RE: [PATCH] arm64: Show three registers per line

From: David Laight
Date: Wed Apr 21 2021 - 04:31:40 EST


From: Matthew Wilcox
> Sent: 20 April 2021 18:23
>
> Displaying two registers per line takes 15 lines. That improves to just
> 10 lines if we display three registers per line, which reduces the amount
> of information lost when oopses are cut off. It stays within 80 columns
> and matches x86-64.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
> arch/arm64/kernel/process.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 6e60aa3b5ea9..aff5a2c12297 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -294,13 +294,10 @@ void __show_regs(struct pt_regs *regs)
> i = top_reg;
>
> while (i >= 0) {
> - printk("x%-2d: %016llx ", i, regs->regs[i]);
> - i--;
> + printk("x%-2d: %016llx", i, regs->regs[i]);
>
> - if (i % 2 == 0) {
> - pr_cont("x%-2d: %016llx ", i, regs->regs[i]);
> - i--;
> - }
> + while (i-- % 3)
> + pr_cont(" x%-2d: %016llx", i, regs->regs[i]);
>
> pr_cont("\n");
> }

I think I'd avoid pr_cont() to avoid 'mishaps' during concurrent oops.
This probably needs something like:
for (; i >= 0; i -= 3) {
switch (i) {
case 0:
printk("x%-2d: %016llx\n", i, regs->regs[i]);
break;
case 1:
printk("x%-2d: %016llx x%-2d: %016llx\n",
i, regs->regs[i], i - 1, regs->regs[i - 1]);
break;
default:
printk("x%-2d: %016llx x%-2d: %016llx x%-2d: %016llx\n",
i, regs->regs[i], i - 1, regs->regs[i - 1],
i - 2, regs->regs[i - 2]);
continue;
}
break;
}

David

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