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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
51 lines
1.0 KiB
C
51 lines
1.0 KiB
C
#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/mutex.h>
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#include <linux/cpu.h>
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#include <linux/jump_label.h>
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#include <linux/memory.h>
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#include <asm/cacheflush.h>
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#ifdef HAVE_JUMP_LABEL
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void arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type)
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{
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u32 *insn = (u32 *) (unsigned long) entry->code;
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u32 val;
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if (type == JUMP_LABEL_JMP) {
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s32 off = (s32)entry->target - (s32)entry->code;
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bool use_v9_branch = false;
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BUG_ON(off & 3);
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#ifdef CONFIG_SPARC64
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if (off <= 0xfffff && off >= -0x100000)
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use_v9_branch = true;
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#endif
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if (use_v9_branch) {
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/* WDISP19 - target is . + immed << 2 */
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/* ba,pt %xcc, . + off */
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val = 0x10680000 | (((u32) off >> 2) & 0x7ffff);
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} else {
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/* WDISP22 - target is . + immed << 2 */
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BUG_ON(off > 0x7fffff);
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BUG_ON(off < -0x800000);
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/* ba . + off */
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val = 0x10800000 | (((u32) off >> 2) & 0x3fffff);
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}
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} else {
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val = 0x01000000;
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}
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mutex_lock(&text_mutex);
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*insn = val;
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flushi(insn);
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mutex_unlock(&text_mutex);
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}
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#endif
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