[Crash-utility] arm64: "bt -f" output

[AKASHI Takahiro]

Dave,

On Fri, Jun 10, 2016 at 04:37:42PM -0400, Dave Anderson wrote:
> Hi Takahiro,
> 
> To address my concerns about your patch, I added a few additional changes and attached
> it to this email.  The changes are:
> 
> (1) Prevent the stack dump "below" the #0 level.  Yes, the stack data region is contained within
>     the incoming frame parameters, but it's ugly and we really don't care to see what's before
>     the #0 crash_kexec and crash_save_cpu #0 frames.
> (2) Fill in the missing stack dump at the top of the process stack, up to, but not including
>     the user-space exception frame.
> (3) Instead of showing the fp of 0 in the top-most frame's stack address, fill it in with the 
>     address of the user-space exception frame.
> 
> Note that there is no dump of the stack containing the user-space exception frame, but the
> register dump itself should suffice.

Well, the essential problem with my patch is that the output from "bt -f"
looks like:
     #XX ['fp'] 'function' at 'pc'  --- (1)
     <function's stack dump>        --- (2)
but that (1) and (2) are not printed as a single stack frame in the same
iteration of while loop in arm64_back_trace_cmd().
(I hope you understand what I mean :)

To be consistent with the out format of x86, the output should be
     <function's stack dump>
     #XX ['fp'] 'function' at 'pc'

Unfortunately, this requires that arm64_back_trace_cmd() and other functions
should be overhauled.
Please take a look at my next patch though it is uncompleted and still has
room for improvement.

Thanks,
-Takahiro AKASHI


> If you can live with the display, I'll clean up the patch, and maybe add the stack-layout diagram
> from your last post into a comment.  It was quite helpful, especially in comparison to the
> x86_64 model, which is what I was mistakenly using as a guide.
> 
> Thanks,
>   Dave
> 
> 
> 

> diff --git a/arm64.c b/arm64.c
> index 86ec348..3b29ef4 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -1407,13 +1407,14 @@ arm64_print_stackframe_entry(struct bt_info *bt, int level, struct arm64_stackfr
>                                  value_to_symstr(frame->pc, buf, bt->radix);
>          }
>  
> -	if (bt->flags & BT_FULL) {
> -		arm64_display_full_frame(bt, frame->sp);
> -		bt->frameptr = frame->sp;
> +	if ((bt->flags & BT_FULL) && level) {
> +		arm64_display_full_frame(bt, frame->fp);
> +		bt->frameptr = frame->fp;
>  	}
>  
>          fprintf(ofp, "%s#%d [%8lx] %s at %lx", level < 10 ? " " : "", level,
> -                frame->sp, name_plus_offset ? name_plus_offset : name, frame->pc);
> +//              frame->fp, name_plus_offset ? name_plus_offset : name, frame->pc);
> +                frame->fp ? frame->fp : bt->stacktop - USER_EFRAME_OFFSET, name_plus_offset ? name_plus_offset : name, frame->pc);
>  
>  	if (BT_REFERENCE_CHECK(bt))
>  		arm64_do_bt_reference_check(bt, frame->pc, name);
> @@ -1447,8 +1448,12 @@ arm64_display_full_frame(struct bt_info *bt, ulong sp)
>  	if (bt->frameptr == sp)
>  		return;
>  
> -	if (!INSTACK(sp, bt) || !INSTACK(bt->frameptr, bt))
> -		return;
> +	if (!INSTACK(sp, bt) || !INSTACK(bt->frameptr, bt)) {
> +		if (sp == 0)
> +			sp = bt->stacktop - USER_EFRAME_OFFSET;
> +		else
> +			return;
> +	}
>  
>  	words = (sp - bt->frameptr) / sizeof(ulong);
>  
> @@ -1471,12 +1476,10 @@ arm64_unwind_frame(struct bt_info *bt, struct arm64_stackframe *frame)
>  {
>  	unsigned long high, low, fp;
>  	unsigned long stack_mask;
> -	unsigned long irq_stack_ptr, orig_sp, sp_in;
> +	unsigned long irq_stack_ptr, orig_sp;
>  	struct arm64_pt_regs *ptregs;
>  	struct machine_specific *ms;
>  
> -	sp_in = frame->sp;
> -
>  	stack_mask = (unsigned long)(ARM64_STACK_SIZE) - 1;
>  	fp = frame->fp;
>  
> @@ -1513,7 +1516,7 @@ arm64_unwind_frame(struct bt_info *bt, struct arm64_stackframe *frame)
>  				ptregs = (struct arm64_pt_regs *)&bt->stackbuf[(ulong)(STACK_OFFSET_TYPE(orig_sp))];
>  				frame->sp = orig_sp;
>  				frame->pc = ptregs->pc;
> -				bt->bptr = sp_in;
> +				bt->bptr = fp;
>  				if (CRASHDEBUG(1))
>  					error(INFO, 
>  					    "arm64_unwind_frame: switch stacks: fp: %lx sp: %lx  pc: %lx\n",
> @@ -1904,8 +1907,10 @@ arm64_print_exception_frame(struct bt_info *bt, ulong pt_regs, int mode, FILE *o
>  	ulong LR, SP, offset;
>  	char buf[BUFSIZE];
>  
> +#if 0 /* FIXME? */
>  	if (bt->flags & BT_FULL)
>  		arm64_display_full_frame(bt, pt_regs);
> +#endif
>  
>  	if (CRASHDEBUG(1)) 
>  		fprintf(ofp, "pt_regs: %lx\n", pt_regs);

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