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.
This patch had to be backported because:
- the documentation for sv57 is not present here (as sv48/57 are not
present)
- handling of sv48/57 is not needed (as not present)
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 # 5.15.x
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
---
Documentation/riscv/vm-layout.rst | 2 +-
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 | 47 ++++++++++++++++++++++---------
5 files changed, 49 insertions(+), 17 deletions(-)
diff --git a/Documentation/riscv/vm-layout.rst b/Documentation/riscv/vm-layout.rst
index b7f98930d38d..a2ec11da38b0 100644
--- a/Documentation/riscv/vm-layout.rst
+++ b/Documentation/riscv/vm-layout.rst
@@ -48,7 +48,7 @@ RISC-V Linux Kernel SV39
____________________________________________________________|___________________________________________________________
| | | |
ffffffc000000000 | -256 GB | ffffffc7ffffffff | 32 GB | kasan
- ffffffcefee00000 | -196 GB | ffffffcefeffffff | 2 MB | fixmap
+ ffffffcefea00000 | -196 GB | ffffffcefeffffff | 6 MB | fixmap
ffffffceff000000 | -196 GB | ffffffceffffffff | 16 MB | PCI io
ffffffcf00000000 | -196 GB | ffffffcfffffffff | 4 GB | vmemmap
ffffffd000000000 | -192 GB | ffffffdfffffffff | 64 GB | vmalloc/ioremap space
diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
index 54cbf07fb4e9..8839cd2b28d1 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_TEXT_POKE1,
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 39b550310ec6..397cb945b16e 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -66,9 +66,13 @@
#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 14b84d09354a..f874fe07fb78 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -291,7 +291,6 @@ 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 830f53b141a0..3f62ff02efc4 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -49,7 +49,6 @@ 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;
@@ -216,6 +215,14 @@ 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
@@ -265,7 +272,6 @@ 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 pmd_t __maybe_unused early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
#ifdef CONFIG_XIP_KERNEL
#define riscv_pfn_base (*(unsigned long *)XIP_FIXUP(&riscv_pfn_base))
@@ -580,24 +586,28 @@ 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) ? (uintptr_t)early_dtb_pmd : pa,
- PGDIR_SIZE,
- IS_ENABLED(CONFIG_64BIT) ? PAGE_TABLE : PAGE_KERNEL);
+#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
@@ -685,7 +695,8 @@ 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
@@ -735,6 +746,16 @@ static void __init setup_vm_final(void)
pt_ops.get_pmd_virt = get_pmd_virt_fixmap;
#endif
/* 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
