[PATCH -fixes v2 1/3] riscv: Move early dtb mapping into the fixmap region
Alexandre Ghiti
alexghiti at rivosinc.com
Wed Mar 29 01:19:30 PDT 2023
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 at microchip.com>
Link: https://lore.kernel.org/all/f8e67f82-103d-156c-deb0-d6d6e2756f5e@microchip.com/
Signed-off-by: Alexandre Ghiti <alexghiti at rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley at microchip.com>
Tested-by: Conor Dooley <conor.dooley at microchip.com>
---
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 3be44e74ec5d..5462c84f4723 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 5c3e7b97fcc6..0a55099bb734 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 ab05f892d317..f641837ccf31 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 376d2827e736..542eed85ad2c 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -283,7 +283,6 @@ void __init setup_arch(char **cmdline_p)
else
pr_err("No DTB found in kernel mappings\n");
#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 478d6763a01a..fb78d6bbabae 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)
@@ -860,32 +860,28 @@ 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
@@ -1055,7 +1051,8 @@ 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
@@ -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);
--
2.37.2
More information about the linux-riscv
mailing list