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Subject[PATCH v2 6/7] 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: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/entry/entry_64.S | 46 ++--------------------------------------------
1 file changed, 2 insertions(+), 44 deletions(-)

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -68,44 +68,6 @@ 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
@@ -879,11 +841,7 @@ apicinterrupt IRQ_WORK_VECTOR irq_work
GET_CR2_INTO(%rdx); /* can clobber %rax */
.endif

- .if \shift_ist != -1
- TRACE_IRQS_OFF_DEBUG /* reload IDT in case of recursion */
- .else
TRACE_IRQS_OFF
- .endif

.if \paranoid == 0
testb $3, CS(%rsp)
@@ -1292,7 +1250,7 @@ END(paranoid_entry)
ENTRY(paranoid_exit)
UNWIND_HINT_REGS
DISABLE_INTERRUPTS(CLBR_ANY)
- TRACE_IRQS_OFF_DEBUG
+ TRACE_IRQS_OFF

/* Handle GS depending on FSGSBASE availability */
ALTERNATIVE "jmp .Lparanoid_exit_checkgs", "nop",X86_FEATURE_FSGSBASE
@@ -1312,7 +1270,7 @@ ENTRY(paranoid_exit)
jmp .Lparanoid_exit_restore

.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


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