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SubjectRe: [PATCH 5/8] riscv: Implement sv48 support
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Le 5/25/20 à 2:45 AM, Anup Patel a écrit :
> On Sun, May 24, 2020 at 2:45 PM Alexandre Ghiti <alex@ghiti.fr> wrote:
>> By adding a new 4th level of page table, give the possibility to 64bit
>> kernel to address 2^48 bytes of virtual address: in practice, that roughly
>> offers ~160TB of virtual address space to userspace and allows up to 64TB
>> of physical memory.
>>
>> If the underlying hardware does not support sv48, we will automatically
>> fallback to a standard 3-level page table by folding the new PUD level into
>> PGDIR level. In order to detect HW capabilities at runtime, we
>> use SATP feature that ignores writes with an unsupported mode.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>> ---
>> arch/riscv/Kconfig | 6 +-
>> arch/riscv/include/asm/csr.h | 3 +-
>> arch/riscv/include/asm/fixmap.h | 1 +
>> arch/riscv/include/asm/page.h | 15 +++
>> arch/riscv/include/asm/pgalloc.h | 36 +++++++
>> arch/riscv/include/asm/pgtable-64.h | 97 ++++++++++++++++-
>> arch/riscv/include/asm/pgtable.h | 9 +-
>> arch/riscv/kernel/head.S | 3 +-
>> arch/riscv/mm/context.c | 4 +-
>> arch/riscv/mm/init.c | 159 +++++++++++++++++++++++++---
>> 10 files changed, 309 insertions(+), 24 deletions(-)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index e167f16131f4..3f73f60e9732 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -68,6 +68,7 @@ config RISCV
>> select ARCH_HAS_GCOV_PROFILE_ALL
>> select HAVE_COPY_THREAD_TLS
>> select HAVE_ARCH_KASAN if MMU && 64BIT
>> + select RELOCATABLE if 64BIT
>>
>> config ARCH_MMAP_RND_BITS_MIN
>> default 18 if 64BIT
>> @@ -106,7 +107,7 @@ config PAGE_OFFSET
>> default 0xC0000000 if 32BIT && MAXPHYSMEM_2GB
>> default 0x80000000 if 64BIT && !MMU
>> default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
>> - default 0xffffffe000000000 if 64BIT && !MAXPHYSMEM_2GB
>> + default 0xffffc00000000000 if 64BIT && !MAXPHYSMEM_2GB
>>
>> config ARCH_FLATMEM_ENABLE
>> def_bool y
>> @@ -155,8 +156,11 @@ config GENERIC_HWEIGHT
>> config FIX_EARLYCON_MEM
>> def_bool MMU
>>
>> +# On a 64BIT relocatable kernel, the 4-level page table is at runtime folded
>> +# on a 3-level page table when sv48 is not supported.
>> config PGTABLE_LEVELS
>> int
>> + default 4 if 64BIT && RELOCATABLE
>> default 3 if 64BIT
>> default 2
>>
>> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
>> index cec462e198ce..d41536c3f8d4 100644
>> --- a/arch/riscv/include/asm/csr.h
>> +++ b/arch/riscv/include/asm/csr.h
>> @@ -40,11 +40,10 @@
>> #ifndef CONFIG_64BIT
>> #define SATP_PPN _AC(0x003FFFFF, UL)
>> #define SATP_MODE_32 _AC(0x80000000, UL)
>> -#define SATP_MODE SATP_MODE_32
>> #else
>> #define SATP_PPN _AC(0x00000FFFFFFFFFFF, UL)
>> #define SATP_MODE_39 _AC(0x8000000000000000, UL)
>> -#define SATP_MODE SATP_MODE_39
>> +#define SATP_MODE_48 _AC(0x9000000000000000, UL)
>> #endif
>>
>> /* Exception cause high bit - is an interrupt if set */
>> diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
>> index 2368d49eb4ef..d891cf9c73c5 100644
>> --- a/arch/riscv/include/asm/fixmap.h
>> +++ b/arch/riscv/include/asm/fixmap.h
>> @@ -27,6 +27,7 @@ enum fixed_addresses {
>> FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
>> FIX_PTE,
>> FIX_PMD,
>> + FIX_PUD,
>> FIX_TEXT_POKE1,
>> FIX_TEXT_POKE0,
>> FIX_EARLYCON_MEM_BASE,
>> diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
>> index 48bb09b6a9b7..5e77fe7f0d6d 100644
>> --- a/arch/riscv/include/asm/page.h
>> +++ b/arch/riscv/include/asm/page.h
>> @@ -31,7 +31,19 @@
>> * When not using MMU this corresponds to the first free page in
>> * physical memory (aligned on a page boundary).
>> */
>> +#ifdef CONFIG_RELOCATABLE
>> +#define PAGE_OFFSET __page_offset
>> +
>> +#ifdef CONFIG_64BIT
>> +/*
>> + * By default, CONFIG_PAGE_OFFSET value corresponds to SV48 address space so
>> + * define the PAGE_OFFSET value for SV39.
>> + */
>> +#define PAGE_OFFSET_L3 0xffffffe000000000
>> +#endif /* CONFIG_64BIT */
>> +#else
>> #define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL)
>> +#endif /* CONFIG_RELOCATABLE */
>>
>> #define KERN_VIRT_SIZE (-PAGE_OFFSET)
>>
>> @@ -102,6 +114,9 @@ extern unsigned long pfn_base;
>> extern unsigned long max_low_pfn;
>> extern unsigned long min_low_pfn;
>> extern unsigned long kernel_virt_addr;
>> +#ifdef CONFIG_RELOCATABLE
>> +extern unsigned long __page_offset;
>> +#endif
>>
>> #define __pa_to_va_nodebug(x) ((void *)((unsigned long) (x) + va_pa_offset))
>> #define linear_mapping_va_to_pa(x) ((unsigned long)(x) - va_pa_offset)
>> diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
>> index 3f601ee8233f..540eaa5a8658 100644
>> --- a/arch/riscv/include/asm/pgalloc.h
>> +++ b/arch/riscv/include/asm/pgalloc.h
>> @@ -36,6 +36,42 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
>>
>> set_pud(pud, __pud((pfn << _PAGE_PFN_SHIFT) | _PAGE_TABLE));
>> }
>> +
>> +static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4d, pud_t *pud)
>> +{
>> + if (pgtable_l4_enabled) {
>> + unsigned long pfn = virt_to_pfn(pud);
>> +
>> + set_p4d(p4d, __p4d((pfn << _PAGE_PFN_SHIFT) | _PAGE_TABLE));
>> + }
>> +}
>> +
>> +static inline void p4d_populate_safe(struct mm_struct *mm, p4d_t *p4d,
>> + pud_t *pud)
>> +{
>> + if (pgtable_l4_enabled) {
>> + unsigned long pfn = virt_to_pfn(pud);
>> +
>> + set_p4d_safe(p4d,
>> + __p4d((pfn << _PAGE_PFN_SHIFT) | _PAGE_TABLE));
>> + }
>> +}
>> +
>> +static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
>> +{
>> + if (pgtable_l4_enabled)
>> + return (pud_t *)__get_free_page(
>> + GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
>> + return NULL;
>> +}
>> +
>> +static inline void pud_free(struct mm_struct *mm, pud_t *pud)
>> +{
>> + if (pgtable_l4_enabled)
>> + free_page((unsigned long)pud);
>> +}
>> +
>> +#define __pud_free_tlb(tlb, pud, addr) pud_free((tlb)->mm, pud)
>> #endif /* __PAGETABLE_PMD_FOLDED */
>>
>> #define pmd_pgtable(pmd) pmd_page(pmd)
>> diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
>> index b15f70a1fdfa..c84c31fbf8da 100644
>> --- a/arch/riscv/include/asm/pgtable-64.h
>> +++ b/arch/riscv/include/asm/pgtable-64.h
>> @@ -8,16 +8,32 @@
>>
>> #include <linux/const.h>
>>
>> -#define PGDIR_SHIFT 30
>> +extern bool pgtable_l4_enabled;
>> +
>> +#define PGDIR_SHIFT (pgtable_l4_enabled ? 39 : 30)
>> /* Size of region mapped by a page global directory */
>> #define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT)
>> #define PGDIR_MASK (~(PGDIR_SIZE - 1))
>>
>> +/* pud is folded into pgd in case of 3-level page table */
>> +#define PUD_SHIFT 30
>> +#define PUD_SIZE (_AC(1, UL) << PUD_SHIFT)
>> +#define PUD_MASK (~(PUD_SIZE - 1))
>> +
>> #define PMD_SHIFT 21
>> /* Size of region mapped by a page middle directory */
>> #define PMD_SIZE (_AC(1, UL) << PMD_SHIFT)
>> #define PMD_MASK (~(PMD_SIZE - 1))
>>
>> +/* Page Upper Directory entry */
>> +typedef struct {
>> + unsigned long pud;
>> +} pud_t;
>> +
>> +#define pud_val(x) ((x).pud)
>> +#define __pud(x) ((pud_t) { (x) })
>> +#define PTRS_PER_PUD (PAGE_SIZE / sizeof(pud_t))
>> +
>> /* Page Middle Directory entry */
>> typedef struct {
>> unsigned long pmd;
>> @@ -60,6 +76,16 @@ static inline void pud_clear(pud_t *pudp)
>> set_pud(pudp, __pud(0));
>> }
>>
>> +static inline pud_t pfn_pud(unsigned long pfn, pgprot_t prot)
>> +{
>> + return __pud((pfn << _PAGE_PFN_SHIFT) | pgprot_val(prot));
>> +}
>> +
>> +static inline unsigned long _pud_pfn(pud_t pud)
>> +{
>> + return pud_val(pud) >> _PAGE_PFN_SHIFT;
>> +}
>> +
>> static inline unsigned long pud_page_vaddr(pud_t pud)
>> {
>> return (unsigned long)pfn_to_virt(pud_val(pud) >> _PAGE_PFN_SHIFT);
>> @@ -70,6 +96,15 @@ static inline struct page *pud_page(pud_t pud)
>> return pfn_to_page(pud_val(pud) >> _PAGE_PFN_SHIFT);
>> }
>>
>> +#define mm_pud_folded mm_pud_folded
>> +static inline bool mm_pud_folded(struct mm_struct *mm)
>> +{
>> + if (pgtable_l4_enabled)
>> + return false;
>> +
>> + return true;
>> +}
>> +
>> #define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
>>
>> static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
>> @@ -90,4 +125,64 @@ static inline unsigned long _pmd_pfn(pmd_t pmd)
>> #define pmd_ERROR(e) \
>> pr_err("%s:%d: bad pmd %016lx.\n", __FILE__, __LINE__, pmd_val(e))
>>
>> +#define pud_ERROR(e) \
>> + pr_err("%s:%d: bad pud %016lx.\n", __FILE__, __LINE__, pud_val(e))
>> +
>> +static inline void set_p4d(p4d_t *p4dp, p4d_t p4d)
>> +{
>> + if (pgtable_l4_enabled)
>> + *p4dp = p4d;
>> + else
>> + set_pud((pud_t *)p4dp, (pud_t){ p4d_val(p4d) });
>> +}
>> +
>> +static inline int p4d_none(p4d_t p4d)
>> +{
>> + if (pgtable_l4_enabled)
>> + return (p4d_val(p4d) == 0);
>> +
>> + return 0;
>> +}
>> +
>> +static inline int p4d_present(p4d_t p4d)
>> +{
>> + if (pgtable_l4_enabled)
>> + return (p4d_val(p4d) & _PAGE_PRESENT);
>> +
>> + return 1;
>> +}
>> +
>> +static inline int p4d_bad(p4d_t p4d)
>> +{
>> + if (pgtable_l4_enabled)
>> + return !p4d_present(p4d);
>> +
>> + return 0;
>> +}
>> +
>> +static inline void p4d_clear(p4d_t *p4d)
>> +{
>> + if (pgtable_l4_enabled)
>> + set_p4d(p4d, __p4d(0));
>> +}
>> +
>> +static inline unsigned long p4d_page_vaddr(p4d_t p4d)
>> +{
>> + if (pgtable_l4_enabled)
>> + return (unsigned long)pfn_to_virt(
>> + p4d_val(p4d) >> _PAGE_PFN_SHIFT);
>> +
>> + return pud_page_vaddr((pud_t) { p4d_val(p4d) });
>> +}
>> +
>> +#define pud_index(addr) (((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1))
>> +
>> +static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
>> +{
>> + if (pgtable_l4_enabled)
>> + return (pud_t *)p4d_page_vaddr(*p4d) + pud_index(address);
>> +
>> + return (pud_t *)p4d;
>> +}
>> +
>> #endif /* _ASM_RISCV_PGTABLE_64_H */
>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>> index 8e96315b3366..b8a8ba69d0a2 100644
>> --- a/arch/riscv/include/asm/pgtable.h
>> +++ b/arch/riscv/include/asm/pgtable.h
>> @@ -20,12 +20,14 @@
>> * the kernel.
>> */
>> #define KERNEL_VIRT_ADDR (VMALLOC_END - SZ_2G + 1)
>> -#define KERNEL_LINK_ADDR KERNEL_VIRT_ADDR
>> +#define KERNEL_LINK_ADDR (VMALLOC_LINK_END - SZ_2G + 1)
>>
>> #define VMALLOC_SIZE (KERN_VIRT_SIZE >> 1)
>> #define VMALLOC_END (PAGE_OFFSET - 1)
>> #define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE)
>>
>> +#define VMALLOC_LINK_END (_AC(CONFIG_PAGE_OFFSET, UL) - 1)
>> +
>> #define BPF_JIT_REGION_SIZE (SZ_128M)
>> #define BPF_JIT_REGION_START (kernel_virt_addr)
>> #define BPF_JIT_REGION_END (kernel_virt_addr + BPF_JIT_REGION_SIZE)
>> @@ -67,8 +69,7 @@
>>
>> #ifndef __ASSEMBLY__
>>
>> -/* Page Upper Directory not used in RISC-V */
>> -#include <asm-generic/pgtable-nopud.h>
>> +#include <asm-generic/pgtable-nop4d.h>
>> #include <asm/page.h>
>> #include <asm/tlbflush.h>
>> #include <linux/mm_types.h>
>> @@ -81,7 +82,7 @@
>>
>> #ifdef CONFIG_MMU
>> #ifdef CONFIG_64BIT
>> -#define VA_BITS 39
>> +#define VA_BITS (pgtable_l4_enabled ? 48 : 39)
>> #define PA_BITS 56
>> #else
>> #define VA_BITS 32
>> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
>> index 8f5bb7731327..0632c4834c68 100644
>> --- a/arch/riscv/kernel/head.S
>> +++ b/arch/riscv/kernel/head.S
>> @@ -62,7 +62,8 @@ relocate:
>>
>> /* Compute satp for kernel page tables, but don't load it yet */
>> srl a2, a0, PAGE_SHIFT
>> - li a1, SATP_MODE
>> + la a1, satp_mode
>> + REG_L a1, 0(a1)
>> or a2, a2, a1
>>
>> /*
>> diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
>> index 613ec81a8979..6830504f8b11 100644
>> --- a/arch/riscv/mm/context.c
>> +++ b/arch/riscv/mm/context.c
>> @@ -9,6 +9,8 @@
>> #include <asm/cacheflush.h>
>> #include <asm/mmu_context.h>
>>
>> +extern u64 satp_mode;
> Please move this to asm/pgtable.h next to "extern void *dtb_early_va".
>
> Same thing can be done for "pgtable_l4_enabled" to help PATCH7.
>
> I forgot to mention this in previous emails.


Ok, I'll do that in v2 too, thanks.
Anup, do you have time to take a look at the relocatable series I have
posted earlier ?
As sv48 support depends on that, it would be nice to have your review too.

Thanks,

Alex


>
> Regards,
> Anup
>
>
>
>> +
>> /*
>> * When necessary, performs a deferred icache flush for the given MM context,
>> * on the local CPU. RISC-V has no direct mechanism for instruction cache
>> @@ -59,7 +61,7 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next,
>> cpumask_set_cpu(cpu, mm_cpumask(next));
>>
>> #ifdef CONFIG_MMU
>> - csr_write(CSR_SATP, virt_to_pfn(next->pgd) | SATP_MODE);
>> + csr_write(CSR_SATP, virt_to_pfn(next->pgd) | satp_mode);
>> local_flush_tlb_all();
>> #endif
>>
>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>> index 5782cae58ac2..bad8da099ff6 100644
>> --- a/arch/riscv/mm/init.c
>> +++ b/arch/riscv/mm/init.c
>> @@ -25,8 +25,23 @@
>>
>> #include "../kernel/head.h"
>>
>> -unsigned long kernel_virt_addr = KERNEL_VIRT_ADDR;
>> +#ifdef CONFIG_64BIT
>> +u64 satp_mode = IS_ENABLED(CONFIG_MAXPHYSMEM_2GB) ?
>> + SATP_MODE_39 : SATP_MODE_48;
>> +bool pgtable_l4_enabled = IS_ENABLED(CONFIG_MAXPHYSMEM_2GB) ? false : true;
>> +#else
>> +u64 satp_mode = SATP_MODE_32;
>> +bool pgtable_l4_enabled;
>> +#endif
>> +EXPORT_SYMBOL(pgtable_l4_enabled);
>> +EXPORT_SYMBOL(satp_mode);
>> +
>> +unsigned long kernel_virt_addr;
>> EXPORT_SYMBOL(kernel_virt_addr);
>> +#ifdef CONFIG_RELOCATABLE
>> +unsigned long __page_offset = _AC(CONFIG_PAGE_OFFSET, UL);
>> +EXPORT_SYMBOL(__page_offset);
>> +#endif
>>
>> unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
>> __page_aligned_bss;
>> @@ -254,9 +269,12 @@ static void __init create_pte_mapping(pte_t *ptep,
>>
>> #ifndef __PAGETABLE_PMD_FOLDED
>>
>> +pud_t trampoline_pud[PTRS_PER_PUD] __page_aligned_bss;
>> pmd_t trampoline_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> +pud_t fixmap_pud[PTRS_PER_PUD] __page_aligned_bss;
>> pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
>> +pud_t early_pud[PTRS_PER_PUD] __initdata __aligned(PAGE_SIZE);
>>
>> static pmd_t *__init get_pmd_virt(phys_addr_t pa)
>> {
>> @@ -273,7 +291,8 @@ static phys_addr_t __init alloc_pmd(uintptr_t va)
>> if (mmu_enabled)
>> return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>>
>> - BUG_ON((va - kernel_virt_addr) >> PGDIR_SHIFT);
>> + /* Only one PMD is available for early mapping */
>> + BUG_ON((va - kernel_virt_addr) >> PUD_SHIFT);
>>
>> return (uintptr_t)early_pmd;
>> }
>> @@ -305,19 +324,70 @@ static void __init create_pmd_mapping(pmd_t *pmdp,
>> create_pte_mapping(ptep, va, pa, sz, prot);
>> }
>>
>> -#define pgd_next_t pmd_t
>> -#define alloc_pgd_next(__va) alloc_pmd(__va)
>> -#define get_pgd_next_virt(__pa) get_pmd_virt(__pa)
>> +static pud_t *__init get_pud_virt(phys_addr_t pa)
>> +{
>> + if (mmu_enabled) {
>> + clear_fixmap(FIX_PUD);
>> + return (pud_t *)set_fixmap_offset(FIX_PUD, pa);
>> + } else {
>> + return (pud_t *)((uintptr_t)pa);
>> + }
>> +}
>> +
>> +static phys_addr_t __init alloc_pud(uintptr_t va)
>> +{
>> + if (mmu_enabled)
>> + return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>> +
>> + /* Only one PUD is available for early mapping */
>> + BUG_ON((va - kernel_virt_addr) >> PGDIR_SHIFT);
>> +
>> + return (uintptr_t)early_pud;
>> +}
>> +
>> +static void __init create_pud_mapping(pud_t *pudp,
>> + uintptr_t va, phys_addr_t pa,
>> + phys_addr_t sz, pgprot_t prot)
>> +{
>> + pmd_t *nextp;
>> + phys_addr_t next_phys;
>> + uintptr_t pud_index = pud_index(va);
>> +
>> + if (sz == PUD_SIZE) {
>> + if (pud_val(pudp[pud_index]) == 0)
>> + pudp[pud_index] = pfn_pud(PFN_DOWN(pa), prot);
>> + return;
>> + }
>> +
>> + if (pud_val(pudp[pud_index]) == 0) {
>> + next_phys = alloc_pmd(va);
>> + pudp[pud_index] = pfn_pud(PFN_DOWN(next_phys), PAGE_TABLE);
>> + nextp = get_pmd_virt(next_phys);
>> + memset(nextp, 0, PAGE_SIZE);
>> + } else {
>> + next_phys = PFN_PHYS(_pud_pfn(pudp[pud_index]));
>> + nextp = get_pmd_virt(next_phys);
>> + }
>> +
>> + create_pmd_mapping(nextp, va, pa, sz, prot);
>> +}
>> +
>> +#define pgd_next_t pud_t
>> +#define alloc_pgd_next(__va) alloc_pud(__va)
>> +#define get_pgd_next_virt(__pa) get_pud_virt(__pa)
>> #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot) \
>> - create_pmd_mapping(__nextp, __va, __pa, __sz, __prot)
>> -#define fixmap_pgd_next fixmap_pmd
>> + create_pud_mapping(__nextp, __va, __pa, __sz, __prot)
>> +#define fixmap_pgd_next (pgtable_l4_enabled ? \
>> + (uintptr_t)fixmap_pud : (uintptr_t)fixmap_pmd)
>> +#define trampoline_pgd_next (pgtable_l4_enabled ? \
>> + (uintptr_t)trampoline_pud : (uintptr_t)trampoline_pmd)
>> #else
>> #define pgd_next_t pte_t
>> #define alloc_pgd_next(__va) alloc_pte(__va)
>> #define get_pgd_next_virt(__pa) get_pte_virt(__pa)
>> #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot) \
>> create_pte_mapping(__nextp, __va, __pa, __sz, __prot)
>> -#define fixmap_pgd_next fixmap_pte
>> +#define fixmap_pgd_next ((uintptr_t)fixmap_pte)
>> #endif
>>
>> static void __init create_pgd_mapping(pgd_t *pgdp,
>> @@ -328,6 +398,13 @@ static void __init create_pgd_mapping(pgd_t *pgdp,
>> phys_addr_t next_phys;
>> uintptr_t pgd_index = pgd_index(va);
>>
>> +#ifndef __PAGETABLE_PMD_FOLDED
>> + if (!pgtable_l4_enabled) {
>> + create_pud_mapping((pud_t *)pgdp, va, pa, sz, prot);
>> + return;
>> + }
>> +#endif
>> +
>> if (sz == PGDIR_SIZE) {
>> if (pgd_val(pgdp[pgd_index]) == 0)
>> pgdp[pgd_index] = pfn_pgd(PFN_DOWN(pa), prot);
>> @@ -419,6 +496,47 @@ void __init relocate_kernel(uintptr_t load_pa)
>> }
>> }
>>
>> +#if defined(CONFIG_64BIT) && !defined(CONFIG_MAXPHYSMEM_2GB)
>> +void disable_pgtable_l4(void)
>> +{
>> + pgtable_l4_enabled = false;
>> + __page_offset = PAGE_OFFSET_L3;
>> + satp_mode = SATP_MODE_39;
>> +}
>> +
>> +/* There is a simple way to determine if 4-level is supported by the
>> + * underlying hardware: establish 1:1 mapping in 4-level page table mode
>> + * then read SATP to see if the configuration was taken into account
>> + * meaning sv48 is supported.
>> + */
>> +asmlinkage __init void set_satp_mode(uintptr_t load_pa)
>> +{
>> + u64 identity_satp, hw_satp;
>> + int cpus_node;
>> +
>> + create_pgd_mapping(early_pg_dir, load_pa, (uintptr_t)early_pud,
>> + PGDIR_SIZE, PAGE_TABLE);
>> + create_pud_mapping(early_pud, load_pa, (uintptr_t)early_pmd,
>> + PUD_SIZE, PAGE_TABLE);
>> + create_pmd_mapping(early_pmd, load_pa, load_pa,
>> + PMD_SIZE, PAGE_KERNEL_EXEC);
>> +
>> + identity_satp = PFN_DOWN((uintptr_t)&early_pg_dir) | satp_mode;
>> + local_flush_tlb_all();
>> + csr_write(CSR_SATP, identity_satp);
>> +
>> + hw_satp = csr_read(CSR_SATP);
>> + csr_write(CSR_SATP, 0ULL);
>> + local_flush_tlb_all();
>> +
>> + if (hw_satp != identity_satp)
>> + disable_pgtable_l4();
>> +
>> + memset(early_pg_dir, 0, PAGE_SIZE);
>> + memset(early_pud, 0, PAGE_SIZE);
>> + memset(early_pmd, 0, PAGE_SIZE);
>> +}
>> +#endif
>> #endif
>>
>> static uintptr_t load_pa, load_sz;
>> @@ -442,9 +560,14 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>> load_pa = (uintptr_t)(&_start);
>> load_sz = (uintptr_t)(&_end) - load_pa;
>>
>> +#if defined(CONFIG_64BIT) && !defined(CONFIG_MAXPHYSMEM_2GB)
>> + set_satp_mode(load_pa);
>> +#endif
>> +
>> + kernel_virt_addr = KERNEL_VIRT_ADDR;
>> +
>> va_pa_offset = PAGE_OFFSET - load_pa;
>> va_kernel_pa_offset = kernel_virt_addr - load_pa;
>> -
>> pfn_base = PFN_DOWN(load_pa);
>>
>> #ifdef CONFIG_RELOCATABLE
>> @@ -473,15 +596,22 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>>
>> /* Setup early PGD for fixmap */
>> create_pgd_mapping(early_pg_dir, FIXADDR_START,
>> - (uintptr_t)fixmap_pgd_next, PGDIR_SIZE, PAGE_TABLE);
>> + fixmap_pgd_next, PGDIR_SIZE, PAGE_TABLE);
>>
>> #ifndef __PAGETABLE_PMD_FOLDED
>> - /* Setup fixmap PMD */
>> + /* Setup fixmap PUD and PMD */
>> + if (pgtable_l4_enabled)
>> + create_pud_mapping(fixmap_pud, FIXADDR_START,
>> + (uintptr_t)fixmap_pmd, PUD_SIZE, PAGE_TABLE);
>> create_pmd_mapping(fixmap_pmd, FIXADDR_START,
>> (uintptr_t)fixmap_pte, PMD_SIZE, PAGE_TABLE);
>> +
>> /* Setup trampoline PGD and PMD */
>> create_pgd_mapping(trampoline_pg_dir, kernel_virt_addr,
>> - (uintptr_t)trampoline_pmd, PGDIR_SIZE, PAGE_TABLE);
>> + trampoline_pgd_next, PGDIR_SIZE, PAGE_TABLE);
>> + if (pgtable_l4_enabled)
>> + create_pud_mapping(trampoline_pud, kernel_virt_addr,
>> + (uintptr_t)trampoline_pmd, PUD_SIZE, PAGE_TABLE);
>> create_pmd_mapping(trampoline_pmd, kernel_virt_addr,
>> load_pa, PMD_SIZE, PAGE_KERNEL_EXEC);
>> #else
>> @@ -558,12 +688,13 @@ static void __init setup_vm_final(void)
>>
>> vm_area_add_early(&vm_kernel);
>>
>> - /* Clear fixmap PTE and PMD mappings */
>> + /* Clear fixmap page table mappings */
>> clear_fixmap(FIX_PTE);
>> clear_fixmap(FIX_PMD);
>> + clear_fixmap(FIX_PUD);
>>
>> /* Move to swapper page table */
>> - csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
>> + csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | satp_mode);
>> local_flush_tlb_all();
>> }
>>
>> --
>> 2.20.1
>>

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