[for-linus][PATCH 2/5] arm64: ftrace: Add direct call trampoline samples support

Steven Rostedt
2023-07-11T14:07:28Z

From: Florent Revest <revest@chromium.org>

The ftrace samples need per-architecture trampoline implementations
to save and restore argument registers around the calls to
my_direct_func* and to restore polluted registers (eg: x30).

These samples also include <asm/asm-offsets.h> which, on arm64, is not
necessary and redefines previously defined macros (resulting in
warnings) so these includes are guarded by !CONFIG_ARM64.

Link: https://lkml.kernel.org/r/20230427140700.625241-3-revest@chromium.org

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
arch/arm64/Kconfig | 2 ++
samples/ftrace/ftrace-direct-modify.c | 34 ++++++++++++++++++
samples/ftrace/ftrace-direct-multi-modify.c | 40 +++++++++++++++++++++
samples/ftrace/ftrace-direct-multi.c | 25 +++++++++++++
samples/ftrace/ftrace-direct-too.c | 26 ++++++++++++++
samples/ftrace/ftrace-direct.c | 24 +++++++++++++
6 files changed, 151 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f90b1780ea6c..d4421356bb3a 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -196,6 +196,8 @@ config ARM64
!CC_OPTIMIZE_FOR_SIZE)
select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \
if DYNAMIC_FTRACE_WITH_ARGS
+ select HAVE_SAMPLE_FTRACE_DIRECT
+ select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
select HAVE_EFFICIENT_UNALIGNED_ACCESS
select HAVE_FAST_GUP
select HAVE_FTRACE_MCOUNT_RECORD
diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
index 06d889149012..e5ed08098ff3 100644
--- a/samples/ftrace/ftrace-direct-modify.c
+++ b/samples/ftrace/ftrace-direct-modify.c
@@ -2,7 +2,9 @@
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/ftrace.h>
+#ifndef CONFIG_ARM64
#include <asm/asm-offsets.h>
+#endif

extern void my_direct_func1(void);
extern void my_direct_func2(void);
@@ -96,6 +98,38 @@ asm (

#endif /* CONFIG_S390 */

+#ifdef CONFIG_ARM64
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp1, @function\n"
+" .globl my_tramp1\n"
+" my_tramp1:"
+" bti c\n"
+" sub sp, sp, #16\n"
+" stp x9, x30, [sp]\n"
+" bl my_direct_func1\n"
+" ldp x30, x9, [sp]\n"
+" add sp, sp, #16\n"
+" ret x9\n"
+" .size my_tramp1, .-my_tramp1\n"
+
+" .type my_tramp2, @function\n"
+" .globl my_tramp2\n"
+" my_tramp2:"
+" bti c\n"
+" sub sp, sp, #16\n"
+" stp x9, x30, [sp]\n"
+" bl my_direct_func2\n"
+" ldp x30, x9, [sp]\n"
+" add sp, sp, #16\n"
+" ret x9\n"
+" .size my_tramp2, .-my_tramp2\n"
+" .popsection\n"
+);
+
+#endif /* CONFIG_ARM64 */
+
#ifdef CONFIG_LOONGARCH

asm (
diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c
index 62f6b681999e..292cff2b3f5d 100644
--- a/samples/ftrace/ftrace-direct-multi-modify.c
+++ b/samples/ftrace/ftrace-direct-multi-modify.c
@@ -2,7 +2,9 @@
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/ftrace.h>
+#ifndef CONFIG_ARM64
#include <asm/asm-offsets.h>
+#endif

extern void my_direct_func1(unsigned long ip);
extern void my_direct_func2(unsigned long ip);
@@ -103,6 +105,44 @@ asm (

#endif /* CONFIG_S390 */

+#ifdef CONFIG_ARM64
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp1, @function\n"
+" .globl my_tramp1\n"
+" my_tramp1:"
+" bti c\n"
+" sub sp, sp, #32\n"
+" stp x9, x30, [sp]\n"
+" str x0, [sp, #16]\n"
+" mov x0, x30\n"
+" bl my_direct_func1\n"
+" ldp x30, x9, [sp]\n"
+" ldr x0, [sp, #16]\n"
+" add sp, sp, #32\n"
+" ret x9\n"
+" .size my_tramp1, .-my_tramp1\n"
+
+" .type my_tramp2, @function\n"
+" .globl my_tramp2\n"
+" my_tramp2:"
+" bti c\n"
+" sub sp, sp, #32\n"
+" stp x9, x30, [sp]\n"
+" str x0, [sp, #16]\n"
+" mov x0, x30\n"
+" bl my_direct_func2\n"
+" ldp x30, x9, [sp]\n"
+" ldr x0, [sp, #16]\n"
+" add sp, sp, #32\n"
+" ret x9\n"
+" .size my_tramp2, .-my_tramp2\n"
+" .popsection\n"
+);
+
+#endif /* CONFIG_ARM64 */
+
#ifdef CONFIG_LOONGARCH
#include <asm/asm.h>

diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c
index 5482cf616b43..b4391e08c913 100644
--- a/samples/ftrace/ftrace-direct-multi.c
+++ b/samples/ftrace/ftrace-direct-multi.c
@@ -4,7 +4,9 @@
#include <linux/mm.h> /* for handle_mm_fault() */
#include <linux/ftrace.h>
#include <linux/sched/stat.h>
+#ifndef CONFIG_ARM64
#include <asm/asm-offsets.h>
+#endif

extern void my_direct_func(unsigned long ip);

@@ -66,6 +68,29 @@ asm (

#endif /* CONFIG_S390 */

+#ifdef CONFIG_ARM64
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .globl my_tramp\n"
+" my_tramp:"
+" bti c\n"
+" sub sp, sp, #32\n"
+" stp x9, x30, [sp]\n"
+" str x0, [sp, #16]\n"
+" mov x0, x30\n"
+" bl my_direct_func\n"
+" ldp x30, x9, [sp]\n"
+" ldr x0, [sp, #16]\n"
+" add sp, sp, #32\n"
+" ret x9\n"
+" .size my_tramp, .-my_tramp\n"
+" .popsection\n"
+);
+
+#endif /* CONFIG_ARM64 */
+
#ifdef CONFIG_LOONGARCH

#include <asm/asm.h>
diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
index 7986033887f6..e9804c5307c0 100644
--- a/samples/ftrace/ftrace-direct-too.c
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -3,7 +3,9 @@

#include <linux/mm.h> /* for handle_mm_fault() */
#include <linux/ftrace.h>
+#ifndef CONFIG_ARM64
#include <asm/asm-offsets.h>
+#endif

extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
unsigned int flags, struct pt_regs *regs);
@@ -72,6 +74,30 @@ asm (

#endif /* CONFIG_S390 */

+#ifdef CONFIG_ARM64
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .globl my_tramp\n"
+" my_tramp:"
+" bti c\n"
+" sub sp, sp, #48\n"
+" stp x9, x30, [sp]\n"
+" stp x0, x1, [sp, #16]\n"
+" stp x2, x3, [sp, #32]\n"
+" bl my_direct_func\n"
+" ldp x30, x9, [sp]\n"
+" ldp x0, x1, [sp, #16]\n"
+" ldp x2, x3, [sp, #32]\n"
+" add sp, sp, #48\n"
+" ret x9\n"
+" .size my_tramp, .-my_tramp\n"
+" .popsection\n"
+);
+
+#endif /* CONFIG_ARM64 */
+
#ifdef CONFIG_LOONGARCH

asm (
diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
index 06879bbd3399..20f4a7caa810 100644
--- a/samples/ftrace/ftrace-direct.c
+++ b/samples/ftrace/ftrace-direct.c
@@ -3,7 +3,9 @@

#include <linux/sched.h> /* for wake_up_process() */
#include <linux/ftrace.h>
+#ifndef CONFIG_ARM64
#include <asm/asm-offsets.h>
+#endif

extern void my_direct_func(struct task_struct *p);

@@ -63,6 +65,28 @@ asm (

#endif /* CONFIG_S390 */

+#ifdef CONFIG_ARM64
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .globl my_tramp\n"
+" my_tramp:"
+" bti c\n"
+" sub sp, sp, #32\n"
+" stp x9, x30, [sp]\n"
+" str x0, [sp, #16]\n"
+" bl my_direct_func\n"
+" ldp x30, x9, [sp]\n"
+" ldr x0, [sp, #16]\n"
+" add sp, sp, #32\n"
+" ret x9\n"
+" .size my_tramp, .-my_tramp\n"
+" .popsection\n"
+);
+
+#endif /* CONFIG_ARM64 */
+
#ifdef CONFIG_LOONGARCH

asm (
--
2.40.1