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2019-01-06jump_label: move 'asm goto' support test to KconfigMasahiro Yamada1-7/+3
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label". The jump label is controlled by HAVE_JUMP_LABEL, which is defined like this: #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL) # define HAVE_JUMP_LABEL #endif We can improve this by testing 'asm goto' support in Kconfig, then make JUMP_LABEL depend on CC_HAS_ASM_GOTO. Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will match to the real kernel capability. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
2018-10-16Merge branch 'x86/build' into locking/core, to pick up dependent patches and ↵Ingo Molnar1-55/+45
unify jump-label work Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-02jump_label: Fix NULL dereference bug in __jump_label_mod_update()Ard Biesheuvel1-1/+1
Commit 19483677684b ("jump_label: Annotate entries that operate on __init code earlier") refactored the code that manages runtime patching of jump labels in modules that are tied to static keys defined in other modules or in the core kernel. In the latter case, we may iterate over the static_key_mod linked list until we hit the entry for the core kernel, whose 'mod' field will be NULL, and attempt to dereference it to get at its 'state' member. So let's add a non-NULL check: this forces the 'init' argument of __jump_label_update() to false for static keys that are defined in the core kernel, which is appropriate given that __init annotated jump_label entries in the core kernel should no longer be active at this point (i.e., when loading modules). Fixes: 19483677684b ("jump_label: Annotate entries that operate on ...") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Jessica Yu <jeyu@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20181001081324.11553-1-ard.biesheuvel@linaro.org
2018-09-27jump_label: Annotate entries that operate on __init code earlierArd Biesheuvel1-34/+14
Jump table entries are mostly read-only, with the exception of the init and module loader code that defuses entries that point into init code when the code being referred to is freed. For robustness, it would be better to move these entries into the ro_after_init section, but clearing the 'code' member of each jump table entry referring to init code at module load time races with the module_enable_ro() call that remaps the ro_after_init section read only, so we'd like to do it earlier. So given that whether such an entry refers to init code can be decided much earlier, we can pull this check forward. Since we may still need the code entry at this point, let's switch to setting a low bit in the 'key' member just like we do to annotate the default state of a jump table entry. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-s390@vger.kernel.org Cc: Arnd Bergmann <arnd@arndb.de> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jessica Yu <jeyu@kernel.org> Link: https://lkml.kernel.org/r/20180919065144.25010-8-ard.biesheuvel@linaro.org
2018-09-27jump_label: Implement generic support for relative referencesArd Biesheuvel1-1/+21
To reduce the size taken up by absolute references in jump label entries themselves and the associated relocation records in the .init segment, add support for emitting them as relative references instead. Note that this requires some extra care in the sorting routine, given that the offsets change when entries are moved around in the jump_entry table. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-s390@vger.kernel.org Cc: Arnd Bergmann <arnd@arndb.de> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Kees Cook <keescook@chromium.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jessica Yu <jeyu@kernel.org> Link: https://lkml.kernel.org/r/20180919065144.25010-3-ard.biesheuvel@linaro.org
2018-09-27jump_label: Abstract jump_entry member accessorsArd Biesheuvel1-25/+15
In preparation of allowing architectures to use relative references in jump_label entries [which can dramatically reduce the memory footprint], introduce abstractions for references to the 'code' and 'key' members of struct jump_entry. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-s390@vger.kernel.org Cc: Arnd Bergmann <arnd@arndb.de> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Kees Cook <keescook@chromium.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jessica Yu <jeyu@kernel.org> Link: https://lkml.kernel.org/r/20180919065144.25010-2-ard.biesheuvel@linaro.org
2018-09-10jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operationsPeter Zijlstra1-0/+5
Weirdly we seem to have forgotten this... Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-10Merge branch 'locking/urgent' into locking/core, to pick up fixesIngo Molnar1-1/+1
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-10jump_label: Fix typo in warning messageBorislav Petkov1-1/+1
There's no 'allocatote' - use the next best thing: 'allocate' :-) Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180907103521.31344-1-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-10jump_label: Use static_key_linked() accessorBorislav Petkov1-1/+1
... instead of open-coding it, in static_key_mod(). No functional changes. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180909114252.17575-1-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-20jump_label: Disable jump labels in __exit codeJosh Poimboeuf1-3/+4
With the following commit: 333522447063 ("jump_label: Explicitly disable jump labels in __init code") ... we explicitly disabled jump labels in __init code, so they could be detected and not warned about in the following commit: dc1dd184c2f0 ("jump_label: Warn on failed jump_label patching attempt") In-kernel __exit code has the same issue. It's never used, so it's freed along with the rest of initmem. But jump label entries in __exit code aren't explicitly disabled, so we get the following warning when enabling pr_debug() in __exit code: can't patch jump_label at dmi_sysfs_exit+0x0/0x2d WARNING: CPU: 0 PID: 22572 at kernel/jump_label.c:376 __jump_label_update+0x9d/0xb0 Fix the warning by disabling all jump labels in initmem (which includes both __init and __exit code). Reported-and-tested-by: Li Wang <liwang@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@suse.de> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: dc1dd184c2f0 ("jump_label: Warn on failed jump_label patching attempt") Link: http://lkml.kernel.org/r/7121e6e595374f06616c505b6e690e275c0054d1.1521483452.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-14jump_label: Fix sparc64 warningJosh Poimboeuf1-1/+2
The kbuild test robot reported the following warning on sparc64: kernel/jump_label.c: In function '__jump_label_update': kernel/jump_label.c:376:51: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] WARN_ONCE(1, "can't patch jump_label at %pS", (void *)entry->code); On sparc64, the jump_label entry->code field is of type u32, but pointers are 64-bit. Silence the warning by casting entry->code to an unsigned long before casting it to a pointer. This is also what the sparc jump label code does. Fixes: dc1dd184c2f0 ("jump_label: Warn on failed jump_label patching attempt") Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Borislav Petkov <bp@suse.de> Cc: "David S . Miller" <davem@davemloft.net> Link: https://lkml.kernel.org/r/c966fed42be6611254a62d46579ec7416548d572.1521041026.git.jpoimboe@redhat.com
2018-02-21extable: Make init_kernel_text() globalJosh Poimboeuf1-3/+1
Convert init_kernel_text() to a global function and use it in a few places instead of manually comparing _sinittext and _einittext. Note that kallsyms.h has a very similar function called is_kernel_inittext(), but its end check is inclusive. I'm not sure whether that's intentional behavior, so I didn't touch it. Suggested-by: Jason Baron <jbaron@akamai.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/4335d02be8d45ca7d265d2f174251d0b7ee6c5fd.1519051220.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-21jump_label: Warn on failed jump_label patching attemptJosh Poimboeuf1-5/+8
Currently when the jump label code encounters an address which isn't recognized by kernel_text_address(), it just silently fails. This can be dangerous because jump labels are used in a variety of places, and are generally expected to work. Convert the silent failure to a warning. This won't warn about attempted writes to tracepoints in __init code after initmem has been freed, as those are already guarded by the entry->code check. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@suse.de> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/de3a271c93807adb7ed48f4e946b4f9156617680.1519051220.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-21jump_label: Explicitly disable jump labels in __init codeJosh Poimboeuf1-0/+16
After initmem has been freed, any jump labels in __init code are prevented from being written to by the kernel_text_address() check in __jump_label_update(). However, this check is quite broad. If kernel_text_address() were to return false for any other reason, the jump label write would fail silently with no warning. For jump labels in module init code, entry->code is set to zero to indicate that the entry is disabled. Do the same thing for core kernel init code. This makes the behavior more consistent, and will also make it more straightforward to detect non-init jump label write failures in the next patch. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@suse.de> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/c52825c73f3a174e8398b6898284ec20d4deb126.1519051220.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-24sched/core: Fix cpu.max vs. cpuhotplug deadlockPeter Zijlstra1-3/+9
Tejun reported the following cpu-hotplug lock (percpu-rwsem) read recursion: tg_set_cfs_bandwidth() get_online_cpus() cpus_read_lock() cfs_bandwidth_usage_inc() static_key_slow_inc() cpus_read_lock() Reported-by: Tejun Heo <tj@kernel.org> Tested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180122215328.GP3397@worktop Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-14jump_label: Invoke jump_label_test() via early_initcall()Jason Baron1-1/+1
Fengguang Wu reported that running the rcuperf test during boot can cause the jump_label_test() to hit a WARN_ON(). The issue is that the core jump label code relies on kernel_text_address() to detect when it can no longer update branches that may be contained in __init sections. The kernel_text_address() in turn assumes that if the system_state variable is greter than or equal to SYSTEM_RUNNING then __init sections are no longer valid (since the assumption is that they have been freed). However, when rcuperf is setup to run in early boot it can call kernel_power_off() which sets the system_state to SYSTEM_POWER_OFF. Since rcuperf initialization is invoked via a module_init(), we can make the dependency of jump_label_test() needing to complete before rcuperf explicit by calling it via early_initcall(). Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Jason Baron <jbaron@akamai.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1510609727-2238-1-git-send-email-jbaron@akamai.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-19locking/static_keys: Improve uninitialized key warningBorislav Petkov1-7/+7
Right now it says: static_key_disable_cpuslocked used before call to jump_label_init ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:161 static_key_disable_cpuslocked+0x68/0x70 Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.14.0-rc5+ #1 Hardware name: SGI.COM C2112-4GP3/X10DRT-P-Series, BIOS 2.0a 05/09/2016 task: ffffffff81c0e480 task.stack: ffffffff81c00000 RIP: 0010:static_key_disable_cpuslocked+0x68/0x70 RSP: 0000:ffffffff81c03ef0 EFLAGS: 00010096 ORIG_RAX: 0000000000000000 RAX: 0000000000000041 RBX: ffffffff81c32680 RCX: ffffffff81c5cbf8 RDX: 0000000000000001 RSI: 0000000000000092 RDI: 0000000000000002 RBP: ffff88807fffd240 R08: 726f666562206465 R09: 0000000000000136 R10: 0000000000000000 R11: 696e695f6c656261 R12: ffffffff82158900 R13: ffffffff8215f760 R14: 0000000000000001 R15: 0000000000000008 FS: 0000000000000000(0000) GS:ffff883f7f400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88807ffff000 CR3: 0000000001c09000 CR4: 00000000000606b0 Call Trace: static_key_disable+0x16/0x20 start_kernel+0x15a/0x45d ? load_ucode_intel_bsp+0x11/0x2d secondary_startup_64+0xa5/0xb0 Code: 48 c7 c7 a0 15 cf 81 e9 47 53 4b 00 48 89 df e8 5f fc ff ff eb e8 48 c7 c6 \ c0 97 83 81 48 c7 c7 d0 ff a2 81 31 c0 e8 c5 9d f5 ff <0f> ff eb a7 0f ff eb \ b0 e8 eb a2 4b 00 53 48 89 fb e8 42 0e f0 but it doesn't tell me which key it is. So dump the key's name too: static_key_disable_cpuslocked(): static key 'virt_spin_lock_key' used before call to jump_label_init() And that makes pinpointing which key is causing that a lot easier. include/linux/jump_label.h | 14 +++++++------- include/linux/jump_label_ratelimit.h | 6 +++--- kernel/jump_label.c | 14 +++++++------- 3 files changed, 17 insertions(+), 17 deletions(-) Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20171018152428.ffjgak4o25f7ept6@pd.tnic Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10jump_label: Provide hotplug context variantsMarc Zyngier1-4/+18
As using the normal static key API under the hotplug lock is pretty much impossible, let's provide a variant of some of them that require the hotplug lock to have already been taken. These function are only meant to be used in CPU hotplug callbacks. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/20170801080257.5056-4-marc.zyngier@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10jump_label: Split out code under the hotplug lockMarc Zyngier1-9/+19
In order to later introduce an "already locked" version of some of the static key funcions, let's split the code into the core stuff (the *_cpuslocked functions) and the usual helpers, which now take/release the hotplug lock and call into the _cpuslocked versions. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/20170801080257.5056-3-marc.zyngier@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10jump_label: Move CPU hotplug lockingMarc Zyngier1-2/+4
As we're about to rework the locking, let's move the taking and release of the CPU hotplug lock to locations that will make its reworking completely obvious. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/20170801080257.5056-2-marc.zyngier@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10jump_label: Add RELEASE barrier after text changesPeter Zijlstra1-2/+9
In the unlikely case text modification does not fully order things, add some extra ordering of our own to ensure we only enabled the fast path after all text is visible. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10jump_label: Fix concurrent static_key_enable/disable()Paolo Bonzini1-22/+37
static_key_enable/disable are trying to cap the static key count to 0/1. However, their use of key->enabled is outside jump_label_lock so they do not really ensure that. Rewrite them to do a quick check for an already enabled (respectively, already disabled), and then recheck under the jump label lock. Unlike static_key_slow_inc/dec, a failed check under the jump label lock does not modify key->enabled. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Jason Baron <jbaron@akamai.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1501601046-35683-2-git-send-email-pbonzini@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-26jump_label: Reorder hotplug lock and jump_label_lockThomas Gleixner1-6/+14
The conversion of the hotplug locking to a percpu rwsem unearthed lock ordering issues all over the place. The jump_label code has two issues: 1) Nested get_online_cpus() invocations 2) Ordering problems vs. the cpus rwsem and the jump_label_mutex To cure these, the following lock order has been established; cpus_rwsem -> jump_label_lock -> text_mutex Even if not all architectures need protection against CPU hotplug, taking cpus_rwsem before jump_label_lock is now mandatory in code pathes which actually modify code and therefor need text_mutex protection. Move the get_online_cpus() invocations into the core jump label code and establish the proper lock order where required. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@kernel.org> Acked-by: "David S. Miller" <davem@davemloft.net> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@akamai.com> Cc: Ralf Baechle <ralf@linux-mips.org> Link: http://lkml.kernel.org/r/20170524081549.025830817@linutronix.de
2017-02-28Merge tag 'trace-v4.11' of ↵Linus Torvalds1-26/+127
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "This release has no new tracing features, just clean ups, minor fixes and small optimizations" * tag 'trace-v4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (25 commits) tracing: Remove outdated ring buffer comment tracing/probes: Fix a warning message to show correct maximum length tracing: Fix return value check in trace_benchmark_reg() tracing: Use modern function declaration jump_label: Reduce the size of struct static_key tracing/probe: Show subsystem name in messages tracing/hwlat: Update old comment about migration timers: Make flags output in the timer_start tracepoint useful tracing: Have traceprobe_probes_write() not access userspace unnecessarily tracing: Have COMM event filter key be treated as a string ftrace: Have set_graph_function handle multiple functions in one write ftrace: Do not hold references of ftrace_graph_{notrace_}hash out of graph_lock tracing: Reset parser->buffer to allow multiple "puts" ftrace: Have set_graph_functions handle write with RDWR ftrace: Reset fgd->hash in ftrace_graph_write() ftrace: Replace (void *)1 with a meaningful macro name FTRACE_GRAPH_EMPTY ftrace: Create a slight optimization on searching the ftrace_hash tracing: Add ftrace_hash_key() helper function ftrace: Convert graph filter to use hash tables ftrace: Expose ftrace_hash_empty and ftrace_lookup_ip ...
2017-02-15jump_label: Reduce the size of struct static_keyJason Baron1-26/+127
The static_key->next field goes mostly unused. The field is used for associating module uses with a static key. Most uses of struct static_key define a static key in the core kernel and make use of it entirely within the core kernel, or define the static key in a module and make use of it only from within that module. In fact, of the ~3,000 static keys defined, I found only about 5 or so that did not fit this pattern. Thus, we can remove the static_key->next field entirely and overload the static_key->entries field. That is, when all the static_key uses are contained within the same module, static_key->entries continues to point to those uses. However, if the static_key uses are not contained within the module where the static_key is defined, then we allocate a struct static_key_mod, store a pointer to the uses within that struct static_key_mod, and have the static key point at the static_key_mod. This does incur some extra memory usage when a static_key is used in a module that does not define it, but since there are only a handful of such cases there is a net savings. In order to identify if the static_key->entries pointer contains a struct static_key_mod or a struct jump_entry pointer, bit 1 of static_key->entries is set to 1 if it points to a struct static_key_mod and is 0 if it points to a struct jump_entry. We were already using bit 0 in a similar way to store the initial value of the static_key. This does mean that allocations of struct static_key_mod and that the struct jump_entry tables need to be at least 4-byte aligned in memory. As far as I can tell all arches meet this criteria. For my .config, the patch increased the text by 778 bytes, but reduced the data + bss size by 14912, for a net savings of 14,134 bytes. text data bss dec hex filename 8092427 5016512 790528 13899467 d416cb vmlinux.pre 8093205 5001600 790528 13885333 d3df95 vmlinux.post Link: http://lkml.kernel.org/r/1486154544-4321-1-git-send-email-jbaron@akamai.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Joe Perches <joe@perches.com> Signed-off-by: Jason Baron <jbaron@akamai.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-01-12jump_labels: API for flushing deferred jump label updatesDavid Matlack1-0/+7
Modules that use static_key_deferred need a way to synchronize with any delayed work that is still pending when the module is unloaded. Introduce static_key_deferred_flush() which flushes any pending jump label updates. Signed-off-by: David Matlack <dmatlack@google.com> Cc: stable@vger.kernel.org Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-08-05Merge tag 'powerpc-4.8-2' of ↵Linus Torvalds1-0/+3
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull more powerpc updates from Michael Ellerman: "These were delayed for various reasons, so I let them sit in next a bit longer, rather than including them in my first pull request. Fixes: - Fix early access to cpu_spec relocation from Benjamin Herrenschmidt - Fix incorrect event codes in power9-event-list from Madhavan Srinivasan - Move register_process_table() out of ppc_md from Michael Ellerman Use jump_label use for [cpu|mmu]_has_feature(): - Add mmu_early_init_devtree() from Michael Ellerman - Move disable_radix handling into mmu_early_init_devtree() from Michael Ellerman - Do hash device tree scanning earlier from Michael Ellerman - Do radix device tree scanning earlier from Michael Ellerman - Do feature patching before MMU init from Michael Ellerman - Check features don't change after patching from Michael Ellerman - Make MMU_FTR_RADIX a MMU family feature from Aneesh Kumar K.V - Convert mmu_has_feature() to returning bool from Michael Ellerman - Convert cpu_has_feature() to returning bool from Michael Ellerman - Define radix_enabled() in one place & use static inline from Michael Ellerman - Add early_[cpu|mmu]_has_feature() from Michael Ellerman - Convert early cpu/mmu feature check to use the new helpers from Aneesh Kumar K.V - jump_label: Make it possible for arches to invoke jump_label_init() earlier from Kevin Hao - Call jump_label_init() in apply_feature_fixups() from Aneesh Kumar K.V - Remove mfvtb() from Kevin Hao - Move cpu_has_feature() to a separate file from Kevin Hao - Add kconfig option to use jump labels for cpu/mmu_has_feature() from Michael Ellerman - Add option to use jump label for cpu_has_feature() from Kevin Hao - Add option to use jump label for mmu_has_feature() from Kevin Hao - Catch usage of cpu/mmu_has_feature() before jump label init from Aneesh Kumar K.V - Annotate jump label assembly from Michael Ellerman TLB flush enhancements from Aneesh Kumar K.V: - radix: Implement tlb mmu gather flush efficiently - Add helper for finding SLBE LLP encoding - Use hugetlb flush functions - Drop multiple definition of mm_is_core_local - radix: Add tlb flush of THP ptes - radix: Rename function and drop unused arg - radix/hugetlb: Add helper for finding page size - hugetlb: Add flush_hugetlb_tlb_range - remove flush_tlb_page_nohash Add new ptrace regsets from Anshuman Khandual and Simon Guo: - elf: Add powerpc specific core note sections - Add the function flush_tmregs_to_thread - Enable in transaction NT_PRFPREG ptrace requests - Enable in transaction NT_PPC_VMX ptrace requests - Enable in transaction NT_PPC_VSX ptrace requests - Adapt gpr32_get, gpr32_set functions for transaction - Enable support for NT_PPC_CGPR - Enable support for NT_PPC_CFPR - Enable support for NT_PPC_CVMX - Enable support for NT_PPC_CVSX - Enable support for TM SPR state - Enable NT_PPC_TM_CTAR, NT_PPC_TM_CPPR, NT_PPC_TM_CDSCR - Enable support for NT_PPPC_TAR, NT_PPC_PPR, NT_PPC_DSCR - Enable support for EBB registers - Enable support for Performance Monitor registers" * tag 'powerpc-4.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (48 commits) powerpc/mm: Move register_process_table() out of ppc_md powerpc/perf: Fix incorrect event codes in power9-event-list powerpc/32: Fix early access to cpu_spec relocation powerpc/ptrace: Enable support for Performance Monitor registers powerpc/ptrace: Enable support for EBB registers powerpc/ptrace: Enable support for NT_PPPC_TAR, NT_PPC_PPR, NT_PPC_DSCR powerpc/ptrace: Enable NT_PPC_TM_CTAR, NT_PPC_TM_CPPR, NT_PPC_TM_CDSCR powerpc/ptrace: Enable support for TM SPR state powerpc/ptrace: Enable support for NT_PPC_CVSX powerpc/ptrace: Enable support for NT_PPC_CVMX powerpc/ptrace: Enable support for NT_PPC_CFPR powerpc/ptrace: Enable support for NT_PPC_CGPR powerpc/ptrace: Adapt gpr32_get, gpr32_set functions for transaction powerpc/ptrace: Enable in transaction NT_PPC_VSX ptrace requests powerpc/ptrace: Enable in transaction NT_PPC_VMX ptrace requests powerpc/ptrace: Enable in transaction NT_PRFPREG ptrace requests powerpc/process: Add the function flush_tmregs_to_thread elf: Add powerpc specific core note sections powerpc/mm: remove flush_tlb_page_nohash powerpc/mm/hugetlb: Add flush_hugetlb_tlb_range ...
2016-08-04Merge tag 'modules-next-for-linus' of ↵Linus Torvalds1-1/+4
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module updates from Rusty Russell: "The only interesting thing here is Jessica's patch to add ro_after_init support to modules. The rest are all trivia" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: extable.h: add stddef.h so "NULL" definition is not implicit modules: add ro_after_init support jump_label: disable preemption around __module_text_address(). exceptions: fork exception table content from module.h into extable.h modules: Add kernel parameter to blacklist modules module: Do a WARN_ON_ONCE() for assert module mutex not held Documentation/module-signing.txt: Note need for version info if reusing a key module: Invalidate signatures on force-loaded modules module: Issue warnings when tainting kernel module: fix redundant test. module: fix noreturn attribute for __module_put_and_exit()
2016-08-04jump_label: remove bug.h, atomic.h dependencies for HAVE_JUMP_LABELJason Baron1-0/+53
The current jump_label.h includes bug.h for things such as WARN_ON(). This makes the header problematic for inclusion by kernel.h or any headers that kernel.h includes, since bug.h includes kernel.h (circular dependency). The inclusion of atomic.h is similarly problematic. Thus, this should make jump_label.h 'includable' from most places. Link: http://lkml.kernel.org/r/7060ce35ddd0d20b33bf170685e6b0fab816bdf2.1467837322.git.jbaron@akamai.com Signed-off-by: Jason Baron <jbaron@akamai.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Joe Perches <joe@perches.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-04jump_label: disable preemption around __module_text_address().Rusty Russell1-1/+4
Steven reported a warning caused by not holding module_mutex or rcu_read_lock_sched: his backtrace was corrupted but a quick audit found this possible cause. It's wrong anyway... Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2016-08-01jump_label: Make it possible for arches to invoke jump_label_init() earlierKevin Hao1-0/+3
Some arches (powerpc at least) would like to invoke jump_label_init() much earlier in boot. So check static_key_initialized in order to make sure this function runs only once. LGTM-by: Ingo (http://marc.info/?l=linux-kernel&m=144049104329961&w=2) Signed-off-by: Kevin Hao <haokexin@gmail.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2016-07-25Merge branch 'locking-core-for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: "The locking tree was busier in this cycle than the usual pattern - a couple of major projects happened to coincide. The main changes are: - implement the atomic_fetch_{add,sub,and,or,xor}() API natively across all SMP architectures (Peter Zijlstra) - add atomic_fetch_{inc/dec}() as well, using the generic primitives (Davidlohr Bueso) - optimize various aspects of rwsems (Jason Low, Davidlohr Bueso, Waiman Long) - optimize smp_cond_load_acquire() on arm64 and implement LSE based atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() on arm64 (Will Deacon) - introduce smp_acquire__after_ctrl_dep() and fix various barrier mis-uses and bugs (Peter Zijlstra) - after discovering ancient spin_unlock_wait() barrier bugs in its implementation and usage, strengthen its semantics and update/fix usage sites (Peter Zijlstra) - optimize mutex_trylock() fastpath (Peter Zijlstra) - ... misc fixes and cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits) locking/atomic: Introduce inc/dec variants for the atomic_fetch_$op() API locking/barriers, arch/arm64: Implement LDXR+WFE based smp_cond_load_acquire() locking/static_keys: Fix non static symbol Sparse warning locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec() locking/atomic, arch/tile: Fix tilepro build locking/atomic, arch/m68k: Remove comment locking/atomic, arch/arc: Fix build locking/Documentation: Clarify limited control-dependency scope locking/atomic, arch/rwsem: Employ atomic_long_fetch_add() locking/atomic, arch/qrwlock: Employ atomic_fetch_add_acquire() locking/atomic, arch/mips: Convert to _relaxed atomics locking/atomic, arch/alpha: Convert to _relaxed atomics locking/atomic: Remove the deprecated atomic_{set,clear}_mask() functions locking/atomic: Remove linux/atomic.h:atomic_fetch_or() locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}() locking/atomic: Fix atomic64_relaxed() bits locking/atomic, arch/xtensa: Implement atomic_fetch_{add,sub,and,or,xor}() locking/atomic, arch/x86: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() locking/atomic, arch/tile: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() locking/atomic, arch/sparc: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() ...
2016-07-07locking/static_keys: Fix non static symbol Sparse warningWei Yongjun1-1/+1
Fix the following sparse warnings: kernel/jump_label.c:473:23: warning: symbol 'jump_label_module_nb' was not declared. Should it be static? Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1466183980-8903-1-git-send-email-weiyj_lk@163.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24locking/static_key: Fix concurrent static_key_slow_inc()Paolo Bonzini1-3/+33
The following scenario is possible: CPU 1 CPU 2 static_key_slow_inc() atomic_inc_not_zero() -> key.enabled == 0, no increment jump_label_lock() atomic_inc_return() -> key.enabled == 1 now static_key_slow_inc() atomic_inc_not_zero() -> key.enabled == 1, inc to 2 return ** static key is wrong! jump_label_update() jump_label_unlock() Testing the static key at the point marked by (**) will follow the wrong path for jumps that have not been patched yet. This can actually happen when creating many KVM virtual machines with userspace LAPIC emulation; just run several copies of the following program: #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> #include <linux/kvm.h> int main(void) { for (;;) { int kvmfd = open("/dev/kvm", O_RDONLY); int vmfd = ioctl(kvmfd, KVM_CREATE_VM, 0); close(ioctl(vmfd, KVM_CREATE_VCPU, 1)); close(vmfd); close(kvmfd); } return 0; } Every KVM_CREATE_VCPU ioctl will attempt a static_key_slow_inc() call. The static key's purpose is to skip NULL pointer checks and indeed one of the processes eventually dereferences NULL. As explained in the commit that introduced the bug: 706249c222f6 ("locking/static_keys: Rework update logic") jump_label_update() needs key.enabled to be true. The solution adopted here is to temporarily make key.enabled == -1, and use go down the slow path when key.enabled <= 0. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> # v4.3+ Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 706249c222f6 ("locking/static_keys: Rework update logic") Link: http://lkml.kernel.org/r/1466527937-69798-1-git-send-email-pbonzini@redhat.com [ Small stylistic edits to the changelog and the code. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-23treewide: Remove old email addressPeter Zijlstra1-1/+1
There were still a number of references to my old Red Hat email address in the kernel source. Remove these while keeping the Red Hat copyright notices intact. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03locking/static_keys: Add selftestPeter Zijlstra1-1/+38
Add a little selftest that validates all combinations. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03locking/static_keys: Add a new static_key interfacePeter Zijlstra1-7/+30
There are various problems and short-comings with the current static_key interface: - static_key_{true,false}() read like a branch depending on the key value, instead of the actual likely/unlikely branch depending on init value. - static_key_{true,false}() are, as stated above, tied to the static_key init values STATIC_KEY_INIT_{TRUE,FALSE}. - we're limited to the 2 (out of 4) possible options that compile to a default NOP because that's what our arch_static_branch() assembly emits. So provide a new static_key interface: DEFINE_STATIC_KEY_TRUE(name); DEFINE_STATIC_KEY_FALSE(name); Which define a key of different types with an initial true/false value. Then allow: static_branch_likely() static_branch_unlikely() to take a key of either type and emit the right instruction for the case. This means adding a second arch_static_branch_jump() assembly helper which emits a JMP per default. In order to determine the right instruction for the right state, encode the branch type in the LSB of jump_entry::key. This is the final step in removing the naming confusion that has led to a stream of avoidable bugs such as: a833581e372a ("x86, perf: Fix static_key bug in load_mm_cr4()") ... but it also allows new static key combinations that will give us performance enhancements in the subsequent patches. Tested-by: Rabin Vincent <rabin@rab.in> # arm Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> # ppc Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # s390 Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03locking/static_keys: Rework update logicPeter Zijlstra1-50/+38
Instead of spreading the branch_default logic all over the place, concentrate it into the one jump_label_type() function. This does mean we need to actually increment/decrement the enabled count _before_ calling the update path, otherwise jump_label_type() will not see the right state. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03jump_label: Add jump_entry_key() helperPeter Zijlstra1-4/+9
Avoid some casting with a helper, also prepares the way for overloading the LSB of jump_entry::key. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03jump_label, locking/static_keys: Rename JUMP_LABEL_TYPE_* and related ↵Peter Zijlstra1-9/+16
helpers to the static_key* pattern Rename the JUMP_LABEL_TYPE_* macros to be JUMP_TYPE_* and move the inline helpers into kernel/jump_label.c, since that's the only place they're ever used. Also rename the helpers where it's all about static keys. This is the second step in removing the naming confusion that has led to a stream of avoidable bugs such as: a833581e372a ("x86, perf: Fix static_key bug in load_mm_cr4()") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-03jump_label: Rename JUMP_LABEL_{EN,DIS}ABLE to JUMP_LABEL_{JMP,NOP}Peter Zijlstra1-9/+9
Since we've already stepped away from ENABLE is a JMP and DISABLE is a NOP with the branch_default bits, and are going to make it even worse, rename it to make it all clearer. This way we don't mix multiple levels of logic attributes, but have a plain 'physical' name for what the current instruction patching status of a jump label is. This is a first step in removing the naming confusion that has led to a stream of avoidable bugs such as: a833581e372a ("x86, perf: Fix static_key bug in load_mm_cr4()") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org [ Beefed up the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-27module, jump_label: Fix module lockingPeter Zijlstra1-4/+6
As per the module core lockdep annotations in the coming patch: [ 18.034047] ---[ end trace 9294429076a9c673 ]--- [ 18.047760] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013 [ 18.059228] ffffffff817d8676 ffff880036683c38 ffffffff8157e98b 0000000000000001 [ 18.067541] 0000000000000000 ffff880036683c78 ffffffff8105fbc7 ffff880036683c68 [ 18.075851] ffffffffa0046b08 0000000000000000 ffffffffa0046d00 ffffffffa0046cc8 [ 18.084173] Call Trace: [ 18.086906] [<ffffffff8157e98b>] dump_stack+0x4f/0x7b [ 18.092649] [<ffffffff8105fbc7>] warn_slowpath_common+0x97/0xe0 [ 18.099361] [<ffffffff8105fc2a>] warn_slowpath_null+0x1a/0x20 [ 18.105880] [<ffffffff810ee502>] __module_address+0x1d2/0x1e0 [ 18.112400] [<ffffffff81161153>] jump_label_module_notify+0x143/0x1e0 [ 18.119710] [<ffffffff810814bf>] notifier_call_chain+0x4f/0x70 [ 18.126326] [<ffffffff8108160e>] __blocking_notifier_call_chain+0x5e/0x90 [ 18.134009] [<ffffffff81081656>] blocking_notifier_call_chain+0x16/0x20 [ 18.141490] [<ffffffff810f0f00>] load_module+0x1b50/0x2660 [ 18.147720] [<ffffffff810f1ade>] SyS_init_module+0xce/0x100 [ 18.154045] [<ffffffff81587429>] system_call_fastpath+0x12/0x17 [ 18.160748] ---[ end trace 9294429076a9c674 ]--- Jump labels is not doing it right; fix this. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jason Baron <jbaron@akamai.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2013-10-20static_key: WARN on usage before jump_label_init was calledHannes Frederic Sowa1-0/+5
Usage of the static key primitives to toggle a branch must not be used before jump_label_init() is called from init/main.c. jump_label_init reorganizes and wires up the jump_entries so usage before that could have unforeseen consequences. Following primitives are now checked for correct use: * static_key_slow_inc * static_key_slow_dec * static_key_slow_dec_deferred * jump_label_rate_limit The x86 architecture already checks this by testing if the default_nop was already replaced with an optimal nop or with a branch instruction. It will panic then. Other architectures don't check for this. Because we need to relax this check for the x86 arch to allow code to transition from default_nop to the enabled state and other architectures did not check for this at all this patch introduces checking on the static_key primitives in a non-arch dependent manner. All checked functions are considered slow-path so the additional check does no harm to performance. The warnings are best observed with earlyprintk. Based on a patch from Andi Kleen. Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-08-09jump_label: Split jumplabel ratelimitAndrew Jones1-0/+1
Commit b202952075f62603bea9bfb6ebc6b0420db11949 ("perf, core: Rate limit perf_sched_events jump_label patching") introduced rate limiting for jump label disabling. The changes were made in the jump label code in order to be more widely available and to keep things tidier. This is all fine, except now jump_label.h includes linux/workqueue.h, which makes it impossible to include jump_label.h from anything that workqueue.h needs. For example, it's now impossible to include jump_label.h from asm/spinlock.h, which is done in proposed pv-ticketlock patches. This patch splits out the rate limiting related changes from jump_label.h into a new file, jump_label_ratelimit.h, to resolve the issue. Signed-off-by: Andrew Jones <drjones@redhat.com> Link: http://lkml.kernel.org/r/1376058122-8248-10-git-send-email-raghavendra.kt@linux.vnet.ibm.com Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2012-08-06jump_label: Export jump_label_rate_limit()Gleb Natapov1-0/+1
CC: Jason Baron <jbaron@redhat.com> CC: Ingo Molnar <mingo@elte.hu> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Gleb Natapov <gleb@redhat.com> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2012-02-28static keys: Inline the static_key_enabled() functionJason Baron1-6/+0
In the jump label enabled case, calling static_key_enabled() results in a function call. The function returns the results of a compare, so it really doesn't need the overhead of a full function call. Let's make it 'static inline' for both the jump label enabled and disabled cases. Signed-off-by: Jason Baron <jbaron@redhat.com> Cc: a.p.zijlstra@chello.nl Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@polymtl.ca Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/201202281849.q1SIn1p2023270@int-mx10.intmail.prod.int.phx2.redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-24static keys: Introduce 'struct static_key', static_key_true()/false() and ↵Ingo Molnar1-54/+74
static_key_slow_[inc|dec]() So here's a boot tested patch on top of Jason's series that does all the cleanups I talked about and turns jump labels into a more intuitive to use facility. It should also address the various misconceptions and confusions that surround jump labels. Typical usage scenarios: #include <linux/static_key.h> struct static_key key = STATIC_KEY_INIT_TRUE; if (static_key_false(&key)) do unlikely code else do likely code Or: if (static_key_true(&key)) do likely code else do unlikely code The static key is modified via: static_key_slow_inc(&key); ... static_key_slow_dec(&key); The 'slow' prefix makes it abundantly clear that this is an expensive operation. I've updated all in-kernel code to use this everywhere. Note that I (intentionally) have not pushed through the rename blindly through to the lowest levels: the actual jump-label patching arch facility should be named like that, so we want to decouple jump labels from the static-key facility a bit. On non-jump-label enabled architectures static keys default to likely()/unlikely() branches. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jason Baron <jbaron@redhat.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: a.p.zijlstra@chello.nl Cc: mathieu.desnoyers@efficios.com Cc: davem@davemloft.net Cc: ddaney.cavm@gmail.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.hu Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-22jump label: Fix compiler warningJason Baron1-1/+1
While cross-compiling on sparc64, I found: kernel/jump_label.c: In function 'jump_label_update': kernel/jump_label.c:447:40: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] Fix by casting to 'unsigned long'. Signed-off-by: Jason Baron <jbaron@redhat.com> Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: davem@davemloft.net Cc: ddaney.cavm@gmail.com Cc: a.p.zijlstra@chello.nl Link: http://lkml.kernel.org/r/08026cbc6df80619cae833ef1ebbbc43efab69ab.1329851692.git.jbaron@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-22jump label: Add a WARN() if jump label key count goes negativeJason Baron1-1/+4
The count on a jump label key should never go negative. Add a WARN() to check for this condition. Signed-off-by: Jason Baron <jbaron@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: davem@davemloft.net Cc: ddaney.cavm@gmail.com Cc: a.p.zijlstra@chello.nl Link: http://lkml.kernel.org/r/3c68556121be4d1920417a3fe367da1ec38246b4.1329851692.git.jbaron@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
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