s390/ftrace: enable HAVE_FUNCTION_GRAPH_RETVAL

Add support for tracing return values in the function graph tracer.
This requires return_to_handler() to record gpr2 and the frame pointer

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index ea0e8f34eb0dbedc8fe6590ac1e7d027d7407bbd..c5be7199067b0e67db12fae01cfe0978c9167bfb 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -174,6 +174,7 @@ config S390
        select HAVE_FTRACE_MCOUNT_RECORD
        select HAVE_FUNCTION_ARG_ACCESS_API
        select HAVE_FUNCTION_ERROR_INJECTION
+       select HAVE_FUNCTION_GRAPH_RETVAL
        select HAVE_FUNCTION_GRAPH_TRACER
        select HAVE_FUNCTION_TRACER
        select HAVE_GCC_PLUGINS

diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index e5c5cb1207e2cf790ff61fa45fe6f06afe757fe2..5a82b08f03cd3e9602311a04ed06b6e52acde3e2 100644 (file)
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -54,6 +54,23 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *
        return NULL;
 }
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+struct fgraph_ret_regs {
+       unsigned long gpr2;
+       unsigned long fp;
+};
+
+static __always_inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
+{
+       return ret_regs->gpr2;
+}
+
+static __always_inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
+{
+       return ret_regs->fp;
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
 static __always_inline unsigned long
 ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs)
 {

diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 81cf7208804137b2b81b2a3fc8e82884c00fd683..150809c9ffa5cffd93e16a21c957c9fe444728a1 100644 (file)
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -12,6 +12,7 @@
 #include <linux/sched.h>
 #include <linux/purgatory.h>
 #include <linux/pgtable.h>
+#include <linux/ftrace.h>
 #include <asm/idle.h>
 #include <asm/gmap.h>
 #include <asm/stacktrace.h>
@@ -177,5 +178,11 @@ int main(void)
        DEFINE(OLDMEM_SIZE, PARMAREA + offsetof(struct parmarea, oldmem_size));
        DEFINE(COMMAND_LINE, PARMAREA + offsetof(struct parmarea, command_line));
        DEFINE(MAX_COMMAND_LINE_SIZE, PARMAREA + offsetof(struct parmarea, max_command_line_size));
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+       /* function graph return value tracing */
+       OFFSET(__FGRAPH_RET_GPR2, fgraph_ret_regs, gpr2);
+       OFFSET(__FGRAPH_RET_FP, fgraph_ret_regs, fp);
+       DEFINE(__FGRAPH_RET_SIZE, sizeof(struct fgraph_ret_regs));
+#endif
        return 0;
 }

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index dbece2803c50bd03d7e03d5b4c41f3b349ad8eb8..fd27ff9f2cf3ea712cecfc43d6ad0eb497f1213b 100644 (file)
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -128,10 +128,14 @@ SYM_CODE_END(ftrace_common)
 SYM_FUNC_START(return_to_handler)
        stmg    %r2,%r5,32(%r15)
        lgr     %r1,%r15
-       aghi    %r15,-STACK_FRAME_OVERHEAD
+       aghi    %r15,-(STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE)
        stg     %r1,__SF_BACKCHAIN(%r15)
+       aghik   %r3,%r15,STACK_FRAME_OVERHEAD
+       stg     %r1,__FGRAPH_RET_FP(%r3)
+       stg     %r2,__FGRAPH_RET_GPR2(%r3)
+       lgr     %r2,%r3
        brasl   %r14,ftrace_return_to_handler
-       aghi    %r15,STACK_FRAME_OVERHEAD
+       aghi    %r15,STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE
        lgr     %r14,%r2
        lmg     %r2,%r5,32(%r15)
        BR_EX   %r14