From: Steven Price <steven.price@arm.com> To: Dave Hansen <dave.hansen@intel.com>, linux-mm@kvack.org 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>, "Catalin Marinas" <catalin.marinas@arm.com>, x86@kernel.org, "Will Deacon" <will.deacon@arm.com>, linux-kernel@vger.kernel.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>, linux-arm-kernel@lists.infradead.org, "Liang, Kan" <kan.liang@linux.intel.com> Subject: Re: [PATCH v3 27/34] mm: pagewalk: Add 'depth' parameter to pte_hole Date: Fri, 1 Mar 2019 11:24:25 +0000 [thread overview] Message-ID: <26df02dd-c54e-ea91-bdd1-0a4aad3a30ac@arm.com> (raw) In-Reply-To: <5f354bf5-4ac8-d0e2-048c-0857c91a21e6@intel.com> On 28/02/2019 19:00, Dave Hansen wrote: > On 2/28/19 3:28 AM, Steven Price wrote: >> static int get_level(unsigned long addr, unsigned long end) >> { >> /* Add 1 to account for ~0ULL */ >> unsigned long size = (end - addr) + 1; >> if (size < PMD_SIZE) >> return 4; >> else if (size < PUD_SIZE) >> return 3; >> else if (size < P4D_SIZE) >> return 2; >> else if (size < PGD_SIZE) >> return 1; >> return 0; >> } >> >> There are two immediate problems with that: >> >> * The "+1" to deal with ~0ULL is fragile >> >> * PGD_SIZE isn't what you might expect, it's not defined for most >> architectures and arm64/x86 use it as the size of the PGD table. >> Although that's easy enough to fix up. >> >> Do you think a function like above would be preferable? > > The question still stands of why we *need* the depth/level in the first > place. As I said, we obviously need it for printing out the "name" of > the level. Is that it? That is the only use I'm currently aware of. >> The other option would of course be to just drop the information from >> the debugfs file about at which level the holes are. But it can be >> useful information to see whether there are empty levels in the page >> table structure. Although this is an area where x86 and arm64 differ >> currently (x86 explicitly shows the gaps, arm64 doesn't), so if x86 >> doesn't mind losing that functionality that would certainly simplify things! > > I think I'd actually be OK with the holes just not showing up. I > actually find it kinda hard to read sometimes with the holes in there. > I'd be curious what others think though. If no-one has any objections to dropping the holes in the output, then I can rebase on something like below and drop this 'depth' patch. Steve ----8<---- From a9eabadfc212389068ec5cc60265c7a55585bb76 Mon Sep 17 00:00:00 2001 From: Steven Price <steven.price@arm.com> Date: Fri, 1 Mar 2019 10:06:33 +0000 Subject: [PATCH] x86: mm: Hide page table holes in debugfs For the /sys/kernel/debug/page_tables/ files, rather than outputing a mostly empty line when a block of memory isn't present just skip the line. This keeps the output shorter and will help with a future change switching to using the generic page walk code as we no longer care about the 'level' that the page table holes are at. Signed-off-by: Steven Price <steven.price@arm.com> --- arch/x86/mm/dump_pagetables.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index e3cdc85ce5b6..a0f4139631dd 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -304,8 +304,8 @@ static void note_page(struct seq_file *m, struct pg_state *st, /* * Now print the actual finished series */ - if (!st->marker->max_lines || - st->lines < st->marker->max_lines) { + if ((cur & _PAGE_PRESENT) && (!st->marker->max_lines || + st->lines < st->marker->max_lines)) { pt_dump_seq_printf(m, st->to_dmesg, "0x%0*lx-0x%0*lx ", width, st->start_address, @@ -321,7 +321,9 @@ static void note_page(struct seq_file *m, struct pg_state *st, printk_prot(m, st->current_prot, st->level, st->to_dmesg); } - st->lines++; + if (cur & _PAGE_PRESENT) { + st->lines++; + } /* * We print markers for special areas of address space, -- 2.20.1
WARNING: multiple messages have this Message-ID (diff)
From: Steven Price <steven.price@arm.com> To: Dave Hansen <dave.hansen@intel.com>, linux-mm@kvack.org Cc: "Mark Rutland" <Mark.Rutland@arm.com>, x86@kernel.org, "Arnd Bergmann" <arnd@arndb.de>, "Ard Biesheuvel" <ard.biesheuvel@linaro.org>, "Peter Zijlstra" <peterz@infradead.org>, "Catalin Marinas" <catalin.marinas@arm.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Will Deacon" <will.deacon@arm.com>, linux-kernel@vger.kernel.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>, linux-arm-kernel@lists.infradead.org, "Liang, Kan" <kan.liang@linux.intel.com> Subject: Re: [PATCH v3 27/34] mm: pagewalk: Add 'depth' parameter to pte_hole Date: Fri, 1 Mar 2019 11:24:25 +0000 [thread overview] Message-ID: <26df02dd-c54e-ea91-bdd1-0a4aad3a30ac@arm.com> (raw) In-Reply-To: <5f354bf5-4ac8-d0e2-048c-0857c91a21e6@intel.com> On 28/02/2019 19:00, Dave Hansen wrote: > On 2/28/19 3:28 AM, Steven Price wrote: >> static int get_level(unsigned long addr, unsigned long end) >> { >> /* Add 1 to account for ~0ULL */ >> unsigned long size = (end - addr) + 1; >> if (size < PMD_SIZE) >> return 4; >> else if (size < PUD_SIZE) >> return 3; >> else if (size < P4D_SIZE) >> return 2; >> else if (size < PGD_SIZE) >> return 1; >> return 0; >> } >> >> There are two immediate problems with that: >> >> * The "+1" to deal with ~0ULL is fragile >> >> * PGD_SIZE isn't what you might expect, it's not defined for most >> architectures and arm64/x86 use it as the size of the PGD table. >> Although that's easy enough to fix up. >> >> Do you think a function like above would be preferable? > > The question still stands of why we *need* the depth/level in the first > place. As I said, we obviously need it for printing out the "name" of > the level. Is that it? That is the only use I'm currently aware of. >> The other option would of course be to just drop the information from >> the debugfs file about at which level the holes are. But it can be >> useful information to see whether there are empty levels in the page >> table structure. Although this is an area where x86 and arm64 differ >> currently (x86 explicitly shows the gaps, arm64 doesn't), so if x86 >> doesn't mind losing that functionality that would certainly simplify things! > > I think I'd actually be OK with the holes just not showing up. I > actually find it kinda hard to read sometimes with the holes in there. > I'd be curious what others think though. If no-one has any objections to dropping the holes in the output, then I can rebase on something like below and drop this 'depth' patch. Steve ----8<---- From a9eabadfc212389068ec5cc60265c7a55585bb76 Mon Sep 17 00:00:00 2001 From: Steven Price <steven.price@arm.com> Date: Fri, 1 Mar 2019 10:06:33 +0000 Subject: [PATCH] x86: mm: Hide page table holes in debugfs For the /sys/kernel/debug/page_tables/ files, rather than outputing a mostly empty line when a block of memory isn't present just skip the line. This keeps the output shorter and will help with a future change switching to using the generic page walk code as we no longer care about the 'level' that the page table holes are at. Signed-off-by: Steven Price <steven.price@arm.com> --- arch/x86/mm/dump_pagetables.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index e3cdc85ce5b6..a0f4139631dd 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -304,8 +304,8 @@ static void note_page(struct seq_file *m, struct pg_state *st, /* * Now print the actual finished series */ - if (!st->marker->max_lines || - st->lines < st->marker->max_lines) { + if ((cur & _PAGE_PRESENT) && (!st->marker->max_lines || + st->lines < st->marker->max_lines)) { pt_dump_seq_printf(m, st->to_dmesg, "0x%0*lx-0x%0*lx ", width, st->start_address, @@ -321,7 +321,9 @@ static void note_page(struct seq_file *m, struct pg_state *st, printk_prot(m, st->current_prot, st->level, st->to_dmesg); } - st->lines++; + if (cur & _PAGE_PRESENT) { + st->lines++; + } /* * We print markers for special areas of address space, -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-01 11:24 UTC|newest] Thread overview: 153+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-27 17:05 [PATCH v3 00/34] Convert x86 & arm64 to use generic page walk Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 01/34] alpha: mm: Add p?d_large() definitions Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 02/34] arc: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 18:18 ` Vineet Gupta 2019-02-27 18:18 ` Vineet Gupta 2019-02-27 18:18 ` Vineet Gupta 2019-02-27 18:18 ` Vineet Gupta 2019-02-27 17:05 ` [PATCH v3 03/34] arm: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-03-01 21:47 ` Kirill A. Shutemov 2019-03-01 21:47 ` Kirill A. Shutemov 2019-03-04 11:56 ` Steven Price 2019-03-04 11:56 ` Steven Price 2019-03-04 13:10 ` Kirill A. Shutemov 2019-03-04 13:10 ` Kirill A. Shutemov 2019-02-27 17:05 ` [PATCH v3 04/34] arm64: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 05/34] c6x: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-03-01 21:48 ` Kirill A. Shutemov 2019-03-01 21:48 ` Kirill A. Shutemov 2019-03-04 12:01 ` Steven Price 2019-03-04 12:01 ` Steven Price 2019-03-04 13:11 ` Kirill A. Shutemov 2019-03-04 13:11 ` Kirill A. Shutemov 2019-02-27 17:05 ` [PATCH v3 06/34] csky: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-03-01 21:51 ` Kirill A. Shutemov 2019-03-01 21:51 ` Kirill A. Shutemov 2019-02-27 17:05 ` [PATCH v3 07/34] hexagon: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 08/34] ia64: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-03-01 21:57 ` Kirill A. Shutemov 2019-03-01 21:57 ` Kirill A. Shutemov 2019-03-01 21:57 ` Kirill A. Shutemov 2019-03-04 13:16 ` Steven Price 2019-03-04 13:16 ` Steven Price 2019-03-04 13:16 ` Steven Price 2019-03-04 19:06 ` Luck, Tony 2019-03-04 19:06 ` Luck, Tony 2019-03-04 19:06 ` Luck, Tony 2019-03-06 13:45 ` Steven Price 2019-03-06 13:45 ` Steven Price 2019-03-06 13:45 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 09/34] m68k: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 19:27 ` Geert Uytterhoeven 2019-02-27 19:27 ` Geert Uytterhoeven 2019-02-28 11:36 ` Mike Rapoport 2019-02-28 11:36 ` Mike Rapoport 2019-02-28 11:53 ` Geert Uytterhoeven 2019-02-28 11:53 ` Geert Uytterhoeven 2019-02-28 12:04 ` Steven Price 2019-02-28 12:04 ` Steven Price 2019-03-01 11:45 ` Mike Rapoport 2019-03-01 11:45 ` Mike Rapoport 2019-02-27 17:05 ` [PATCH v3 10/34] microblaze: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 11/34] mips: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-28 2:15 ` Paul Burton 2019-02-28 2:15 ` Paul Burton 2019-02-28 12:11 ` Steven Price 2019-02-28 12:11 ` Steven Price 2019-02-28 18:55 ` Paul Burton 2019-02-28 18:55 ` Paul Burton 2019-03-01 11:02 ` Steven Price 2019-03-01 11:02 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 12/34] nds32: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 13/34] nios2: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 14/34] openrisc: " Steven Price 2019-02-27 17:05 ` [OpenRISC] " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 15/34] parisc: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 18:54 ` Helge Deller 2019-02-27 18:54 ` Helge Deller 2019-03-01 22:12 ` Kirill A. Shutemov 2019-03-01 22:12 ` Kirill A. Shutemov 2019-03-05 21:45 ` Helge Deller 2019-03-05 21:45 ` Helge Deller 2019-02-27 17:05 ` [PATCH v3 16/34] powerpc: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 17/34] riscv: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 18/34] s390: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:40 ` Martin Schwidefsky 2019-02-27 17:40 ` Martin Schwidefsky 2019-02-28 11:43 ` Steven Price 2019-02-28 11:43 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 19/34] sh: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 20/34] sparc: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 18:38 ` David Miller 2019-02-27 18:38 ` David Miller 2019-02-27 18:38 ` David Miller 2019-02-28 11:49 ` Steven Price 2019-02-28 11:49 ` Steven Price 2019-02-28 11:49 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 21/34] um: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 22/34] unicore32: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 23/34] xtensa: " Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:29 ` Max Filippov 2019-02-27 17:29 ` Max Filippov 2019-02-27 17:05 ` [PATCH v3 24/34] mm: Add generic p?d_large() macros Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:05 ` [PATCH v3 25/34] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price 2019-02-27 17:05 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 26/34] mm: pagewalk: Allow walking without vma Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 27/34] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:38 ` Dave Hansen 2019-02-27 17:38 ` Dave Hansen 2019-02-28 11:28 ` Steven Price 2019-02-28 11:28 ` Steven Price 2019-02-28 19:00 ` Dave Hansen 2019-02-28 19:00 ` Dave Hansen 2019-03-01 11:24 ` Steven Price [this message] 2019-03-01 11:24 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 28/34] mm: pagewalk: Add test_p?d callbacks Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 29/34] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 30/34] x86/mm: Point to struct seq_file from struct pg_state Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 31/34] x86/mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 32/34] x86/mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 33/34] x86/mm: Convert ptdump_walk_pgd_level_core() " Steven Price 2019-02-27 17:06 ` Steven Price 2019-02-27 17:06 ` [PATCH v3 34/34] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price 2019-02-27 17:06 ` Steven Price
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