Re: [PATCH v3 3/4] arm64: ftrace: Add direct call trampoline samples support
From: Florent Revest <hidden>
Date: 2023-03-27 13:45:42
Also in:
bpf, linux-arm-kernel, lkml
On Fri, Mar 24, 2023 at 6:15 PM Florent Revest [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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. Signed-off-by: Florent Revest <redacted> --- arch/arm64/Kconfig | 2 ++ samples/ftrace/ftrace-direct-modify.c | 32 ++++++++++++++++++ samples/ftrace/ftrace-direct-multi-modify.c | 36 +++++++++++++++++++++ samples/ftrace/ftrace-direct-multi.c | 22 +++++++++++++ samples/ftrace/ftrace-direct-too.c | 25 ++++++++++++++ samples/ftrace/ftrace-direct.c | 23 +++++++++++++ 6 files changed, 140 insertions(+)diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f3503d0cc1b8..c2bf28099abd 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig@@ -194,6 +194,8 @@ 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_RECORDdiff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c index 25fba66f61c0..32ed0e1f8699 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 +98,36 @@ asm ( #endif /* CONFIG_S390 */ +#ifdef CONFIG_ARM64 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" +" sub sp, sp, #16\n"
Oh, one thing I realize only now: I haven't properly tested this series on a machine with BTI enabled. All these sample trampolines should have a BTI C here. Also, from a quick look, after adding -cpu max to my QEMU test setup, there seem to be other BTI related errors. I'll investigate them further and send a v4 that addresses them properly.
quoted hunk ↗ jump to hunk
+" 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:" +" 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 */ + static struct ftrace_ops direct; static unsigned long my_tramp = (unsigned long)my_tramp1;diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c index f72623899602..0ba40891d43e 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 +105,40 @@ asm ( #endif /* CONFIG_S390 */ +#ifdef CONFIG_ARM64 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" +" sub sp, sp, #32\n" +" stp x9, x30, [sp]\n" +" str x0, [sp, #16]\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:" +" sub sp, sp, #32\n" +" stp x9, x30, [sp]\n" +" str x0, [sp, #16]\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 */ + static unsigned long my_tramp = (unsigned long)my_tramp1; static unsigned long tramps[2] = { (unsigned long)my_tramp1,diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c index 1547c2c6be02..0b072e763c97 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 +68,26 @@ asm ( #endif /* CONFIG_S390 */ +#ifdef CONFIG_ARM64 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp, @function\n" +" .globl my_tramp\n" +" my_tramp:" +" 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 */ static struct ftrace_ops direct; static int __init ftrace_direct_multi_init(void)diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c index f28e7b99840f..5606b7ad1950 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);@@ -70,6 +72,29 @@ asm ( #endif /* CONFIG_S390 */ +#ifdef CONFIG_ARM64 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp, @function\n" +" .globl my_tramp\n" +" my_tramp:" +" sub sp, sp, #48\n" +" stp x9, x30, [sp]\n" +" stp x0, x1, [sp, #16]\n" +" str x2, [sp, #32]\n" +" bl my_direct_func\n" +" ldp x30, x9, [sp]\n" +" ldp x0, x1, [sp, #16]\n" +" ldr x2, [sp, #32]\n" +" add sp, sp, #48\n" +" ret x9\n" +" .size my_tramp, .-my_tramp\n" +" .popsection\n" +); + +#endif /* CONFIG_ARM64 */ + static struct ftrace_ops direct; static int __init ftrace_direct_init(void)diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c index d81a9473b585..7e20529ef132 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 +65,27 @@ asm ( #endif /* CONFIG_S390 */ +#ifdef CONFIG_ARM64 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp, @function\n" +" .globl my_tramp\n" +" my_tramp:" +" 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 */ + static struct ftrace_ops direct; static int __init ftrace_direct_init(void) --2.40.0.348.gf938b09366-goog