The previous patch ("function_graph: Support recording and printing
the return value of function") has laid the groundwork for the for
the funcgraph-retval, and this modification makes it available on
the ARM platform.
We introduce a new structure called fgraph_ret_regs for the ARM platform
to hold return registers and the frame pointer. We then fill its content
in the return_to_handler and pass its address to the function
ftrace_return_to_handler to record the return value.
Signed-off-by: Donglin Peng <[email protected]>
---
v10:
- Use CONFIG_FUNCTION_GRAPH_TRACER to control fgraph_ret_regs definition
v9:
- Fix stack pointer align issues
- Update the commit message
v8:
- Modify the control range of CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/ftrace.h | 22 ++++++++++++++++++++++
arch/arm/kernel/asm-offsets.c | 8 +++++++-
arch/arm/kernel/entry-ftrace.S | 10 ++++++----
4 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e24a9820e12f..73061379855a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -98,6 +98,7 @@ config ARM
select HAVE_FAST_GUP if ARM_LPAE
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_ERROR_INJECTION
+ select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER if !XIP_KERNEL
select HAVE_GCC_PLUGINS
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 7e9251ca29fe..3c457902b355 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -77,4 +77,26 @@ static inline bool arch_syscall_match_sym_name(const char *sym,
#endif /* ifndef __ASSEMBLY__ */
+#ifndef __ASSEMBLY__
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+struct fgraph_ret_regs {
+ /* r0 - r3 */
+ unsigned long regs[4];
+
+ unsigned long fp;
+ unsigned long __unused;
+};
+
+static inline unsigned long fgraph_ret_regs_return_value(struct fgraph_ret_regs *ret_regs)
+{
+ return ret_regs->regs[0];
+}
+
+static inline unsigned long fgraph_ret_regs_frame_pointer(struct fgraph_ret_regs *ret_regs)
+{
+ return ret_regs->fp;
+}
+#endif /* ifdef CONFIG_FUNCTION_GRAPH_TRACER */
+#endif
+
#endif /* _ASM_ARM_FTRACE */
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 38121c59cbc2..18bb85115b21 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -23,6 +23,7 @@
#include <asm/suspend.h>
#include <asm/vdso_datapage.h>
#include <asm/hardware/cache-l2x0.h>
+#include <asm/ftrace.h>
#include <linux/kbuild.h>
#include <linux/arm-smccc.h>
#include "signal.h"
@@ -170,5 +171,10 @@ int main(void)
DEFINE(KEXEC_INDIR_PAGE, offsetof(struct kexec_relocate_data, kexec_indirection_page));
DEFINE(KEXEC_MACH_TYPE, offsetof(struct kexec_relocate_data, kexec_mach_type));
DEFINE(KEXEC_R2, offsetof(struct kexec_relocate_data, kexec_r2));
- return 0;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ BLANK();
+ DEFINE(FGRET_REGS_SIZE, sizeof(struct fgraph_ret_regs));
+ BLANK();
+#endif
+ return 0;
}
diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S
index 3e7bcaca5e07..d41a1676608c 100644
--- a/arch/arm/kernel/entry-ftrace.S
+++ b/arch/arm/kernel/entry-ftrace.S
@@ -257,11 +257,13 @@ ENDPROC(ftrace_graph_regs_caller)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(return_to_handler)
- stmdb sp!, {r0-r3}
- add r0, sp, #16 @ sp at exit of instrumented routine
+ mov ip, sp @ sp at exit of instrumented routine
+ stmdb sp!, {r0-r3, ip, lr} @ fill fgraph_ret_regs
+ mov r0, sp
bl ftrace_return_to_handler
- mov lr, r0 @ r0 has real ret addr
- ldmia sp!, {r0-r3}
+ mov lr, r0 @ r0 has real ret addr
+ ldmia sp, {r0-r3}
+ add sp, sp, #FGRET_REGS_SIZE @ restore stack pointer
ret lr
ENDPROC(return_to_handler)
#endif
--
2.25.1