From 1256e70a082ad855efe351146dfa39207d5e3e70 Mon Sep 17 00:00:00 2001
From: Sven Schnelle <svens@linux.ibm.com>
Date: Thu, 29 Jun 2023 12:02:19 +0200
Subject: [PATCH] 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>
---
arch/s390/Kconfig | 1 +
arch/s390/include/asm/ftrace.h | 17 +++++++++++++++++
arch/s390/kernel/asm-offsets.c | 7 +++++++
arch/s390/kernel/mcount.S | 8 ++++++--
4 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index ea0e8f34eb0db..c5be7199067b0 100644
--- 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 e5c5cb1207e2c..5a82b08f03cd3 100644
--- 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 81cf720880413..150809c9ffa5c 100644
--- 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 dbece2803c50b..fd27ff9f2cf3e 100644
--- 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
--
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