powerpc/xmon: Add xmon command to dump process/task similar to ps(1)

powerpc/xmon: Add xmon command to dump process/task similar to ps(1)

[Douglas Miller]

    Add 'P' command with optional task_struct address to dump all/one task's
    information: task pointer, kernel stack pointer, PID, PPID, state
    (interpreted), CPU where (last) running, and command.
    
    Introduce XMON_PROTECT macro to standardize memory-access-fault
    protection (setjmp). Initially used only by the 'P' command.

[PATCH] powerpc/xmon: Add xmon command to dump process/task similar to ps(1)

[Douglas Miller]

Add 'P' command with optional task_struct address to dump all/one task's
information: task pointer, kernel stack pointer, PID, PPID, state
(interpreted), CPU where (last) running, and command.

Introduce XMON_PROTECT macro to standardize memory-access-fault
protection (setjmp). Initially used only by the 'P' command.

Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
---
 arch/powerpc/xmon/xmon.c |   63 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 63 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 13c6e20..8e203f0 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -149,6 +149,7 @@ static int  cpu_cmd(void);
 static void csum(void);
 static void bootcmds(void);
 static void proccall(void);
+static void proclist(void);
 void dump_segments(void);
 static void symbol_lookup(void);
 static void xmon_show_stack(unsigned long sp, unsigned long lr,
@@ -191,6 +192,24 @@ extern void xmon_leave(void);
 			 || ('A' <= (c) && (c) <= 'Z'))
 #define isspace(c)	(c == ' ' || c == '\t' || c == 10 || c == 13 || c == 0)
 
+/*
+ * Wrap a statement (typically function call) in setjmp to
+ * protect it from memory access errors. msg... are printf
+ * fmt+args used if error is trapped.
+ */
+#define XMON_PROTECT(stmt, msg...) 		\
+	if (setjmp(bus_error_jmp) != 0) {	\
+		catch_memory_errors = 0;	\
+		printf(msg);			\
+	} else {				\
+		catch_memory_errors = 1;	\
+		sync();				\
+		stmt;				\
+		sync();				\
+		__delay(200);			\
+		catch_memory_errors = 0;	\
+	}
+
 static char *help_string = "\
 Commands:\n\
   b	show breakpoints\n\
@@ -228,6 +247,7 @@ Commands:\n\
   mz	zero a block of memory\n\
   mi	show information about memory allocation\n\
   p 	call a procedure\n\
+  P 	list processes/tasks\n\
   r	print registers\n\
   s	single step\n"
 #ifdef CONFIG_SPU_BASE
@@ -947,6 +967,9 @@ cmds(struct pt_regs *excp)
 		case 'p':
 			proccall();
 			break;
+		case 'P':
+			proclist();
+			break;
 #ifdef CONFIG_PPC_STD_MMU
 		case 'u':
 			dump_segments();
@@ -2450,6 +2473,46 @@ memzcan(void)
 		printf("%.8x\n", a - mskip);
 }
 
+static void procshow(struct task_struct *tsk)
+{
+	char state;
+
+	/*
+	 * Cloned from kdb_task_state_char(), which is not entirely
+	 * appropriate for calling from xmon. This could be moved
+	 * to a common, generic, routine used by both.
+	 */
+	state = (tsk->state == 0) ? 'R' :
+		(tsk->state < 0) ? 'U' :
+		(tsk->state & TASK_UNINTERRUPTIBLE) ? 'D' :
+		(tsk->state & TASK_STOPPED) ? 'T' :
+		(tsk->state & TASK_TRACED) ? 'C' :
+		(tsk->exit_state & EXIT_ZOMBIE) ? 'Z' :
+		(tsk->exit_state & EXIT_DEAD) ? 'E' :
+		(tsk->state & TASK_INTERRUPTIBLE) ? 'S' : '?';
+
+	printf("%p %016lx %6d %6d %c %2d %s\n", tsk,
+		tsk->thread.ksp,
+		tsk->pid, tsk->parent->pid,
+		state, task_thread_info(tsk)->cpu,
+		tsk->comm);
+}
+
+static void proclist(void)
+{
+	unsigned long tskv;
+	struct task_struct *tsk = NULL;
+
+	printf("     task_struct     ->thread.ksp    PID   PPID S  P CMD\n");
+	if (scanhex(&tskv)) {
+		tsk = (struct task_struct *)tskv;
+		XMON_PROTECT(procshow(tsk), "*** Error dumping task %p\n", tsk);
+	} else {
+		XMON_PROTECT(for_each_process(tsk) procshow(tsk),
+			"*** Error dumping task %p\n", tsk);
+	}
+}
+
 static void proccall(void)
 {
 	unsigned long args[8];
-- 
1.7.1

Re: powerpc/xmon: Add xmon command to dump process/task similar to ps(1)

[Michael Ellerman]

On Mon, 2015-23-11 at 15:01:15 UTC, Douglas Miller wrote:
> Add 'P' command with optional task_struct address to dump all/one task's
> information: task pointer, kernel stack pointer, PID, PPID, state
> (interpreted), CPU where (last) running, and command.
> 
> Introduce XMON_PROTECT macro to standardize memory-access-fault
> protection (setjmp). Initially used only by the 'P' command.

Hi Doug,

Sorry this has taken a while, it keeps getting preempted by more important
patches.

I'm also not a big fan of the protect macro, it works for this case, but it's
already a bit ugly calling for_each_process() inside the macro, and it would be
even worse for multi line logic.

I think I'd rather just open code it, and hopefully we can come up with a
better solution for catching errors in the long run.

I also renamed the routines to use "task", because "proc" in xmon is already
used to mean "procedure", and the struct is task_struct after all.

How does this look?

cheers

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 47e195d66a9a..942796fa4767 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -163,6 +163,7 @@ static int  cpu_cmd(void);
 static void csum(void);
 static void bootcmds(void);
 static void proccall(void);
+static void show_tasks(void);
 void dump_segments(void);
 static void symbol_lookup(void);
 static void xmon_show_stack(unsigned long sp, unsigned long lr,
@@ -238,6 +239,7 @@ Commands:\n\
   mz	zero a block of memory\n\
   mi	show information about memory allocation\n\
   p 	call a procedure\n\
+  P 	list processes/tasks\n\
   r	print registers\n\
   s	single step\n"
 #ifdef CONFIG_SPU_BASE
@@ -967,6 +969,9 @@ cmds(struct pt_regs *excp)
 		case 'p':
 			proccall();
 			break;
+		case 'P':
+			show_tasks();
+			break;
 #ifdef CONFIG_PPC_STD_MMU
 		case 'u':
 			dump_segments();
@@ -2566,6 +2571,61 @@ memzcan(void)
 		printf("%.8x\n", a - mskip);
 }
 
+static void show_task(struct task_struct *tsk)
+{
+	char state;
+
+	/*
+	 * Cloned from kdb_task_state_char(), which is not entirely
+	 * appropriate for calling from xmon. This could be moved
+	 * to a common, generic, routine used by both.
+	 */
+	state = (tsk->state == 0) ? 'R' :
+		(tsk->state < 0) ? 'U' :
+		(tsk->state & TASK_UNINTERRUPTIBLE) ? 'D' :
+		(tsk->state & TASK_STOPPED) ? 'T' :
+		(tsk->state & TASK_TRACED) ? 'C' :
+		(tsk->exit_state & EXIT_ZOMBIE) ? 'Z' :
+		(tsk->exit_state & EXIT_DEAD) ? 'E' :
+		(tsk->state & TASK_INTERRUPTIBLE) ? 'S' : '?';
+
+	printf("%p %016lx %6d %6d %c %2d %s\n", tsk,
+		tsk->thread.ksp,
+		tsk->pid, tsk->parent->pid,
+		state, task_thread_info(tsk)->cpu,
+		tsk->comm);
+}
+
+static void show_tasks(void)
+{
+	unsigned long tskv;
+	struct task_struct *tsk = NULL;
+
+	printf("     task_struct     ->thread.ksp    PID   PPID S  P CMD\n");
+
+	if (scanhex(&tskv))
+		tsk = (struct task_struct *)tskv;
+
+	if (setjmp(bus_error_jmp) != 0) {
+		catch_memory_errors = 0;
+		printf("*** Error dumping task %p\n", tsk);
+		return;
+	}
+
+	catch_memory_errors = 1;
+	sync();
+
+	if (tsk)
+		show_task(tsk);
+	else
+		for_each_process(tsk)
+			show_task(tsk);
+
+	sync();
+	__delay(200);
+	catch_memory_errors = 0;
+}
+
 static void proccall(void)
 {
 	unsigned long args[8];

Re: powerpc/xmon: Add xmon command to dump process/task similar to ps(1)

[Douglas Miller]

That looks fine to me.

Thanks!


On 02/09/2016 04:58 AM, Michael Ellerman wrote:
> On Mon, 2015-23-11 at 15:01:15 UTC, Douglas Miller wrote:
>> Add 'P' command with optional task_struct address to dump all/one task's
>> information: task pointer, kernel stack pointer, PID, PPID, state
>> (interpreted), CPU where (last) running, and command.
>>
>> Introduce XMON_PROTECT macro to standardize memory-access-fault
>> protection (setjmp). Initially used only by the 'P' command.
> Hi Doug,
>
> Sorry this has taken a while, it keeps getting preempted by more important
> patches.
>
> I'm also not a big fan of the protect macro, it works for this case, but it's
> already a bit ugly calling for_each_process() inside the macro, and it would be
> even worse for multi line logic.
>
> I think I'd rather just open code it, and hopefully we can come up with a
> better solution for catching errors in the long run.
>
> I also renamed the routines to use "task", because "proc" in xmon is already
> used to mean "procedure", and the struct is task_struct after all.
>
> How does this look?
>
> cheers
>
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index 47e195d66a9a..942796fa4767 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -163,6 +163,7 @@ static int  cpu_cmd(void);
>   static void csum(void);
>   static void bootcmds(void);
>   static void proccall(void);
> +static void show_tasks(void);
>   void dump_segments(void);
>   static void symbol_lookup(void);
>   static void xmon_show_stack(unsigned long sp, unsigned long lr,
> @@ -238,6 +239,7 @@ Commands:\n\
>     mz	zero a block of memory\n\
>     mi	show information about memory allocation\n\
>     p 	call a procedure\n\
> +  P 	list processes/tasks\n\
>     r	print registers\n\
>     s	single step\n"
>   #ifdef CONFIG_SPU_BASE
> @@ -967,6 +969,9 @@ cmds(struct pt_regs *excp)
>   		case 'p':
>   			proccall();
>   			break;
> +		case 'P':
> +			show_tasks();
> +			break;
>   #ifdef CONFIG_PPC_STD_MMU
>   		case 'u':
>   			dump_segments();
> @@ -2566,6 +2571,61 @@ memzcan(void)
>   		printf("%.8x\n", a - mskip);
>   }
>   
> +static void show_task(struct task_struct *tsk)
> +{
> +	char state;
> +
> +	/*
> +	 * Cloned from kdb_task_state_char(), which is not entirely
> +	 * appropriate for calling from xmon. This could be moved
> +	 * to a common, generic, routine used by both.
> +	 */
> +	state = (tsk->state == 0) ? 'R' :
> +		(tsk->state < 0) ? 'U' :
> +		(tsk->state & TASK_UNINTERRUPTIBLE) ? 'D' :
> +		(tsk->state & TASK_STOPPED) ? 'T' :
> +		(tsk->state & TASK_TRACED) ? 'C' :
> +		(tsk->exit_state & EXIT_ZOMBIE) ? 'Z' :
> +		(tsk->exit_state & EXIT_DEAD) ? 'E' :
> +		(tsk->state & TASK_INTERRUPTIBLE) ? 'S' : '?';
> +
> +	printf("%p %016lx %6d %6d %c %2d %s\n", tsk,
> +		tsk->thread.ksp,
> +		tsk->pid, tsk->parent->pid,
> +		state, task_thread_info(tsk)->cpu,
> +		tsk->comm);
> +}
> +
> +static void show_tasks(void)
> +{
> +	unsigned long tskv;
> +	struct task_struct *tsk = NULL;
> +
> +	printf("     task_struct     ->thread.ksp    PID   PPID S  P CMD\n");
> +
> +	if (scanhex(&tskv))
> +		tsk = (struct task_struct *)tskv;
> +
> +	if (setjmp(bus_error_jmp) != 0) {
> +		catch_memory_errors = 0;
> +		printf("*** Error dumping task %p\n", tsk);
> +		return;
> +	}
> +
> +	catch_memory_errors = 1;
> +	sync();
> +
> +	if (tsk)
> +		show_task(tsk);
> +	else
> +		for_each_process(tsk)
> +			show_task(tsk);
> +
> +	sync();
> +	__delay(200);
> +	catch_memory_errors = 0;
> +}
> +
>   static void proccall(void)
>   {
>   	unsigned long args[8];
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

Re: powerpc/xmon: Add xmon command to dump process/task similar to ps(1)

[Michael Ellerman]

On Mon, 2015-23-11 at 15:01:15 UTC, Douglas Miller wrote:
> Add 'P' command with optional task_struct address to dump all/one task's
> information: task pointer, kernel stack pointer, PID, PPID, state
> (interpreted), CPU where (last) running, and command.
> 
> Introduce XMON_PROTECT macro to standardize memory-access-fault
> protection (setjmp). Initially used only by the 'P' command.
> 
> Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/6dfb54049f9a99b24fe5d5cd2d

cheers