Re: [PATCH v14 21/22] arm64: mm: Convert mm/dump.c to use walk_page_range()

From: Catalin Marinas <catalin.marinas@arm.com>
To: Steven Price <steven.price@arm.com>
Cc: "Mark Rutland" <Mark.Rutland@arm.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Andy Lutomirski" <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"James Morse" <james.morse@arm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Will Deacon" <will@kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	linux-arm-kernel@lists.infradead.org, "Liang,
	Kan" <kan.liang@linux.intel.com>
Subject: Re: [PATCH v14 21/22] arm64: mm: Convert mm/dump.c to use walk_page_range()
Date: Thu, 31 Oct 2019 14:37:24 +0000	[thread overview]
Message-ID: <20191031143724.GE39590@arrakis.emea.arm.com> (raw)
In-Reply-To: <20191031140038.GC39590@arrakis.emea.arm.com>

On Thu, Oct 31, 2019 at 02:00:38PM +0000, Catalin Marinas wrote:
> On Thu, Oct 31, 2019 at 01:32:34PM +0000, Steven Price wrote:
> > On 30/10/2019 16:45, Catalin Marinas wrote:
> > > On Mon, Oct 28, 2019 at 01:59:09PM +0000, Steven Price wrote:
> > >> diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
> > >> index 93f9f77582ae..9d9b740a86d2 100644
> > >> --- a/arch/arm64/mm/dump.c
> > >> +++ b/arch/arm64/mm/dump.c
> > >> @@ -15,6 +15,7 @@
> > >>  #include <linux/io.h>
> > >>  #include <linux/init.h>
> > >>  #include <linux/mm.h>
> > >> +#include <linux/ptdump.h>
> > >>  #include <linux/sched.h>
> > >>  #include <linux/seq_file.h>
> > >>  
> > >> @@ -75,10 +76,11 @@ static struct addr_marker address_markers[] = {
> > >>   * dumps out a description of the range.
> > >>   */
> > >>  struct pg_state {
> > >> +	struct ptdump_state ptdump;
> > >>  	struct seq_file *seq;
> > >>  	const struct addr_marker *marker;
> > >>  	unsigned long start_address;
> > >> -	unsigned level;
> > >> +	int level;
> > >>  	u64 current_prot;
> > >>  	bool check_wx;
> > >>  	unsigned long wx_pages;
> > >> @@ -178,6 +180,10 @@ static struct pg_level pg_level[] = {
> > >>  		.name	= "PGD",
> > >>  		.bits	= pte_bits,
> > >>  		.num	= ARRAY_SIZE(pte_bits),
> > >> +	}, { /* p4d */
> > >> +		.name	= "P4D",
> > >> +		.bits	= pte_bits,
> > >> +		.num	= ARRAY_SIZE(pte_bits),
> > >>  	}, { /* pud */
> > >>  		.name	= (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
> > >>  		.bits	= pte_bits,
> > > 
> > > We could use "PGD" for the p4d entry since we don't have five levels.
> > > This patches the "PGD" name used for pud/pmd when these levels are
> > > folded.
> > 
> > Good point, although I'd actually be more tempted to do the opposite -
> > remove the special casing for PUD/PMD as the generic code should now
> > never provide those levels if they are folded. What do you think?
> 
> I agree, it makes sense.

Forgot to mention. With the additional patch you sent, feel free to also
add my r-o-b on this one.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>