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Subject[tip: x86/entry] x86/entry/64: Remove TRACE_IRQS_*_DEBUG
The following commit has been merged into the x86/entry branch of tip:

Commit-ID: c15984f06ca917411a4d8dc66d03edcb029fd0ea
Gitweb: https://git.kernel.org/tip/c15984f06ca917411a4d8dc66d03edcb029fd0ea
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Thu, 21 May 2020 22:05:50 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 26 May 2020 19:06:29 +02:00

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

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 29a8a83..fb7f126 100644
--- 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
@@ -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
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