[Crash-utility] [PATCH 3/3] mips: use get_stackframe() implementation from ARM

[Dave Anderson]

----- Original Message -----
> On Wed, Oct 19, 2016 at 09:56:08AM -0400, Dave Anderson wrote:
> > But with the patch installed, both dumpfiles show the "WARNING: cannot
> > retrieve registers for active task" during initialization, and "bt" fails
> > as expected:
> 
> Right, thanks for catching this.  The code borrowed from ARM assumes
> that the kernel was built with core dump support, which is not
> necessarily the case if the dump was saved via some external means which
> creates ELF dumps (QEMU in the case of my example dumps).
> 
> Folding in the following patch makes it work for both the example dumps
> you have and dumps with crash_notes.  Thanks.

That works -- queued for crash-7.1.7:

   https://github.com/crash-utility/crash/commit/5bca61c0eb44729b541da02bcc48b8b85d21358b

Thanks,
  Dave


> 
> 8<----
> >From fd9cec4ae5e5f310e3de073e66825b7b9df07573 Mon Sep 17 00:00:00 2001
> From: Rabin Vincent <rabinv at axis.com>
> Date: Wed, 19 Oct 2016 21:18:31 +0200
> Subject: [PATCH] mips: get regs from ELF notes if no crash_notes
> 
> ---
>  mips.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/mips.c b/mips.c
> index e3f1569..4eeab55 100644
> --- a/mips.c
> +++ b/mips.c
> @@ -898,6 +898,54 @@ fail:
>  	return FALSE;
>  }
>  
> +static int mips_get_elf_notes(void)
> +{
> +	struct machine_specific *ms = machdep->machspec;
> +	int i;
> +
> +	if (!DISKDUMP_DUMPFILE() && !KDUMP_DUMPFILE())
> +		return FALSE;
> +
> +	panic_task_regs = calloc(kt->cpus, sizeof(*panic_task_regs));
> +	if (!panic_task_regs)
> +		error(FATAL, "cannot calloc panic_task_regs space\n");
> +
> +	for (i = 0; i < kt->cpus; i++) {
> +		Elf32_Nhdr *note = NULL;
> +		size_t len;
> +
> +		if (DISKDUMP_DUMPFILE())
> +			note = diskdump_get_prstatus_percpu(i);
> +		else if (KDUMP_DUMPFILE())
> +			note = netdump_get_prstatus_percpu(i);
> +
> +		if (!note)
> +			error(WARNING,
> +			      "cannot find NT_PRSTATUS note for cpu: %d\n", i);
> +
> +		len = sizeof(Elf32_Nhdr);
> +		len = roundup(len + note->n_namesz, 4);
> +
> +		BCOPY((char *)note + len + OFFSET(elf_prstatus_pr_reg),
> +		      &panic_task_regs[i], sizeof(panic_task_regs[i]));
> +	}
> +
> +	ms->crash_task_regs = panic_task_regs;
> +
> +	return TRUE;
> +}
> +
> +static int mips_init_active_task_regs(void)
> +{
> +	int retval;
> +
> +	retval = mips_get_crash_notes();
> +	if (retval == TRUE)
> +		return retval;
> +
> +	return mips_get_elf_notes();
> +}
> +
>  static int
>  mips_verify_symbol(const char *name, ulong value, char type)
>  {
> @@ -1075,7 +1123,7 @@ mips_init(int when)
>  		 * of the crash. We need this information to extract correct
>  		 * backtraces from the panic task.
>  		 */
> -		if (!ACTIVE() && !mips_get_crash_notes())
> +		if (!ACTIVE() && !mips_init_active_task_regs())
>  			error(WARNING,
>  			    "cannot retrieve registers for active task%s\n\n",
>  				kt->cpus > 1 ? "s" : "");
> --
> 2.1.4
> 
> --
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