| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <8d8daf85-0015-4221-aad5-5baa03e3f699@redhat.com>
Date: Fri, 23 Jul 2021 11:00:15 +1000
From: Gavin Shan <gshan@...hat.com>
To: Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, catalin.marinas@....com,
will@...nel.org, akpm@...ux-foundation.org, chuhu@...hat.com,
shan.gavin@...il.com
Subject: Re: [PATCH v3 08/12] mm/debug_vm_pgtable: Use struct
pgtable_debug_args in PMD modifying tests
Hi Anshuman,
On 7/22/21 5:11 PM, Anshuman Khandual wrote:
> On 7/22/21 12:11 PM, Gavin Shan wrote:
>> On 7/22/21 3:45 PM, Anshuman Khandual wrote:
>>> On 7/19/21 6:36 PM, Gavin Shan wrote:
>>>> This uses struct pgtable_debug_args in PMD modifying tests. The allocated
>>>> huge page is used when set_pmd_at() is used. The corresponding tests
>>>> are skipped if the huge page doesn't exist. Besides, the unused variable
>>>> @pmd_aligned in debug_vm_pgtable() is dropped.
>>>
>>> Please dont drop @pmd_aligned just yet.
>>>
>>
>> We need do so. Otherwise, there is build warning to complain
>> something like 'unused variable' after this patch is applied.
>>
>>>>
>>>> Signed-off-by: Gavin Shan <gshan@...hat.com>
>>>> ---
>>>> mm/debug_vm_pgtable.c | 102 ++++++++++++++++++++----------------------
>>>> 1 file changed, 48 insertions(+), 54 deletions(-)
>>>>
>>>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
>>>> index eb6dda88e0d9..cec3cbf99a6b 100644
>>>> --- a/mm/debug_vm_pgtable.c
>>>> +++ b/mm/debug_vm_pgtable.c
>>>> @@ -213,54 +213,54 @@ static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)
>>>> WARN_ON(!pmd_bad(pmd_mkhuge(pmd)));
>>>> }
>>>> -static void __init pmd_advanced_tests(struct mm_struct *mm,
>>>> - struct vm_area_struct *vma, pmd_t *pmdp,
>>>> - unsigned long pfn, unsigned long vaddr,
>>>> - pgprot_t prot, pgtable_t pgtable)
>>>> +static void __init pmd_advanced_tests(struct pgtable_debug_args *args)
>>>> {
>>>> pmd_t pmd;
>>>> + unsigned long vaddr = (args->vaddr & HPAGE_PMD_MASK);
>>>> if (!has_transparent_hugepage())
>>>> return;
>>>> pr_debug("Validating PMD advanced\n");
>>>> - /* Align the address wrt HPAGE_PMD_SIZE */
>>>> - vaddr &= HPAGE_PMD_MASK;
>>>
>>> Please just leave these unchanged. If has_transparent_hugepage() evaluates
>>> negative, it skips the masking operation. As mentioned earlier please avoid
>>> changing the test in any manner during these transition patches.
>>>
>>
>> Ok.
>>
>>>> + if (args->pmd_pfn == ULONG_MAX) {
>>>> + pr_debug("%s: Skipped\n", __func__);
>>>> + return;
>>>> + }
>>>
>>> Just return. Please dont call out "Skipped".
>>>
>>
>> Ok.
>>
>>>> - pgtable_trans_huge_deposit(mm, pmdp, pgtable);
>>>> + pgtable_trans_huge_deposit(args->mm, args->pmdp, args->start_ptep);
>>>> - pmd = pfn_pmd(pfn, prot);
>>>> - set_pmd_at(mm, vaddr, pmdp, pmd);
>>>> - pmdp_set_wrprotect(mm, vaddr, pmdp);
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + pmd = pfn_pmd(args->pmd_pfn, args->page_prot);
>>>> + set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
>>>> + pmdp_set_wrprotect(args->mm, vaddr, args->pmdp);
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(pmd_write(pmd));
>>>> - pmdp_huge_get_and_clear(mm, vaddr, pmdp);
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp);
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(!pmd_none(pmd));
>>>> - pmd = pfn_pmd(pfn, prot);
>>>> + pmd = pfn_pmd(args->pmd_pfn, args->page_prot);
>>>> pmd = pmd_wrprotect(pmd);
>>>> pmd = pmd_mkclean(pmd);
>>>> - set_pmd_at(mm, vaddr, pmdp, pmd);
>>>> + set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
>>>> pmd = pmd_mkwrite(pmd);
>>>> pmd = pmd_mkdirty(pmd);
>>>> - pmdp_set_access_flags(vma, vaddr, pmdp, pmd, 1);
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + pmdp_set_access_flags(args->vma, vaddr, args->pmdp, pmd, 1);
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd)));
>>>> - pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1);
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + pmdp_huge_get_and_clear_full(args->vma, vaddr, args->pmdp, 1);
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(!pmd_none(pmd));
>>>> - pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
>>>> + pmd = pmd_mkhuge(pfn_pmd(args->pmd_pfn, args->page_prot));
>>>> pmd = pmd_mkyoung(pmd);
>>>> - set_pmd_at(mm, vaddr, pmdp, pmd);
>>>> - pmdp_test_and_clear_young(vma, vaddr, pmdp);
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + set_pmd_at(args->mm, vaddr, args->pmdp, pmd);
>>>> + pmdp_test_and_clear_young(args->vma, vaddr, args->pmdp);
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(pmd_young(pmd));
>>>> /* Clear the pte entries */
>>>> - pmdp_huge_get_and_clear(mm, vaddr, pmdp);
>>>> - pgtable = pgtable_trans_huge_withdraw(mm, pmdp);
>>>> + pmdp_huge_get_and_clear(args->mm, vaddr, args->pmdp);
>>>> + pgtable_trans_huge_withdraw(args->mm, args->pmdp);
>>>> }
>>>> static void __init pmd_leaf_tests(struct pgtable_debug_args *args)
>>>> @@ -417,12 +417,7 @@ static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }
>>>> #else /* !CONFIG_TRANSPARENT_HUGEPAGE */
>>>> static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx) { }
>>>> static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { }
>>>> -static void __init pmd_advanced_tests(struct mm_struct *mm,
>>>> - struct vm_area_struct *vma, pmd_t *pmdp,
>>>> - unsigned long pfn, unsigned long vaddr,
>>>> - pgprot_t prot, pgtable_t pgtable)
>>>> -{
>>>> -}
>>>> +static void __init pmd_advanced_tests(struct pgtable_debug_args *args) { }
>>>> static void __init pud_advanced_tests(struct mm_struct *mm,
>>>> struct vm_area_struct *vma, pud_t *pudp,
>>>> unsigned long pfn, unsigned long vaddr,
>>>> @@ -435,11 +430,11 @@ static void __init pmd_savedwrite_tests(struct pgtable_debug_args *args) { }
>>>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>>>> #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
>>>> -static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
>>>> +static void __init pmd_huge_tests(struct pgtable_debug_args *args)
>>>> {
>>>> pmd_t pmd;
>>>> - if (!arch_vmap_pmd_supported(prot))
>>>> + if (!arch_vmap_pmd_supported(args->page_prot))
>>>> return;
>>>> pr_debug("Validating PMD huge\n");
>>>> @@ -447,10 +442,11 @@ static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
>>>> * X86 defined pmd_set_huge() verifies that the given
>>>> * PMD is not a populated non-leaf entry.
>>>> */
>>>> - WRITE_ONCE(*pmdp, __pmd(0));
>>>> - WARN_ON(!pmd_set_huge(pmdp, __pfn_to_phys(pfn), prot));
>>>> - WARN_ON(!pmd_clear_huge(pmdp));
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + WRITE_ONCE(*(args->pmdp), __pmd(0));
>>>
>>> Possible extra braces.
>>>
>>
>> Will drop it in v4, thanks!
>>
>>>> + WARN_ON(!pmd_set_huge(args->pmdp, __pfn_to_phys(args->fixed_pmd_pfn),
>>>> + args->page_prot));
>>>
>>> Dont break the line.
>>>
>>
>> Ok.
>>
>>>> + WARN_ON(!pmd_clear_huge(args->pmdp));
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(!pmd_none(pmd));
>>>> }
>>>> @@ -473,7 +469,7 @@ static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
>>>> WARN_ON(!pud_none(pud));
>>>> }
>>>> #else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
>>>> -static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot) { }
>>>> +static void __init pmd_huge_tests(struct pgtable_debug_args *args) { }
>>>> static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot) { }
>>>> #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
>>>> @@ -640,20 +636,19 @@ static void __init pte_clear_tests(struct pgtable_debug_args *args)
>>>> WARN_ON(!pte_none(pte));
>>>> }
>>>> -static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp)
>>>> +static void __init pmd_clear_tests(struct pgtable_debug_args *args)
>>>> {
>>>> - pmd_t pmd = READ_ONCE(*pmdp);
>>>> + pmd_t pmd = READ_ONCE(*(args->pmdp));
>>>> pr_debug("Validating PMD clear\n");
>>>> pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE);
>>>> - WRITE_ONCE(*pmdp, pmd);
>>>> - pmd_clear(pmdp);
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + WRITE_ONCE(*(args->pmdp), pmd);
>>>> + pmd_clear(args->pmdp);
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(!pmd_none(pmd));
>>>> }
>>>> -static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
>>>> - pgtable_t pgtable)
>>>> +static void __init pmd_populate_tests(struct pgtable_debug_args *args)
>>>> {
>>>> pmd_t pmd;
>>>> @@ -662,8 +657,8 @@ static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
>>>> * This entry points to next level page table page.
>>>> * Hence this must not qualify as pmd_bad().
>>>> */
>>>> - pmd_populate(mm, pmdp, pgtable);
>>>> - pmd = READ_ONCE(*pmdp);
>>>> + pmd_populate(args->mm, args->pmdp, args->start_ptep);
>>>> + pmd = READ_ONCE(*(args->pmdp));
>>>> WARN_ON(pmd_bad(pmd));
>>>> }
>>>> @@ -1159,7 +1154,7 @@ static int __init debug_vm_pgtable(void)
>>>> pgtable_t saved_ptep;
>>>> pgprot_t prot;
>>>> phys_addr_t paddr;
>>>> - unsigned long vaddr, pmd_aligned;
>>>> + unsigned long vaddr;
>>>> unsigned long pud_aligned;
>>>> spinlock_t *ptl = NULL;
>>>> int idx, ret;
>>>> @@ -1194,7 +1189,6 @@ static int __init debug_vm_pgtable(void)
>>>> */
>>>> paddr = __pa_symbol(&start_kernel);
>>>> - pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
>>>
>>> Please dont drop these just yet and wait until [PATCH 11/12].
>>>
>>
>> Otherwise, it causes build warning: 'unused variable'.
>
> Why ? Just the evaluation of 'pmd_aligned' from 'paddr' should
> be enough to avoid such warning. 'pmd_aligned' need not be used
> afterwards.
>
It's not enough to avoid the warning. I apply the patches till
this one (PATCH[v3 08/12]) and have additional code to keep
@pmd_aligned, then I run into build warning as below:
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index cec3cbf99a6b..961c9bb6fc7c 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -1154,7 +1154,7 @@ static int __init debug_vm_pgtable(void)
pgtable_t saved_ptep;
pgprot_t prot;
phys_addr_t paddr;
- unsigned long vaddr;
+ unsigned long vaddr, pmd_aligned;
unsigned long pud_aligned;
spinlock_t *ptl = NULL;
int idx, ret;
@@ -1189,6 +1189,7 @@ static int __init debug_vm_pgtable(void)
*/
paddr = __pa_symbol(&start_kernel);
+ pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
pgdp = pgd_offset(mm, vaddr);
[gwshan@...an l]$ make W=1 mm/debug_vm_pgtable.o
:
mm/debug_vm_pgtable.c: In function ‘debug_vm_pgtable’:
mm/debug_vm_pgtable.c:1157:23: warning: variable ‘pmd_aligned’ set but not used [-Wunused-but-set-variable]
1157 | unsigned long vaddr, pmd_aligned;
| ^~~~~~~~~~~
By the way, 0-day is trying to build kernel with "W=1". It means the
build warnings will be reported by 0-day if the unused variables aren't
dropped from individual patches. It makes the review a bit harder. However,
we still need to keep each individual patch complete to make 'git bisect'
friendly.
Thanks,
Gavin
Powered by blists - more mailing lists