From b12265656af9ce4a1b26b0e3653993e40f8de44f Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 30 May 2012 11:54:53 -0400
Subject: [PATCH] --- yaml --- r: 310398 b: refs/heads/master c:
 5963e317b1e9d2a4511503916d8fd664bb8fa8fb h: refs/heads/master v: v3

---
 [refs]                           |  2 +-
 trunk/arch/x86/kernel/entry_64.S | 44 +++++++++++++++++++++++++++++---
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 23b3b3d21810..6ec497a0082a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f8988175fd70874d1fb3712b1c5d3bfc6d455202
+refs/heads/master: 5963e317b1e9d2a4511503916d8fd664bb8fa8fb
diff --git a/trunk/arch/x86/kernel/entry_64.S b/trunk/arch/x86/kernel/entry_64.S
index 320852d02026..7d65133b51be 100644
--- a/trunk/arch/x86/kernel/entry_64.S
+++ b/trunk/arch/x86/kernel/entry_64.S
@@ -190,6 +190,44 @@ ENDPROC(native_usergs_sysret64)
 #endif
 .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 offset=ARGOFFSET
+	bt   $9,EFLAGS-\offset(%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
+
 /*
  * C code is not supposed to know about undefined top of stack. Every time
  * a C function with an pt_regs argument is called from the SYSCALL based
@@ -1098,7 +1136,7 @@ ENTRY(\sym)
 	subq $ORIG_RAX-R15, %rsp
 	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
 	call save_paranoid
-	TRACE_IRQS_OFF
+	TRACE_IRQS_OFF_DEBUG
 	movq %rsp,%rdi		/* pt_regs pointer */
 	xorl %esi,%esi		/* no error code */
 	subq $EXCEPTION_STKSZ, INIT_TSS_IST(\ist)
@@ -1393,7 +1431,7 @@ paranoidzeroentry machine_check *machine_check_vector(%rip)
 ENTRY(paranoid_exit)
 	DEFAULT_FRAME
 	DISABLE_INTERRUPTS(CLBR_NONE)
-	TRACE_IRQS_OFF
+	TRACE_IRQS_OFF_DEBUG
 	testl %ebx,%ebx				/* swapgs needed? */
 	jnz paranoid_restore
 	testl $3,CS(%rsp)
@@ -1404,7 +1442,7 @@ paranoid_swapgs:
 	RESTORE_ALL 8
 	jmp irq_return
 paranoid_restore:
-	TRACE_IRQS_IRETQ 0
+	TRACE_IRQS_IRETQ_DEBUG 0
 	RESTORE_ALL 8
 	jmp irq_return
 paranoid_userspace: