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Date:   Tue, 05 May 2020 15:54:11 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>
Subject: [patch V4 part 5 30/31] x86/entry: Move paranoid irq tracing out of ASM code

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/entry/entry_64.S |   13 -------------
 arch/x86/kernel/nmi.c     |   11 +++++++----
 2 files changed, 7 insertions(+), 17 deletions(-)

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -16,7 +16,6 @@
  *
  * Some macro usage:
  * - SYM_FUNC_START/END:Define functions in the symbol table.
- * - TRACE_IRQ_*:	Trace hardirq state for lock debugging.
  * - idtentry:		Define exception entry points.
  */
 #include <linux/linkage.h>
@@ -107,11 +106,6 @@ SYM_CODE_END(native_usergs_sysret64)
 
 SYM_CODE_START(entry_SYSCALL_64)
 	UNWIND_HINT_EMPTY
-	/*
-	 * Interrupts are off on entry.
-	 * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
-	 * it is too small to ever cause noticeable irq latency.
-	 */
 
 	swapgs
 	/* tss.sp2 is scratch space. */
@@ -463,8 +457,6 @@ SYM_CODE_START(\asmsym)
 
 	UNWIND_HINT_REGS
 
-	TRACE_IRQS_OFF
-
 	movq	%rsp, %rdi		/* pt_regs pointer */
 
 	.if \vector == X86_TRAP_DB
@@ -842,17 +834,13 @@ SYM_CODE_END(paranoid_entry)
  */
 SYM_CODE_START_LOCAL(paranoid_exit)
 	UNWIND_HINT_REGS
-	DISABLE_INTERRUPTS(CLBR_ANY)
-	TRACE_IRQS_OFF
 	testl	%ebx, %ebx			/* swapgs needed? */
 	jnz	.Lparanoid_exit_no_swapgs
-	TRACE_IRQS_IRETQ
 	/* Always restore stashed CR3 value (see paranoid_entry) */
 	RESTORE_CR3	scratch_reg=%rbx save_reg=%r14
 	SWAPGS_UNSAFE_STACK
 	jmp	restore_regs_and_return_to_kernel
 .Lparanoid_exit_no_swapgs:
-	TRACE_IRQS_IRETQ
 	/* Always restore stashed CR3 value (see paranoid_entry) */
 	RESTORE_CR3	scratch_reg=%rbx save_reg=%r14
 	jmp restore_regs_and_return_to_kernel
@@ -1254,7 +1242,6 @@ SYM_CODE_START(asm_exc_nmi)
 	call	paranoid_entry
 	UNWIND_HINT_REGS
 
-	/* paranoidentry exc_nmi(), 0; without TRACE_IRQS_OFF */
 	movq	%rsp, %rdi
 	movq	$-1, %rsi
 	call	exc_nmi
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -334,6 +334,8 @@ static noinstr void default_do_nmi(struc
 	__this_cpu_write(last_nmi_rip, regs->ip);
 
 	instr_begin();
+	trace_hardirqs_off_prepare();
+
 	handled = nmi_handle(NMI_LOCAL, regs);
 	__this_cpu_add(nmi_stats.normal, handled);
 	if (handled) {
@@ -347,8 +349,7 @@ static noinstr void default_do_nmi(struc
 		 */
 		if (handled > 1)
 			__this_cpu_write(swallow_nmi, true);
-		instr_end();
-		return;
+		goto out;
 	}
 
 	/*
@@ -380,8 +381,7 @@ static noinstr void default_do_nmi(struc
 #endif
 		__this_cpu_add(nmi_stats.external, 1);
 		raw_spin_unlock(&nmi_reason_lock);
-		instr_end();
-		return;
+		goto out;
 	}
 	raw_spin_unlock(&nmi_reason_lock);
 
@@ -419,6 +419,9 @@ static noinstr void default_do_nmi(struc
 		__this_cpu_add(nmi_stats.swallow, 1);
 	else
 		unknown_nmi_error(reason, regs);
+out:
+	if (regs->flags & X86_EFLAGS_IF)
+		trace_hardirqs_on_prepare();
 	instr_end();
 }
 

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