support PTRACE_SINGLESTEP.

support debug/int3 exception.

arch/x86/kernel/cpu.c

@@ -107,6 +107,7 @@ void reload_idt(void)
 
 static struct list_head handlers[256 - 32];
 extern char page_fault[], general_protection_exception[];
+extern char debug_exception[], int3_exception[];
 
 static void init_idt(void)
 {
@@ -125,6 +126,9 @@ static void init_idt(void)
 	set_idt_entry(13, (unsigned long)general_protection_exception);
 	set_idt_entry(14, (unsigned long)page_fault);
 
+	set_idt_entry_trap_gate(1, (unsigned long)debug_exception);
+	set_idt_entry_trap_gate(3, (unsigned long)int3_exception);
+
 	reload_idt();
 }
 
@@ -467,6 +471,50 @@ void gpe_handler(struct x86_regs *regs)
 	// panic("GPF");
 }
 
+void debug_handler(struct x86_regs *regs)
+{
+	unsigned long db6;
+	int si_code = 0;
+	struct siginfo info;
+
+#ifdef DEBUG_PRINT_CPU
+	kprintf("debug exception (err: %lx, %lx:%lx)\n",
+	        regs->error, regs->cs, regs->rip);
+	arch_show_interrupt_context(regs);
+#endif
+
+	asm("mov %%db6, %0" :"=r" (db6));
+	if (db6 & DB6_BS) {
+	        regs->rflags &= ~RFLAGS_TF;
+		si_code = TRAP_TRACE;
+	} else if (db6 & (DB6_B3|DB6_B2|DB6_B1|DB6_B0)) {
+		si_code = TRAP_HWBKPT;
+	}
+
+	memset(&info, '\0', sizeof info);
+	info.si_code = si_code;
+	set_signal(SIGTRAP, regs, &info);
+	check_signal(0, regs);
+	check_need_resched();
+}
+
+void int3_handler(struct x86_regs *regs)
+{
+	struct siginfo info;
+
+#ifdef DEBUG_PRINT_CPU
+	kprintf("int3 exception (err: %lx, %lx:%lx)\n",
+	        regs->error, regs->cs, regs->rip);
+	arch_show_interrupt_context(regs);
+#endif
+
+	memset(&info, '\0', sizeof info);
+	info.si_code = TRAP_BRKPT;
+	set_signal(SIGTRAP, regs, &info);
+	check_signal(0, regs);
+	check_need_resched();
+}
+
 void x86_issue_ipi(unsigned int apicid, unsigned int low)
 {
 	lapic_icr_write(apicid << LAPIC_ICR_ID_SHIFT, low);

arch/x86/kernel/include/registers.h

@@ -34,6 +34,14 @@
 #define RFLAGS_VIP     (1 << 20)
 #define RFLAGS_ID      (1 << 21)
 
+#define DB6_B0         (1 << 0)
+#define DB6_B1         (1 << 1)
+#define DB6_B2         (1 << 2)
+#define DB6_B3         (1 << 3)
+#define DB6_BD         (1 << 13)
+#define DB6_BS         (1 << 14)
+#define DB6_BT         (1 << 15)
+
 #define MSR_EFER       0xc0000080
 #define MSR_STAR       0xc0000081
 #define MSR_LSTAR      0xc0000082

arch/x86/kernel/interrupt.S

@@ -154,3 +154,25 @@ enter_user_mode:
 		POP_ALL_REGS
 		addq	$8, %rsp
 		iretq
+
+.globl debug_exception
+debug_exception:
+		cld
+		pushq   $0	/* error */
+		PUSH_ALL_REGS
+		movq	%rsp, %rdi
+		call	debug_handler
+		POP_ALL_REGS
+		addq	$8, %rsp
+		iretq
+
+.globl int3_exception
+int3_exception:
+		cld
+		pushq   $0	/* error */
+		PUSH_ALL_REGS
+		movq	%rsp, %rdi
+		call	int3_handler
+		POP_ALL_REGS
+		addq	$8, %rsp
+		iretq

arch/x86/kernel/syscall.c

@@ -384,6 +384,11 @@ void clear_single_step(struct process *proc)
 	proc->uctx->rflags &= ~RFLAGS_TF;
 }
 
+void set_single_step(struct process *proc)
+{
+	proc->uctx->rflags |= RFLAGS_TF;
+}
+
 extern void coredump(struct process *proc, void *regs);
 
 static void ptrace_report_signal(struct process *proc, struct x86_regs *regs, int sig)

kernel/syscall.c

@@ -2557,6 +2557,8 @@ SYSCALL_DECLARE(getrlimit)
 }
 
 extern int ptrace_traceme(void);
+extern void clear_single_step(struct process *proc);
+extern void set_single_step(struct process *proc);
 
 static int ptrace_wakeup_sig(int pid, long request, long data) {
 	dkprintf("ptrace_wakeup_sig,pid=%d,data=%08x\n", pid, data);
@@ -2588,6 +2590,14 @@ static int ptrace_wakeup_sig(int pid, long request, long data) {
 		}
 		break;
 	case PTRACE_CONT:
+	case PTRACE_SINGLESTEP:
+	case PTRACE_SYSCALL:
+		if (request == PTRACE_SINGLESTEP) {
+			set_single_step(child);
+		}
+		if (request == PTRACE_SYSCALL) {
+			/* TODO: may set PTRACE_SYSCALL flag */
+		}
 		if(data != 0 && data != SIGSTOP) {
 			struct process *proc;
 
@@ -2823,8 +2833,6 @@ out:
 	return ret;
 }
 
-extern void clear_single_step(struct process *proc);
-
 static int ptrace_detach(int pid, int data)
 {
 	int error;
@@ -2991,7 +2999,8 @@ SYSCALL_DECLARE(ptrace)
 		dkprintf("PTRACE_POKEDATA: addr=%p data=%p\n", addr, data);
 		break;
 	case PTRACE_SINGLESTEP:
-		dkprintf("ptrace: unimplemented ptrace(PTRACE_SINGLESTEP) called.\n");
+		dkprintf("ptrace: PTRACE_SINGLESTEP: data=%d\n", data);
+		error = ptrace_wakeup_sig(pid, request, data);
 		break;
 	case PTRACE_GETFPREGS:
 		dkprintf("ptrace: unimplemented ptrace(PTRACE_GETFPREGS) called.\n");