diff options
Diffstat (limited to 'samples/ftrace')
| -rw-r--r-- | samples/ftrace/Makefile | 10 | ||||
| -rw-r--r-- | samples/ftrace/ftrace-direct-modify.c | 146 | ||||
| -rw-r--r-- | samples/ftrace/ftrace-direct-multi-modify.c | 160 | ||||
| -rw-r--r-- | samples/ftrace/ftrace-direct-multi.c | 88 | ||||
| -rw-r--r-- | samples/ftrace/ftrace-direct-too.c | 90 | ||||
| -rw-r--r-- | samples/ftrace/ftrace-direct.c | 81 | ||||
| -rw-r--r-- | samples/ftrace/sample-trace-array.c | 143 | ||||
| -rw-r--r-- | samples/ftrace/sample-trace-array.h | 84 |
8 files changed, 802 insertions, 0 deletions
diff --git a/samples/ftrace/Makefile b/samples/ftrace/Makefile new file mode 100644 index 000000000..faf8cdb79 --- /dev/null +++ b/samples/ftrace/Makefile @@ -0,0 +1,10 @@ +# SPDX-License-Identifier: GPL-2.0-only + +obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct.o +obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-too.o +obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-modify.o +obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) += ftrace-direct-multi.o +obj-$(CONFIG_SAMPLE_FTRACE_DIRECT_MULTI) += ftrace-direct-multi-modify.o + +CFLAGS_sample-trace-array.o := -I$(src) +obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += sample-trace-array.o diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c new file mode 100644 index 000000000..39146fa83 --- /dev/null +++ b/samples/ftrace/ftrace-direct-modify.c @@ -0,0 +1,146 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/ftrace.h> +#include <asm/asm-offsets.h> + +extern void my_direct_func1(void); +extern void my_direct_func2(void); + +void my_direct_func1(void) +{ + trace_printk("my direct func1\n"); +} + +void my_direct_func2(void) +{ + trace_printk("my direct func2\n"); +} + +extern void my_tramp1(void *); +extern void my_tramp2(void *); + +static unsigned long my_ip = (unsigned long)schedule; + +#ifdef CONFIG_X86_64 + +#include <asm/ibt.h> + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" + ASM_ENDBR +" pushq %rbp\n" +" movq %rsp, %rbp\n" +" call my_direct_func1\n" +" leave\n" +" .size my_tramp1, .-my_tramp1\n" + ASM_RET + +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:" + ASM_ENDBR +" pushq %rbp\n" +" movq %rsp, %rbp\n" +" call my_direct_func2\n" +" leave\n" + ASM_RET +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_X86_64 */ + +#ifdef CONFIG_S390 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" +" 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_func1\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_tramp1, .-my_tramp1\n" +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:" +" 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_func2\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_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_S390 */ + +static unsigned long my_tramp = (unsigned long)my_tramp1; +static unsigned long tramps[2] = { + (unsigned long)my_tramp1, + (unsigned long)my_tramp2, +}; + +static int simple_thread(void *arg) +{ + static int t; + int ret = 0; + + while (!kthread_should_stop()) { + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(2 * HZ); + + if (ret) + continue; + t ^= 1; + ret = modify_ftrace_direct(my_ip, my_tramp, tramps[t]); + if (!ret) + my_tramp = tramps[t]; + WARN_ON_ONCE(ret); + } + + return 0; +} + +static struct task_struct *simple_tsk; + +static int __init ftrace_direct_init(void) +{ + int ret; + + ret = register_ftrace_direct(my_ip, my_tramp); + if (!ret) + simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); + return ret; +} + +static void __exit ftrace_direct_exit(void) +{ + kthread_stop(simple_tsk); + unregister_ftrace_direct(my_ip, my_tramp); +} + +module_init(ftrace_direct_init); +module_exit(ftrace_direct_exit); + +MODULE_AUTHOR("Steven Rostedt"); +MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()"); +MODULE_LICENSE("GPL"); diff --git a/samples/ftrace/ftrace-direct-multi-modify.c b/samples/ftrace/ftrace-direct-multi-modify.c new file mode 100644 index 000000000..6f23b1413 --- /dev/null +++ b/samples/ftrace/ftrace-direct-multi-modify.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/ftrace.h> +#include <asm/asm-offsets.h> + +extern void my_direct_func1(unsigned long ip); +extern void my_direct_func2(unsigned long ip); + +void my_direct_func1(unsigned long ip) +{ + trace_printk("my direct func1 ip %lx\n", ip); +} + +void my_direct_func2(unsigned long ip) +{ + trace_printk("my direct func2 ip %lx\n", ip); +} + +extern void my_tramp1(void *); +extern void my_tramp2(void *); + +#ifdef CONFIG_X86_64 + +#include <asm/ibt.h> + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" + ASM_ENDBR +" pushq %rbp\n" +" movq %rsp, %rbp\n" +" pushq %rdi\n" +" movq 8(%rbp), %rdi\n" +" call my_direct_func1\n" +" popq %rdi\n" +" leave\n" + ASM_RET +" .size my_tramp1, .-my_tramp1\n" + +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:" + ASM_ENDBR +" pushq %rbp\n" +" movq %rsp, %rbp\n" +" pushq %rdi\n" +" movq 8(%rbp), %rdi\n" +" call my_direct_func2\n" +" popq %rdi\n" +" leave\n" + ASM_RET +" .size my_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_X86_64 */ + +#ifdef CONFIG_S390 + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" .type my_tramp1, @function\n" +" .globl my_tramp1\n" +" my_tramp1:" +" 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" +" lgr %r2,%r0\n" +" brasl %r14,my_direct_func1\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_tramp1, .-my_tramp1\n" +"\n" +" .type my_tramp2, @function\n" +" .globl my_tramp2\n" +" my_tramp2:" +" 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" +" lgr %r2,%r0\n" +" brasl %r14,my_direct_func2\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_tramp2, .-my_tramp2\n" +" .popsection\n" +); + +#endif /* CONFIG_S390 */ + +static unsigned long my_tramp = (unsigned long)my_tramp1; +static unsigned long tramps[2] = { + (unsigned long)my_tramp1, + (unsigned long)my_tramp2, +}; + +static struct ftrace_ops direct; + +static int simple_thread(void *arg) +{ + static int t; + int ret = 0; + + while (!kthread_should_stop()) { + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(2 * HZ); + + if (ret) + continue; + t ^= 1; + ret = modify_ftrace_direct_multi(&direct, tramps[t]); + if (!ret) + my_tramp = tramps[t]; + WARN_ON_ONCE(ret); + } + + return 0; +} + +static struct task_struct *simple_tsk; + +static int __init ftrace_direct_multi_init(void) +{ + int ret; + + ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0); + ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0); + + ret = register_ftrace_direct_multi(&direct, my_tramp); + + if (!ret) + simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); + return ret; +} + +static void __exit ftrace_direct_multi_exit(void) +{ + kthread_stop(simple_tsk); + unregister_ftrace_direct_multi(&direct, my_tramp); + ftrace_free_filter(&direct); +} + +module_init(ftrace_direct_multi_init); +module_exit(ftrace_direct_multi_exit); + +MODULE_AUTHOR("Jiri Olsa"); +MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct_multi()"); +MODULE_LICENSE("GPL"); diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c new file mode 100644 index 000000000..a9a5c90fb --- /dev/null +++ b/samples/ftrace/ftrace-direct-multi.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> + +#include <linux/mm.h> /* for handle_mm_fault() */ +#include <linux/ftrace.h> +#include <linux/sched/stat.h> +#include <asm/asm-offsets.h> + +extern void my_direct_func(unsigned long ip); + +void my_direct_func(unsigned long ip) +{ + trace_printk("ip %lx\n", ip); +} + +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" +" movq 8(%rbp), %rdi\n" +" call my_direct_func\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" +" lgr %r2,%r0\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 struct ftrace_ops direct; + +static int __init ftrace_direct_multi_init(void) +{ + ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0); + ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0); + + return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp); +} + +static void __exit ftrace_direct_multi_exit(void) +{ + unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp); + ftrace_free_filter(&direct); +} + +module_init(ftrace_direct_multi_init); +module_exit(ftrace_direct_multi_exit); + +MODULE_AUTHOR("Jiri Olsa"); +MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()"); +MODULE_LICENSE("GPL"); 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"); diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c new file mode 100644 index 000000000..e8f1e440b --- /dev/null +++ b/samples/ftrace/ftrace-direct.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> + +#include <linux/sched.h> /* for wake_up_process() */ +#include <linux/ftrace.h> +#include <asm/asm-offsets.h> + +extern void my_direct_func(struct task_struct *p); + +void my_direct_func(struct task_struct *p) +{ + trace_printk("waking up %s-%d\n", p->comm, p->pid); +} + +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" +" call my_direct_func\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)wake_up_process, + (unsigned long)my_tramp); +} + +static void __exit ftrace_direct_exit(void) +{ + unregister_ftrace_direct((unsigned long)wake_up_process, + (unsigned long)my_tramp); +} + +module_init(ftrace_direct_init); +module_exit(ftrace_direct_exit); + +MODULE_AUTHOR("Steven Rostedt"); +MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); +MODULE_LICENSE("GPL"); diff --git a/samples/ftrace/sample-trace-array.c b/samples/ftrace/sample-trace-array.c new file mode 100644 index 000000000..6aba02a31 --- /dev/null +++ b/samples/ftrace/sample-trace-array.c @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/trace.h> +#include <linux/trace_events.h> +#include <linux/timer.h> +#include <linux/err.h> +#include <linux/jiffies.h> +#include <linux/workqueue.h> + +/* + * Any file that uses trace points, must include the header. + * But only one file, must include the header by defining + * CREATE_TRACE_POINTS first. This will make the C code that + * creates the handles for the trace points. + */ +#define CREATE_TRACE_POINTS +#include "sample-trace-array.h" + +struct trace_array *tr; +static void mytimer_handler(struct timer_list *unused); +static struct task_struct *simple_tsk; + +static void trace_work_fn(struct work_struct *work) +{ + /* + * Disable tracing for event "sample_event". + */ + trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", + false); +} +static DECLARE_WORK(trace_work, trace_work_fn); + +/* + * mytimer: Timer setup to disable tracing for event "sample_event". This + * timer is only for the purposes of the sample module to demonstrate access of + * Ftrace instances from within kernel. + */ +static DEFINE_TIMER(mytimer, mytimer_handler); + +static void mytimer_handler(struct timer_list *unused) +{ + schedule_work(&trace_work); +} + +static void simple_thread_func(int count) +{ + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(HZ); + + /* + * Printing count value using trace_array_printk() - trace_printk() + * equivalent for the instance buffers. + */ + trace_array_printk(tr, _THIS_IP_, "trace_array_printk: count=%d\n", + count); + /* + * Tracepoint for event "sample_event". This will print the + * current value of count and current jiffies. + */ + trace_sample_event(count, jiffies); +} + +static int simple_thread(void *arg) +{ + int count = 0; + unsigned long delay = msecs_to_jiffies(5000); + + /* + * Enable tracing for "sample_event". + */ + trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", true); + + /* + * Adding timer - mytimer. This timer will disable tracing after + * delay seconds. + * + */ + add_timer(&mytimer); + mod_timer(&mytimer, jiffies+delay); + + while (!kthread_should_stop()) + simple_thread_func(count++); + + del_timer(&mytimer); + cancel_work_sync(&trace_work); + + /* + * trace_array_put() decrements the reference counter associated with + * the trace array - "tr". We are done using the trace array, hence + * decrement the reference counter so that it can be destroyed using + * trace_array_destroy(). + */ + trace_array_put(tr); + + return 0; +} + +static int __init sample_trace_array_init(void) +{ + /* + * Return a pointer to the trace array with name "sample-instance" if it + * exists, else create a new trace array. + * + * NOTE: This function increments the reference counter + * associated with the trace array - "tr". + */ + tr = trace_array_get_by_name("sample-instance"); + + if (!tr) + return -1; + /* + * If context specific per-cpu buffers havent already been allocated. + */ + trace_printk_init_buffers(); + + simple_tsk = kthread_run(simple_thread, NULL, "sample-instance"); + if (IS_ERR(simple_tsk)) { + trace_array_put(tr); + trace_array_destroy(tr); + return -1; + } + + return 0; +} + +static void __exit sample_trace_array_exit(void) +{ + kthread_stop(simple_tsk); + + /* + * We are unloading our module and no longer require the trace array. + * Remove/destroy "tr" using trace_array_destroy() + */ + trace_array_destroy(tr); +} + +module_init(sample_trace_array_init); +module_exit(sample_trace_array_exit); + +MODULE_AUTHOR("Divya Indi"); +MODULE_DESCRIPTION("Sample module for kernel access to Ftrace instances"); +MODULE_LICENSE("GPL"); diff --git a/samples/ftrace/sample-trace-array.h b/samples/ftrace/sample-trace-array.h new file mode 100644 index 000000000..6f8962428 --- /dev/null +++ b/samples/ftrace/sample-trace-array.h @@ -0,0 +1,84 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * If TRACE_SYSTEM is defined, that will be the directory created + * in the ftrace directory under /sys/kernel/tracing/events/<system> + * + * The define_trace.h below will also look for a file name of + * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here. + * In this case, it would look for sample-trace.h + * + * If the header name will be different than the system name + * (as in this case), then you can override the header name that + * define_trace.h will look up by defining TRACE_INCLUDE_FILE + * + * This file is called sample-trace-array.h but we want the system + * to be called "sample-subsystem". Therefore we must define the name of this + * file: + * + * #define TRACE_INCLUDE_FILE sample-trace-array + * + * As we do in the bottom of this file. + * + * Notice that TRACE_SYSTEM should be defined outside of #if + * protection, just like TRACE_INCLUDE_FILE. + */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM sample-subsystem + +/* + * TRACE_SYSTEM is expected to be a C valid variable (alpha-numeric + * and underscore), although it may start with numbers. If for some + * reason it is not, you need to add the following lines: + */ +#undef TRACE_SYSTEM_VAR +#define TRACE_SYSTEM_VAR sample_subsystem + +/* + * But the above is only needed if TRACE_SYSTEM is not alpha-numeric + * and underscored. By default, TRACE_SYSTEM_VAR will be equal to + * TRACE_SYSTEM. As TRACE_SYSTEM_VAR must be alpha-numeric, if + * TRACE_SYSTEM is not, then TRACE_SYSTEM_VAR must be defined with + * only alpha-numeric and underscores. + * + * The TRACE_SYSTEM_VAR is only used internally and not visible to + * user space. + */ + +/* + * Notice that this file is not protected like a normal header. + * We also must allow for rereading of this file. The + * + * || defined(TRACE_HEADER_MULTI_READ) + * + * serves this purpose. + */ +#if !defined(_SAMPLE_TRACE_ARRAY_H) || defined(TRACE_HEADER_MULTI_READ) +#define _SAMPLE_TRACE_ARRAY_H + +#include <linux/tracepoint.h> +TRACE_EVENT(sample_event, + + TP_PROTO(int count, unsigned long time), + + TP_ARGS(count, time), + + TP_STRUCT__entry( + __field(int, count) + __field(unsigned long, time) + ), + + TP_fast_assign( + __entry->count = count; + __entry->time = time; + ), + + TP_printk("count value=%d at jiffies=%lu", __entry->count, + __entry->time) + ); +#endif + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH . +#define TRACE_INCLUDE_FILE sample-trace-array +#include <trace/define_trace.h> |