I enable a jump_label_key, the jump_label_init() initializer ends up nopping out all the code sites.
This series enables early use of jump labels by making jump_label_init() respect already-enabled keys.
To do this, I've dropped arch_jump_label_poke_text_early() and replaced it with arch_jump_label_transform(), allowing it to either insert an optimal nop, or leave the jump in place.
Part of this series makes sure that stop_machine() is safe to call in an early pre-SMP environment, by making it just call the function with interrupts disabled.
git://github.com/jsgf/linux-xen upstream/jump-label-noearly
Jeremy Fitzhardinge (8): jump_label: use proper atomic_t initializer stop_machine: make stop_machine safe and efficient to call early jump_label: if a key has already been initialized, don't nop it out x86/jump_label: drop arch_jump_label_text_poke_early() sparc/jump_label: drop arch_jump_label_text_poke_early() jump_label: add arch_jump_label_transform_static() to optimise non-live code updates s390/jump-label: add arch_jump_label_transform_static() x86/jump_label: add arch_jump_label_transform_static()
arch/s390/kernel/jump_label.c | 51 ++++++++++++++++++++++++--------------- arch/sparc/kernel/jump_label.c | 8 ------ arch/x86/kernel/jump_label.c | 20 +++++++++++---- include/linux/jump_label.h | 9 ++++--- kernel/jump_label.c | 32 +++++++++++++++--------- kernel/stop_machine.c | 22 +++++++++++++++++ 6 files changed, 92 insertions(+), 50 deletions(-)
-- 1.7.6.4
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