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authorHeiko Carstens <heiko.carstens@de.ibm.com>2013-05-13 12:48:52 (GMT)
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-05-15 11:09:09 (GMT)
commitaca91209775514b5a335e7ef11f1d636618590c7 (patch)
treed2bc7248e2a4451e0a68c1680106770ad64874eb /arch/s390/kernel/ftrace.c
parentbb4b42ce0ca36af8c113587ab64b138b3cf5459c (diff)
downloadlinux-aca91209775514b5a335e7ef11f1d636618590c7.tar.xz
s390/ftrace: fix mcount adjustment
Tony Jones reported that the ftrace self tests on s390 do not work: <6>Testing dynamic ftrace ops #1: (0 0 0 0 0) FAILED! <6>Testing tracer irqsoff: <3>failed to start irqsoff tracer <4>.. no entries found ..FAILED! <6>Testing tracer wakeup: <3>failed to start wakeup tracer <4>.. no entries found ..FAILED! <6>Testing tracer function_graph: <4>Failed to init function_graph tracer, init returned -19 <4>FAILED! This happens because we forgot to adjust the instruction pointer that gets passed to the ftrace trace function by MCOUNT_INSN_SIZE. In addition change MCOUNT_INSN_SIZE to the correct value on 31 bit. It only worked so far because the to be patched instruction was identical. Reported-by: Tony Jones <tonyj@suse.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/ftrace.c')
-rw-r--r--arch/s390/kernel/ftrace.c9
1 files changed, 2 insertions, 7 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 78bdf0e..e3043ae 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -16,12 +16,6 @@
#include <trace/syscall.h>
#include <asm/asm-offsets.h>
-#ifdef CONFIG_64BIT
-#define MCOUNT_OFFSET_RET 12
-#else
-#define MCOUNT_OFFSET_RET 22
-#endif
-
#ifdef CONFIG_DYNAMIC_FTRACE
void ftrace_disable_code(void);
@@ -155,9 +149,10 @@ unsigned long __kprobes prepare_ftrace_return(unsigned long parent,
if (unlikely(atomic_read(&current->tracing_graph_pause)))
goto out;
+ ip = (ip & PSW_ADDR_INSN) - MCOUNT_INSN_SIZE;
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
goto out;
- trace.func = (ip & PSW_ADDR_INSN) - MCOUNT_OFFSET_RET;
+ trace.func = ip;
/* Only trace if the calling function expects to. */
if (!ftrace_graph_entry(&trace)) {
current->curr_ret_stack--;