我正在开发一个允许使用的“绑定”库ptrace()
在 OCaml 语言中,但我的问题仅涉及ptrace()
.
所以,现在,我正在尝试编写一小段代码,以便使用以下命令在 Linux x86-64 上创建一个简单的硬件断点ptrace()
:
#define DR_OFFSET(x) (((struct user *)0)->u_debugreg + x)
typedef struct {
int dr0_local: 1;
int dr0_global: 1;
int dr1_local: 1;
int dr1_global: 1;
int dr2_local: 1;
int dr2_global: 1;
int dr3_local: 1;
int dr3_global: 1;
int reserverd: 8;
break_flag_t dr0_break: 2;
data_length_t dr0_len: 2;
break_flag_t dr1_break: 2;
data_length_t dr1_len: 2;
break_flag_t dr2_break: 2;
data_length_t dr2_len: 2;
break_flag_t dr3_break: 2;
data_length_t dr3_len: 2;
} dr7_t;
CAMLprim value ptrace_breakpoint(value ml_pid, value ml_addr)
{
CAMLparam2(ml_pid, ml_addr);
dr7_t dr7 = {0};
dr7.dr0_local = 1;
dr7.dr0_break = 0; /* break on execution */
dr7.dr0_len = 0x03; /* len 4 */
ptrace(PTRACE_POKEUSER, Int_val(ml_pid), DR_OFFSET(0), (void*)Int64_val(ml_addr));
ptrace(PTRACE_POKEUSER, Int_val(ml_pid), DR_OFFSET(7), (void*)dr7));
ptrace(PTRACE_POKEUSER, Int_val(ml_pid), DR_OFFSET(6), (void*)0);
CAMLreturn0;
}
当我执行这段代码时,我得到了一个Invalid argument
。的价值dr7
is 0xc0001
。为了找到有效值,我检查了GDB如何使用ptrace
通过使用strace
:
ptrace(PTRACE_POKEUSER, 6459, offsetof(struct user, u_debugreg), 0x400519) = 0
ptrace(PTRACE_POKEUSER, 6459, offsetof(struct user, u_debugreg) + 56, 0x101) = 0
ptrace(PTRACE_POKEUSER, 6459, offsetof(struct user, u_debugreg) + 48, 0) = 0
因此,GDB将dr7寄存器设置为值0x101
。我尝试了这个值并且它有效。因此,我想知道GDB使用的值的含义是什么?是个dr7_t
我之前使用的位字段有效吗?
谢谢。
Edit:
感谢 Neitsa,解决方案如下:
typedef struct {
unsigned int dr0_local: 1;
unsigned int dr0_global: 1;
unsigned int dr1_local: 1;
unsigned int dr1_global: 1;
unsigned int dr2_local: 1;
unsigned int dr2_global: 1;
unsigned int dr3_local: 1;
unsigned int dr3_global: 1;
unsigned int le: 1;
unsigned int ge: 1;
unsigned int reserved_10: 1;
unsigned int rtm: 1;
unsigned int reserved_12: 1;
unsigned int gd: 1;
unsigned int reserved_14_15: 2;
break_flag_t dr0_break: 2;
data_length_t dr0_len: 2;
break_flag_t dr1_break: 2;
data_length_t dr1_len: 2;
break_flag_t dr2_break: 2;
data_length_t dr2_len: 2;
break_flag_t dr3_break: 2;
data_length_t dr3_len: 2;
} dr7_t;
CAMLprim value ptrace_breakpoint(value ml_pid, value ml_addr)
{
CAMLparam2(ml_pid, ml_addr);
dr7_t dr7 = {0};
dr7.dr0_local = 1;
dr7.le = 1;
dr7.ge = 1;
dr7.reserved_10 = 1;
my_ptrace(PTRACE_POKEUSER, Int_val(ml_pid), DR_OFFSET(0), (void*)Int64_val(ml_addr));
my_ptrace(PTRACE_POKEUSER, Int_val(ml_pid), DR_OFFSET(7), (void*)dr7));
my_ptrace(PTRACE_POKEUSER, Int_val(ml_pid), DR_OFFSET(6), (void*)0);
CAMLreturn0;
}