On Tue, Apr 18, 2023 at 02:23:05PM +0200, Greg Kroah-Hartman wrote:
> From: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
>
> [ Upstream commit ef69d2559fe91f23d27a3d6fd640b5641787d22e ]
Hey Greg,
Please check out <e3a6656c-0ec4-9d54-b262-1af08c292ed5@xxxxxxxxxxxxx>
(I can't find a lore link for stable-commit@vger stuff)
as I am not sure whether it is okay to backport this in isolation.
Cheers,
Conor.
>
> riscv establishes 2 virtual mappings:
>
> - early_pg_dir maps the kernel which allows to discover the system
> memory
> - swapper_pg_dir installs the final mapping (linear mapping included)
>
> We used to map the dtb in early_pg_dir using DTB_EARLY_BASE_VA, and this
> mapping was not carried over in swapper_pg_dir. It happens that
> early_init_fdt_scan_reserved_mem() must be called before swapper_pg_dir is
> setup otherwise we could allocate reserved memory defined in the dtb.
> And this function initializes reserved_mem variable with addresses that
> lie in the early_pg_dir dtb mapping: when those addresses are reused
> with swapper_pg_dir, this mapping does not exist and then we trap.
>
> The previous "fix" was incorrect as early_init_fdt_scan_reserved_mem()
> must be called before swapper_pg_dir is set up otherwise we could
> allocate in reserved memory defined in the dtb.
>
> So move the dtb mapping in the fixmap region which is established in
> early_pg_dir and handed over to swapper_pg_dir.
>
> Fixes: 922b0375fc93 ("riscv: Fix memblock reservation for device tree blob")
> Fixes: 8f3a2b4a96dc ("RISC-V: Move DT mapping outof fixmap")
> Fixes: 50e63dd8ed92 ("riscv: fix reserved memory setup")
> Reported-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Link: https://lore.kernel.org/all/f8e67f82-103d-156c-deb0-d6d6e2756f5e@xxxxxxxxxxxxx/
> Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
> Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Tested-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/20230329081932.79831-2-alexghiti@xxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> Documentation/riscv/vm-layout.rst | 6 +--
> arch/riscv/include/asm/fixmap.h | 8 ++++
> arch/riscv/include/asm/pgtable.h | 8 +++-
> arch/riscv/kernel/setup.c | 1 -
> arch/riscv/mm/init.c | 61 +++++++++++++++++--------------
> 5 files changed, 51 insertions(+), 33 deletions(-)
>
> diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst
> index 3be44e74ec5d6..5462c84f4723f 100644
> --- a/Documentation/riscv/vm-layout.rst
> +++ b/Documentation/riscv/vm-layout.rst
> @@ -47,7 +47,7 @@ RISC-V Linux Kernel SV39
> | Kernel-space virtual memory, shared between all processes:
> ____________________________________________________________|___________________________________________________________
> | | | |
> - ffffffc6fee00000 | -228 GB | ffffffc6feffffff | 2 MB | fixmap
> + ffffffc6fea00000 | -228 GB | ffffffc6feffffff | 6 MB | fixmap
> ffffffc6ff000000 | -228 GB | ffffffc6ffffffff | 16 MB | PCI io
> ffffffc700000000 | -228 GB | ffffffc7ffffffff | 4 GB | vmemmap
> ffffffc800000000 | -224 GB | ffffffd7ffffffff | 64 GB | vmalloc/ioremap space
> @@ -83,7 +83,7 @@ RISC-V Linux Kernel SV48
> | Kernel-space virtual memory, shared between all processes:
> ____________________________________________________________|___________________________________________________________
> | | | |
> - ffff8d7ffee00000 | -114.5 TB | ffff8d7ffeffffff | 2 MB | fixmap
> + ffff8d7ffea00000 | -114.5 TB | ffff8d7ffeffffff | 6 MB | fixmap
> ffff8d7fff000000 | -114.5 TB | ffff8d7fffffffff | 16 MB | PCI io
> ffff8d8000000000 | -114.5 TB | ffff8f7fffffffff | 2 TB | vmemmap
> ffff8f8000000000 | -112.5 TB | ffffaf7fffffffff | 32 TB | vmalloc/ioremap space
> @@ -119,7 +119,7 @@ RISC-V Linux Kernel SV57
> | Kernel-space virtual memory, shared between all processes:
> ____________________________________________________________|___________________________________________________________
> | | | |
> - ff1bfffffee00000 | -57 PB | ff1bfffffeffffff | 2 MB | fixmap
> + ff1bfffffea00000 | -57 PB | ff1bfffffeffffff | 6 MB | fixmap
> ff1bffffff000000 | -57 PB | ff1bffffffffffff | 16 MB | PCI io
> ff1c000000000000 | -57 PB | ff1fffffffffffff | 1 PB | vmemmap
> ff20000000000000 | -56 PB | ff5fffffffffffff | 16 PB | vmalloc/ioremap space
> diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
> index 5c3e7b97fcc6f..0a55099bb7349 100644
> --- a/arch/riscv/include/asm/fixmap.h
> +++ b/arch/riscv/include/asm/fixmap.h
> @@ -22,6 +22,14 @@
> */
> enum fixed_addresses {
> FIX_HOLE,
> + /*
> + * The fdt fixmap mapping must be PMD aligned and will be mapped
> + * using PMD entries in fixmap_pmd in 64-bit and a PGD entry in 32-bit.
> + */
> + FIX_FDT_END,
> + FIX_FDT = FIX_FDT_END + FIX_FDT_SIZE / PAGE_SIZE - 1,
> +
> + /* Below fixmaps will be mapped using fixmap_pte */
> FIX_PTE,
> FIX_PMD,
> FIX_PUD,
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 92ec2d9d7273f..2aeaf8e3a4ab0 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -87,9 +87,13 @@
>
> #define FIXADDR_TOP PCI_IO_START
> #ifdef CONFIG_64BIT
> -#define FIXADDR_SIZE PMD_SIZE
> +#define MAX_FDT_SIZE PMD_SIZE
> +#define FIX_FDT_SIZE (MAX_FDT_SIZE + SZ_2M)
> +#define FIXADDR_SIZE (PMD_SIZE + FIX_FDT_SIZE)
> #else
> -#define FIXADDR_SIZE PGDIR_SIZE
> +#define MAX_FDT_SIZE PGDIR_SIZE
> +#define FIX_FDT_SIZE MAX_FDT_SIZE
> +#define FIXADDR_SIZE (PGDIR_SIZE + FIX_FDT_SIZE)
> #endif
> #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
>
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index d4a12233e728d..2acf51c235673 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -280,7 +280,6 @@ void __init setup_arch(char **cmdline_p)
> #else
> unflatten_device_tree();
> #endif
> - early_init_fdt_scan_reserved_mem();
> misc_mem_init();
>
> init_resources();
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 50a1b6edd4918..5570c52deb0b5 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -57,7 +57,6 @@ unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
> EXPORT_SYMBOL(empty_zero_page);
>
> extern char _start[];
> -#define DTB_EARLY_BASE_VA PGDIR_SIZE
> void *_dtb_early_va __initdata;
> uintptr_t _dtb_early_pa __initdata;
>
> @@ -236,6 +235,14 @@ static void __init setup_bootmem(void)
> set_max_mapnr(max_low_pfn - ARCH_PFN_OFFSET);
>
> reserve_initrd_mem();
> +
> + /*
> + * No allocation should be done before reserving the memory as defined
> + * in the device tree, otherwise the allocation could end up in a
> + * reserved region.
> + */
> + early_init_fdt_scan_reserved_mem();
> +
> /*
> * If DTB is built in, no need to reserve its memblock.
> * Otherwise, do reserve it but avoid using
> @@ -279,9 +286,6 @@ pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> static pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;
>
> pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
> -static p4d_t __maybe_unused early_dtb_p4d[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
> -static pud_t __maybe_unused early_dtb_pud[PTRS_PER_PUD] __initdata __aligned(PAGE_SIZE);
> -static pmd_t __maybe_unused early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
>
> #ifdef CONFIG_XIP_KERNEL
> #define pt_ops (*(struct pt_alloc_ops *)XIP_FIXUP(&pt_ops))
> @@ -626,9 +630,6 @@ static void __init create_p4d_mapping(p4d_t *p4dp,
> #define trampoline_pgd_next (pgtable_l5_enabled ? \
> (uintptr_t)trampoline_p4d : (pgtable_l4_enabled ? \
> (uintptr_t)trampoline_pud : (uintptr_t)trampoline_pmd))
> -#define early_dtb_pgd_next (pgtable_l5_enabled ? \
> - (uintptr_t)early_dtb_p4d : (pgtable_l4_enabled ? \
> - (uintptr_t)early_dtb_pud : (uintptr_t)early_dtb_pmd))
> #else
> #define pgd_next_t pte_t
> #define alloc_pgd_next(__va) pt_ops.alloc_pte(__va)
> @@ -636,7 +637,6 @@ static void __init create_p4d_mapping(p4d_t *p4dp,
> #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot) \
> create_pte_mapping(__nextp, __va, __pa, __sz, __prot)
> #define fixmap_pgd_next ((uintptr_t)fixmap_pte)
> -#define early_dtb_pgd_next ((uintptr_t)early_dtb_pmd)
> #define create_p4d_mapping(__pmdp, __va, __pa, __sz, __prot) do {} while(0)
> #define create_pud_mapping(__pmdp, __va, __pa, __sz, __prot) do {} while(0)
> #define create_pmd_mapping(__pmdp, __va, __pa, __sz, __prot) do {} while(0)
> @@ -859,32 +859,28 @@ static void __init create_kernel_page_table(pgd_t *pgdir, bool early)
> * this means 2 PMD entries whereas for 32-bit kernel, this is only 1 PGDIR
> * entry.
> */
> -static void __init create_fdt_early_page_table(pgd_t *pgdir, uintptr_t dtb_pa)
> +static void __init create_fdt_early_page_table(pgd_t *pgdir,
> + uintptr_t fix_fdt_va,
> + uintptr_t dtb_pa)
> {
> -#ifndef CONFIG_BUILTIN_DTB
> uintptr_t pa = dtb_pa & ~(PMD_SIZE - 1);
>
> - create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA,
> - IS_ENABLED(CONFIG_64BIT) ? early_dtb_pgd_next : pa,
> - PGDIR_SIZE,
> - IS_ENABLED(CONFIG_64BIT) ? PAGE_TABLE : PAGE_KERNEL);
> -
> - if (pgtable_l5_enabled)
> - create_p4d_mapping(early_dtb_p4d, DTB_EARLY_BASE_VA,
> - (uintptr_t)early_dtb_pud, P4D_SIZE, PAGE_TABLE);
> -
> - if (pgtable_l4_enabled)
> - create_pud_mapping(early_dtb_pud, DTB_EARLY_BASE_VA,
> - (uintptr_t)early_dtb_pmd, PUD_SIZE, PAGE_TABLE);
> +#ifndef CONFIG_BUILTIN_DTB
> + /* Make sure the fdt fixmap address is always aligned on PMD size */
> + BUILD_BUG_ON(FIX_FDT % (PMD_SIZE / PAGE_SIZE));
>
> - if (IS_ENABLED(CONFIG_64BIT)) {
> - create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA,
> + /* In 32-bit only, the fdt lies in its own PGD */
> + if (!IS_ENABLED(CONFIG_64BIT)) {
> + create_pgd_mapping(early_pg_dir, fix_fdt_va,
> + pa, MAX_FDT_SIZE, PAGE_KERNEL);
> + } else {
> + create_pmd_mapping(fixmap_pmd, fix_fdt_va,
> pa, PMD_SIZE, PAGE_KERNEL);
> - create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA + PMD_SIZE,
> + create_pmd_mapping(fixmap_pmd, fix_fdt_va + PMD_SIZE,
> pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
> }
>
> - dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 1));
> + dtb_early_va = (void *)fix_fdt_va + (dtb_pa & (PMD_SIZE - 1));
> #else
> /*
> * For 64-bit kernel, __va can't be used since it would return a linear
> @@ -1054,7 +1050,8 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> create_kernel_page_table(early_pg_dir, true);
>
> /* Setup early mapping for FDT early scan */
> - create_fdt_early_page_table(early_pg_dir, dtb_pa);
> + create_fdt_early_page_table(early_pg_dir,
> + __fix_to_virt(FIX_FDT), dtb_pa);
>
> /*
> * Bootime fixmap only can handle PMD_SIZE mapping. Thus, boot-ioremap
> @@ -1096,6 +1093,16 @@ static void __init setup_vm_final(void)
> u64 i;
>
> /* Setup swapper PGD for fixmap */
> +#if !defined(CONFIG_64BIT)
> + /*
> + * In 32-bit, the device tree lies in a pgd entry, so it must be copied
> + * directly in swapper_pg_dir in addition to the pgd entry that points
> + * to fixmap_pte.
> + */
> + unsigned long idx = pgd_index(__fix_to_virt(FIX_FDT));
> +
> + set_pgd(&swapper_pg_dir[idx], early_pg_dir[idx]);
> +#endif
> create_pgd_mapping(swapper_pg_dir, FIXADDR_START,
> __pa_symbol(fixmap_pgd_next),
> PGDIR_SIZE, PAGE_TABLE);
> --
> 2.39.2
>
>
>
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