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

[HAGIO KAZUHITO(萩尾 一仁)]

-----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