[Crash-utility] Problem in bt for ARM64

AKASHI Takahiro takahiro.akashi at linaro.org
Tue Oct 17 02:51:31 UTC 2017


On Mon, Oct 16, 2017 at 03:33:45PM -0400, Dave Anderson wrote:
> 
> Hi Takahiro,
> 
> One question about a segment of your patch that I can't test because
> I don't have a 4.14 dumpfile.  Here in arm64_switch_stack(), you have
> conditionalized the display of the exception frame:
> 
> @@ -2669,7 +2753,9 @@ arm64_switch_stack(struct bt_info *bt, struct arm64_stackframe *frame, FILE *ofp
>         if (frame->fp == 0)
>                 return USER_MODE;
> 
> -       arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
> +       if (!(machdep->flags & UNW_4_14))
> +               arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
> +
>         return KERNEL_MODE;
>  }
> 
> I don't understand -- what happens with a UNW_4_14 dumpfile?

One of changes made in v4.14 around entry.S is to add a "real stackframe"
to exception entry code. So arm64_print_exception_frame() in main loop
of arm64_back_trace_cmd() should work alike for irq and other exceptions.
So I would say "redundant."

=== for your reference, when irq takes place, ===
before calling irq handler(gic_handle_irq), the process stack looks like:
sp +--------+
   |  saved |
   |  regs  |
   |  ...   |
fp +- - - - +
   |prev fp |
   |prev lr |
   +--------+ <--- interrupted stackframe
   |        |
   |        |

and after entering irq handler, the irq stack looks like:
sp |        |
fp +--------+
   |prev fp |
   |prev lr |
   |   ...  |
   +--------+ <--- top of irq stack
===========================

A bonus from v4.14 changes is that we are now able to observe a "hidden"
stackframe under exception frame, which can only appear with "bt -o"
if it works :)

=== before v4.14, no frame for sys_handle_crash ===
crash-arm64> bt
PID: 1189   TASK: ffff80000d1bc100  CPU: 1   COMMAND: "sh"
 #0 [ffff80000cd07a30] crash_kexec at ffff0000081423a4
 #1 [ffff80000cd07a60] die at ffff000008088850
 #2 [ffff80000cd07aa0] __do_kernel_fault at ffff000008099900
 #3 [ffff80000cd07ad0] do_page_fault at ffff0000089238e0
 #4 [ffff80000cd07b40] do_translation_fault at ffff000008923920
 #5 [ffff80000cd07b50] do_mem_abort at ffff000008081354
 #6 [ffff80000cd07d30] el1_ia at ffff000008082600
     PC: ffff000008514060  [sysrq_handle_crash+32]
     LR: ffff00000851404c  [sysrq_handle_crash+12]
     SP: ffff80000cd07d30  PSTATE: 60000145
    X29: ffff80000cd07d30  X28: ffff80000d1bc100  X27: ffff000008932000
    X26: 0000000000000040  X25: 0000000000000123  X24: 0000000000000000
    X23: 0000000000000009  X22: ffff000008ede000  X21: ffff000008ede870
    X20: 0000000000000063  X19: ffff000008e51000  X18: 0000000000000010
    X17: 0000ffff98268e90  X16: ffff000008200000  X15: ffffffffffffffff
    X14: ffff000088f2cf77  X13: ffff000008f2cf85  X12: ffff000008e39e08
    X11: ffff000008536220  X10: ffff80000cd07a30   X9: 0000000000000016
     X8: 6120726567676972   X7: 54203a2071527379   X6: 000000000000011a
     X5: 0000000000000000   X4: 0000000000000000   X3: 0000000000000000
     X2: ffff80001ff60960   X1: 0000000000000000   X0: 0000000000000001
 #7 [ffff80000cd07d40] __handle_sysrq at ffff00000851467c
 #8 [ffff80000cd07d80] write_sysrq_trigger at ffff000008514c04
 #9 [ffff80000cd07da0] proc_reg_write at ffff000008266910
#10 [ffff80000cd07dc0] __vfs_write at ffff0000081fd6c4
#11 [ffff80000cd07e40] vfs_write at ffff0000081feab0
#12 [ffff80000cd07e80] sys_write at ffff000008200044
#13 [ffff80000cd07ec0] el0_svc_naked at ffff000008082f2c
     PC: 0000ffff98268e78   LR: 000000000040a074   SP: 0000ffffff8ad7f0
    X29: 0000ffffff8ae1d0  X28: 000000000047d2c0  X27: 0000000000000000
    X26: 0000000005ac2440  X25: 0000000000000000  X24: 0000000000000020
    X23: 0000000005ac55e0  X22: 0000000000000002  X21: 0000000005ac55e0
    X20: 0000000000000001  X19: 00000000004ae000  X18: 0000ffffff8ac758
    X17: 0000ffff98268e90  X16: 0000000000000000  X15: 0000000000000008
    X14: 0000ffff98218a24  X13: 0000ffffff8ad8a0  X12: 0101010101010101
    X11: 0101010101010101  X10: 0101010101010101   X9: fffffffffffffff0
     X8: 0000000000000040   X7: 0000000000000000   X6: 0080000080808080
     X5: 0000000000000000   X4: 0000000005ac0063   X3: 0000000005ac55e1
     X2: 0000000000000002   X1: 0000000005ac55e0   X0: 0000000000000001
    ORIG_X0: 0000000000000001  SYSCALLNO: 40  PSTATE: 80000000

==== v4.14 or later, see #7 ===
crash-arm64> bt 
PID: 1326   TASK: ffff80000d260e00  CPU: 1   COMMAND: "sh"
 #0 [ffff00000b413a20] crash_kexec at ffff00000814c010
 #1 [ffff00000b413a50] die at ffff000008089088
 #2 [ffff00000b413a90] __do_kernel_fault at ffff000008097ac0
 #3 [ffff00000b413ac0] do_page_fault at ffff000008097bdc
 #4 [ffff00000b413b30] do_translation_fault at ffff000008097f60
 #5 [ffff00000b413b40] do_mem_abort at ffff0000080812ac
 #6 [ffff00000b413d20] el1_ia at ffff000008082f10
     PC: ffff000008544330  [sysrq_handle_crash+32]
     LR: ffff00000854431c  [sysrq_handle_crash+12]
     SP: ffff00000b413d30  PSTATE: 60000145
    X29: ffff00000b413d30  X28: ffff80000d260e00  X27: ffff0000089c1000
    X26: 0000000000000040  X25: 0000000000000124  X24: 0000000000000000
    X23: 0000000000000009  X22: ffff000008fda000  X21: ffff000008fdaa48
    X20: 0000000000000063  X19: ffff000008f33000  X18: 0000000000000010
    X17: 0000ffffa1c93e90  X16: ffff00000820b370  X15: ffffffffffffffff
    X14: ffff00008903c37f  X13: ffff00000903c38d  X12: ffff000008f19df0
    X11: ffff000008566d30  X10: ffff00000b413a50   X9: 0000000000000015
     X8: 54203a2071527379   X7: 53203a7172737973   X6: 000000000000010e
     X5: 0000000000000000   X4: 0000000000000000   X3: 0000000000000000
     X2: ffff80000ef627f0   X1: 0000000000000000   X0: 0000000000000001
 #7 [ffff00000b413d30] sysrq_handle_crash at ffff00000854432c
 #8 [ffff00000b413d40] __handle_sysrq at ffff00000854494c
 #9 [ffff00000b413d80] write_sysrq_trigger at ffff000008544ed4
#10 [ffff00000b413da0] proc_reg_write at ffff00000827273c
#11 [ffff00000b413dc0] __vfs_write at ffff00000820ae34
#12 [ffff00000b413e40] vfs_write at ffff00000820b108
#13 [ffff00000b413e80] sys_write at ffff00000820b3b4
#14 [ffff00000b413ff0] el0_svc_naked at ffff0000080837ac
     PC: 0000ffffa1c93e78   LR: 000000000040a074   SP: 0000ffffd2703e60
    X29: 0000ffffd2704840  X28: 000000000047d2c0  X27: 0000000000000000
    X26: 000000003c71a440  X25: 0000000000000000  X24: 0000000000000020
    X23: 000000003c71cf90  X22: 0000000000000002  X21: 000000003c71cf90
    X20: 0000000000000001  X19: 00000000004ae000  X18: 0000ffffd2702dc8
    X17: 0000ffffa1c93e90  X16: 0000000000000000  X15: 0000000000000008
    X14: 0000ffffa1c43a24  X13: 0000ffffd2703f10  X12: 0101010101010101
    X11: 0101010101010101  X10: 0101010101010101   X9: fffffffffffffff0
     X8: 0000000000000040   X7: 0000000000000000   X6: 0080808080808080
     X5: 0000000000000000   X4: 0000000000000063   X3: 000000003c71cf91
     X2: 0000000000000002   X1: 000000003c71cf90   X0: 0000000000000001
    ORIG_X0: 0000000000000001  SYSCALLNO: 40  PSTATE: 80000000
===========================

So I'm thinking of disabling "bt -o" for v4.14 or later since "bt -o"
may partly lose its "reason d'etre."

-Takahiro AKASHI

> Thanks,
>   Dave
> 
> 
> 
> 
> ----- Original Message -----
> > 
> > Hi Takahiro,
> > 
> > Welcome back!  It's great to get you back in the fold again...
> > 
> > I just ran a quick test of your patch on a set of sample dumpfiles,
> > and only found one issue.  It was on a 4.2 QEMU dump where all of the
> > active tasks were running in user-space, and all of their "bt" commands
> > fail immediately with a "zero-size" allocation message.  As it turns out,
> > that was due to this GETBUF() call in arm64_in_kdump_text_on_irq_stack():
> > 
> > static int
> > arm64_in_kdump_text_on_irq_stack(struct bt_info *bt)
> > {
> >         int cpu;
> >         ulong stackbase;
> >         char *stackbuf;
> >         ulong *ptr, *start, *base;
> >         struct machine_specific *ms;
> > 
> >         if ((machdep->flags & (IRQ_STACKS|KDUMP_ENABLED)) !=
> >         (IRQ_STACKS|KDUMP_ENABLED))
> >                 return FALSE;
> > 
> >         ms = machdep->machspec;
> >         cpu = bt->tc->processor;
> >         stackbase = ms->irq_stacks[cpu];
> >         stackbuf = GETBUF(ms->irq_stack_size);  <===
> > ...
> > 
> > ms->irq_stack_size is zero because that kernel version does not have IRQ
> > stacks.
> > As it turns out, the problem is that your reworked arm64_irq_stack_init() is
> > setting
> > the IRQ_STACKS flag unconditionally at the bottom of the function.  Moving
> > the
> > flag setting up into the two if-else segments fixes it.
> > 
> > I'll check out the patches in detail next week, but this looks good.
> > 
> > Thanks,
> >   Dave
> > 
> >    
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > ----- Original Message -----
> > > Dave,
> > > 
> > > On Fri, Sep 22, 2017 at 03:06:00PM -0400, Dave Anderson wrote:
> > > > 
> > > > Jan,
> > > > 
> > > > I went back to creating a machdep->machspec->user_eframe_offset value
> > > > to be able to account for both the 4.7 and the upcoming 4.14 pt_regs
> > > > changes:
> > > > 
> > > >   https://github.com/crash-utility/crash/commit/c975008e61121ef8785622c3bc26964da8fe0deb
> > > >  
> > > > Again, though, note that "bt" does not work with 4.14.
> > > 
> > > Even with your latest changes in 7.2.0, "bt" still has some issues:
> > > a.register dump at exception frame doesn't have correct values
> > >   (due to added stackframe[] in pt_regs)
> > > b. tracing irq stack to process stack fails
> > >   (due to irq-stack implementation changes and VMAP_STACK)
> > > c."bt -o" seems to have been broken for a while
> > > 
> > > Attached is my tentative patch, which hopefully addresses (a) and (b).
> > > While it is still far from perfect, it may help give you a heads-up.
> > > 
> > > Thanks,
> > > -Takahiro AKASHI
> > > 
> > > ===8<===
> > > >From 156ec115b2a436a0738908153d676f8eeed84cb1 Mon Sep 17 00:00:00 2001
> > > From: AKASHI Takahiro <takahiro.akashi at linaro.org>
> > > Date: Thu, 12 Oct 2017 10:46:34 +0900
> > > Subject: [PATCH] arm64: backtrace for v4.14
> > > 
> > > ---
> > >  arm64.c | 172
> > >  ++++++++++++++++++++++++++++++++++++++++++++++++++--------------
> > >  1 file changed, 136 insertions(+), 36 deletions(-)
> > > 
> > > diff --git a/arm64.c b/arm64.c
> > > index 20c5d34..22c8556 100644
> > > --- a/arm64.c
> > > +++ b/arm64.c
> > > @@ -72,6 +72,7 @@ static void arm64_cmd_mach(void);
> > >  static void arm64_display_machine_stats(void);
> > >  static int arm64_get_smp_cpus(void);
> > >  static void arm64_clear_machdep_cache(void);
> > > +static int arm64_on_process_stack(struct bt_info *, ulong);
> > >  static int arm64_in_alternate_stack(int, ulong);
> > >  static int arm64_on_irq_stack(int, ulong);
> > >  static void arm64_set_irq_stack(struct bt_info *);
> > > @@ -1336,29 +1337,60 @@ arm64_irq_stack_init(void)
> > >  	req = &request;
> > >  	struct machine_specific *ms = machdep->machspec;
> > >  
> > > -	if (!symbol_exists("irq_stack") ||
> > > -	    !(sp = per_cpu_symbol_search("irq_stack")) ||
> > > -	    !get_symbol_type("irq_stack", NULL, req) ||
> > > -	    (req->typecode != TYPE_CODE_ARRAY) ||
> > > -	    (req->target_typecode != TYPE_CODE_INT))
> > > -		return;
> > > +	if (!(ms->irq_stacks = (ulong *)malloc((size_t)(kt->cpus
> > > +						* sizeof(ulong)))))
> > > +		error(FATAL, "cannot malloc irq_stack addresses\n");
> > >  
> > > -	if (CRASHDEBUG(1)) {
> > > -		fprintf(fp, "irq_stack: \n");
> > > -		fprintf(fp, "  type: %s\n",
> > > -			(req->typecode == TYPE_CODE_ARRAY) ? "TYPE_CODE_ARRAY" : "other");
> > > -		fprintf(fp, "  target_typecode: %s\n",
> > > -			req->target_typecode == TYPE_CODE_INT ? "TYPE_CODE_INT" : "other");
> > > -		fprintf(fp, "  target_length: %ld\n", req->target_length);
> > > -		fprintf(fp, "  length: %ld\n", req->length);
> > > -	}
> > > +	if (symbol_exists("irq_stack") &&
> > > +	    (sp = per_cpu_symbol_search("irq_stack")) &&
> > > +	    get_symbol_type("irq_stack", NULL, req)) {
> > > +		/* before v4.14 or CONFIG_VMAP_STACK disabled */
> > > +		if (CRASHDEBUG(1)) {
> > > +			fprintf(fp, "irq_stack: \n");
> > > +			fprintf(fp, "  type: %s\n",
> > > +				(req->typecode == TYPE_CODE_ARRAY) ?
> > > +						"TYPE_CODE_ARRAY" : "other");
> > > +			fprintf(fp, "  target_typecode: %s\n",
> > > +				req->target_typecode == TYPE_CODE_INT ?
> > > +						"TYPE_CODE_INT" : "other");
> > > +			fprintf(fp, "  target_length: %ld\n",
> > > +						req->target_length);
> > > +			fprintf(fp, "  length: %ld\n", req->length);
> > > +		}
> > >  
> > > -	ms->irq_stack_size = req->length;
> > > -	if (!(ms->irq_stacks = (ulong *)malloc((size_t)(kt->cpus *
> > > sizeof(ulong)))))
> > > -		error(FATAL, "cannot malloc irq_stack addresses\n");
> > > +		ms->irq_stack_size = req->length;
> > > +
> > > +		for (i = 0; i < kt->cpus; i++)
> > > +			ms->irq_stacks[i] = kt->__per_cpu_offset[i] + sp->value;
> > > +	} else if (symbol_exists("irq_stack_ptr") &&
> > > +		   (sp = per_cpu_symbol_search("irq_stack_ptr")) &&
> > > +		   get_symbol_type("irq_stack_ptr", NULL, req)) {
> > > +		/* v4.14 and later with CONFIG_VMAP_STACK enabled */
> > > +		if (CRASHDEBUG(1)) {
> > > +			fprintf(fp, "irq_stack_ptr: \n");
> > > +			fprintf(fp, "  type: %x, %s\n",
> > > +				(int)req->typecode,
> > > +				(req->typecode == TYPE_CODE_PTR) ?
> > > +						"TYPE_CODE_PTR" : "other");
> > > +			fprintf(fp, "  target_typecode: %x, %s\n",
> > > +				(int)req->target_typecode,
> > > +				req->target_typecode == TYPE_CODE_INT ?
> > > +						"TYPE_CODE_INT" : "other");
> > > +			fprintf(fp, "  target_length: %ld\n",
> > > +						req->target_length);
> > > +			fprintf(fp, "  length: %ld\n", req->length);
> > > +		}
> > > +
> > > +		ms->irq_stack_size = 16384;
> > > +
> > > +		for (i = 0; i < kt->cpus; i++) {
> > > +			ulong p;
> > >  
> > > -	for (i = 0; i < kt->cpus; i++)
> > > -		ms->irq_stacks[i] = kt->__per_cpu_offset[i] + sp->value;
> > > +			p = kt->__per_cpu_offset[i] + sp->value;
> > > +			readmem(p, KVADDR, &(ms->irq_stacks[i]), sizeof(ulong),
> > > +					"IRQ stack pointer", RETURN_ON_ERROR);
> > > +		}
> > > +	}
> > >  
> > >  	machdep->flags |= IRQ_STACKS;
> > >  }
> > > @@ -1750,11 +1782,20 @@ arm64_display_full_frame(struct bt_info *bt, ulong
> > > sp)
> > >  	if (bt->frameptr == sp)
> > >  		return;
> > >  
> > > -	if (!INSTACK(sp, bt) || !INSTACK(bt->frameptr, bt)) {
> > > -		if (sp == 0)
> > > -			sp = bt->stacktop - USER_EFRAME_OFFSET;
> > > -		else
> > > -			return;
> > > +	if (INSTACK(bt->frameptr, bt)) {
> > > +		if (INSTACK(sp, bt)) {
> > > +			/* normal case */;
> > > +		} else {
> > > +			if (sp == 0)
> > > +				/* interrupt in user mode */
> > > +				sp = bt->stacktop - USER_EFRAME_OFFSET;
> > > +			else
> > > +				/* interrupt in kernel mode */
> > > +				sp = bt->stacktop;
> > > +		}
> > > +	} else {
> > > +		error(WARNING, "full display ?\n");
> > > +		return;
> > >  	}
> > >  
> > >  	words = (sp - bt->frameptr) / sizeof(ulong);
> > > @@ -1873,6 +1914,25 @@ arm64_unwind_frame(struct bt_info *bt, struct
> > > arm64_stackframe *frame)
> > >  	 *  orig_sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);   (pt_regs pointer
> > >  	 on
> > >  	 process stack)
> > >  	 */
> > >  	if (machdep->flags & IRQ_STACKS) {
> > > +		if (machdep->flags & UNW_4_14) {
> > > +			if ((bt->flags & BT_IRQSTACK) &&
> > > +			    !arm64_on_irq_stack(bt->tc->processor, frame->fp)) {
> > > +				if (arm64_on_process_stack(bt, frame->fp)) {
> > > +					arm64_set_process_stack(bt);
> > > +
> > > +					frame->sp = frame->fp - SIZE(pt_regs) + 16;
> > > +					/* for switch_stack */
> > > +					/* fp still points to irq stack */
> > > +					bt->bptr = fp;
> > > +					/* for display_full_frame */
> > > +					/* sp points to process stack */
> > > +					bt->frameptr = frame->sp;
> > > +				} else {
> > > +					/* irq -> user */
> > > +					return FALSE;
> > > +				}
> > > +			}
> > > +		} else { /* !UNW_4_14 */
> > >  		ms = machdep->machspec;
> > >  		irq_stack_ptr = ms->irq_stacks[bt->tc->processor] + ms->irq_stack_size -
> > >  		16;
> > >  
> > > @@ -1896,6 +1956,7 @@ arm64_unwind_frame(struct bt_info *bt, struct
> > > arm64_stackframe *frame)
> > >  				return FALSE;
> > >  			}
> > >  		}
> > > +		} /* UNW_4_14 */
> > >  	}
> > >  
> > >  	return TRUE;
> > > @@ -2086,10 +2147,17 @@ arm64_unwind_frame_v2(struct bt_info *bt, struct
> > > arm64_stackframe *frame,
> > >  			 * We are on process stack. Just add a faked frame
> > >  			 */
> > >  
> > > -			if (!arm64_on_irq_stack(bt->tc->processor, ext_frame.fp))
> > > -				frame->sp = ext_frame.fp
> > > -					    - sizeof(struct arm64_pt_regs);
> > > -			else {
> > > +			if (!arm64_on_irq_stack(bt->tc->processor, ext_frame.fp)) {
> > > +				if (MEMBER_EXISTS("pt_regs", "stackframe")) {
> > > +					frame->sp = ext_frame.fp
> > > +						    - sizeof(struct arm64_pt_regs) - 16;
> > > +					frame->fp = ext_frame.fp;
> > > +				} else {
> > > +					frame->sp = ext_frame.fp
> > > +						    - sizeof(struct arm64_pt_regs);
> > > +					frame->fp = frame->sp;
> > > +				}
> > > +			} else {
> > >  				/*
> > >  				 * FIXME: very exceptional case
> > >  				 * We are already back on process stack, but
> > > @@ -2109,10 +2177,10 @@ arm64_unwind_frame_v2(struct bt_info *bt, struct
> > > arm64_stackframe *frame,
> > >  				 * Really ugly
> > >  				 */
> > >  				frame->sp = frame->fp + 0x20;
> > > +				frame->fp = frame->sp;
> > >  				fprintf(ofp, " (Next exception frame might be wrong)\n");
> > >  			}
> > >  
> > > -			frame->fp = frame->sp;
> > >  		} else {
> > >  			/* We are on IRQ stack */
> > >  
> > > @@ -2122,9 +2190,15 @@ arm64_unwind_frame_v2(struct bt_info *bt, struct
> > > arm64_stackframe *frame,
> > >  			if (ext_frame.fp != irq_stack_ptr) {
> > >  				/* (2) Just add a faked frame */
> > >  
> > > -				frame->sp = ext_frame.fp
> > > -					    - sizeof(struct arm64_pt_regs);
> > > -				frame->fp = frame->sp;
> > > +				if (MEMBER_EXISTS("pt_regs", "stackframe")) {
> > > +					frame->sp = ext_frame.fp
> > > +						    - sizeof(struct arm64_pt_regs);
> > > +					frame->fp = ext_frame.fp;
> > > +				} else {
> > > +					frame->sp = ext_frame.fp
> > > +						    - sizeof(struct arm64_pt_regs) - 16;
> > > +					frame->fp = frame->sp;
> > > +				}
> > >  			} else {
> > >  				/*
> > >  				 * (3)
> > > @@ -2304,11 +2378,19 @@ arm64_back_trace_cmd(struct bt_info *bt)
> > >  		if (arm64_in_exception_text(bt->instptr) && INSTACK(stackframe.fp, bt))
> > >  		{
> > >  			if (!(bt->flags & BT_IRQSTACK) ||
> > >  			    (((stackframe.sp + SIZE(pt_regs)) < bt->stacktop)))
> > > -				exception_frame = stackframe.fp - SIZE(pt_regs);
> > > +			{
> > > +				if (MEMBER_EXISTS("pt_regs", "stackframe"))
> > > +					/* v4.14 or later */
> > > +					exception_frame = stackframe.fp
> > > +							  - SIZE(pt_regs) + 16;
> > > +				else
> > > +					exception_frame = stackframe.fp
> > > +							  - SIZE(pt_regs);
> > > +			}
> > >  		}
> > >  
> > >  		if ((bt->flags & BT_IRQSTACK) &&
> > > -		    !arm64_on_irq_stack(bt->tc->processor, stackframe.sp)) {
> > > +		    !arm64_on_irq_stack(bt->tc->processor, stackframe.fp)) {
> > >  			bt->flags &= ~BT_IRQSTACK;
> > >  			if (arm64_switch_stack(bt, &stackframe, ofp) == USER_MODE)
> > >  				break;
> > > @@ -2424,6 +2506,8 @@ user_space:
> > >  		 * otherwise show an exception frame.
> > >  		 * Since exception entry code doesn't have a real
> > >  		 * stackframe, we fake a dummy frame here.
> > > +		 * Note: Since we have a real stack frame in pt_regs,
> > > +		 * We no longer need a dummy frame on v4.14 or later.
> > >  		 */
> > >  		if (!arm64_in_exp_entry(stackframe.pc))
> > >  			continue;
> > > @@ -2669,7 +2753,9 @@ arm64_switch_stack(struct bt_info *bt, struct
> > > arm64_stackframe *frame, FILE *ofp
> > >  	if (frame->fp == 0)
> > >  		return USER_MODE;
> > >  
> > > -	arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
> > > +	if (!(machdep->flags & UNW_4_14))
> > > +		arm64_print_exception_frame(bt, frame->sp, KERNEL_MODE, ofp);
> > > +
> > >  	return KERNEL_MODE;
> > >  }
> > >  
> > > @@ -3362,6 +3448,20 @@ arm64_clear_machdep_cache(void) {
> > >  	return;
> > >  }
> > >  
> > > +static int
> > > +arm64_on_process_stack(struct bt_info *bt, ulong stkptr)
> > > +{
> > > +	ulong stackbase, stacktop;
> > > +
> > > +	stackbase = GET_STACKBASE(bt->task);
> > > +	stacktop = GET_STACKTOP(bt->task);
> > > +
> > > +	if ((stkptr >= stackbase) && (stkptr < stacktop))
> > > +		return TRUE;
> > > +
> > > +	return FALSE;
> > > +}
> > > +
> > >  static int
> > >  arm64_on_irq_stack(int cpu, ulong stkptr)
> > >  {
> > > --
> > > 2.14.1
> > > 
> > > --
> > > Crash-utility mailing list
> > > Crash-utility at redhat.com
> > > https://www.redhat.com/mailman/listinfo/crash-utility
> > > 
> > 
> 
> --
> Crash-utility mailing list
> Crash-utility at redhat.com
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