显然，使用内核 3.5+ 上的内置 uprobes 会容易得多；但鉴于我的内核 2.6.38 的 uprobes 是一个非常深入的补丁（我无法真正将其隔离在单独的内核模块中，以避免修补内核），这是我可以为独立模块注意的内容在 2.6.38。（由于我仍然不确定很多事情，我仍然希望看到一个可以纠正本文中任何误解的答案。）
我想我到了某个地方，但没有kprobes。我不确定，但似乎我设法获得了正确的物理地址；但是，kprobes文档是特定的，当使用“ @ADDR : fetch memory at ADDR (ADDR should be in kernel) ”时；并且我得到的物理地址低于 0xc0000000 的内核边界（但是，0xc0000000 通常与虚拟内存布局一起？）。
所以我改用了硬件断点——模块在下面，但是需要注意的是——它的行为是随机的，偶尔会导致内核糟糕！通过编译模块并运行bash：
$ sudo bash -c 'KDBGPATH="/sys/kernel/debug/tracing" ;
echo function_graph > $KDBGPATH/current_tracer ; echo funcgraph-abstime > $KDBGPATH/trace_options
echo funcgraph-proc > $KDBGPATH/trace_options ; echo 8192 > $KDBGPATH/buffer_size_kb ;
echo 0 > $KDBGPATH/tracing_on ; echo > $KDBGPATH/trace'
$ sudo insmod ./callmodule.ko && sleep 0.1 && sudo rmmod callmodule && \
tail -n25 /var/log/syslog | tee log.txt && \
sudo cat /sys/kernel/debug/tracing/trace >> log.txt
...我得到一个日志。我想跟踪 of 的前两个指令，main()对wtest我来说是：
$ objdump -S wtest/wtest | grep -A3 'int main'
int main(void) {
8048474: 55 push %ebp
8048475: 89 e5 mov %esp,%ebp
8048477: 83 e4 f0 and $0xfffffff0,%esp
...在虚拟地址 0x08048474 和 0x08048475。在syslog输出中，我可以说：
...
[ 1106.383011] callmodule: parent task a: f40a9940 c: kworker/u:1 p: [14] s: stopped
[ 1106.383017] callmodule: - wtest [9404]
[ 1106.383023] callmodule: Trying to walk page table; addr task 0xEAE90CA0 ->mm ->start_code: 0x08048000 ->end_code: 0x080485F4
[ 1106.383029] callmodule: walk_ 0x8048000 callmodule: Valid pgd : Valid pud: Valid pmd: page frame struct is @ f63e5d80; *virtual (page_address) @ (null) (is_vmalloc_addr 0 virt_addr_valid 0 virt_to_phys 0x40000000) page_to_pfn 639ec page_to_phys 0x639ec000
[ 1106.383049] callmodule: walk_ 0x80483c0 callmodule: Valid pgd : Valid pud: Valid pmd: page frame struct is @ f63e5d80; *virtual (page_address) @ (null) (is_vmalloc_addr 0 virt_addr_valid 0 virt_to_phys 0x40000000) page_to_pfn 639ec page_to_phys 0x639ec000
[ 1106.383067] callmodule: walk_ 0x8048474 callmodule: Valid pgd : Valid pud: Valid pmd: page frame struct is @ f63e5d80; *virtual (page_address) @ (null) (is_vmalloc_addr 0 virt_addr_valid 0 virt_to_phys 0x40000000) page_to_pfn 639ec page_to_phys 0x639ec000
[ 1106.383083] callmodule: physaddr : (0x080483c0 ->) 0x639ec3c0 : (0x08048474 ->) 0x639ec474
[ 1106.383106] callmodule: 0x08048474 id [3]
[ 1106.383113] callmodule: 0x08048475 id [4]
[ 1106.383118] callmodule: (( 0x08048000 is_vmalloc_addr 0 virt_addr_valid 0 ))
[ 1106.383130] callmodule: cont pid task a: eae90ca0 c: wtest p: [9404] s: runnable
[ 1106.383147] initcall callmodule_init+0x0/0x1000 [callmodule] returned with preemption imbalance
[ 1106.518074] callmodule: < exit
...意味着它将虚拟地址 0x08048474 映射到物理地址 0x639ec474。但是，物理断点不用于硬件断点 - 我们可以直接提供虚拟地址register_user_hw_breakpoint；但是，我们也需要提供task_struct进程的。有了这个，我可以在ftrace输出中得到这样的东西：
...
597.907256 | 1) wtest-5339 | | handle_mm_fault() {
...
597.907310 | 1) wtest-5339 | + 35.627 us | }
597.907311 | 1) wtest-5339 | + 46.245 us | }
597.907312 | 1) wtest-5339 | + 56.143 us | }
597.907313 | 1) wtest-5339 | 1.039 us | up_read();
597.907317 | 1) wtest-5339 | 1.285 us | native_get_debugreg();
597.907319 | 1) wtest-5339 | 1.075 us | native_set_debugreg();
597.907322 | 1) wtest-5339 | 1.129 us | native_get_debugreg();
597.907324 | 1) wtest-5339 | 1.189 us | native_set_debugreg();
597.907329 | 1) wtest-5339 | | () {
597.907333 | 1) wtest-5339 | | /* callmodule: hwbp hit: id [3] */
597.907334 | 1) wtest-5339 | 5.567 us | }
597.907336 | 1) wtest-5339 | 1.123 us | native_set_debugreg();
597.907339 | 1) wtest-5339 | 1.130 us | native_get_debugreg();
597.907341 | 1) wtest-5339 | 1.075 us | native_set_debugreg();
597.907343 | 1) wtest-5339 | 1.075 us | native_get_debugreg();
597.907345 | 1) wtest-5339 | 1.081 us | native_set_debugreg();
597.907348 | 1) wtest-5339 | | () {
597.907350 | 1) wtest-5339 | | /* callmodule: hwbp hit: id [4] */
597.907351 | 1) wtest-5339 | 3.033 us | }
597.907352 | 1) wtest-5339 | 1.105 us | native_set_debugreg();
597.907358 | 1) wtest-5339 | 1.315 us | down_read_trylock();
597.907360 | 1) wtest-5339 | 1.123 us | _cond_resched();
597.907362 | 1) wtest-5339 | 1.027 us | find_vma();
597.907364 | 1) wtest-5339 | | handle_mm_fault() {
...
...其中与程序集对应的跟踪由断点 id 标记。值得庆幸的是，正如预期的那样，他们一个接一个。但是，ftrace也捕获了一些中间的调试命令。无论如何，这就是我想看到的。
以下是有关该模块的一些说明：
- 大部分模块来自执行/调用用户空间程序，并从内核模块获取其 pid；启动用户进程并获得 pid
- 因为我们必须到达 task_struct 才能到达 pid；在这里我都保存了（这有点多余）
- 不导出函数符号的地方；如果符号在
kallsyms，那么我使用指向地址的函数指针；否则其他需要的功能是从源代码复制的
- 我不知道如何启动用户空间进程停止，所以在生成后我发出 a
SIGSTOP（它本身似乎有点不可靠），并将状态设置为__TASK_STOPPED）。
- 我有时可能仍然会在我不期望的情况下获得“可运行”状态 - 但是，如果 init 因错误而提前退出，我注意到
wtest它会在自然终止后很长时间挂在进程列表中，所以我想这可行。
- 为了获取绝对/物理地址，我在 Linux 中使用遍历进程的页表来获取与虚拟地址对应的页面，然后挖掘我找到的内核源代码
page_to_phys()以获取该地址（内部通过页框号）；LDD3 ch.15 有助于理解 pfn 和物理地址之间的关系。
- 因为这里我希望有物理地址，所以我不使用 PAGE_SHIFT，而是直接从
objdump的汇编输出中计算偏移量——不过，我不能 100% 确定这是正确的。
- 请注意，（另请参阅如何从 Linux 内核中的任何地址获取结构页面），模块输出显示虚拟地址
0x08048000既不是is_vmalloc_addr也不是virt_addr_valid；我想，这应该告诉我，一个人既不能使用也vmalloc_to_pfn()不能到达virt_to_page()它的物理地址！？
- 从内核空间设置有点棘手（需要复制函数
kprobes）ftrace
- 尝试
kprobe在我得到的物理地址上设置 a（例如 0x639ec474），总是导致“无法插入探针（-22） ”
- 只是为了查看格式是否被解析，我正在尝试使用下面
kallsyms的函数地址tracing_on()（0xc10bcf60）；这似乎可行——因为它引发了一个致命的“ BUG：原子时调度”（显然，我们不打算在 module_init 中设置断点？）。错误是致命的，因为它使kprobes目录从ftrace调试目录中消失
- 只是创建
kprobe不会让它出现在ftrace日志中 - 它还需要启用；启用的必要代码在那里 - 但我从未尝试过，因为以前的错误
- 最后，断点设置是从Watch a variable (memory address) change in Linux kernel, and print stack trace when it change?
- 我从未见过设置可执行硬件断点的示例；它对我来说一直失败，直到通过内核源搜索，我发现 for
HW_BREAKPOINT_X,attr.bp_len需要设置为sizeof(long)
- 如果我尝试
printk使用attr变量 - 从 _init 或从处理程序 - 事情会严重混乱，无论我接下来尝试打印什么变量，我都会得到它的值 0x5（或 0x48）（？！）
- 由于我试图对两个断点使用单个处理程序函数，从 _init 到处理程序的唯一可靠信息，能够区分两者，似乎是
bp->id
- 这些 id 是自动分配的，如果您取消注册断点，它们似乎不会被重新声明（我不会取消注册它们以避免额外的 ftrace 打印输出）。
就随机性而言，我认为这是因为进程不是在停止状态下启动的；当它停止时，它最终处于不同的状态（或者，很可能，我在某处丢失了一些锁定）。无论如何，您也可以期待syslog：
[ 1661.815114] callmodule: Trying to walk page table; addr task 0xEAF68CA0 ->mm ->start_code: 0x08048000 ->end_code: 0x080485F4
[ 1661.815319] callmodule: walk_ 0x8048000 callmodule: Valid pgd : Valid pud: Valid pmd: page frame struct is @ f5772000; *virtual (page_address) @ c0000000 (is_vmalloc_addr 0 virt_addr_valid 1 virt_to_phys 0x0) page_to_pfn 0 page_to_phys 0x0
[ 1661.815837] callmodule: walk_ 0x80483c0 callmodule: Valid pgd : Valid pud: Valid pmd: page frame struct is @ f5772000; *virtual (page_address) @ c0000000 (is_vmalloc_addr 0 virt_addr_valid 1 virt_to_phys 0x0) page_to_pfn 0 page_to_phys 0x0
[ 1661.816846] callmodule: walk_ 0x8048474 callmodule: Valid pgd : Valid pud: Valid pmd: page frame struct is @ f5772000; *virtual (page_address) @ c0000000 (is_vmalloc_addr 0 virt_addr_valid 1 virt_to_phys 0x0) page_to_pfn 0 page_to_phys 0x0
...也就是说，即使使用正确的任务指针（通过 start_code 判断），也只能获得 0x0 作为物理地址。有时您会得到相同的结果，但使用start_code: 0x00000000 ->end_code: 0x00000000. 有时，atask_struct无法获得，即使 pid 可以：
[ 833.380417] callmodule:c: pid 7663
[ 833.380424] callmodule: everything all right; pid 7663 (7663)
[ 833.380430] callmodule: p is NULL - exiting
[ 833.516160] callmodule: < exit
好吧，希望有人会评论并澄清这个模块的一些行为:)
希望这对某人有帮助，
干杯！
Makefile：
EXTRA_CFLAGS=-g -O0
obj-m += callmodule.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
callmodule.c：
#include <linux/module.h>
#include <linux/slab.h> //kzalloc
#include <linux/syscalls.h> // SIGCHLD, ... sys_wait4, ...
#include <linux/kallsyms.h> // kallsyms_lookup, print_symbol
#include <linux/highmem.h> // ‘kmap_atomic’ (via pte_offset_map)
#include <asm/io.h> // page_to_phys (arch/x86/include/asm/io.h)
struct subprocess_infoB; // forward declare
// global variable - to avoid intervening too much in the return of call_usermodehelperB:
static int callmodule_pid;
static struct subprocess_infoB* callmodule_infoB;
#define TRY_USE_KPROBES 0 // 1 // enable/disable kprobes usage code
#include <linux/kprobes.h> // enable_kprobe
// for hardware breakpoint:
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
// define a modified struct (with extra fields) here:
struct subprocess_infoB {
struct work_struct work;
struct completion *complete;
char *path;
char **argv;
char **envp;
int wait; //enum umh_wait wait;
int retval;
int (*init)(struct subprocess_info *info);
void (*cleanup)(struct subprocess_info *info);
void *data;
pid_t pid;
struct task_struct *task;
unsigned long long last_page_physaddr;
};
struct subprocess_infoB *call_usermodehelper_setupB(char *path, char **argv,
char **envp, gfp_t gfp_mask);
static inline int
call_usermodehelper_fnsB(char *path, char **argv, char **envp,
int wait, //enum umh_wait wait,
int (*init)(struct subprocess_info *info),
void (*cleanup)(struct subprocess_info *), void *data)
{
struct subprocess_info *info;
struct subprocess_infoB *infoB;
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
int ret;
populate_rootfs_wait();
infoB = call_usermodehelper_setupB(path, argv, envp, gfp_mask);
printk(KBUILD_MODNAME ":a: pid %d\n", infoB->pid);
info = (struct subprocess_info *) infoB;
if (info == NULL)
return -ENOMEM;
call_usermodehelper_setfns(info, init, cleanup, data);
printk(KBUILD_MODNAME ":b: pid %d\n", infoB->pid);
// this must be called first, before infoB->pid is populated (by __call_usermodehelperB):
ret = call_usermodehelper_exec(info, wait);
// assign global pid (and infoB) here, so rest of the code has it:
callmodule_pid = infoB->pid;
callmodule_infoB = infoB;
printk(KBUILD_MODNAME ":c: pid %d\n", callmodule_pid);
return ret;
}
static inline int
call_usermodehelperB(char *path, char **argv, char **envp, int wait) //enum umh_wait wait)
{
return call_usermodehelper_fnsB(path, argv, envp, wait,
NULL, NULL, NULL);
}
static void __call_usermodehelperB(struct work_struct *work)
{
struct subprocess_infoB *sub_infoB =
container_of(work, struct subprocess_infoB, work);
int wait = sub_infoB->wait; // enum umh_wait wait = sub_info->wait;
pid_t pid;
struct subprocess_info *sub_info;
// hack - declare function pointers
int (*ptrwait_for_helper)(void *data);
int (*ptr____call_usermodehelper)(void *data);
// assign function pointers to verbatim addresses as obtained from /proc/kallsyms
int killret;
struct task_struct *spawned_task;
ptrwait_for_helper = (void *)0xc1065b60;
ptr____call_usermodehelper = (void *)0xc1065ed0;
sub_info = (struct subprocess_info *)sub_infoB;
if (wait == UMH_WAIT_PROC)
pid = kernel_thread((*ptrwait_for_helper), sub_info, //(wait_for_helper, sub_info,
CLONE_FS | CLONE_FILES | SIGCHLD);
else
pid = kernel_thread((*ptr____call_usermodehelper), sub_info, //(____call_usermodehelper, sub_info,
CLONE_VFORK | SIGCHLD);
spawned_task = pid_task(find_vpid(pid), PIDTYPE_PID);
// stop/suspend/pause task
killret = kill_pid(find_vpid(pid), SIGSTOP, 1);
if (spawned_task!=NULL) {
// does this stop the process really?
spawned_task->state = __TASK_STOPPED;
printk(KBUILD_MODNAME ": : exst %d exco %d exsi %d diex %d inex %d inio %d\n", spawned_task->exit_state, spawned_task->exit_code, spawned_task->exit_signal, spawned_task->did_exec, spawned_task->in_execve, spawned_task->in_iowait);
}
printk(KBUILD_MODNAME ": : (kr: %d)\n", killret);
printk(KBUILD_MODNAME ": : pid %d (%p) (%s)\n", pid, spawned_task,
(spawned_task!=NULL)?((spawned_task->state==-1)?"unrunnable":((spawned_task->state==0)?"runnable":"stopped")):"null" );
// grab and save the pid (and task_struct) here:
sub_infoB->pid = pid;
sub_infoB->task = spawned_task;
switch (wait) {
case UMH_NO_WAIT:
call_usermodehelper_freeinfo(sub_info);
break;
case UMH_WAIT_PROC:
if (pid > 0)
break;
/* FALLTHROUGH */
case UMH_WAIT_EXEC:
if (pid < 0)
sub_info->retval = pid;
complete(sub_info->complete);
}
}
struct subprocess_infoB *call_usermodehelper_setupB(char *path, char **argv,
char **envp, gfp_t gfp_mask)
{
struct subprocess_infoB *sub_infoB;
sub_infoB = kzalloc(sizeof(struct subprocess_infoB), gfp_mask);
if (!sub_infoB)
goto out;
INIT_WORK(&sub_infoB->work, __call_usermodehelperB);
sub_infoB->path = path;
sub_infoB->argv = argv;
sub_infoB->envp = envp;
out:
return sub_infoB;
}
#if TRY_USE_KPROBES
// copy from /kernel/trace/trace_probe.c (is unexported)
int traceprobe_command(const char *buf, int (*createfn)(int, char **))
{
char **argv;
int argc, ret;
argc = 0;
ret = 0;
argv = argv_split(GFP_KERNEL, buf, &argc);
if (!argv)
return -ENOMEM;
if (argc)
ret = createfn(argc, argv);
argv_free(argv);
return ret;
}
// copy from kernel/trace/trace_kprobe.c?v=2.6.38 (is unexported)
#define TP_FLAG_TRACE 1
#define TP_FLAG_PROFILE 2
typedef void (*fetch_func_t)(struct pt_regs *, void *, void *);
struct fetch_param {
fetch_func_t fn;
void *data;
};
typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *, void *);
enum {
FETCH_MTD_reg = 0,
FETCH_MTD_stack,
FETCH_MTD_retval,
FETCH_MTD_memory,
FETCH_MTD_symbol,
FETCH_MTD_deref,
FETCH_MTD_END,
};
// Fetch type information table * /
struct fetch_type {
const char *name; /* Name of type */
size_t size; /* Byte size of type */
int is_signed; /* Signed flag */
print_type_func_t print; /* Print functions */
const char *fmt; /* Fromat string */
const char *fmttype; /* Name in format file */
// Fetch functions * /
fetch_func_t fetch[FETCH_MTD_END];
};
struct probe_arg {
struct fetch_param fetch;
struct fetch_param fetch_size;
unsigned int offset; /* Offset from argument entry */
const char *name; /* Name of this argument */
const char *comm; /* Command of this argument */
const struct fetch_type *type; /* Type of this argument */
};
struct trace_probe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
unsigned long nhit;
unsigned int flags; /* For TP_FLAG_* */
const char *symbol; /* symbol name */
struct ftrace_event_class class;
struct ftrace_event_call call;
ssize_t size; /* trace entry size */
unsigned int nr_args;
struct probe_arg args[];
};
static int probe_is_return(struct trace_probe *tp)
{
return tp->rp.handler != NULL;
}
static int probe_event_enable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;
tp->flags |= TP_FLAG_TRACE;
if (probe_is_return(tp))
return enable_kretprobe(&tp->rp);
else
return enable_kprobe(&tp->rp.kp);
}
#define KPROBE_EVENT_SYSTEM "kprobes"
#endif // TRY_USE_KPROBES
// <<<<<<<<<<<<<<<<<<<<<<
static struct page *walk_page_table(unsigned long addr, struct task_struct *intask)
{
pgd_t *pgd;
pte_t *ptep, pte;
pud_t *pud;
pmd_t *pmd;
struct page *page = NULL;
struct mm_struct *mm = intask->mm;
callmodule_infoB->last_page_physaddr = 0ULL; // reset here, in case of early exit
printk(KBUILD_MODNAME ": walk_ 0x%lx ", addr);
pgd = pgd_offset(mm, addr);
if (pgd_none(*pgd) || pgd_bad(*pgd))
goto out;
printk(KBUILD_MODNAME ": Valid pgd ");
pud = pud_offset(pgd, addr);
if (pud_none(*pud) || pud_bad(*pud))
goto out;
printk( ": Valid pud");
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd) || pmd_bad(*pmd))
goto out;
printk( ": Valid pmd");
ptep = pte_offset_map(pmd, addr);
if (!ptep)
goto out;
pte = *ptep;
page = pte_page(pte);
if (page) {
callmodule_infoB->last_page_physaddr = (unsigned long long)page_to_phys(page);
printk( ": page frame struct is @ %p; *virtual (page_address) @ %p (is_vmalloc_addr %d virt_addr_valid %d virt_to_phys 0x%llx) page_to_pfn %lx page_to_phys 0x%llx", page, page_address(page), is_vmalloc_addr((void*)page_address(page)), virt_addr_valid(page_address(page)), (unsigned long long)virt_to_phys(page_address(page)), page_to_pfn(page), callmodule_infoB->last_page_physaddr);
}
//~ pte_unmap(ptep);
out:
printk("\n");
return page;
}
static void sample_hbp_handler(struct perf_event *bp,
struct perf_sample_data *data,
struct pt_regs *regs)
{
trace_printk(KBUILD_MODNAME ": hwbp hit: id [%llu]\n", bp->id );
//~ unregister_hw_breakpoint(bp);
}
// ----------------------
static int __init callmodule_init(void)
{
int ret = 0;
char userprog[] = "/path/to/wtest";
char *argv[] = {userprog, "2", NULL };
char *envp[] = {"HOME=/", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
struct task_struct *p;
struct task_struct *par;
struct task_struct *pc;
struct list_head *children_list_head;
struct list_head *cchildren_list_head;
char *state_str;
unsigned long offset, taddr;
int (*ptr_create_trace_probe)(int argc, char **argv);
struct trace_probe* (*ptr_find_probe_event)(const char *event, const char *group);
//int (*ptr_probe_event_enable)(struct ftrace_event_call *call); // not exported, copy
#if TRY_USE_KPROBES
char trcmd[256] = "";
struct trace_probe *tp;
#endif //TRY_USE_KPROBES
struct perf_event *sample_hbp, *sample_hbpb;
struct perf_event_attr attr, attrb;
printk(KBUILD_MODNAME ": > init %s\n", userprog);
ptr_create_trace_probe = (void *)0xc10d5120;
ptr_find_probe_event = (void *)0xc10d41e0;
print_symbol(KBUILD_MODNAME ": symbol @ 0xc1065b60 is %s\n", 0xc1065b60); // shows wait_for_helper+0x0/0xb0
print_symbol(KBUILD_MODNAME ": symbol @ 0xc1065ed0 is %s\n", 0xc1065ed0); // shows ____call_usermodehelper+0x0/0x90
print_symbol(KBUILD_MODNAME ": symbol @ 0xc10d5120 is %s\n", 0xc10d5120); // shows create_trace_probe+0x0/0x590
ret = call_usermodehelperB(userprog, argv, envp, UMH_WAIT_EXEC);
if (ret != 0)
printk(KBUILD_MODNAME ": error in call to usermodehelper: %i\n", ret);
else
printk(KBUILD_MODNAME ": everything all right; pid %d (%d)\n", callmodule_pid, callmodule_infoB->pid);
tracing_on(); // earlier, so trace_printk of handler is caught!
// find the task:
rcu_read_lock();
p = pid_task(find_vpid(callmodule_pid), PIDTYPE_PID);
rcu_read_unlock();
if (p == NULL) {
printk(KBUILD_MODNAME ": p is NULL - exiting\n");
return 0;
}
state_str = (p->state==-1)?"unrunnable":((p->state==0)?"runnable":"stopped");
printk(KBUILD_MODNAME ": pid task a: %p c: %s p: [%d] s: %s\n",
p, p->comm, p->pid, state_str);
// find parent task:
par = p->parent;
if (par == NULL) {
printk(KBUILD_MODNAME ": par is NULL - exiting\n");
return 0;
}
state_str = (par->state==-1)?"unrunnable":((par->state==0)?"runnable":"stopped");
printk(KBUILD_MODNAME ": parent task a: %p c: %s p: [%d] s: %s\n",
par, par->comm, par->pid, state_str);
// iterate through parent's (and our task's) child processes:
rcu_read_lock(); // read_lock(&tasklist_lock);
list_for_each(children_list_head, &par->children){
p = list_entry(children_list_head, struct task_struct, sibling);
printk(KBUILD_MODNAME ": - %s [%d] \n", p->comm, p->pid);
if (p->pid == callmodule_pid) {
list_for_each(cchildren_list_head, &p->children){
pc = list_entry(cchildren_list_head, struct task_struct, sibling);
printk(KBUILD_MODNAME ": - - %s [%d] \n", pc->comm, pc->pid);
}
}
}
rcu_read_unlock(); //~ read_unlock(&tasklist_lock);
// NOTE: here p == callmodule_infoB->task !!
printk(KBUILD_MODNAME ": Trying to walk page table; addr task 0x%X ->mm ->start_code: 0x%08lX ->end_code: 0x%08lX \n", (unsigned int) callmodule_infoB->task, callmodule_infoB->task->mm->start_code, callmodule_infoB->task->mm->end_code);
walk_page_table(0x08048000, callmodule_infoB->task);
// 080483c0 is start of .text; 08048474 start of main; for objdump -S wtest
walk_page_table(0x080483c0, callmodule_infoB->task);
walk_page_table(0x08048474, callmodule_infoB->task);
if (callmodule_infoB->last_page_physaddr != 0ULL) {
printk(KBUILD_MODNAME ": physaddr ");
taddr = 0x080483c0; // .text
offset = taddr - callmodule_infoB->task->mm->start_code;
printk(": (0x%08lx ->) 0x%08llx ", taddr, callmodule_infoB->last_page_physaddr+offset);
taddr = 0x08048474; // main
offset = taddr - callmodule_infoB->task->mm->start_code;
printk(": (0x%08lx ->) 0x%08llx ", taddr, callmodule_infoB->last_page_physaddr+offset);
printk("\n");
#if TRY_USE_KPROBES // can't use this here (BUG: scheduling while atomic, if probe inserts)
//~ sprintf(trcmd, "p:myprobe 0x%08llx", callmodule_infoB->last_page_physaddr+offset);
// try symbol for c10bcf60 - tracing_on
sprintf(trcmd, "p:myprobe 0x%08llx", (unsigned long long)0xc10bcf60);
ret = traceprobe_command(trcmd, ptr_create_trace_probe); //create_trace_probe);
printk("%s -- ret: %d\n", trcmd, ret);
// try find probe and enable it (compiles, but untested):
tp = ptr_find_probe_event("myprobe", KPROBE_EVENT_SYSTEM);
if (tp != NULL) probe_event_enable(&tp->call);
#endif //TRY_USE_KPROBES
}
hw_breakpoint_init(&attr);
attr.bp_len = sizeof(long); //HW_BREAKPOINT_LEN_1;
attr.bp_type = HW_BREAKPOINT_X ;
attr.bp_addr = 0x08048474; // main
sample_hbp = register_user_hw_breakpoint(&attr, (perf_overflow_handler_t)sample_hbp_handler, p);
printk(KBUILD_MODNAME ": 0x08048474 id [%llu]\n", sample_hbp->id); //
if (IS_ERR((void __force *)sample_hbp)) {
int ret = PTR_ERR((void __force *)sample_hbp);
printk(KBUILD_MODNAME ": Breakpoint registration failed (%d)\n", ret);
//~ return ret;
}
hw_breakpoint_init(&attrb);
attrb.bp_len = sizeof(long);
attrb.bp_type = HW_BREAKPOINT_X ;
attrb.bp_addr = 0x08048475; // first instruction after main
sample_hbpb = register_user_hw_breakpoint(&attrb, (perf_overflow_handler_t)sample_hbp_handler, p);
printk(KBUILD_MODNAME ": 0x08048475 id [%llu]\n", sample_hbpb->id); //45
if (IS_ERR((void __force *)sample_hbpb)) {
int ret = PTR_ERR((void __force *)sample_hbpb);
printk(KBUILD_MODNAME ": Breakpoint registration failed (%d)\n", ret);
//~ return ret;
}
printk(KBUILD_MODNAME ": (( 0x08048000 is_vmalloc_addr %d virt_addr_valid %d ))\n", is_vmalloc_addr((void*)0x08048000), virt_addr_valid(0x08048000));
kill_pid(find_vpid(callmodule_pid), SIGCONT, 1); // resume/continue/restart task
state_str = (p->state==-1)?"unrunnable":((p->state==0)?"runnable":"stopped");
printk(KBUILD_MODNAME ": cont pid task a: %p c: %s p: [%d] s: %s\n",
p, p->comm, p->pid, state_str);
return 0;
}
static void __exit callmodule_exit(void)
{
tracing_off(); //corresponds to the user space /sys/kernel/debug/tracing/tracing_on file
printk(KBUILD_MODNAME ": < exit\n");
}
module_init(callmodule_init);
module_exit(callmodule_exit);
MODULE_LICENSE("GPL");