linux-toradex.git/include/linux/static_call.h, branch v6.4-rc1

static_call: Add call depth tracking support

2022-10-17T14:41:16+00:00

When indirect calls are switched to direct calls then it has to be ensured
that the call target is not the function, but the call thunk when call
depth tracking is enabled. But static calls are available before call
thunks have been set up.

Ensure a second run through the static call patching code after call thunks
have been created. When call thunks are not enabled this has no side
effects.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20220915111148.306100465@infradead.org

static_call: Remove __DEFINE_STATIC_CALL macro

2022-04-05T07:59:38+00:00

Only DEFINE_STATIC_CALL use __DEFINE_STATIC_CALL macro now when
CONFIG_HAVE_STATIC_CALL is selected.

Only keep __DEFINE_STATIC_CALL() for the generic fallback, and
also use it to implement DEFINE_STATIC_CALL_NULL() in that case.

Signed-off-by: Christophe Leroy 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/329074f92d96e3220ebe15da7bbe2779beee31eb.1647253456.git.christophe.leroy@csgroup.eu

static_call: Properly initialise DEFINE_STATIC_CALL_RET0()

2022-04-05T07:59:38+00:00

When a static call is updated with __static_call_return0() as target,
arch_static_call_transform() set it to use an optimised set of
instructions which are meant to lay in the same cacheline.

But when initialising a static call with DEFINE_STATIC_CALL_RET0(),
we get a branch to the real __static_call_return0() function instead
of getting the optimised setup:

	c00d8120 <__SCT__perf_snapshot_branch_stack>:
	c00d8120:	4b ff ff f4 	b       c00d8114 <__static_call_return0>
	c00d8124:	3d 80 c0 0e 	lis     r12,-16370
	c00d8128:	81 8c 81 3c 	lwz     r12,-32452(r12)
	c00d812c:	7d 89 03 a6 	mtctr   r12
	c00d8130:	4e 80 04 20 	bctr
	c00d8134:	38 60 00 00 	li      r3,0
	c00d8138:	4e 80 00 20 	blr
	c00d813c:	00 00 00 00 	.long 0x0

Add ARCH_DEFINE_STATIC_CALL_RET0_TRAMP() defined by each architecture
to setup the optimised configuration, and rework
DEFINE_STATIC_CALL_RET0() to call it:

	c00d8120 <__SCT__perf_snapshot_branch_stack>:
	c00d8120:	48 00 00 14 	b       c00d8134 <__SCT__perf_snapshot_branch_stack+0x14>
	c00d8124:	3d 80 c0 0e 	lis     r12,-16370
	c00d8128:	81 8c 81 3c 	lwz     r12,-32452(r12)
	c00d812c:	7d 89 03 a6 	mtctr   r12
	c00d8130:	4e 80 04 20 	bctr
	c00d8134:	38 60 00 00 	li      r3,0
	c00d8138:	4e 80 00 20 	blr
	c00d813c:	00 00 00 00 	.long 0x0

Signed-off-by: Christophe Leroy 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/1e0a61a88f52a460f62a58ffc2a5f847d1f7d9d8.1647253456.git.christophe.leroy@csgroup.eu

static_call: Don't make __static_call_return0 static

2022-04-05T07:59:38+00:00

System.map shows that vmlinux contains several instances of
__static_call_return0():

	c0004fc0 t __static_call_return0
	c0011518 t __static_call_return0
	c00d8160 t __static_call_return0

arch_static_call_transform() uses the middle one to check whether we are
setting a call to __static_call_return0 or not:

	c0011520 :
	c0011520:       3d 20 c0 01     lis     r9,-16383	<== r9 =  0xc001 << 16
	c0011524:       39 29 15 18     addi    r9,r9,5400	<== r9 += 0x1518
	c0011528:       7c 05 48 00     cmpw    r5,r9		<== r9 has value 0xc0011518 here

So if static_call_update() is called with one of the other instances of
__static_call_return0(), arch_static_call_transform() won't recognise it.

In order to work properly, global single instance of __static_call_return0() is required.

Fixes: 3f2a8fc4b15d ("static_call/x86: Add __static_call_return0()")
Signed-off-by: Christophe Leroy 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lkml.kernel.org/r/30821468a0e7d28251954b578e5051dc09300d04.1647258493.git.christophe.leroy@csgroup.eu

static_call: Update API documentation

2021-08-17T17:09:27+00:00

Update the comment with the new features.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Reviewed-by: Steven Rostedt (VMware) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/YQwIorQBHEq+s73b@hirez.programming.kicks-ass.net

Merge tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-04-28T19:37:53+00:00

Pull locking updates from Ingo Molnar:

 - rtmutex cleanup & spring cleaning pass that removes ~400 lines of
   code

 - Futex simplifications & cleanups

 - Add debugging to the CSD code, to help track down a tenacious race
   (or hw problem)

 - Add lockdep_assert_not_held(), to allow code to require a lock to not
   be held, and propagate this into the ath10k driver

 - Misc LKMM documentation updates

 - Misc KCSAN updates: cleanups & documentation updates

 - Misc fixes and cleanups

 - Fix locktorture bugs with ww_mutexes

* tag 'locking-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
  kcsan: Fix printk format string
  static_call: Relax static_call_update() function argument type
  static_call: Fix unused variable warn w/o MODULE
  locking/rtmutex: Clean up signal handling in __rt_mutex_slowlock()
  locking/rtmutex: Restrict the trylock WARN_ON() to debug
  locking/rtmutex: Fix misleading comment in rt_mutex_postunlock()
  locking/rtmutex: Consolidate the fast/slowpath invocation
  locking/rtmutex: Make text section and inlining consistent
  locking/rtmutex: Move debug functions as inlines into common header
  locking/rtmutex: Decrapify __rt_mutex_init()
  locking/rtmutex: Remove pointless CONFIG_RT_MUTEXES=n stubs
  locking/rtmutex: Inline chainwalk depth check
  locking/rtmutex: Move rt_mutex_debug_task_free() to rtmutex.c
  locking/rtmutex: Remove empty and unused debug stubs
  locking/rtmutex: Consolidate rt_mutex_init()
  locking/rtmutex: Remove output from deadlock detector
  locking/rtmutex: Remove rtmutex deadlock tester leftovers
  locking/rtmutex: Remove rt_mutex_timed_lock()
  MAINTAINERS: Add myself as futex reviewer
  locking/mutex: Remove repeated declaration
  ...

static_call: Relax static_call_update() function argument type

2021-04-09T11:22:12+00:00

static_call_update() had stronger type requirements than regular C,
relax them to match. Instead of requiring the @func argument has the
exact matching type, allow any type which C is willing to promote to the
right (function) pointer type. Specifically this allows (void *)
arguments.

This cleans up a bunch of static_call_update() callers for
PREEMPT_DYNAMIC and should get around silly GCC11 warnings for free.

Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/YFoN7nCl8OfGtpeh@hirez.programming.kicks-ass.net

static_call: Add function to query current function

2021-03-11T15:12:33+00:00

Some users of paravirtualized functions need to query which function
has been specified in a pv_ops vector element. In order to be able to
switch such paravirtualized functions to static_calls instead, there
needs to be a function to query the function which will be called via
static_call().

Signed-off-by: Juergen Gross 
Signed-off-by: Borislav Petkov 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20210311142319.4723-4-jgross@suse.com

static_call: Move struct static_call_key definition to static_call_types.h

2021-03-11T15:04:39+00:00

Having the definition of static_call() in static_call_types.h makes
no sense as long struct static_call_key isn't defined there, as the
generic implementation of static_call() is referencing this structure.

So move the definition of struct static_call_key to static_call_types.h.

Signed-off-by: Juergen Gross 
Signed-off-by: Borislav Petkov 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20210311142319.4723-3-jgross@suse.com

static_call: Allow module use without exposing static_call_key

2021-02-17T13:12:42+00:00

When exporting static_call_key; with EXPORT_STATIC_CALL*(), the module
can use static_call_update() to change the function called.  This is
not desirable in general.

Not exporting static_call_key however also disallows usage of
static_call(), since objtool needs the key to construct the
static_call_site.

Solve this by allowing objtool to create the static_call_site using
the trampoline address when it builds a module and cannot find the
static_call_key symbol. The module loader will then try and map the
trampole back to a key before it constructs the normal sites list.

Doing this requires a trampoline -> key associsation, so add another
magic section that keeps those.

Originally-by: Peter Zijlstra (Intel) 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Link: https://lkml.kernel.org/r/20210127231837.ifddpn7rhwdaepiu@treble