非常感谢各位的回复@CosminRatiu https://stackoverflow.com/a/19734787/277826 and Eugene https://stackoverflow.com/questions/19725900/watch-a-variable-memory-address-change-in-linux-kernel-and-print-stack-trace#comment29352526_19734787;感谢那些，我发现：
- 调试 - Linux内核硬件断点 - VoidCC https://stackoverflow.com/questions/16362063/linux-kernel-hardware-break-points/16377522#16377522
- 硬件断点（或观察点） - Linux 内核档案 https://www.kernel.org/doc/ols/2009/ols2009-pages-149-158.pdf
...我可以用它来开发我在这里发布的示例，testhrarr.c内核模块/驱动程序和Makefile（以下）。它演示了硬件观察点跟踪可以通过两种方式实现：使用perf程序，可以在不改变的情况下探测驱动程序；或者通过向驱动程序添加一些硬件断点代码（在示例中，由HWDEBUG_STACK定义变量）。
本质上，调试标准原子变量类型（如 int）的内容（如runcount变量）很简单，只要它们在内核模块中定义为全局变量，因此它们最终会在全局范围内显示为内核符号。因此，下面的代码添加了testhrarr_作为变量的前缀（以避免命名冲突）。但是，由于需要取消引用，调试数组的内容可能会有点棘手 - 这就是本文演示的内容，调试数组的第一个字节testhrarr_arr大批。它是在以下时间完成的：
$ echo `cat /etc/lsb-release`
DISTRIB_ID=Ubuntu DISTRIB_RELEASE=11.04 DISTRIB_CODENAME=natty DISTRIB_DESCRIPTION="Ubuntu 11.04"
$ uname -a
Linux mypc 2.6.38-16-generic #67-Ubuntu SMP Thu Sep 6 18:00:43 UTC 2012 i686 i686 i386 GNU/Linux
$ cat /proc/cpuinfo | grep "model name"
model name : Intel(R) Atom(TM) CPU N450 @ 1.66GHz
model name : Intel(R) Atom(TM) CPU N450 @ 1.66GHz
The testhrarr模块基本上在模块初始化时为一个小数组分配内存，设置一个计时器函数，并公开一个/proc/testhrarr_proc文件（使用较新的proc_create界面）。然后，尝试从/proc/testhrarr_proc文件（例如，使用cat）将触发定时器功能，这将修改testhrarr_arr数组值，并将消息转储到/var/log/syslog。我们期望testhrarr_arr[0]运行过程中会改变3次；曾在testhrarr_startup，并两次testhrarr_timer_function（由于包装）。
using perf
构建模块后make，您可以使用以下命令加载它：
sudo insmod ./testhrarr.ko
在那时候，/var/log/syslog将包含：
kernel: [40277.199913] Init testhrarr: 0 ; HZ: 250 ; 1/HZ (ms): 4 ; hrres: 0.000000001
kernel: [40277.199930] Addresses: _runcount 0xf84be22c ; _arr 0xf84be2a0 ; _arr[0] 0xed182a80 (0xed182a80) ; _timer_function 0xf84bc1c3 ; my_hrtimer 0xf84be260; my_hrt.f 0xf84be27c
kernel: [40277.220329] HW Breakpoint for testhrarr_arr write installed (0xf84be2a0)
请注意，只是通过testhrarr_arr作为硬件观察点的符号扫描该变量的地址（0xf84be2a0)，而不是数组第一个元素的地址 (0xed182a80）！因此，硬件断点是not将要触发 - 因此行为就像硬件断点代码根本不存在一样（这可以通过取消定义来实现）HWDEBUG_STACK)!
因此，即使没有通过内核模块代码设置硬件断点，我们仍然可以使用perf观察内存地址的变化 - 在perf，我们指定我们想要观看的地址（这里是第一个元素的地址testhrarr_arr, 0xed182a80），以及应该运行的进程：这里我们运行bash，所以我们可以执行cat /proc/testhrarr_proc这将触发内核模块计时器，然后是sleep 0.5这将使计时器完成。这-a还需要参数，否则可能会错过一些事件：
$ sudo perf record -a --call-graph --event=mem:0xed182a80:w bash -c 'cat /proc/testhrarr_proc ; sleep 0.5'
testhrarr proc: startup
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.485 MB perf.data (~21172 samples) ]
在此刻，/var/log/syslog还会包含类似的内容：
[40822.114964] testhrarr_timer_function: testhrarr_runcount 0
[40822.114980] testhrarr jiffies 10130528 ; ret: 1 ; ktnsec: 40822114975062
[40822.118956] testhrarr_timer_function: testhrarr_runcount 1
[40822.118977] testhrarr jiffies 10130529 ; ret: 1 ; ktnsec: 40822118973195
[40822.122940] testhrarr_timer_function: testhrarr_runcount 2
[40822.122956] testhrarr jiffies 10130530 ; ret: 1 ; ktnsec: 40822122951143
[40822.126962] testhrarr_timer_function: testhrarr_runcount 3
[40822.126978] testhrarr jiffies 10130531 ; ret: 1 ; ktnsec: 40822126973583
[40822.130941] testhrarr_timer_function: testhrarr_runcount 4
[40822.130961] testhrarr jiffies 10130532 ; ret: 1 ; ktnsec: 40822130955167
[40822.134940] testhrarr_timer_function: testhrarr_runcount 5
[40822.134962] testhrarr jiffies 10130533 ; ret: 1 ; ktnsec: 40822134958888
[40822.138936] testhrarr_timer_function: testhrarr_runcount 6
[40822.138958] testhrarr jiffies 10130534 ; ret: 1 ; ktnsec: 40822138955693
[40822.142940] testhrarr_timer_function: testhrarr_runcount 7
[40822.142962] testhrarr jiffies 10130535 ; ret: 1 ; ktnsec: 40822142959345
[40822.146936] testhrarr_timer_function: testhrarr_runcount 8
[40822.146957] testhrarr jiffies 10130536 ; ret: 1 ; ktnsec: 40822146954479
[40822.150949] testhrarr_timer_function: testhrarr_runcount 9
[40822.150970] testhrarr jiffies 10130537 ; ret: 1 ; ktnsec: 40822150963438
[40822.154974] testhrarr_timer_function: testhrarr_runcount 10
[40822.154988] testhrarr [ 5, 7, 9, 11, 13, ]
读取捕获的perf（一个名为perf.data） 我们可以用：
$ sudo perf report --call-graph flat --stdio
No kallsyms or vmlinux with build-id 5031df4d8668bcc45a7bdb4023909c6f8e2d3d34 was found
[testhrarr] with build id 5031df4d8668bcc45a7bdb4023909c6f8e2d3d34 not found, continuing without symbols
Failed to open /bin/cat, continuing without symbols
Failed to open /usr/lib/libpixman-1.so.0.20.2, continuing without symbols
Failed to open /usr/lib/xorg/modules/drivers/intel_drv.so, continuing without symbols
Failed to open /usr/bin/Xorg, continuing without symbols
# Events: 5 unknown
#
# Overhead Command Shared Object Symbol
# ........ ....... ............. ....................................
#
87.50% Xorg [testhrarr] [k] testhrarr_timer_function
87.50%
testhrarr_timer_function
__run_hrtimer
hrtimer_interrupt
smp_apic_timer_interrupt
apic_timer_interrupt
0x30185d
0x2ed701
0x2ed8cc
0x2edba0
0x9d0386
0x8126fc8
0x81217a1
0x811bdd3
0x8070aa7
0x806281c
__libc_start_main
0x8062411
6.25% cat [testhrarr] [k] testhrarr_timer_function
6.25%
testhrarr_timer_function
testhrarr_proc_show
seq_read
proc_reg_read
vfs_read
sys_read
syscall_call
0xaa2416
0x8049f4d
__libc_start_main
0x8049081
3.12% swapper [testhrarr] [k] testhrarr_timer_function
3.12%
testhrarr_timer_function
__run_hrtimer
hrtimer_interrupt
smp_apic_timer_interrupt
apic_timer_interrupt
cpuidle_idle_call
cpu_idle
start_secondary
3.12% cat [testhrarr] [k] 0x356
3.12%
0xf84bc356
0xf84bc3a7
seq_read
proc_reg_read
vfs_read
sys_read
syscall_call
0xaa2416
0x8049f4d
__libc_start_main
0x8049081
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
因此，由于我们正在构建内核模块并进行调试（-g in the Makefile），这不是问题perf找到该模块的符号，即使实时内核不是调试内核。所以它正确解释testhrarr_timer_function大多数时候作为二传手，尽管它不报告testhrarr_startup（但它确实报告testhrarr_proc_show这就是所谓的）。也有参考文献0xf84bc3a7 and 0xf84bc356它无法解决；但是，请注意该模块的加载时间为0xf84bc000:
$ sudo cat /proc/modules | grep testhr
testhrarr 13433 0 - Live 0xf84bc000
...该条目也以...[k] 0x356;如果我们看看objdump内核模块的：
$ objdump -S testhrarr.ko | less
...
00000323 :
static void testhrarr_startup(void)
{
...
testhrarr_arr[0] = 0; //just the first element
34b: a1 80 00 00 00 mov 0x80,%eax
350: c7 00 00 00 00 00 movl $0x0,(%eax)
hrtimer_start(&my;_hrtimer, ktime_period_ns, HRTIMER_MODE_REL);
356: c7 04 24 01 00 00 00 movl $0x1,(%esp) **********
35d: 8b 15 1c 00 00 00 mov 0x1c,%edx
...
00000375 :
static int testhrarr_proc_show(struct seq_file *m, void *v) {
...
seq_printf(m, "testhrarr proc: startup\n");
38f: c7 44 24 04 79 00 00 movl $0x79,0x4(%esp)
396: 00
397: 8b 45 fc mov -0x4(%ebp),%eax
39a: 89 04 24 mov %eax,(%esp)
39d: e8 fc ff ff ff call 39e
testhrarr_startup();
3a2: e8 7c ff ff ff call 323
3a7: eb 1c jmp 3c5 **********
} else {
seq_printf(m, "testhrarr proc: (is running, %d)\n", testhrarr_runcount);
3a9: a1 0c 00 00 00 mov 0xc,%eax
...
... so 0xf84bc356显然是指hrtimer_start; and 0xf84bc3a7 -> 3a7指的是它的调用testhrarr_proc_show功能;值得庆幸的是，这是有道理的。 （请注意，我体验过不同版本的驱动程序，_start可以显示，并且timer_function用纯粹的地址来表达；不确定这是由于什么）。
有一个问题perf不过，它给了我这些函数发生的统计“开销”（不确定它指的是什么——可能是函数进入和退出之间花费的时间？）——但我真正想要的是堆栈日志跟踪是连续的。不知道perf可以为此进行设置 - 但它肯定是通过硬件断点的内核模块代码来完成的。
使用内核模块硬件断点
代码位于HWDEBUG_STACK实现硬件断点设置和处理。如前所述，符号的默认设置ksym_name（如果未指定），是testhrarr_arr，这根本不会触发硬件断点。这ksym_name可以在命令行中指定参数insmod;这里我们可以注意到：
$ sudo rmmod testhrarr # remove module if still loaded
$ sudo insmod ./testhrarr.ko ksym=testhrarr_arr[0]
... 结果与HW Breakpoint for testhrarr_arr[0] write installed (0x (null)) in /var/log/syslog; - 这意味着我们不能使用带有括号表示法的符号进行数组访问；值得庆幸的是，这里的空指针仅仅意味着硬件断点将再次不会触发；它不会使操作系统完全崩溃:)
然而，有一个全局变量来引用第一个元素testhrarr_arr数组，称为testhrarr_arr_first- 注意这个全局变量在代码中是如何特殊处理的，需要解引用，这样才能获得正确的地址。所以我们这样做：
$ sudo rmmod testhrarr # remove module if still loaded
$ sudo insmod ./testhrarr.ko ksym=testhrarr_arr_first
...并且系统日志通知：
kernel: [43910.509726] Init testhrarr: 0 ; HZ: 250 ; 1/HZ (ms): 4 ; hrres: 0.000000001
kernel: [43910.509765] Addresses: _runcount 0xf84be22c ; _arr 0xf84be2a0 ; _arr[0] 0xedf6c5c0 (0xedf6c5c0) ; _timer_function 0xf84bc1c3 ; my_hrtimer 0xf84be260; my_hrt.f 0xf84be27c
kernel: [43910.538535] HW Breakpoint for testhrarr_arr_first write installed (0xedf6c5c0)
...我们可以看到硬件断点设置在0xedf6c5c0，这是地址testhrarr_arr[0]。现在，如果我们通过以下方式触发驱动程序/proc file:
$ cat /proc/testhrarr_proc
testhrarr proc: startup
...我们得到syslog:
kernel: [44069.735695] testhrarr_arr_first value is changed
[44069.735711] Pid: 29320, comm: cat Not tainted 2.6.38-16-generic #67-Ubuntu
[44069.735719] Call Trace:
[44069.735737] [] ? sample_hbp_handler+0x2d/0x3b [testhrarr]
[44069.735755] [] ? __perf_event_overflow+0x90/0x240
[44069.735768] [] ? proc_alloc_inode+0x23/0x90
[44069.735778] [] ? proc_alloc_inode+0x23/0x90
[44069.735790] [] ? perf_swevent_event+0x136/0x140
[44069.735801] [] ? perf_bp_event+0x70/0x80
[44069.735812] [] ? prep_new_page+0x110/0x1a0
[44069.735824] [] ? get_page_from_freelist+0x12e/0x320
[44069.735836] [] ? seq_open+0x3d/0xa0
[44069.735848] [] ? hw_breakpoint_handler.clone.0+0x102/0x130
[44069.735861] [] ? hw_breakpoint_exceptions_notify+0x22/0x30
[44069.735872] [] ? notifier_call_chain+0x45/0x60
[44069.735883] [] ? atomic_notifier_call_chain+0x22/0x30
[44069.735894] [] ? notify_die+0x2d/0x30
[44069.735904] [] ? do_debug+0x88/0x180
[44069.735915] [] ? debug_stack_correct+0x30/0x38
[44069.735928] [] ? testhrarr_startup+0x33/0x52 [testhrarr]
[44069.735940] [] ? testhrarr_proc_show+0x32/0x57 [testhrarr]
[44069.735952] [] ? seq_read+0x145/0x390
[44069.735963] [] ? seq_read+0x0/0x390
[44069.735973] [] ? proc_reg_read+0x64/0xa0
[44069.735985] [] ? vfs_read+0x9f/0x160
[44069.735995] [] ? proc_reg_read+0x0/0xa0
[44069.736003] [] ? sys_read+0x42/0x70
[44069.736013] [] ? syscall_call+0x7/0xb
[44069.736019] Dump stack from sample_hbp_handler
[44069.740132] testhrarr_timer_function: testhrarr_runcount 0
[44069.740146] testhrarr jiffies 10942435 ; ret: 1 ; ktnsec: 44069740142485
[44069.740159] testhrarr_arr_first value is changed
[44069.740169] Pid: 4302, comm: gnome-terminal Not tainted 2.6.38-16-generic #67-Ubuntu
[44069.740176] Call Trace:
[44069.740195] [] ? sample_hbp_handler+0x2d/0x3b [testhrarr]
[44069.740213] [] ? __perf_event_overflow+0x90/0x240
[44069.740227] [] ? perf_swevent_event+0x136/0x140
[44069.740239] [] ? perf_bp_event+0x70/0x80
[44069.740253] [] ? sched_clock_local+0xd3/0x1c0
[44069.740267] [] ? format_decode+0x323/0x380
[44069.740280] [] ? hw_breakpoint_handler.clone.0+0x102/0x130
[44069.740292] [] ? hw_breakpoint_exceptions_notify+0x22/0x30
[44069.740302] [] ? notifier_call_chain+0x45/0x60
[44069.740313] [] ? atomic_notifier_call_chain+0x22/0x30
[44069.740324] [] ? notify_die+0x2d/0x30
[44069.740335] [] ? do_debug+0x88/0x180
[44069.740345] [] ? debug_stack_correct+0x30/0x38
[44069.740364] [] ? init_intel_cacheinfo+0x103/0x394
[44069.740379] [] ? testhrarr_timer_function+0xed/0x160 [testhrarr]
[44069.740391] [] ? __run_hrtimer+0x6f/0x190
[44069.740404] [] ? testhrarr_timer_function+0x0/0x160 [testhrarr]
[44069.740416] [] ? hrtimer_interrupt+0x108/0x240
[44069.740430] [] ? smp_apic_timer_interrupt+0x56/0x8a
[44069.740441] [] ? apic_timer_interrupt+0x31/0x38
[44069.740453] [] ? _raw_spin_unlock_irqrestore+0x15/0x20
[44069.740465] [] ? try_to_del_timer_sync+0x67/0xb0
[44069.740476] [] ? del_timer_sync+0x29/0x50
[44069.740486] [] ? flush_delayed_work+0x13/0x40
[44069.740500] [] ? tty_flush_to_ldisc+0x12/0x20
[44069.740510] [] ? n_tty_poll+0x4f/0x190
[44069.740523] [] ? tty_poll+0x6d/0x90
[44069.740531] [] ? n_tty_poll+0x0/0x190
[44069.740542] [] ? do_poll.clone.3+0xd0/0x210
[44069.740553] [] ? do_sys_poll+0x134/0x1e0
[44069.740563] [] ? __pollwait+0x0/0xd0
[44069.740572] [] ? pollwake+0x0/0x60
...
[44069.740742] [] ? pollwake+0x0/0x60
[44069.740757] [] ? rw_verify_area+0x6c/0x130
[44069.740770] [] ? ktime_get_ts+0xf8/0x120
[44069.740781] [] ? poll_select_set_timeout+0x64/0x70
[44069.740793] [] ? sys_poll+0x5a/0xd0
[44069.740804] [] ? syscall_call+0x7/0xb
[44069.740815] [] ? init_intel_cacheinfo+0x23/0x394
[44069.740822] Dump stack from sample_hbp_handler
[44069.744130] testhrarr_timer_function: testhrarr_runcount 1
[44069.744143] testhrarr jiffies 10942436 ; ret: 1 ; ktnsec: 44069744140055
[44069.748132] testhrarr_timer_function: testhrarr_runcount 2
[44069.748145] testhrarr jiffies 10942437 ; ret: 1 ; ktnsec: 44069748141271
[44069.752131] testhrarr_timer_function: testhrarr_runcount 3
[44069.752145] testhrarr jiffies 10942438 ; ret: 1 ; ktnsec: 44069752141164
[44069.756131] testhrarr_timer_function: testhrarr_runcount 4
[44069.756141] testhrarr jiffies 10942439 ; ret: 1 ; ktnsec: 44069756138318
[44069.760130] testhrarr_timer_function: testhrarr_runcount 5
[44069.760141] testhrarr jiffies 10942440 ; ret: 1 ; ktnsec: 44069760138469
[44069.760154] testhrarr_arr_first value is changed
[44069.760164] Pid: 4302, comm: gnome-terminal Not tainted 2.6.38-16-generic #67-Ubuntu
[44069.760170] Call Trace:
[44069.760187] [] ? sample_hbp_handler+0x2d/0x3b [testhrarr]
[44069.760202] [] ? __perf_event_overflow+0x90/0x240
[44069.760213] [] ? perf_swevent_event+0x136/0x140
[44069.760224] [] ? perf_bp_event+0x70/0x80
[44069.760235] [] ? sched_clock_local+0xd3/0x1c0
[44069.760247] [] ? format_decode+0x323/0x380
[44069.760258] [] ? hw_breakpoint_handler.clone.0+0x102/0x130
[44069.760269] [] ? hw_breakpoint_exceptions_notify+0x22/0x30
[44069.760279] [] ? notifier_call_chain+0x45/0x60
[44069.760289] [] ? atomic_notifier_call_chain+0x22/0x30
[44069.760299] [] ? notify_die+0x2d/0x30
[44069.760308] [] ? do_debug+0x88/0x180
[44069.760318] [] ? debug_stack_correct+0x30/0x38
[44069.760334] [] ? init_intel_cacheinfo+0x103/0x394
[44069.760345] [] ? testhrarr_timer_function+0xed/0x160 [testhrarr]
[44069.760356] [] ? __run_hrtimer+0x6f/0x190
[44069.760366] [] ? send_to_group.clone.1+0xf8/0x150
[44069.760376] [] ? testhrarr_timer_function+0x0/0x160 [testhrarr]
[44069.760387] [] ? hrtimer_interrupt+0x108/0x240
[44069.760396] [] ? fsnotify+0x1a5/0x290
[44069.760407] [] ? smp_apic_timer_interrupt+0x56/0x8a
[44069.760416] [] ? apic_timer_interrupt+0x31/0x38
[44069.760428] [] ? mem_cgroup_resize_limit+0x108/0x1c0
[44069.760437] [] ? fput+0x0/0x30
[44069.760446] [] ? sys_write+0x67/0x70
[44069.760455] [] ? syscall_call+0x7/0xb
[44069.760464] [] ? init_intel_cacheinfo+0x23/0x394
[44069.760470] Dump stack from sample_hbp_handler
[44069.764134] testhrarr_timer_function: testhrarr_runcount 6
[44069.764147] testhrarr jiffies 10942441 ; ret: 1 ; ktnsec: 44069764144141
[44069.768133] testhrarr_timer_function: testhrarr_runcount 7
[44069.768146] testhrarr jiffies 10942442 ; ret: 1 ; ktnsec: 44069768142976
[44069.772134] testhrarr_timer_function: testhrarr_runcount 8
[44069.772148] testhrarr jiffies 10942443 ; ret: 1 ; ktnsec: 44069772144121
[44069.776132] testhrarr_timer_function: testhrarr_runcount 9
[44069.776145] testhrarr jiffies 10942444 ; ret: 1 ; ktnsec: 44069776141971
[44069.780133] testhrarr_timer_function: testhrarr_runcount 10
[44069.780141] testhrarr [ 5, 7, 9, 11, 13, ]
...我们得到了三次堆栈跟踪 - 一次在testhrarr_startup，并两次testhrarr_timer_function: 一次runcount==0一次runcount==5，正如预期的那样。
好吧，希望这对某人有帮助，
Cheers!
Makefile
CONFIG_MODULE_FORCE_UNLOAD=y
# debug build:
# "CFLAGS was changed ... Fix it to use EXTRA_CFLAGS."
override EXTRA_CFLAGS+=-g -O0
obj-m += testhrarr.o
#testhrarr-objs := testhrarr.o
all:
@echo EXTRA_CFLAGS = $(EXTRA_CFLAGS)
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
testhrarr.c
/*
* [http://www.tldp.org/LDP/lkmpg/2.6/html/lkmpg.html#AEN189 The Linux Kernel Module Programming Guide]
* https://stackoverflow.com/questions/16920238/reliability-of-linux-kernel-add-timer-at-resolution-of-one-jiffy/17055867#17055867
* https://stackoverflow.com/questions/8516021/proc-create-example-for-kernel-module/18924359#18924359
* http://lxr.free-electrons.com/source/samples/hw_breakpoint/data_breakpoint.c
*/
#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
#include <linux/init.h> /* Needed for the macros */
#include <linux/jiffies.h>
#include <linux/time.h>
#include <linux/proc_fs.h> /* /proc entry */
#include <linux/seq_file.h> /* /proc entry */
#define ARRSIZE 5
#define MAXRUNS 2*ARRSIZE
#include <linux/hrtimer.h>
#define HWDEBUG_STACK 1
#if (HWDEBUG_STACK == 1)
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
struct perf_event * __percpu *sample_hbp;
static char ksym_name[KSYM_NAME_LEN] = "testhrarr_arr";
module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any"
" write operations on the kernel symbol");
#endif
static volatile int testhrarr_runcount = 0;
static volatile int testhrarr_isRunning = 0;
static unsigned long period_ms;
static unsigned long period_ns;
static ktime_t ktime_period_ns;
static struct hrtimer my_hrtimer;
static int* testhrarr_arr;
static int* testhrarr_arr_first;
static enum hrtimer_restart testhrarr_timer_function(struct hrtimer *timer)
{
unsigned long tjnow;
ktime_t kt_now;
int ret_overrun;
printk(KERN_INFO
" %s: testhrarr_runcount %d \n",
__func__, testhrarr_runcount);
if (testhrarr_runcount < MAXRUNS) {
tjnow = jiffies;
kt_now = hrtimer_cb_get_time(&my_hrtimer);
ret_overrun = hrtimer_forward(&my_hrtimer, kt_now, ktime_period_ns);
printk(KERN_INFO
" testhrarr jiffies %lu ; ret: %d ; ktnsec: %lld\n",
tjnow, ret_overrun, ktime_to_ns(kt_now));
testhrarr_arr[(testhrarr_runcount % ARRSIZE)] += testhrarr_runcount;
testhrarr_runcount++;
return HRTIMER_RESTART;
}
else {
int i;
testhrarr_isRunning = 0;
// do not use KERN_DEBUG etc, if printk buffering until newline is desired!
printk("testhrarr_arr [ ");
for(i=0; i<ARRSIZE; i++) {
printk("%d, ", testhrarr_arr[i]);
}
printk("]\n");
return HRTIMER_NORESTART;
}
}
static void testhrarr_startup(void)
{
if (testhrarr_isRunning == 0) {
testhrarr_isRunning = 1;
testhrarr_runcount = 0;
testhrarr_arr[0] = 0; //just the first element
hrtimer_start(&my_hrtimer, ktime_period_ns, HRTIMER_MODE_REL);
}
}
static int testhrarr_proc_show(struct seq_file *m, void *v) {
if (testhrarr_isRunning == 0) {
seq_printf(m, "testhrarr proc: startup\n");
testhrarr_startup();
} else {
seq_printf(m, "testhrarr proc: (is running, %d)\n", testhrarr_runcount);
}
return 0;
}
static int testhrarr_proc_open(struct inode *inode, struct file *file) {
return single_open(file, testhrarr_proc_show, NULL);
}
static const struct file_operations testhrarr_proc_fops = {
.owner = THIS_MODULE,
.open = testhrarr_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
#if (HWDEBUG_STACK == 1)
static void sample_hbp_handler(struct perf_event *bp,
struct perf_sample_data *data,
struct pt_regs *regs)
{
printk(KERN_INFO "%s value is changed\n", ksym_name);
dump_stack();
printk(KERN_INFO "Dump stack from sample_hbp_handler\n");
}
#endif
static int __init testhrarr_init(void)
{
struct timespec tp_hr_res;
#if (HWDEBUG_STACK == 1)
struct perf_event_attr attr;
#endif
period_ms = 1000/HZ;
hrtimer_get_res(CLOCK_MONOTONIC, &tp_hr_res);
printk(KERN_INFO
"Init testhrarr: %d ; HZ: %d ; 1/HZ (ms): %ld ; hrres: %lld.%.9ld\n",
testhrarr_runcount, HZ, period_ms, (long long)tp_hr_res.tv_sec, tp_hr_res.tv_nsec );
testhrarr_arr = (int*)kcalloc(ARRSIZE, sizeof(int), GFP_ATOMIC);
testhrarr_arr_first = &testhrarr_arr[0];
hrtimer_init(&my_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
my_hrtimer.function = &testhrarr_timer_function;
period_ns = period_ms*( (unsigned long)1E6L );
ktime_period_ns = ktime_set(0,period_ns);
printk(KERN_INFO
" Addresses: _runcount 0x%p ; _arr 0x%p ; _arr[0] 0x%p (0x%p) ; _timer_function 0x%p ; my_hrtimer 0x%p; my_hrt.f 0x%p\n",
&testhrarr_runcount, &testhrarr_arr, &(testhrarr_arr[0]), testhrarr_arr_first, &testhrarr_timer_function, &my_hrtimer, &my_hrtimer.function);
proc_create("testhrarr_proc", 0, NULL, &testhrarr_proc_fops);
#if (HWDEBUG_STACK == 1)
hw_breakpoint_init(&attr);
if (strcmp(ksym_name, "testhrarr_arr_first") == 0) {
// just for testhrarr_arr_first - interpret the found symbol address
// as int*, and dereference it to get the "real" address it points to
attr.bp_addr = *((int*)kallsyms_lookup_name(ksym_name));
} else {
// the usual - address is kallsyms_lookup_name result
attr.bp_addr = kallsyms_lookup_name(ksym_name);
}
attr.bp_len = HW_BREAKPOINT_LEN_1;
attr.bp_type = HW_BREAKPOINT_W ; //| HW_BREAKPOINT_R;
sample_hbp = register_wide_hw_breakpoint(&attr, (perf_overflow_handler_t)sample_hbp_handler);
if (IS_ERR((void __force *)sample_hbp)) {
int ret = PTR_ERR((void __force *)sample_hbp);
printk(KERN_INFO "Breakpoint registration failed\n");
return ret;
}
// explicit cast needed to show 64-bit bp_addr as 32-bit address
// https://stackoverflow.com/questions/11796909/how-to-resolve-cast-to-pointer-from-integer-of-different-size-warning-in-c-co/11797103#11797103
printk(KERN_INFO "HW Breakpoint for %s write installed (0x%p)\n", ksym_name, (void*)(uintptr_t)attr.bp_addr);
#endif
return 0;
}
static void __exit testhrarr_exit(void)
{
int ret_cancel = 0;
kfree(testhrarr_arr);
while( hrtimer_callback_running(&my_hrtimer) ) {
ret_cancel++;
}
if (ret_cancel != 0) {
printk(KERN_INFO " testhrarr Waited for hrtimer callback to finish (%d)\n", ret_cancel);
}
if (hrtimer_active(&my_hrtimer) != 0) {
ret_cancel = hrtimer_cancel(&my_hrtimer);
printk(KERN_INFO " testhrarr active hrtimer cancelled: %d (%d)\n", ret_cancel, testhrarr_runcount);
}
if (hrtimer_is_queued(&my_hrtimer) != 0) {
ret_cancel = hrtimer_cancel(&my_hrtimer);
printk(KERN_INFO " testhrarr queued hrtimer cancelled: %d (%d)\n", ret_cancel, testhrarr_runcount);
}
remove_proc_entry("testhrarr_proc", NULL);
#if (HWDEBUG_STACK == 1)
unregister_wide_hw_breakpoint(sample_hbp);
printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name);
#endif
printk(KERN_INFO "Exit testhrarr\n");
}
module_init(testhrarr_init);
module_exit(testhrarr_exit);
MODULE_LICENSE("GPL");
