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From: Steven Price <steven.price@arm.com>
To: Andrew Morton <akpm@linux-foundation.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>,
	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>,
	linux-arm-kernel@lists.infradead.org, "Liang,
	Kan" <kan.liang@linux.intel.com>
Subject: Re: [PATCH v10 20/22] x86: mm: Convert dump_pagetables to use walk_page_range
Date: Wed, 7 Aug 2019 13:58:21 +0100	[thread overview]
Message-ID: <066fa4ca-5a46-ba86-607f-9c3e16f79cde@arm.com> (raw)
In-Reply-To: <20190806165823.3f735b45a7c4163aca20a767@linux-foundation.org>

On 07/08/2019 00:58, Andrew Morton wrote:
> On Wed, 31 Jul 2019 16:46:01 +0100 Steven Price <steven.price@arm.com> wrote:
> 
>> Make use of the new functionality in walk_page_range to remove the
>> arch page walking code and use the generic code to walk the page tables.
>>
>> The effective permissions are passed down the chain using new fields
>> in struct pg_state.
>>
>> The KASAN optimisation is implemented by including test_p?d callbacks
>> which can decide to skip an entire tree of entries
>>
>> ...
>>
>> +static const struct ptdump_range ptdump_ranges[] = {
>> +#ifdef CONFIG_X86_64
>>  
>> -#define pgd_large(a) (pgtable_l5_enabled() ? pgd_large(a) : p4d_large(__p4d(pgd_val(a))))
>> -#define pgd_none(a)  (pgtable_l5_enabled() ? pgd_none(a) : p4d_none(__p4d(pgd_val(a))))
>> +#define normalize_addr_shift (64 - (__VIRTUAL_MASK_SHIFT + 1))
>> +#define normalize_addr(u) ((signed long)(u << normalize_addr_shift) \
>> +				>> normalize_addr_shift)
>>  
>> -static inline bool is_hypervisor_range(int idx)
>> -{
>> -#ifdef CONFIG_X86_64
>> -	/*
>> -	 * A hole in the beginning of kernel address space reserved
>> -	 * for a hypervisor.
>> -	 */
>> -	return	(idx >= pgd_index(GUARD_HOLE_BASE_ADDR)) &&
>> -		(idx <  pgd_index(GUARD_HOLE_END_ADDR));
>> +	{0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
>> +	{normalize_addr(PTRS_PER_PGD * PGD_LEVEL_MULT / 2), ~0UL},
> 
> This blows up because PGD_LEVEL_MULT is sometimes not a constant.
> 
> x86_64 allmodconfig:
> 
> In file included from ./arch/x86/include/asm/pgtable_types.h:249:0,
>                  from ./arch/x86/include/asm/paravirt_types.h:45,
>                  from ./arch/x86/include/asm/ptrace.h:94,
>                  from ./arch/x86/include/asm/math_emu.h:5,
>                  from ./arch/x86/include/asm/processor.h:12,
>                  from ./arch/x86/include/asm/cpufeature.h:5,
>                  from ./arch/x86/include/asm/thread_info.h:53,
>                  from ./include/linux/thread_info.h:38,
>                  from ./arch/x86/include/asm/preempt.h:7,
>                  from ./include/linux/preempt.h:78,
>                  from ./include/linux/spinlock.h:51,
>                  from ./include/linux/wait.h:9,
>                  from ./include/linux/wait_bit.h:8,
>                  from ./include/linux/fs.h:6,
>                  from ./include/linux/debugfs.h:15,
>                  from arch/x86/mm/dump_pagetables.c:11:
> ./arch/x86/include/asm/pgtable_64_types.h:56:22: error: initializer element is not constant
>  #define PTRS_PER_PGD 512
>                       ^

This is very unhelpful of GCC - it's actually PTRS_PER_P4D which isn't
constant!

> arch/x86/mm/dump_pagetables.c:363:6: note: in expansion of macro ‘PTRS_PER_PGD’
>   {0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
>       ^~~~~~~~~~~~
> ./arch/x86/include/asm/pgtable_64_types.h:56:22: note: (near initialization for ‘ptdump_ranges[0].end’)
>  #define PTRS_PER_PGD 512
>                       ^
> arch/x86/mm/dump_pagetables.c:363:6: note: in expansion of macro ‘PTRS_PER_PGD’
>   {0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
>       ^~~~~~~~~~~~
> arch/x86/mm/dump_pagetables.c:360:27: error: initializer element is not constant
>  #define normalize_addr(u) ((signed long)(u << normalize_addr_shift) \
>                            ^
> arch/x86/mm/dump_pagetables.c:364:3: note: in expansion of macro ‘normalize_addr’
>   {normalize_addr(PTRS_PER_PGD * PGD_LEVEL_MULT / 2), ~0UL},
>    ^~~~~~~~~~~~~~
> arch/x86/mm/dump_pagetables.c:360:27: note: (near initialization for ‘ptdump_ranges[1].start’)
>  #define normalize_addr(u) ((signed long)(u << normalize_addr_shift) \
>                            ^
> arch/x86/mm/dump_pagetables.c:364:3: note: in expansion of macro ‘normalize_addr’
>   {normalize_addr(PTRS_PER_PGD * PGD_LEVEL_MULT / 2), ~0UL},
> 
> I don't know what to do about this so I'll drop the series.

My best solution to this is to simply make ptdump_ranges dynamic (see
below). But there are other problems with this series (thanks for
spotting them), so I'll send out another version later.

Thanks,

Steve

----8<-----
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 998c7f46763c..8fc129ff985e 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -353,7 +353,10 @@ static void note_page(struct ptdump_state *pt_st,
unsigned long addr, int level,
        }
 }

-static const struct ptdump_range ptdump_ranges[] = {
+static void ptdump_walk_pgd_level_core(struct seq_file *m, struct
mm_struct *mm,
+                                      bool checkwx, bool dmesg)
+{
+       const struct ptdump_range ptdump_ranges[] = {
 #ifdef CONFIG_X86_64

 #define normalize_addr_shift (64 - (__VIRTUAL_MASK_SHIFT + 1))
@@ -368,9 +371,6 @@ static const struct ptdump_range ptdump_ranges[] = {
        {0, 0}
 };

-static void ptdump_walk_pgd_level_core(struct seq_file *m, struct
mm_struct *mm,
-                                      bool checkwx, bool dmesg)
-{
        struct pg_state st = {
                .ptdump = {
                        .note_page      = note_page,

  reply	other threads:[~2019-08-07 12:58 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-31 15:45 [PATCH v10 00/22] Generic page walk and ptdump Steven Price
2019-07-31 15:45 ` [PATCH v10 01/22] mm: Add generic p?d_leaf() macros Steven Price
2019-07-31 15:45 ` [PATCH v10 02/22] arc: mm: Add p?d_leaf() definitions Steven Price
2019-07-31 15:45 ` [PATCH v10 03/22] arm: " Steven Price
2019-07-31 15:45 ` [PATCH v10 04/22] arm64: " Steven Price
2019-07-31 15:45 ` [PATCH v10 05/22] mips: " Steven Price
2019-07-31 18:35   ` Paul Burton
2019-07-31 15:45 ` [PATCH v10 06/22] powerpc: " Steven Price
2019-07-31 15:45 ` [PATCH v10 07/22] riscv: " Steven Price
2019-07-31 15:45 ` [PATCH v10 08/22] s390: " Steven Price
2019-07-31 15:45 ` [PATCH v10 09/22] sparc: " Steven Price
2019-07-31 15:45 ` [PATCH v10 10/22] x86: " Steven Price
2019-07-31 15:45 ` [PATCH v10 11/22] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price
2019-07-31 15:45 ` [PATCH v10 12/22] mm: pagewalk: Allow walking without vma Steven Price
2019-07-31 15:45 ` [PATCH v10 13/22] mm: pagewalk: Add test_p?d callbacks Steven Price
2019-07-31 15:45 ` [PATCH v10 14/22] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price
2019-07-31 15:45 ` [PATCH v10 15/22] x86: mm: Point to struct seq_file from struct pg_state Steven Price
2019-07-31 15:45 ` [PATCH v10 16/22] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price
2019-07-31 15:45 ` [PATCH v10 17/22] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price
2019-07-31 15:45 ` [PATCH v10 18/22] x86: mm: Convert ptdump_walk_pgd_level_core() " Steven Price
2019-07-31 15:46 ` [PATCH v10 19/22] mm: Add generic ptdump Steven Price
2019-07-31 15:46 ` [PATCH v10 20/22] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price
2019-08-06 23:58   ` Andrew Morton
2019-08-07 12:58     ` Steven Price [this message]
2019-08-07 20:16       ` Andrew Morton
2019-07-31 15:46 ` [PATCH v10 21/22] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price
2019-07-31 15:46 ` [PATCH v10 22/22] arm64: mm: Display non-present entries in ptdump Steven Price

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