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:

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

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202120.319418546@linutronix.de

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 29a8a83..fb7f126 100644 (file)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -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
+       TRACE_IRQS_OFF
 
        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