[Crash-utility] arm64: Get CPU registers without crash_notes symbol

[HAGIO KAZUHITO(萩尾 一仁)]

-----Original Message-----
> Dear Kazu,
> 
> Sorry for late reply
> Thanks for your suggestion and I have prepared a V2 patch, please help
> to review.

ok, I've modified your v2 patch to fix the following compilation warning
and rewrite the commit log, and attached it.

arm64.c: In function ‘arm64_init’:
arm64.c:3728:35: warning: ‘note’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     offset = roundup(offset + note->n_namesz, 4);
                                   ^~

Lianbo, could you review the attached patch?

Thanks,
Kazu

> 
> BTW, I have switched to evolution mail system, if still look like html
> format, please let me know, thanks.
> 
> Signed-off-by: James Hsu <james.hsu at mediatek.com>
> 
> diff --git a/arm64.c b/arm64.c
> index 8934961..03c8167 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -3667,8 +3667,42 @@ arm64_get_crash_notes(void)
>  	ulong *notes_ptrs;
>  	ulong i, found;
> 
> -	if (!symbol_exists("crash_notes"))
> +	if (!symbol_exists("crash_notes")) {
> +		if (DISKDUMP_DUMPFILE() || KDUMP_DUMPFILE()) {
> +			if (!(ms->panic_task_regs = calloc((size_t)kt-
> >cpus, sizeof(struct arm64_pt_regs))))
> +				error(FATAL, "cannot calloc
> panic_task_regs space\n");
> +
> +			for  (i = found = 0; i < kt->cpus; i++) {
> +				if (DISKDUMP_DUMPFILE())
> +					note =
> diskdump_get_prstatus_percpu(i);
> +				else if (KDUMP_DUMPFILE())
> +					note =
> netdump_get_prstatus_percpu(i);
> +
> +				if(!note) {
> +					error(WARNING, "cpu %d: cannot
> find NT_PRSTATUS note\n", i);
> +					continue;
> +				}
> +
> +				/*
> +				 * Find correct location of note data.
> This contains elf_prstatus
> +				 * structure which has registers etc.
> for the crashed task.
> +				 */
> +				offset = sizeof(Elf64_Nhdr);
> +				offset = roundup(offset + note-
> >n_namesz, 4);
> +				p = (char *)note + offset; /* start of
> elf_prstatus */
> +
> +				BCOPY(p + OFFSET(elf_prstatus_pr_reg),
> &ms->panic_task_regs[i],
> +				      sizeof(struct arm64_pt_regs));
> +
> +				found++;
> +			}
> +			if (!found) {
> +				free(ms->panic_task_regs);
> +				ms->panic_task_regs = NULL;
> +			}
> +		}
>  		return;
> +	}
> 
>  	crash_notes = symbol_value("crash_notes");
> 
> Thanks
> James Hsu
> 
> On Wed, 2021-08-11 at 02:52 +0000, HAGIO KAZUHITO(萩尾　一仁) wrote:
> > -----Original Message-----
> > >
> > > Dear Crash maintainers,
> > >
> > > We want to improve the crash_tool for the case that need offline
> > > cpu  register info even Kdump without
> > > crash_notes.
> > >
> > > For one thing,  we will prepare a Kdump with all CPU register info
> > > in ELF note.
> > > For another thing, we need to modify crash_tool and make it support
> > > adding offline cpu register info even
> > > Kdump without crash_notes.
> > >
> > > We prepare a patch for the case with ARCH=arm64.
> > > It is verified with our kdump without crash_note and can get all
> > > cpu register.
> > > Please take your time to review our patch and look forward to
> > > receiving your comments.
> > >
> > > Patch detail as below
> >
> > I've rewritten the commit log, is this ok?
> > --
> > arm64: Get CPU registers from ELF notes even without crash_notes
> > symbol
> >
> > Currently arm64 crash retrieves the CPU registers from crash_notes
> > symbol
> > or ELF notes only when the symbol exists, but there are dumpfiles
> > which
> > have the registers in ELF notes without the symbol.
> >
> > With the patch, crash can retrieve the registers from ELF notes
> > without
> > the crash_notes symbol.
> > --
> >
> > And please add Signed-off-by tag.
> >
> > > --- crash-7.3.0/arm64.c	2021-04-27 16:01:07.000000000 +0800
> > > +++ crash-7.3.0.mod/arm64.c	2021-06-15 17:13:54.037273227 +0800
> > > @@ -3667,8 +3667,41 @@ arm64_get_crash_notes(void)
> > >  	ulong *notes_ptrs;
> > >  	ulong i, found;
> > >
> > > -	if (!symbol_exists("crash_notes"))
> > > +	if (!symbol_exists("crash_notes")) {
> > > +		if (DISKDUMP_DUMPFILE() || KDUMP_DUMPFILE()) {
> > > +			if (!(ms->panic_task_regs = calloc((size_t)kt-
> > > >cpus, sizeof(struct arm64_pt_regs))))
> > > +				error(FATAL, "cannot calloc
> > > panic_task_regs space\n");
> > > +
> > > +			for  (i = found = 0; i < kt->cpus; i++) {
> > > +				if (DISKDUMP_DUMPFILE())
> > > +					note =
> > > diskdump_get_prstatus_percpu(i);
> > > +				else if (KDUMP_DUMPFILE())
> > > +					note =
> > > netdump_get_prstatus_percpu(i);
> > > +				else {
> > > +					error(WARNING, "cpu %d: cannot
> > > find NT_PRSTATUS note\n", i);
> > > +					continue;
> > > +				}
> >
> > This else block should be separated from the if block like this?
> >
> > if (!note) {
> > 	error(WARNING, "cpu %d: cannot find NT_PRSTATUS note\n", i);
> > 	continue;
> > }
> >
> > > +
> > > +				/*
> > > +				 * Find correct location of note data.
> > > This contains elf_prstatus
> > > +				 * structure which has registers etc.
> > > for the crashed task.
> > > +				 */
> > > +				offset = sizeof(Elf64_Nhdr);
> > > +				offset = roundup(offset + note-
> > > >n_namesz, 4);
> > > +				p = (char *)note + offset; /* start of
> > > elf_prstatus */
> > > +
> > > +				BCOPY(p + OFFSET(elf_prstatus_pr_reg),
> > > &ms->panic_task_regs[i],
> > > +				      sizeof(struct arm64_pt_regs));
> > > +
> > > +				found++;
> > > +			}
> > > +		}
> > > +		if (!found) {
> > > +			free(ms->panic_task_regs);
> > > +			ms->panic_task_regs = NULL;
> > > +		}
> >
> > This if block should be within the if (DISKDUMP_DUMPFILE()... block.
> >
> > >  		return;
> > > +	}
> > >
> > >  	crash_notes = symbol_value("crash_notes");
> > >
> >
> > (and this email still looks HTML one to me :-)
> >
> > Thanks,
> > Kazu
> >
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