1 files changed, 41 insertions, 3 deletions

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 320852d02026..7d65133b51be 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -191,6 +191,44 @@ ENDPROC(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 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
  * fast path FIXUP_TOP_OF_STACK is needed.
@@ -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: