[patch V4 part 5 29/31] x86/entry/64: Remove TRACE_IRQS_*_DEBUG

[Thomas Gleixner]

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

Since INT3/#BP no longer runs on an IST, this workaround is no longer
required.

Tested by running lockdep+ftrace as described in the initial commit:

  5963e317b1e9 ("ftrace/x86: Do not change stacks in DEBUG when calling lockdep")

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

---
 arch/x86/entry/entry_64.S |   48 ++--------------------------------------------
 1 file changed, 3 insertions(+), 45 deletions(-)

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -68,44 +68,6 @@ SYM_CODE_END(native_usergs_sysret64)
 .endm
 
 /*
- * When dynamic function tracer is enabled it will add a breakpoint
- * to all locations that it is about to modify, sync CPUs, update
- * all the code, sync CPUs, then remove the breakpoints. In this time
- * if lockdep is enabled, it might jump back into the debug handler
- * outside the updating of the IST protection. (TRACE_IRQS_ON/OFF).
- *
- * We need to change the IDT table before calling TRACE_IRQS_ON/OFF to
- * make sure the stack pointer does not get reset back to the top
- * of the debug stack, and instead just reuses the current stack.
- */
-#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_TRACE_IRQFLAGS)
-
-.macro TRACE_IRQS_OFF_DEBUG
-	call	debug_stack_set_zero
-	TRACE_IRQS_OFF
-	call	debug_stack_reset
-.endm
-
-.macro TRACE_IRQS_ON_DEBUG
-	call	debug_stack_set_zero
-	TRACE_IRQS_ON
-	call	debug_stack_reset
-.endm
-
-.macro TRACE_IRQS_IRETQ_DEBUG
-	btl	$9, EFLAGS(%rsp)		/* interrupts off? */
-	jnc	1f
-	TRACE_IRQS_ON_DEBUG
-1:
-.endm
-
-#else
-# define TRACE_IRQS_OFF_DEBUG			TRACE_IRQS_OFF
-# define TRACE_IRQS_ON_DEBUG			TRACE_IRQS_ON
-# define TRACE_IRQS_IRETQ_DEBUG			TRACE_IRQS_IRETQ
-#endif
-
-/*
  * 64-bit SYSCALL instruction entry. Up to 6 arguments in registers.
  *
  * This is the only entry point used for 64-bit system calls.  The
@@ -501,11 +463,7 @@ SYM_CODE_START(\asmsym)
 
 	UNWIND_HINT_REGS
 
-	.if \vector == X86_TRAP_DB
-		TRACE_IRQS_OFF_DEBUG
-	.else
-		TRACE_IRQS_OFF
-	.endif
+	TRACE_IRQS_OFF
 
 	movq	%rsp, %rdi		/* pt_regs pointer */
 
@@ -885,7 +843,7 @@ SYM_CODE_END(paranoid_entry)
 SYM_CODE_START_LOCAL(paranoid_exit)
 	UNWIND_HINT_REGS
 	DISABLE_INTERRUPTS(CLBR_ANY)
-	TRACE_IRQS_OFF_DEBUG
+	TRACE_IRQS_OFF
 	testl	%ebx, %ebx			/* swapgs needed? */
 	jnz	.Lparanoid_exit_no_swapgs
 	TRACE_IRQS_IRETQ
@@ -894,7 +852,7 @@ SYM_CODE_START_LOCAL(paranoid_exit)
 	SWAPGS_UNSAFE_STACK
 	jmp	restore_regs_and_return_to_kernel
 .Lparanoid_exit_no_swapgs:
-	TRACE_IRQS_IRETQ_DEBUG
+	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