f2545b2d4c
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
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/*
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* Copyright 2015 Tilera Corporation. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for
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* more details.
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*
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* jump label TILE-Gx support
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*/
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#include <linux/jump_label.h>
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#include <linux/memory.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/cpu.h>
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#include <asm/cacheflush.h>
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#include <asm/insn.h>
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#ifdef HAVE_JUMP_LABEL
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static void __jump_label_transform(struct jump_entry *e,
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enum jump_label_type type)
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{
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tilegx_bundle_bits opcode;
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/* Operate on writable kernel text mapping. */
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unsigned long pc_wr = ktext_writable_addr(e->code);
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if (type == JUMP_LABEL_JMP)
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opcode = tilegx_gen_branch(e->code, e->target, false);
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else
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opcode = NOP();
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*(tilegx_bundle_bits *)pc_wr = opcode;
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/* Make sure that above mem writes were issued towards the memory. */
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smp_wmb();
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}
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void arch_jump_label_transform(struct jump_entry *e,
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enum jump_label_type type)
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{
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mutex_lock(&text_mutex);
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__jump_label_transform(e, type);
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flush_icache_range(e->code, e->code + sizeof(tilegx_bundle_bits));
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mutex_unlock(&text_mutex);
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}
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__init_or_module void arch_jump_label_transform_static(struct jump_entry *e,
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enum jump_label_type type)
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{
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__jump_label_transform(e, type);
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}
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#endif /* HAVE_JUMP_LABEL */
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