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2022-04-05static_call: Remove __DEFINE_STATIC_CALL macroChristophe Leroy
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 <christophe.leroy@csgroup.eu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/329074f92d96e3220ebe15da7bbe2779beee31eb.1647253456.git.christophe.leroy@csgroup.eu
2022-04-05static_call: Properly initialise DEFINE_STATIC_CALL_RET0()Christophe Leroy
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 <christophe.leroy@csgroup.eu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/1e0a61a88f52a460f62a58ffc2a5f847d1f7d9d8.1647253456.git.christophe.leroy@csgroup.eu
2022-04-05static_call: Don't make __static_call_return0 staticChristophe Leroy
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 <arch_static_call_transform>: 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 <christophe.leroy@csgroup.eu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/30821468a0e7d28251954b578e5051dc09300d04.1647258493.git.christophe.leroy@csgroup.eu
2021-08-17static_call: Update API documentationPeter Zijlstra
Update the comment with the new features. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/YQwIorQBHEq+s73b@hirez.programming.kicks-ass.net
2021-04-28Merge tag 'locking-core-2021-04-28' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 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 ...
2021-04-09static_call: Relax static_call_update() function argument typePeter Zijlstra
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) <peterz@infradead.org> Link: https://lkml.kernel.org/r/YFoN7nCl8OfGtpeh@hirez.programming.kicks-ass.net
2021-03-11static_call: Add function to query current functionJuergen Gross
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 <jgross@suse.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210311142319.4723-4-jgross@suse.com
2021-03-11static_call: Move struct static_call_key definition to static_call_types.hJuergen Gross
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 <jgross@suse.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210311142319.4723-3-jgross@suse.com
2021-02-17static_call: Allow module use without exposing static_call_keyJosh Poimboeuf
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) <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20210127231837.ifddpn7rhwdaepiu@treble
2021-02-17static_call: Provide DEFINE_STATIC_CALL_RET0()Frederic Weisbecker
DECLARE_STATIC_CALL() must pass the original function targeted for a given static call. But DEFINE_STATIC_CALL() may want to initialize it as off. In this case we can't pass NULL (for functions without return value) or __static_call_return0 (for functions returning a value) directly to DEFINE_STATIC_CALL() as that may trigger a static call redeclaration with a different function prototype. Type casts neither can work around that as they don't get along with typeof(). The proper way to do that for functions that don't return a value is to use DEFINE_STATIC_CALL_NULL(). But functions returning a actual value don't have an equivalent yet. Provide DEFINE_STATIC_CALL_RET0() to solve this situation. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20210118141223.123667-3-frederic@kernel.org
2021-02-17static_call/x86: Add __static_call_return0()Peter Zijlstra
Provide a stub function that return 0 and wire up the static call site patching to replace the CALL with a single 5 byte instruction that clears %RAX, the return value register. The function can be cast to any function pointer type that has a single %RAX return (including pointers). Also provide a version that returns an int for convenience. We are clearing the entire %RAX register in any case, whether the return value is 32 or 64 bits, since %RAX is always a scratch register anyway. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20210118141223.123667-2-frederic@kernel.org
2021-02-17static_call: Pull some static_call declarations to the type headersPeter Zijlstra
Some static call declarations are going to be needed on low level header files. Move the necessary material to the dedicated static call types header to avoid inclusion dependency hell. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20210118141223.123667-4-frederic@kernel.org
2020-10-02static_call: Fix return type of static_call_initNathan Chancellor
Functions that are passed to early_initcall should be of type initcall_t, which expects a return type of int. This is not currently an error but a patch in the Clang LTO series could change that in the future. Fixes: 9183c3f9ed71 ("static_call: Add inline static call infrastructure") Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Link: https://lore.kernel.org/lkml/20200903203053.3411268-17-samitolvanen@google.com/
2020-09-01static_call: Allow early initPeter Zijlstra
In order to use static_call() to wire up x86_pmu, we need to initialize earlier, specifically before memory allocation works; copy some of the tricks from jump_label to enable this. Primarily we overload key->next to store a sites pointer when there are no modules, this avoids having to use kmalloc() to initialize the sites and allows us to run much earlier. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Link: https://lore.kernel.org/r/20200818135805.220737930@infradead.org
2020-09-01static_call: Handle tail-callsPeter Zijlstra
GCC can turn our static_call(name)(args...) into a tail call, in which case we get a JMP.d32 into the trampoline (which then does a further tail-call). Teach objtool to recognise and mark these in .static_call_sites and adjust the code patching to deal with this. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20200818135805.101186767@infradead.org
2020-09-01static_call: Add static_call_cond()Peter Zijlstra
Extend the static_call infrastructure to optimize the following common pattern: if (func_ptr) func_ptr(args...) For the trampoline (which is in effect a tail-call), we patch the JMP.d32 into a RET, which then directly consumes the trampoline call. For the in-line sites we replace the CALL with a NOP5. NOTE: this is 'obviously' limited to functions with a 'void' return type. NOTE: DEFINE_STATIC_COND_CALL() only requires a typename, as opposed to a full function. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20200818135805.042977182@infradead.org
2020-09-01static_call: Avoid kprobes on inline static_call()sPeter Zijlstra
Similar to how we disallow kprobes on any other dynamic text (ftrace/jump_label) also disallow kprobes on inline static_call()s. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200818135804.744920586@infradead.org
2020-09-01static_call: Add inline static call infrastructureJosh Poimboeuf
Add infrastructure for an arch-specific CONFIG_HAVE_STATIC_CALL_INLINE option, which is a faster version of CONFIG_HAVE_STATIC_CALL. At runtime, the static call sites are patched directly, rather than using the out-of-line trampolines. Compared to out-of-line static calls, the performance benefits are more modest, but still measurable. Steven Rostedt did some tracepoint measurements: https://lkml.kernel.org/r/20181126155405.72b4f718@gandalf.local.home This code is heavily inspired by the jump label code (aka "static jumps"), as some of the concepts are very similar. For more details, see the comments in include/linux/static_call.h. [peterz: simplified interface; merged trampolines] Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20200818135804.684334440@infradead.org
2020-09-01static_call: Add basic static call infrastructureJosh Poimboeuf
Static calls are a replacement for global function pointers. They use code patching to allow direct calls to be used instead of indirect calls. They give the flexibility of function pointers, but with improved performance. This is especially important for cases where retpolines would otherwise be used, as retpolines can significantly impact performance. The concept and code are an extension of previous work done by Ard Biesheuvel and Steven Rostedt: https://lkml.kernel.org/r/20181005081333.15018-1-ard.biesheuvel@linaro.org https://lkml.kernel.org/r/20181006015110.653946300@goodmis.org There are two implementations, depending on arch support: 1) out-of-line: patched trampolines (CONFIG_HAVE_STATIC_CALL) 2) basic function pointers For more details, see the comments in include/linux/static_call.h. [peterz: simplified interface] Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20200818135804.623259796@infradead.org
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