Commit 50bec4ce authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

[S390] ftrace: fix kernel stack backchain walking 



With CONFIG_IRQSOFF_TRACER the trace_hardirqs_off() function includes
a call to __builtin_return_address(1). But we calltrace_hardirqs_off()
from early entry code. There we have just a single stack frame.
So this results in a kernel stack backchain walk that would walk beyond
the kernel stack. Following the NULL terminated backchain this results
in a lowcore read access.

To fix this we simply call trace_hardirqs_off_caller() and pass the
current instruction pointer.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 632448f6

arch/s390/kernel/entry.S

+11 −7
Original line number Diff line number Diff line
@@ -61,22 +61,25 @@ STACK_SIZE = 1 << STACK_SHIFT 


#ifdef CONFIG_TRACE_IRQFLAGS

	.macro	TRACE_IRQS_ON

	l	%r1,BASED(.Ltrace_irq_on)

	basr	%r2,%r0

	l	%r1,BASED(.Ltrace_irq_on_caller)

	basr	%r14,%r1

	.endm



	.macro	TRACE_IRQS_OFF

	l	%r1,BASED(.Ltrace_irq_off)

	basr	%r2,%r0

	l	%r1,BASED(.Ltrace_irq_off_caller)

	basr	%r14,%r1

	.endm



	.macro	TRACE_IRQS_CHECK

	basr	%r2,%r0

	tm	SP_PSW(%r15),0x03	# irqs enabled?

	jz	0f

	l	%r1,BASED(.Ltrace_irq_on)

	l	%r1,BASED(.Ltrace_irq_on_caller)

	basr	%r14,%r1

	j	1f

0:	l	%r1,BASED(.Ltrace_irq_off)

0:	l	%r1,BASED(.Ltrace_irq_off_caller)

	basr	%r14,%r1

1:

	.endm
@@ -1113,9 +1116,10 @@ cleanup_io_leave_insn: 
.Lschedtail:	.long	schedule_tail

.Lsysc_table:	.long	sys_call_table

#ifdef CONFIG_TRACE_IRQFLAGS

.Ltrace_irq_on: .long	trace_hardirqs_on

.Ltrace_irq_off:

		.long	trace_hardirqs_off

.Ltrace_irq_on_caller:

		.long	trace_hardirqs_on_caller

.Ltrace_irq_off_caller:

		.long	trace_hardirqs_off_caller

#endif

#ifdef CONFIG_LOCKDEP

.Llockdep_sys_exit:

arch/s390/kernel/entry64.S

+7 −4
Original line number Diff line number Diff line
@@ -61,19 +61,22 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \ 


#ifdef CONFIG_TRACE_IRQFLAGS

	.macro	TRACE_IRQS_ON

	 brasl	%r14,trace_hardirqs_on

	 basr	%r2,%r0

	 brasl	%r14,trace_hardirqs_on_caller

	.endm



	.macro	TRACE_IRQS_OFF

	 brasl	%r14,trace_hardirqs_off

	 basr	%r2,%r0

	 brasl	%r14,trace_hardirqs_off_caller

	.endm



	.macro TRACE_IRQS_CHECK

	basr	%r2,%r0

	tm	SP_PSW(%r15),0x03	# irqs enabled?

	jz	0f

	brasl	%r14,trace_hardirqs_on

	brasl	%r14,trace_hardirqs_on_caller

	j	1f

0:	brasl	%r14,trace_hardirqs_off

0:	brasl	%r14,trace_hardirqs_off_caller

1:

	.endm

#else

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