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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>
This commit is contained in:
Heiko Carstens 2013-05-13 14:48:52 +02:00 committed by Martin Schwidefsky
parent bb4b42ce0c
commit aca9120977
4 changed files with 13 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/s390/include/asm/ftrace.h
View File

@ -9,11 +9,6 @@ struct dyn_arch_ftrace { };
#define MCOUNT_ADDR ((long)_mcount)
#ifdef CONFIG_64BIT
#define MCOUNT_INSN_SIZE 12
#else
#define MCOUNT_INSN_SIZE 20
#endif
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
@ -21,4 +16,11 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
}
#endif /* __ASSEMBLY__ */
#ifdef CONFIG_64BIT
#define MCOUNT_INSN_SIZE 12
#else
#define MCOUNT_INSN_SIZE 22
#endif
#endif /* _ASM_S390_FTRACE_H */

9
arch/s390/kernel/ftrace.c
View File

@ -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--;

2
arch/s390/kernel/mcount.S
View File

@ -7,6 +7,7 @@
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/ftrace.h>
.section .kprobes.text, "ax"
@ -33,6 +34,7 @@ ENTRY(ftrace_caller)
la %r2,0(%r14)
st %r0,__SF_BACKCHAIN(%r15)
la %r3,0(%r3)
ahi %r2,-MCOUNT_INSN_SIZE
l %r14,0b-0b(%r1)
l %r14,0(%r14)
basr %r14,%r14

2
arch/s390/kernel/mcount64.S
View File

@ -7,6 +7,7 @@
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/ftrace.h>
.section .kprobes.text, "ax"
@ -29,6 +30,7 @@ ENTRY(ftrace_caller)
stg %r1,__SF_BACKCHAIN(%r15)
lgr %r2,%r14
lg %r3,168(%r15)
aghi %r2,-MCOUNT_INSN_SIZE
larl %r14,ftrace_trace_function
lg %r14,0(%r14)
basr %r14,%r14