----- Original Message -----
> Ok. I have seen this change in the pt_regs struct before but did not connect
> it to this problem. I see these new field in pt_regs in earlier kernel
> versions than 4.7, but it is probably backports. It really does not matter
> for the solution of the problem. The following change works for me:
> Change:
> #define USER_EFRAME_OFFSET (304)
> to:
> #define USER_EFRAME_OFFSET (STRUCT_SIZE("pt_regs") + 16)
>
> Then you might want to avoid the recalculation of the struct size. I think
> your patch does the same thing.
>
> Jan
>
> ________________________________________
> Från: crash-utility-bounces@xxxxxxxxxx <crash-utility-bounces@xxxxxxxxxx> för
> Dave Anderson <anderson@xxxxxxxxxx>
> Skickat: den 21 september 2017 17:38
> Till: Discussion list for crash utility usage, maintenance and development
> Ämne: Re: Problem in bt for ARM64
>
> ----- Original Message -----
> >
> >
> > ----- Original Message -----
> > > Hi Dave
> > >
> > > I have experienced some problems in the bt command for ARM64. It seems
> > > that
> > > the test in arm64_print_exception_frame in arm64.c if the task is running
> > > in
> > > 32 or 64-bit mode in userland does not work. It "always" becomes 32-bit
> > > mode. Example:
> > >
> > > crash> bt 1
> > > PID: 1 TASK: ffffffe1f90f8000 CPU: 2 COMMAND: "init"
> > > #0 [ffffffe1f9103c80] __switch_to at ffffff85b6a862f8
> > > #1 [ffffffe1f9103ca0] __schedule at ffffff85b7b0d9b0
> > > #2 [ffffffe1f9103d00] schedule at ffffff85b7b0df28
> > > #3 [ffffffe1f9103d20] schedule_hrtimeout_range_clock at ffffff85b7b11308
> > > #4 [ffffffe1f9103da0] schedule_hrtimeout_range at ffffff85b7b11320
> > > #5 [ffffffe1f9103db0] sys_epoll_wait at ffffff85b6c394c8
> > > #6 [ffffffe1f9103e70] sys_epoll_pwait at ffffff85b6c396fc
> > > #7 [ffffffe1f9103ed0] el0_svc_naked at ffffff85b6a8312c
> > > PC: 00000004 LR: 00000000 SP: 00000000 PSTATE: 00000016
> > > X12: 00546694 X11: 3431206c616e6769 X10: 00546338 X9: 00000000
> > > X8: 00000112 X7: dfdab819254dd1e8 X6: 00000016 X5: 0000000a
> > > X4: 00000031 X3: 00000008 X2: 00000000 X1: ffffffff
> > > X0: 00000001
> > >
> > > The register values are:
> > > r0: 4 r1: 7ff0b27f90
> > > r2: 1 r3: ffffffff
> > > r4: 0 r5: 8
> > > r6: 31 r7: a
> > > r8: 16 r9: dfdab819254dd1e8
> > > r10: 112 r11: 0
> > > r12: 546338 r13: 3431206c616e6769
> > > r14: 546694 r15: 0
> > > r16: 0 r17: f04245b7
> > > r18: 51f2a993 r19: 5783c0
> > > r20: 415254 r21: 527a5c
> > > r22: 527e04 r23: ffffffff
> > > r24: ffffffff r25: 576000
> > > r26: 578000 r27: 578000
> > > r28: 3e8 fp: 7ff0b27ec0
> > > lr: 4f4f24 sp: 7ff0b27eb0
> > > pc: 4fb8d4 psr: 40000000
> > >
> > > I have unfortunately not had the time to look for a solution, so I just
> > > want
> > > to report what I have seen. The kernel running in the example above is
> > > 4.4.74 and I have seen the same problem for a 4.9.40 kernel.
> > >
> > > Jan
> >
> > Yeah, even the functions that do show 64-bit user mode exception frames
> > appear to have invalid contents. It looks like the pt_regs is not at the
> > same fixed location on the stack where it has always been, i.e., as it gets
> > set here unconditionally at the bottom of arm64_back_trace_cmd():
> >
> > complete_user:
> > exception_frame = bt->stacktop - USER_EFRAME_OFFSET;
> > arm64_print_exception_frame(bt, exception_frame, USER_MODE, ofp);
> >
>
> Jan,
>
> I don't see the problem in anything before 4.7, and I do have a set
> of 4.5 dumpfiles and an early 4.7-rc0 dumpfile that do not show the
> problem. Are you sure about seeing it in a "4.4.74" kernel?
>
> I say that because it does seem to be confluent with v4.7-rc7 commit
> e19a6ee2460bdd0d0055a6029383422773f9999a that has this:
>
> diff --git a/arch/arm64/include/asm/ptrace.h
> b/arch/arm64/include/asm/ptrace.h
> index a307eb6..7f94755 100644
> --- a/arch/arm64/include/asm/ptrace.h
> +++ b/arch/arm64/include/asm/ptrace.h
> @@ -117,6 +117,8 @@ struct pt_regs {
> };
> u64 orig_x0;
> u64 syscallno;
> + u64 orig_addr_limit;
> + u64 unused; // maintain 16 byte alignment
> };
>
> Does the attached patch work for you?
>
> Thanks,
> Dave
>
>
>
> diff --git a/arm64.c b/arm64.c
> index 0ab8396..9fe0c87 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -393,6 +393,11 @@ arm64_init(int when)
> get_symbol_data("nr_irqs", sizeof(unsigned int),
> &machdep->nr_irqs);
>
> + if (MEMBER_EXISTS("pt_regs", "orig_addr_limit"))
> + ms->user_eframe_offset = 320;
> + else
> + ms->user_eframe_offset = 304;
> +
> if (!machdep->hz)
> machdep->hz = 100;
>
> @@ -608,6 +613,7 @@ arm64_dump_machdep_table(ulong arg)
> fprintf(fp, " exp_entry2_start: %lx\n", ms->exp_entry2_start);
> fprintf(fp, " exp_entry2_end: %lx\n", ms->exp_entry2_end);
> fprintf(fp, " panic_task_regs: %lx\n",
> (ulong)ms->panic_task_regs);
> + fprintf(fp, " user_eframe_offset: %ld\n", ms->user_eframe_offset);
> fprintf(fp, " PTE_PROT_NONE: %lx\n", ms->PTE_PROT_NONE);
> fprintf(fp, " PTE_FILE: ");
> if (ms->PTE_FILE)
> @@ -1461,7 +1467,7 @@ arm64_stackframe_init(void)
> #define KERNEL_MODE (1)
> #define USER_MODE (2)
>
> -#define USER_EFRAME_OFFSET (304)
> +#define USER_EFRAME_OFFSET (machdep->machspec->user_eframe_offset)
>
> /*
> * PSR bits
> diff --git a/defs.h b/defs.h
> index fd97ffe..8534d40 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -3110,6 +3110,7 @@ struct machine_specific {
> ulong kimage_voffset;
> ulong kimage_text;
> ulong kimage_end;
> + ulong user_eframe_offset;
> };
>
> struct arm64_stackframe {
>
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