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-rw-r--r--samples/ftrace/ftrace-direct-too.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
new file mode 100644
index 000000000..14c6859e1
--- /dev/null
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+
+#include <linux/mm.h> /* for handle_mm_fault() */
+#include <linux/ftrace.h>
+#include <asm/asm-offsets.h>
+
+extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
+ unsigned int flags, struct pt_regs *regs);
+
+void my_direct_func(struct vm_area_struct *vma, unsigned long address,
+ unsigned int flags, struct pt_regs *regs)
+{
+ trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
+ vma, address, flags, regs);
+}
+
+extern void my_tramp(void *);
+
+#ifdef CONFIG_X86_64
+
+#include <asm/ibt.h>
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .globl my_tramp\n"
+" my_tramp:"
+ ASM_ENDBR
+" pushq %rbp\n"
+" movq %rsp, %rbp\n"
+" pushq %rdi\n"
+" pushq %rsi\n"
+" pushq %rdx\n"
+" pushq %rcx\n"
+" call my_direct_func\n"
+" popq %rcx\n"
+" popq %rdx\n"
+" popq %rsi\n"
+" popq %rdi\n"
+" leave\n"
+ ASM_RET
+" .size my_tramp, .-my_tramp\n"
+" .popsection\n"
+);
+
+#endif /* CONFIG_X86_64 */
+
+#ifdef CONFIG_S390
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .globl my_tramp\n"
+" my_tramp:"
+" lgr %r1,%r15\n"
+" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
+" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
+" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
+" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
+" brasl %r14,my_direct_func\n"
+" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
+" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
+" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
+" lgr %r1,%r0\n"
+" br %r1\n"
+" .size my_tramp, .-my_tramp\n"
+" .popsection\n"
+);
+
+#endif /* CONFIG_S390 */
+
+static int __init ftrace_direct_init(void)
+{
+ return register_ftrace_direct((unsigned long)handle_mm_fault,
+ (unsigned long)my_tramp);
+}
+
+static void __exit ftrace_direct_exit(void)
+{
+ unregister_ftrace_direct((unsigned long)handle_mm_fault,
+ (unsigned long)my_tramp);
+}
+
+module_init(ftrace_direct_init);
+module_exit(ftrace_direct_exit);
+
+MODULE_AUTHOR("Steven Rostedt");
+MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
+MODULE_LICENSE("GPL");