sw64: clean up unused single step support in kernel

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5PNCX

--------------------------------

Single step is supported by GDB on sw64, and those unused code
can be removed.
Signed-off-by: NHe Sheng <hesheng@wxiat.com>
Signed-off-by: NGu Zitao <guzitao@wxiat.com>

arch/sw_64/include/asm/ptrace.h

@@ -54,7 +54,6 @@ struct pt_regs {
 	unsigned long r18;
 };
 
-#define arch_has_single_step()		(1)
 #define user_mode(regs) (((regs)->ps & 8) != 0)
 #define instruction_pointer(regs) ((regs)->pc)
 #define profile_pc(regs) instruction_pointer(regs)

arch/sw_64/include/asm/thread_info.h

@@ -34,9 +34,6 @@ struct thread_info {
 	int			preempt_count;	/* 0 => preemptible, <0 => BUG */
 	unsigned int		status;		/* thread-synchronous flags */
 
-	int bpt_nsaved;
-	unsigned long bpt_addr[2];		/* breakpoint handling  */
-	unsigned int bpt_insn[2];
 #ifdef CONFIG_DYNAMIC_FTRACE
 	unsigned long		dyn_ftrace_addr;
 #endif

arch/sw_64/kernel/proto.h

@@ -7,10 +7,6 @@
 #include <asm/pgtable.h>
 #include <asm/sw64io.h>
 
-/* ptrace.c */
-extern int ptrace_set_bpt(struct task_struct *child);
-extern int ptrace_cancel_bpt(struct task_struct *child);
-
 /* traps.c */
 extern void show_regs(struct pt_regs *regs);
 extern void die(char *str, struct pt_regs *regs, long err);

arch/sw_64/kernel/ptrace.c

@@ -154,119 +154,12 @@ put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
 	return 0;
 }
 
-static inline int
-read_int(struct task_struct *task, unsigned long addr, int *data)
-{
-	int copied = access_process_vm(task, addr, data, sizeof(int), FOLL_FORCE);
-
-	return (copied == sizeof(int)) ? 0 : -EIO;
-}
-
-static inline int
-write_int(struct task_struct *task, unsigned long addr, int data)
-{
-	int copied = access_process_vm(task, addr, &data, sizeof(int),
-			FOLL_FORCE | FOLL_WRITE);
-	return (copied == sizeof(int)) ? 0 : -EIO;
-}
-
-/*
- * Set breakpoint.
- */
-int
-ptrace_set_bpt(struct task_struct *child)
-{
-	int displ, i, res, reg_b, nsaved = 0;
-	unsigned int insn, op_code;
-	unsigned long pc;
-
-	pc = get_reg(child, REG_PC);
-	res = read_int(child, pc, (int *)&insn);
-	if (res < 0)
-		return res;
-
-	op_code = insn >> 26;
-	/* br bsr beq bne blt ble bgt bge blbc blbs fbeq fbne fblt fble fbgt fbge */
-	if ((1UL << op_code) & 0x3fff000000000030UL) {
-		/*
-		 * It's a branch: instead of trying to figure out
-		 * whether the branch will be taken or not, we'll put
-		 * a breakpoint at either location.  This is simpler,
-		 * more reliable, and probably not a whole lot slower
-		 * than the alternative approach of emulating the
-		 * branch (emulation can be tricky for fp branches).
-		 */
-		displ = ((s32)(insn << 11)) >> 9;
-		task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
-		if (displ) /* guard against unoptimized code */
-			task_thread_info(child)->bpt_addr[nsaved++]
-				= pc + 4 + displ;
-		/*call ret jmp*/
-	} else if (op_code >= 0x1 && op_code <= 0x3) {
-		reg_b = (insn >> 16) & 0x1f;
-		task_thread_info(child)->bpt_addr[nsaved++] = get_reg(child, reg_b);
-	} else {
-		task_thread_info(child)->bpt_addr[nsaved++] = pc + 4;
-	}
-
-	/* install breakpoints: */
-	for (i = 0; i < nsaved; ++i) {
-		res = read_int(child, task_thread_info(child)->bpt_addr[i],
-				(int *)&insn);
-		if (res < 0)
-			return res;
-		task_thread_info(child)->bpt_insn[i] = insn;
-		res = write_int(child, task_thread_info(child)->bpt_addr[i],
-				BREAKINST);
-		if (res < 0)
-			return res;
-	}
-	task_thread_info(child)->bpt_nsaved = nsaved;
-	return 0;
-}
-
 /*
- * Ensure no single-step breakpoint is pending.  Returns non-zero
- * value if child was being single-stepped.
- */
-int
-ptrace_cancel_bpt(struct task_struct *child)
-{
-	int i, nsaved = task_thread_info(child)->bpt_nsaved;
-
-	task_thread_info(child)->bpt_nsaved = 0;
-
-	if (nsaved > 2) {
-		printk("%s: bogus nsaved: %d!\n", __func__, nsaved);
-		nsaved = 2;
-	}
-
-	for (i = 0; i < nsaved; ++i) {
-		write_int(child, task_thread_info(child)->bpt_addr[i],
-				task_thread_info(child)->bpt_insn[i]);
-	}
-	return (nsaved != 0);
-}
-
-void user_enable_single_step(struct task_struct *child)
-{
-	/* Mark single stepping.  */
-	task_thread_info(child)->bpt_nsaved = -1;
-}
-
-void user_disable_single_step(struct task_struct *child)
-{
-	ptrace_cancel_bpt(child);
-}
-
-/*
- * Called by kernel/ptrace.c when detaching..
- *
- * Make sure the single step bit is not set.
+ * Called by ptrace_detach
  */
 void ptrace_disable(struct task_struct *child)
 {
-	user_disable_single_step(child);
+	/**/
 }
 
 static int gpr_get(struct task_struct *target,

arch/sw_64/kernel/signal.c

@@ -163,11 +163,6 @@ do_sigreturn(struct sigcontext __user *sc)
 	if (restore_sigcontext(sc, regs))
 		goto give_sigsegv;
 
-	/* Send SIGTRAP if we're single-stepping: */
-	if (ptrace_cancel_bpt(current)) {
-		force_sig_fault(SIGTRAP, TRAP_BRKPT,
-				(void __user *)regs->pc, 0);
-	}
 	return;
 
 give_sigsegv:
@@ -194,11 +189,6 @@ do_rt_sigreturn(struct rt_sigframe __user *frame)
 	if (restore_altstack(&frame->uc.uc_stack))
 		goto give_sigsegv;
 
-	/* Send SIGTRAP if we're single-stepping: */
-	if (ptrace_cancel_bpt(current)) {
-		force_sig_fault(SIGTRAP, TRAP_BRKPT,
-				(void __user *)regs->pc, 0);
-	}
 	return;
 
 give_sigsegv:
@@ -381,19 +371,15 @@ syscall_restart(unsigned long r0, unsigned long r19,
 static void
 do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 {
-	unsigned long single_stepping = ptrace_cancel_bpt(current);
 	struct ksignal ksig;
 
 	/* This lets the debugger run, ... */
 	if (get_signal(&ksig)) {
-		/* ... so re-check the single stepping. */
-		single_stepping |= ptrace_cancel_bpt(current);
 		/* Whee!  Actually deliver the signal.  */
 		if (r0)
 			syscall_restart(r0, r19, regs, &ksig.ka);
 		handle_signal(&ksig, regs);
 	} else {
-		single_stepping |= ptrace_cancel_bpt(current);
 		if (r0) {
 			switch (regs->r0) {
 			case ERESTARTNOHAND:
@@ -413,8 +399,6 @@ do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 		}
 		restore_saved_sigmask();
 	}
-	if (single_stepping)
-		ptrace_set_bpt(current);        /* re-set breakpoint */
 }
 
 void