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Convert #XF to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Handle INVD_BUG in C
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
- Remove the RCU warning as the new entry macro ensures correctness
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #AC to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
- Remove the RCU warning as the new entry macro ensures correctness
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #MF to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
- Remove the RCU warning as the new entry macro ensures correctness
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #SPURIOUS to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #GP to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
- Remove the RCU warning as the new entry macro ensures correctness
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #SS to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #NP to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #TS to IDTENTRY_ERRORCODE:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Same as IDTENTRY but the C entry point has an error code argument.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #OLD_MF to IDTENTRY:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #NM to IDTENTRY:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
- Remove the RCU warning as the new entry macro ensures correctness
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #UD to IDTENTRY:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Fixup the FOOF bug call in fault.c
- Remove the old prototyoes
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #BR to IDTENTRY:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
- Remove the RCU warning as the new entry macro ensures correctness
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #OF to IDTENTRY:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
- Remove the old prototyoes
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Convert #DE to IDTENTRY:
- Implement the C entry point with DEFINE_IDTENTRY
- Emit the ASM stub with DECLARE_IDTENTRY
- Remove the ASM idtentry in 64bit
- Remove the open coded ASM entry code in 32bit
- Fixup the XEN/PV code
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Prepare for using IDTENTRY to define the C exception/trap entry points. It
would be possible to glue this into the existing macro maze, but it's
simpler and better to read at the end to just make them distinct. Provide
a trivial inline helper to read the trap address.
The existing macros will be removed once all instances are converted.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Provide functions which handle the low level entry and exit similiar to
enter/exit from user mode.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Interrupts and exceptions invoke rcu_irq_enter() on entry and need to
invoke rcu_irq_exit() before they either return to the interrupted code or
invoke the scheduler due to preemption.
The general assumption is that RCU idle code has to have preemption
disabled so that a return from interrupt cannot schedule. So the return
from interrupt code invokes rcu_irq_exit() and preempt_schedule_irq().
If there is any imbalance in the rcu_irq/nmi* invocations or RCU idle code
had preemption enabled then this goes unnoticed until the CPU goes idle or
some other RCU check is executed.
Provide rcu_irq_exit_preempt() which can be invoked from the
interrupt/exception return code in case that preemption is enabled. It
invokes rcu_irq_exit() and contains a few sanity checks in case that
CONFIG_PROVE_RCU is enabled to catch such issues directly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
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Provide DECLARE/DEFINE_IDTENTRY() macros.
DEFINE_IDTENTRY() provides a wrapper which acts as the function
definition. The exception handler body is just appended to it with curly
brackets. The entry point is marked notrace/noprobe so that irq tracing and
the enter_from_user_mode() can be moved into the C-entry point. As all
C-entries use the same macro (or a later variant) the necessary entry
handling can be implemented at one central place.
DECLARE_IDTENTRY() provides the function prototypes:
- The C entry point cfunc
- The ASM entry point asm_cfunc
- The XEN/PV entry point xen_asm_cfunc
They all follow the same naming convention.
When included from ASM code DECLARE_IDTENTRY() is a macro which emits the
low level entry point in assembly by instantiating idtentry.
IDTENTRY is the simplest variant which just has a pt_regs argument. It's
going to be used for all exceptions which have no error code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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32 and 64 bit have unnecessary different ways to populate the exception
entry code. Provide a idtentry macro which allows to consolidate all of
that.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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For gradual conversion provide a macro parameter and the required code
which allows to handle instrumentation and interrupt flags tracking in C.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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idtentry is a completely unreadable maze. Split it into distinct idtentry
variants which only contain the minimal code:
- idtentry for regular exceptions
- idtentry_mce_debug for #MCE and #DB
- idtentry_df for #DF
The generated binary code is equivalent.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Move them all together so verifying the cleanup patches for binary
equivalence will be easier.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
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So they can be used in ASM code. For this it is also necessary to convert
them to defines. Will be used for the rework of the entry code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Traps enable interrupts conditionally but rely on the ASM return code to
disable them again. That results in redundant interrupt disable and trace
calls.
Make the trap handlers disable interrupts before returning to avoid that,
which allows simplification of the ASM entry code.
Originally-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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There is absolutely no point in doing this in ASM code. Move it to C.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Replace the notrace and NOKPROBE annotations with noinstr.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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This is called from deep entry ASM in a situation where instrumentation
will cause more harm than providing useful information.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Move the functions which are inside the RCU off region into the
non-instrumentable text section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
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Move the functions which are inside the RCU off region into the
non-instrumentable text section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
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Force inlining of the helpers and mark the instrumentable parts
accordingly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
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Add hardirq tracing to guest enter/exit functions in the same way as it is
done in the user mode enter/exit code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
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Add hardirq tracing to guest enter/exit functions in the same way as it
is done in the user mode enter/exit code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
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Context tracking for KVM happens way too early in the vcpu_run()
code. Anything after guest_enter_irqoff() and before guest_exit_irqoff()
cannot use RCU and should also be not instrumented.
The current way of doing this covers way too much code. Move it closer to
the actual vmenter/exit code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
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Currently entry_64_compat is exempt from objtool, but with vmlinux
mode there is no hiding it.
Make the following changes to make it pass:
- change entry_SYSENTER_compat to STT_NOTYPE; it's not a function
and doesn't have function type stack setup.
- mark all STT_NOTYPE symbols with UNWIND_HINT_EMPTY; so we do
validate them and don't treat them as unreachable.
- don't abuse RSP as a temp register, this confuses objtool
mightily as it (rightfully) thinks we're doing unspeakable
things to the stack.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Code calling this from noinstr sections, e.g. entry code, has interrupts
disabled, so the actual call into the scheduler code does not happen.
The objtool section check complains nevertheless, so mark the call "safe".
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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The preempt_enable_notrace() ASM thunk is called from tracing, entry code
RCU and other places which are already in or going to be in the noinstr
section which protects sensitve code from being instrumented.
Calls out of these sections happen with interrupts disabled, which is
handled in C code, but the push regs, call, pop regs sequence can be
completely avoided in this case.
This is also a preparatory step for annotating the call from the thunk to
preempt_enable_notrace() safe from a noinstr section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Prevent the compiler from uninlining and creating traceable/probable
functions as this is invoked _after_ context tracking switched to
CONTEXT_USER and rcu idle.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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That code is already not traceable. Move it into the noinstr section so the
objtool section validation does not trigger.
Annotate the warning code as "safe". While it might be not under all
circumstances, getting the information out is important enough.
Should this ever trigger from the sensitive code which is shielded against
instrumentation, e.g. low level entry, then the printk is the least of the
worries.
Addresses the objtool warnings:
vmlinux.o: warning: objtool: context_tracking_recursion_enter()+0x7: call to __this_cpu_preempt_check() leaves .noinstr.text section
vmlinux.o: warning: objtool: __context_tracking_exit()+0x17: call to __this_cpu_preempt_check() leaves .noinstr.text section
vmlinux.o: warning: objtool: __context_tracking_enter()+0x2a: call to __this_cpu_preempt_check() leaves .noinstr.text section
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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context tracking lacks a few protection mechanisms against instrumentation:
- While the core functions are marked NOKPROBE they lack protection
against function tracing which is required as the function entry/exit
points can be utilized by BPF.
- static functions invoked from the protected functions need to be marked
as well as they can be instrumented otherwise.
- using plain inline allows the compiler to emit traceable and probable
functions.
Fix this by marking the functions noinstr and converting the plain inlines
to __always_inline.
The NOKPROBE_SYMBOL() annotations are removed as the .noinstr.text section
is already excluded from being probed.
Cures the following objtool warnings:
vmlinux.o: warning: objtool: enter_from_user_mode()+0x34: call to __context_tracking_exit() leaves .noinstr.text section
vmlinux.o: warning: objtool: prepare_exit_to_usermode()+0x29: call to __context_tracking_enter() leaves .noinstr.text section
vmlinux.o: warning: objtool: syscall_return_slowpath()+0x29: call to __context_tracking_enter() leaves .noinstr.text section
vmlinux.o: warning: objtool: do_syscall_64()+0x7f: call to __context_tracking_enter() leaves .noinstr.text section
vmlinux.o: warning: objtool: do_int80_syscall_32()+0x3d: call to __context_tracking_enter() leaves .noinstr.text section
vmlinux.o: warning: objtool: do_fast_syscall_32()+0x9c: call to __context_tracking_enter() leaves .noinstr.text section
and generates new ones...
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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This is another step towards more C-code and less convoluted ASM.
Similar to the entry path, invoke the tracer before context tracking which
might turn off RCU and invoke lockdep as the last step before going back to
user space. Annotate the code sections in exit_to_user_mode() accordingly
so objtool won't complain about the tracer invocation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Now that the C entry points are safe, move the irq flags tracing code into
the entry helper:
- Invoke lockdep before calling into context tracking
- Use the safe trace_hardirqs_on_prepare() trace function after context
tracking established state and RCU is watching.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Mark the various syscall entries with noinstr to protect them against
instrumentation and add the noinstr_begin()/end() annotations to mark the
parts of the functions which are safe to call out into instrumentable code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Both the callers in the low level ASM code and __context_tracking_exit()
which is invoked from enter_from_user_mode() via user_exit_irqoff() are
marked NOKPROBE. Allowing enter_from_user_mode() to be probed is
inconsistent at best.
Aside of that while function tracing per se is safe the function trace
entry/exit points can be used via BPF as well which is not safe to use
before context tracking has reached CONTEXT_KERNEL and adjusted RCU.
Mark it noinstr which moves it into the instrumentation protected text
section and includes notrace.
Note, this needs further fixups in context tracking to ensure that the
full call chain is protected. Will be addressed in follow up changes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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All ASM code which is not part of the entry functionality can move out into
the .text section. No reason to keep it in the non-instrumentable entry
section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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All ASM code which is not part of the entry functionality can move out into
the .text section. No reason to keep it in the non-instrumentable entry
section.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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The rcu_nmi_enter_common() and rcu_nmi_exit_common() functions take an
"irq" parameter that indicates whether these functions are invoked from
an irq handler (irq==true) or an NMI handler (irq==false). However,
recent changes have applied notrace to a few critical functions such
that rcu_nmi_enter_common() and rcu_nmi_exit_common() many now rely
on in_nmi(). Note that in_nmi() works no differently than before,
but rather that tracing is now prohibited in code regions where in_nmi()
would incorrectly report NMI state.
Therefore remove the "irq" parameter and inlines rcu_nmi_enter_common() and
rcu_nmi_exit_common() into rcu_nmi_enter() and rcu_nmi_exit(),
respectively.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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A few exceptions (like #DB and #BP) can happen at any location in the code,
this then means that tracers should treat events from these exceptions as
NMI-like. The interrupted context could be holding locks with interrupts
disabled for instance.
Similarly, #MC is an actual NMI-like exception.
All of them use ist_enter() which only concerns itself with RCU, but does
not do any of the other setup that NMIs need. This means things like:
printk()
raw_spin_lock_irq(&logbuf_lock);
<#DB/#BP/#MC>
printk()
raw_spin_lock_irq(&logbuf_lock);
are entirely possible (well, not really since printk tries hard to
play nice, but the concept stands).
So replace ist_enter() with nmi_enter(). Also observe that any nmi_enter()
caller must be both notrace and NOKPROBE, or in the noinstr text section.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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If a tracer is invoked before in_nmi() becomes true, the tracer can no
longer detect it is called from NMI context and behave correctly.
Therefore change nmi_{enter,exit}() to use __preempt_count_{add,sub}()
as the normal preempt_count_{add,sub}() have a (desired) function
trace entry.
This fixes a potential issue with the current code; when the function-tracer
has stack-tracing enabled __trace_stack() will malfunction when it hits the
preempt_count_add() function entry from NMI context.
Suggested-by: Steven Rostedt (VMware) <rosted@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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ftrace_nmi_enter()
trace_hwlat_callback()
trace_clock_local()
sched_clock()
paravirt_sched_clock()
native_sched_clock()
All must not be traced or kprobed, it will be called from do_debug()
before the kprobe handler.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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