linux-kernel - Re: [PATCH v14 21/22] arm64: mm: Convert mm/dump.c to use walk_page

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Message-ID: <20191031140038.GC39590@arrakis.emea.arm.com>
Date:   Thu, 31 Oct 2019 14:00:38 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Steven Price <steven.price@....com>
Cc:     Mark Rutland <Mark.Rutland@....com>, x86@...nel.org,
        Arnd Bergmann <arnd@...db.de>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Jérôme Glisse <jglisse@...hat.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        James Morse <james.morse@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-arm-kernel@...ts.infradead.org,
        "Liang, Kan" <kan.liang@...ux.intel.com>
Subject: Re: [PATCH v14 21/22] arm64: mm: Convert mm/dump.c to use
 walk_page_range()

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.

-- 
Catalin