€•!,      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ1/translations/zh_CN/core-api/irq/irqflags-tracing”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/zh_TW/core-api/irq/irqflags-tracing”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/it_IT/core-api/irq/irqflags-tracing”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/ja_JP/core-api/irq/irqflags-tracing”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/ko_KR/core-api/irq/irqflags-tracing”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/sp_SP/core-api/irq/irqflags-tracing”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒIRQ-flags state tracing”h]”hŒIRQ-flags state tracing”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒK/var/lib/git/docbuild/linux/Documentation/core-api/irq/irqflags-tracing.rst”h KubhŒ
field_list”“”)”}”(hhh]”hŒfield”“”)”}”(hhh]”(hŒ
field_name”“”)”}”(hŒAuthor”h]”hŒAuthor”…””}”(hhÃhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÁhh¾hŸh¶h K ubhŒ
field_body”“”)”}”(hŒ*started by Ingo Molnar <mingo@redhat.com>
”h]”hŒ	paragraph”“”)”}”(hŒ)started by Ingo Molnar <mingo@redhat.com>”h]”(hŒstarted by Ingo Molnar <”…””}”(hhÙhžhhŸNh NubhŒ	reference”“”)”}”(hŒmingo@redhat.com”h]”hŒmingo@redhat.com”…””}”(hhãhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œmailto:mingo@redhat.com”uh1háhhÙubhŒ>”…””}”(hhÙhžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KhhÓubah}”(h]”h ]”h"]”h$]”h&]”uh1hÑhh¾ubeh}”(h]”h ]”h"]”h$]”h&]”uh1h¼hŸh¶h Khh¹hžhubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hh£hžhhŸh¶h KubhØ)”}”(hŒæThe "irq-flags tracing" feature "traces" hardirq and softirq state, in
that it gives interested subsystems an opportunity to be notified of
every hardirqs-off/hardirqs-on, softirqs-off/softirqs-on event that
happens in the kernel.”h]”hŒîThe â€œirq-flags tracingâ€ feature â€œtracesâ€ hardirq and softirq state, in
that it gives interested subsystems an opportunity to be notified of
every hardirqs-off/hardirqs-on, softirqs-off/softirqs-on event that
happens in the kernel.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hXj  CONFIG_TRACE_IRQFLAGS_SUPPORT is needed for CONFIG_PROVE_SPIN_LOCKING
and CONFIG_PROVE_RW_LOCKING to be offered by the generic lock debugging
code. Otherwise only CONFIG_PROVE_MUTEX_LOCKING and
CONFIG_PROVE_RWSEM_LOCKING will be offered on an architecture - these
are locking APIs that are not used in IRQ context. (the one exception
for rwsems is worked around)”h]”hXj  CONFIG_TRACE_IRQFLAGS_SUPPORT is needed for CONFIG_PROVE_SPIN_LOCKING
and CONFIG_PROVE_RW_LOCKING to be offered by the generic lock debugging
code. Otherwise only CONFIG_PROVE_MUTEX_LOCKING and
CONFIG_PROVE_RWSEM_LOCKING will be offered on an architecture - these
are locking APIs that are not used in IRQ context. (the one exception
for rwsems is worked around)”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hŒúArchitecture support for this is certainly not in the "trivial"
category, because lots of lowlevel assembly code deal with irq-flags
state changes. But an architecture can be irq-flags-tracing enabled in a
rather straightforward and risk-free manner.”h]”hŒþArchitecture support for this is certainly not in the â€œtrivialâ€
category, because lots of lowlevel assembly code deal with irq-flags
state changes. But an architecture can be irq-flags-tracing enabled in a
rather straightforward and risk-free manner.”…””}”(hj+  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhØ)”}”(hŒaArchitectures that want to support this need to do a couple of
code-organizational changes first:”h]”hŒaArchitectures that want to support this need to do a couple of
code-organizational changes first:”…””}”(hj9  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubhŒbullet_list”“”)”}”(hhh]”hŒ	list_item”“”)”}”(hŒGadd and enable TRACE_IRQFLAGS_SUPPORT in their arch level Kconfig file
”h]”hØ)”}”(hŒFadd and enable TRACE_IRQFLAGS_SUPPORT in their arch level Kconfig file”h]”hŒFadd and enable TRACE_IRQFLAGS_SUPPORT in their arch level Kconfig file”…””}”(hjR  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h KhjN  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jL  hjI  hžhhŸh¶h Nubah}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1jG  hŸh¶h Khh£hžhubhØ)”}”(hŒband then a couple of functional changes are needed as well to implement
irq-flags-tracing support:”h]”hŒband then a couple of functional changes are needed as well to implement
irq-flags-tracing support:”…””}”(hjn  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h Khh£hžhubjH  )”}”(hhh]”(jM  )”}”(hX\  in lowlevel entry code add (build-conditional) calls to the
trace_hardirqs_off()/trace_hardirqs_on() functions. The lock validator
closely guards whether the 'real' irq-flags matches the 'virtual'
irq-flags state, and complains loudly (and turns itself off) if the
two do not match. Usually most of the time for arch support for
irq-flags-tracing is spent in this state: look at the lockdep
complaint, try to figure out the assembly code we did not cover yet,
fix and repeat. Once the system has booted up and works without a
lockdep complaint in the irq-flags-tracing functions arch support is
complete.”h]”hØ)”}”(hX\  in lowlevel entry code add (build-conditional) calls to the
trace_hardirqs_off()/trace_hardirqs_on() functions. The lock validator
closely guards whether the 'real' irq-flags matches the 'virtual'
irq-flags state, and complains loudly (and turns itself off) if the
two do not match. Usually most of the time for arch support for
irq-flags-tracing is spent in this state: look at the lockdep
complaint, try to figure out the assembly code we did not cover yet,
fix and repeat. Once the system has booted up and works without a
lockdep complaint in the irq-flags-tracing functions arch support is
complete.”h]”hXd  in lowlevel entry code add (build-conditional) calls to the
trace_hardirqs_off()/trace_hardirqs_on() functions. The lock validator
closely guards whether the â€˜realâ€™ irq-flags matches the â€˜virtualâ€™
irq-flags state, and complains loudly (and turns itself off) if the
two do not match. Usually most of the time for arch support for
irq-flags-tracing is spent in this state: look at the lockdep
complaint, try to figure out the assembly code we did not cover yet,
fix and repeat. Once the system has booted up and works without a
lockdep complaint in the irq-flags-tracing functions arch support is
complete.”…””}”(hjƒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K hj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jL  hj|  hžhhŸh¶h NubjM  )”}”(hŒ¤if the architecture has non-maskable interrupts then those need to be
excluded from the irq-tracing [and lock validation] mechanism via
lockdep_off()/lockdep_on().
”h]”hØ)”}”(hŒ£if the architecture has non-maskable interrupts then those need to be
excluded from the irq-tracing [and lock validation] mechanism via
lockdep_off()/lockdep_on().”h]”hŒ£if the architecture has non-maskable interrupts then those need to be
excluded from the irq-tracing [and lock validation] mechanism via
lockdep_off()/lockdep_on().”…””}”(hj›  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h×hŸh¶h K*hj—  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jL  hj|  hžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”jl  jm  uh1jG  hŸh¶h K hh£hžhubhØ)”}”(hXj  In general there is no risk from having an incomplete irq-flags-tracing
implementation in an architecture: lockdep will detect that and will
turn itself off. I.e. the lock validator will still be reliable. There
should be no crashes due to irq-tracing bugs. (except if the assembly
changes break other code by modifying conditions or registers that
shouldn't be)”h]”hXl  In general there is no risk from having an incomplete irq-flags-tracing
implementation in an architecture: lockdep will detect that and will
turn itself off. I.e. the lock validator will still be reliable. There
should be no crashes due to irq-tracing bugs. (except if the assembly
changes break other code by modifying conditions or registers that
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source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
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id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.