From: Alexandre Ghiti alexghiti@rivosinc.com
commit ef69d2559fe91f23d27a3d6fd640b5641787d22e upstream.
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@microchip.com Link: https://lore.kernel.org/all/f8e67f82-103d-156c-deb0-d6d6e2756f5e@microchip.c... Signed-off-by: Alexandre Ghiti alexghiti@rivosinc.com Reviewed-by: Conor Dooley conor.dooley@microchip.com Tested-by: Conor Dooley conor.dooley@microchip.com Link: https://lore.kernel.org/r/20230329081932.79831-2-alexghiti@rivosinc.com Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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(-)
--- 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 --- 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, --- 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)
--- 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(); --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -57,7 +57,6 @@ unsigned long empty_zero_page[PAGE_SIZE 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] __ 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(p4 #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(p4 #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) @@ -860,32 +860,28 @@ static void __init create_kernel_page_ta * 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 @@ -1055,7 +1051,8 @@ asmlinkage void __init setup_vm(uintptr_ 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 @@ -1097,6 +1094,16 @@ 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);