| 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: <f3089991-fd49-8d55-9ede-62ab1555c9fa@loongson.cn>
Date: Fri, 18 Oct 2024 11:44:20 +0800
From: maobibo <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
David Hildenbrand <david@...hat.com>, Barry Song <baohua@...nel.org>,
loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org,
kasan-dev@...glegroups.com, linux-mm@...ck.org
Subject: Re: [PATCH v2 1/3] LoongArch: Set initial pte entry with PAGE_GLOBAL
for kernel space
On 2024/10/18 上午11:14, Huacai Chen wrote:
> Hi, Bibo,
>
> I applied this patch but drop the part of arch/loongarch/mm/kasan_init.c:
> https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson.git/commit/?h=loongarch-next&id=15832255e84494853f543b4c70ced50afc403067
>
> Because kernel_pte_init() should operate on page-table pages, not on
> data pages. You have already handle page-table page in
> mm/kasan/init.c, and if we don't drop the modification on data pages
> in arch/loongarch/mm/kasan_init.c, the kernel fail to boot if KASAN is
> enabled.
>
static inline void set_pte(pte_t *ptep, pte_t pteval)
{
WRITE_ONCE(*ptep, pteval);
-
- if (pte_val(pteval) & _PAGE_GLOBAL) {
- pte_t *buddy = ptep_buddy(ptep);
- /*
- * Make sure the buddy is global too (if it's !none,
- * it better already be global)
- */
- if (pte_none(ptep_get(buddy))) {
-#ifdef CONFIG_SMP
- /*
- * For SMP, multiple CPUs can race, so we need
- * to do this atomically.
- */
- __asm__ __volatile__(
- __AMOR "$zero, %[global], %[buddy] \n"
- : [buddy] "+ZB" (buddy->pte)
- : [global] "r" (_PAGE_GLOBAL)
- : "memory");
-
- DBAR(0b11000); /* o_wrw = 0b11000 */
-#else /* !CONFIG_SMP */
- WRITE_ONCE(*buddy, __pte(pte_val(ptep_get(buddy)) | _PAGE_GLOBAL));
-#endif /* CONFIG_SMP */
- }
- }
+ DBAR(0b11000); /* o_wrw = 0b11000 */
}
No, please hold on. This issue exists about twenty years, Do we need be
in such a hurry now?
why is DBAR(0b11000) added in set_pte()?
Regards
Bibo Mao
> Huacai
>
> On Mon, Oct 14, 2024 at 11:59 AM Bibo Mao <maobibo@...ngson.cn> wrote:
>>
>> Unlike general architectures, there are two pages in one TLB entry
>> on LoongArch system. For kernel space, it requires both two pte
>> entries with PAGE_GLOBAL bit set, else HW treats it as non-global
>> tlb, there will be potential problems if tlb entry for kernel space
>> is not global. Such as fail to flush kernel tlb with function
>> local_flush_tlb_kernel_range() which only flush tlb with global bit.
>>
>> With function kernel_pte_init() added, it can be used to init pte
>> table when it is created for kernel address space, and the default
>> initial pte value is PAGE_GLOBAL rather than zero at beginning.
>>
>> Kernel address space areas includes fixmap, percpu, vmalloc, kasan
>> and vmemmap areas set default pte entry with PAGE_GLOBAL set.
>>
>> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
>> ---
>> arch/loongarch/include/asm/pgalloc.h | 13 +++++++++++++
>> arch/loongarch/include/asm/pgtable.h | 1 +
>> arch/loongarch/mm/init.c | 4 +++-
>> arch/loongarch/mm/kasan_init.c | 4 +++-
>> arch/loongarch/mm/pgtable.c | 22 ++++++++++++++++++++++
>> include/linux/mm.h | 1 +
>> mm/kasan/init.c | 8 +++++++-
>> mm/sparse-vmemmap.c | 5 +++++
>> 8 files changed, 55 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
>> index 4e2d6b7ca2ee..b2698c03dc2c 100644
>> --- a/arch/loongarch/include/asm/pgalloc.h
>> +++ b/arch/loongarch/include/asm/pgalloc.h
>> @@ -10,8 +10,21 @@
>>
>> #define __HAVE_ARCH_PMD_ALLOC_ONE
>> #define __HAVE_ARCH_PUD_ALLOC_ONE
>> +#define __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL
>> #include <asm-generic/pgalloc.h>
>>
>> +static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
>> +{
>> + pte_t *pte;
>> +
>> + pte = (pte_t *) __get_free_page(GFP_KERNEL);
>> + if (!pte)
>> + return NULL;
>> +
>> + kernel_pte_init(pte);
>> + return pte;
>> +}
>> +
>> static inline void pmd_populate_kernel(struct mm_struct *mm,
>> pmd_t *pmd, pte_t *pte)
>> {
>> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
>> index 9965f52ef65b..22e3a8f96213 100644
>> --- a/arch/loongarch/include/asm/pgtable.h
>> +++ b/arch/loongarch/include/asm/pgtable.h
>> @@ -269,6 +269,7 @@ extern void set_pmd_at(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, pm
>> extern void pgd_init(void *addr);
>> extern void pud_init(void *addr);
>> extern void pmd_init(void *addr);
>> +extern void kernel_pte_init(void *addr);
>>
>> /*
>> * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
>> diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
>> index 8a87a482c8f4..9f26e933a8a3 100644
>> --- a/arch/loongarch/mm/init.c
>> +++ b/arch/loongarch/mm/init.c
>> @@ -198,9 +198,11 @@ pte_t * __init populate_kernel_pte(unsigned long addr)
>> if (!pmd_present(pmdp_get(pmd))) {
>> pte_t *pte;
>>
>> - pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
>> + pte = memblock_alloc_raw(PAGE_SIZE, PAGE_SIZE);
>> if (!pte)
>> panic("%s: Failed to allocate memory\n", __func__);
>> +
>> + kernel_pte_init(pte);
>> pmd_populate_kernel(&init_mm, pmd, pte);
>> }
>>
>> diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c
>> index 427d6b1aec09..34988573b0d5 100644
>> --- a/arch/loongarch/mm/kasan_init.c
>> +++ b/arch/loongarch/mm/kasan_init.c
>> @@ -152,6 +152,8 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
>> phys_addr_t page_phys = early ?
>> __pa_symbol(kasan_early_shadow_page)
>> : kasan_alloc_zeroed_page(node);
>> + if (!early)
>> + kernel_pte_init(__va(page_phys));
>> next = addr + PAGE_SIZE;
>> set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
>> } while (ptep++, addr = next, addr != end && __pte_none(early, ptep_get(ptep)));
>> @@ -287,7 +289,7 @@ void __init kasan_init(void)
>> set_pte(&kasan_early_shadow_pte[i],
>> pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
>>
>> - memset(kasan_early_shadow_page, 0, PAGE_SIZE);
>> + kernel_pte_init(kasan_early_shadow_page);
>> csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
>> local_flush_tlb_all();
>>
>> diff --git a/arch/loongarch/mm/pgtable.c b/arch/loongarch/mm/pgtable.c
>> index eb6a29b491a7..228ffc1db0a3 100644
>> --- a/arch/loongarch/mm/pgtable.c
>> +++ b/arch/loongarch/mm/pgtable.c
>> @@ -38,6 +38,28 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
>> }
>> EXPORT_SYMBOL_GPL(pgd_alloc);
>>
>> +void kernel_pte_init(void *addr)
>> +{
>> + unsigned long *p, *end;
>> + unsigned long entry;
>> +
>> + entry = (unsigned long)_PAGE_GLOBAL;
>> + p = (unsigned long *)addr;
>> + end = p + PTRS_PER_PTE;
>> +
>> + do {
>> + p[0] = entry;
>> + p[1] = entry;
>> + p[2] = entry;
>> + p[3] = entry;
>> + p[4] = entry;
>> + p += 8;
>> + p[-3] = entry;
>> + p[-2] = entry;
>> + p[-1] = entry;
>> + } while (p != end);
>> +}
>> +
>> void pgd_init(void *addr)
>> {
>> unsigned long *p, *end;
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index ecf63d2b0582..6909fe059a2c 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -3818,6 +3818,7 @@ void *sparse_buffer_alloc(unsigned long size);
>> struct page * __populate_section_memmap(unsigned long pfn,
>> unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
>> struct dev_pagemap *pgmap);
>> +void kernel_pte_init(void *addr);
>> void pmd_init(void *addr);
>> void pud_init(void *addr);
>> pgd_t *vmemmap_pgd_populate(unsigned long addr, int node);
>> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
>> index 89895f38f722..ac607c306292 100644
>> --- a/mm/kasan/init.c
>> +++ b/mm/kasan/init.c
>> @@ -106,6 +106,10 @@ static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
>> }
>> }
>>
>> +void __weak __meminit kernel_pte_init(void *addr)
>> +{
>> +}
>> +
>> static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
>> unsigned long end)
>> {
>> @@ -126,8 +130,10 @@ static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
>>
>> if (slab_is_available())
>> p = pte_alloc_one_kernel(&init_mm);
>> - else
>> + else {
>> p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
>> + kernel_pte_init(p);
>> + }
>> if (!p)
>> return -ENOMEM;
>>
>> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
>> index edcc7a6b0f6f..c0388b2e959d 100644
>> --- a/mm/sparse-vmemmap.c
>> +++ b/mm/sparse-vmemmap.c
>> @@ -184,6 +184,10 @@ static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
>> return p;
>> }
>>
>> +void __weak __meminit kernel_pte_init(void *addr)
>> +{
>> +}
>> +
>> pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
>> {
>> pmd_t *pmd = pmd_offset(pud, addr);
>> @@ -191,6 +195,7 @@ pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
>> void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
>> if (!p)
>> return NULL;
>> + kernel_pte_init(p);
>> pmd_populate_kernel(&init_mm, pmd, p);
>> }
>> return pmd;
>> --
>> 2.39.3
>>
Powered by blists - more mailing lists