x86/traps: Get rid of unnecessary preempt_disable/preempt_enable_no_resched
Exception handlers which may run on IST stack call ist_enter() at the start of execution and ist_exit() in the end. ist_enter() disables preemption unconditionally and ist_exit() enables it. So the extra preempt_disable/enable() pairs nested inside the ist_enter/exit() regions are pointless and can be removed. Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Jianyu Zhan <nasa4836@gmail.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@suse.de> Link: http://lkml.kernel.org/r/20161128075057.7724-1-kuleshovmail@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -563,11 +563,9 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
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* as we may switch to the interrupt stack.
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*/
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debug_stack_usage_inc();
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preempt_disable();
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cond_local_irq_enable(regs);
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do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
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cond_local_irq_disable(regs);
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preempt_enable_no_resched();
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debug_stack_usage_dec();
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exit:
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ist_exit(regs);
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@ -742,14 +740,12 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
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debug_stack_usage_inc();
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/* It's safe to allow irq's after DR6 has been saved */
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preempt_disable();
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cond_local_irq_enable(regs);
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if (v8086_mode(regs)) {
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handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
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X86_TRAP_DB);
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cond_local_irq_disable(regs);
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preempt_enable_no_resched();
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debug_stack_usage_dec();
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goto exit;
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}
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@ -769,7 +765,6 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
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if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
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send_sigtrap(tsk, regs, error_code, si_code);
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cond_local_irq_disable(regs);
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preempt_enable_no_resched();
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debug_stack_usage_dec();
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exit:
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