[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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 5f0c4fba87c3786805398ee0452d76552c351e3e..08844fc24a2e7b8f042364e7e0bf44a0ca4bbb3c 100644 (file)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -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:

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index d7ce150453f2865bfa4c9e99f53c03cda198442d..41aca06682aa19e294ac54160500da46594cb97a 100644 (file)
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -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