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arm64: ftrace: Add direct call trampoline samples support
JIRA: https://issues.redhat.com/browse/RHEL-101598 commit 8c3526f Author: Florent Revest <[email protected]> Date: Thu Apr 27 16:07:00 2023 +0200 arm64: ftrace: Add direct call trampoline samples support 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/[email protected] Reviewed-by: Mark Rutland <[email protected]> Tested-by: Mark Rutland <[email protected]> Acked-by: Catalin Marinas <[email protected]> Signed-off-by: Florent Revest <[email protected]> Signed-off-by: Steven Rostedt (Google) <[email protected]> Conflicts: - Context change from missing commits a743f26 ("arm64: ftrace: Don't forbid CALL_OPS+CC_OPTIMIZE_FOR_SIZE with Clang") 22f367a ("LoongArch: ftrace: Add direct call trampoline samples support") Signed-off-by: Jerome Marchand <[email protected]>
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arch/arm64/Kconfig

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@@ -200,6 +200,8 @@ config ARM64
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if (DYNAMIC_FTRACE_WITH_ARGS && !CFI_CLANG)
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select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \
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if DYNAMIC_FTRACE_WITH_ARGS
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select HAVE_SAMPLE_FTRACE_DIRECT
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select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
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select HAVE_EFFICIENT_UNALIGNED_ACCESS
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select HAVE_FAST_GUP
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select HAVE_FTRACE_MCOUNT_RECORD

samples/ftrace/ftrace-direct-modify.c

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@@ -2,7 +2,9 @@
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/ftrace.h>
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#ifndef CONFIG_ARM64
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#include <asm/asm-offsets.h>
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#endif
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extern void my_direct_func1(void);
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extern void my_direct_func2(void);
@@ -96,6 +98,38 @@ asm (
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#endif /* CONFIG_S390 */
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#ifdef CONFIG_ARM64
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp1, @function\n"
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" .globl my_tramp1\n"
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" my_tramp1:"
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" bti c\n"
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" sub sp, sp, #16\n"
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" stp x9, x30, [sp]\n"
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" bl my_direct_func1\n"
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" ldp x30, x9, [sp]\n"
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" add sp, sp, #16\n"
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" ret x9\n"
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" .size my_tramp1, .-my_tramp1\n"
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" .type my_tramp2, @function\n"
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" .globl my_tramp2\n"
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" my_tramp2:"
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" bti c\n"
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" sub sp, sp, #16\n"
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" stp x9, x30, [sp]\n"
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" bl my_direct_func2\n"
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" ldp x30, x9, [sp]\n"
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" add sp, sp, #16\n"
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" ret x9\n"
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" .size my_tramp2, .-my_tramp2\n"
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" .popsection\n"
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);
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#endif /* CONFIG_ARM64 */
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static struct ftrace_ops direct;
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static unsigned long my_tramp = (unsigned long)my_tramp1;

samples/ftrace/ftrace-direct-multi-modify.c

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@@ -2,7 +2,9 @@
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/ftrace.h>
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#ifndef CONFIG_ARM64
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#include <asm/asm-offsets.h>
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#endif
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extern void my_direct_func1(unsigned long ip);
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extern void my_direct_func2(unsigned long ip);
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#endif /* CONFIG_S390 */
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#ifdef CONFIG_ARM64
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp1, @function\n"
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" .globl my_tramp1\n"
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" my_tramp1:"
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" bti c\n"
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" sub sp, sp, #32\n"
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" stp x9, x30, [sp]\n"
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" str x0, [sp, #16]\n"
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" mov x0, x30\n"
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" bl my_direct_func1\n"
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" ldp x30, x9, [sp]\n"
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" ldr x0, [sp, #16]\n"
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" add sp, sp, #32\n"
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" ret x9\n"
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" .size my_tramp1, .-my_tramp1\n"
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" .type my_tramp2, @function\n"
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" .globl my_tramp2\n"
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" my_tramp2:"
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" bti c\n"
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" sub sp, sp, #32\n"
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" stp x9, x30, [sp]\n"
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" str x0, [sp, #16]\n"
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" mov x0, x30\n"
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" bl my_direct_func2\n"
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" ldp x30, x9, [sp]\n"
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" ldr x0, [sp, #16]\n"
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" add sp, sp, #32\n"
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" ret x9\n"
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" .size my_tramp2, .-my_tramp2\n"
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" .popsection\n"
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);
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#endif /* CONFIG_ARM64 */
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static unsigned long my_tramp = (unsigned long)my_tramp1;
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static unsigned long tramps[2] = {
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(unsigned long)my_tramp1,

samples/ftrace/ftrace-direct-multi.c

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@@ -4,7 +4,9 @@
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#include <linux/mm.h> /* for handle_mm_fault() */
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#include <linux/ftrace.h>
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#include <linux/sched/stat.h>
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#ifndef CONFIG_ARM64
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#include <asm/asm-offsets.h>
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#endif
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extern void my_direct_func(unsigned long ip);
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#endif /* CONFIG_S390 */
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#ifdef CONFIG_ARM64
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp, @function\n"
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" .globl my_tramp\n"
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" my_tramp:"
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" bti c\n"
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" sub sp, sp, #32\n"
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" stp x9, x30, [sp]\n"
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" str x0, [sp, #16]\n"
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" mov x0, x30\n"
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" bl my_direct_func\n"
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" ldp x30, x9, [sp]\n"
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" ldr x0, [sp, #16]\n"
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" add sp, sp, #32\n"
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" ret x9\n"
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" .size my_tramp, .-my_tramp\n"
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" .popsection\n"
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);
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#endif /* CONFIG_ARM64 */
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static struct ftrace_ops direct;
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static int __init ftrace_direct_multi_init(void)

samples/ftrace/ftrace-direct-too.c

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@@ -3,7 +3,9 @@
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#include <linux/mm.h> /* for handle_mm_fault() */
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#include <linux/ftrace.h>
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#ifndef CONFIG_ARM64
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#include <asm/asm-offsets.h>
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#endif
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extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
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unsigned int flags, struct pt_regs *regs);
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#endif /* CONFIG_S390 */
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#ifdef CONFIG_ARM64
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp, @function\n"
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" .globl my_tramp\n"
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" my_tramp:"
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" bti c\n"
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" sub sp, sp, #48\n"
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" stp x9, x30, [sp]\n"
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" stp x0, x1, [sp, #16]\n"
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" stp x2, x3, [sp, #32]\n"
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" bl my_direct_func\n"
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" ldp x30, x9, [sp]\n"
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" ldp x0, x1, [sp, #16]\n"
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" ldp x2, x3, [sp, #32]\n"
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" add sp, sp, #48\n"
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" ret x9\n"
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" .size my_tramp, .-my_tramp\n"
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" .popsection\n"
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);
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#endif /* CONFIG_ARM64 */
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static struct ftrace_ops direct;
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static int __init ftrace_direct_init(void)

samples/ftrace/ftrace-direct.c

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@@ -3,7 +3,9 @@
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#include <linux/sched.h> /* for wake_up_process() */
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#include <linux/ftrace.h>
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#ifndef CONFIG_ARM64
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#include <asm/asm-offsets.h>
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#endif
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extern void my_direct_func(struct task_struct *p);
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@@ -63,6 +65,28 @@ asm (
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#endif /* CONFIG_S390 */
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#ifdef CONFIG_ARM64
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asm (
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" .pushsection .text, \"ax\", @progbits\n"
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" .type my_tramp, @function\n"
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" .globl my_tramp\n"
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" my_tramp:"
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" bti c\n"
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" sub sp, sp, #32\n"
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" stp x9, x30, [sp]\n"
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" str x0, [sp, #16]\n"
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" bl my_direct_func\n"
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" ldp x30, x9, [sp]\n"
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" ldr x0, [sp, #16]\n"
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" add sp, sp, #32\n"
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" ret x9\n"
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" .size my_tramp, .-my_tramp\n"
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" .popsection\n"
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);
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#endif /* CONFIG_ARM64 */
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static struct ftrace_ops direct;
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static int __init ftrace_direct_init(void)

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