Commit 9628f26b authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/entry/64: Remove TRACE_IRQS_*_DEBUG 



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:

  5963e317 ("ftrace/x86: Do not change stacks in DEBUG when calling lockdep")

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202120.319418546@linutronix.de
parent fa95a0cb

arch/x86/entry/entry_64.S

+3 −45
Original line number Diff line number Diff line
@@ -67,44 +67,6 @@ SYM_CODE_END(native_usergs_sysret64) 
	TRACE_IRQS_FLAGS EFLAGS(%rsp)

.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.

 *
@@ -500,11 +462,7 @@ SYM_CODE_START(\asmsym) 


	UNWIND_HINT_REGS



	.if \vector == X86_TRAP_DB

		TRACE_IRQS_OFF_DEBUG

	.else

	TRACE_IRQS_OFF

	.endif



	movq	%rsp, %rdi		/* pt_regs pointer */
@@ -924,7 +882,7 @@ 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
@@ -933,7 +891,7 @@ 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