[PATCH v4 23/33] arm64: ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS

Masami Hiramatsu (Google)
2023-12-08T10:30:20Z

Enable CONFIG_HAVE_FUNCTION_GRAPH_FREGS on arm64. Note that this
depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS which is enabled if the
compiler supports "-fpatchable-function-entry=2". If not, it
continue to use ftrace_ret_regs.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Newly added.
---
arch/arm64/Kconfig | 2 ++
arch/arm64/include/asm/ftrace.h | 6 ++++++
arch/arm64/kernel/entry-ftrace.S | 28 ++++++++++++++++++++++++++++
3 files changed, 36 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7b071a00425d..beebc724dcae 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -192,6 +192,8 @@ config ARM64
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_ARGS \
if $(cc-option,-fpatchable-function-entry=2)
+ select HAVE_FUNCTION_GRAPH_FREGS \
+ if HAVE_DYNAMIC_FTRACE_WITH_ARGS
select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS \
if DYNAMIC_FTRACE_WITH_ARGS && DYNAMIC_FTRACE_WITH_CALL_OPS
select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS \
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index ab158196480c..efd5dbf74dd6 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -131,6 +131,12 @@ ftrace_regs_set_return_value(struct ftrace_regs *fregs,
fregs->regs[0] = ret;
}

+static __always_inline unsigned long
+ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
+{
+ return fregs->fp;
+}
+
static __always_inline void
ftrace_override_function_with_return(struct ftrace_regs *fregs)
{
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index f0c16640ef21..d87ccdb9e678 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -328,6 +328,33 @@ SYM_FUNC_END(ftrace_stub_graph)
* Run ftrace_return_to_handler() before going back to parent.
* @fp is checked against the value passed by ftrace_graph_caller().
*/
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+SYM_CODE_START(return_to_handler)
+ /* save ftrace_regs except for PC */
+ sub sp, sp, #FREGS_SIZE
+ stp x0, x1, [sp, #FREGS_X0]
+ stp x2, x3, [sp, #FREGS_X2]
+ stp x4, x5, [sp, #FREGS_X4]
+ stp x6, x7, [sp, #FREGS_X6]
+ str x8, [sp, #FREGS_X8]
+ str x29, [sp, #FREGS_FP]
+ str x9, [sp, #FREGS_LR]
+ str x10, [sp, #FREGS_SP]
+
+ mov x0, sp
+ bl ftrace_return_to_handler // addr = ftrace_return_to_hander(fregs);
+ mov x30, x0 // restore the original return address
+
+ /* restore return value regs */
+ ldp x0, x1, [sp, #FREGS_X0]
+ ldp x2, x3, [sp, #FREGS_X2]
+ ldp x4, x5, [sp, #FREGS_X4]
+ ldp x6, x7, [sp, #FREGS_X6]
+ add sp, sp, #FREGS_SIZE
+
+ ret
+SYM_CODE_END(return_to_handler)
+#else /* !CONFIG_HAVE_FUNCTION_GRAPH_FREGS */
SYM_CODE_START(return_to_handler)
/* save return value regs */
sub sp, sp, #FGRET_REGS_SIZE
@@ -350,4 +377,5 @@ SYM_CODE_START(return_to_handler)

ret
SYM_CODE_END(return_to_handler)
+#endif /* CONFIG_HAVE_FUNCTION_GRAPH_FREGS */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */