[PATCH 4/7] RISC-V: Update page tables to cover the whole linear mapping

[Logan Gunthorpe <logang@deltatee.com>]

With the new virtual address changes in an earlier patch, we want the
page tables to cover more of the linear mapping region. Instead of
only mapping from PAGE_OFFSET and up, we instead map starting
from an aligned version of va_pa_offset such that all of the physical
address space will be mapped.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anup Patel <anup.patel@wdc.com>
Cc: Atish Patra <atish.patra@wdc.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Zong Li <zongbox@gmail.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
---
 arch/riscv/kernel/setup.c |  1 -
 arch/riscv/mm/init.c      | 27 +++++++++++++++------------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index ecb654f6a79e..8286df8be31a 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -59,7 +59,6 @@ EXPORT_SYMBOL(empty_zero_page);
 /* The lucky hart to first increment this variable will boot the other cores */
 atomic_t hart_lottery;
 unsigned long boot_cpu_hartid;
-
 void __init parse_dtb(unsigned int hartid, void *dtb)
 {
 	if (early_init_dt_scan(__va(dtb)))
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index b9d50031e78f..315194557c3d 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -150,8 +150,8 @@ pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
 pgd_t trampoline_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
 
 #ifndef __PAGETABLE_PMD_FOLDED
-#define NUM_SWAPPER_PMDS ((uintptr_t)-PAGE_OFFSET >> PGDIR_SHIFT)
-pmd_t swapper_pmd[PTRS_PER_PMD*((-PAGE_OFFSET)/PGDIR_SIZE)] __page_aligned_bss;
+#define NUM_SWAPPER_PMDS ((uintptr_t)-VMALLOC_END >> PGDIR_SHIFT)
+pmd_t swapper_pmd[PTRS_PER_PMD*((-VMALLOC_END)/PGDIR_SIZE)] __page_aligned_bss;
 pmd_t trampoline_pmd[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
 pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
 #endif
@@ -180,13 +180,18 @@ asmlinkage void __init setup_vm(void)
 	extern char _start;
 	uintptr_t i;
 	uintptr_t pa = (uintptr_t) &_start;
+	uintptr_t linear_start;
+	uintptr_t off;
 	pgprot_t prot = __pgprot(pgprot_val(PAGE_KERNEL) | _PAGE_EXEC);
 
 	va_pa_offset = PAGE_OFFSET - pa;
 	pfn_base = PFN_DOWN(pa);
 
+	linear_start = ALIGN_DOWN(va_pa_offset, PGDIR_SIZE);
+	off = linear_start - va_pa_offset;
+
 	/* Sanity check alignment and size */
-	BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
+	BUG_ON(linear_start <= VMALLOC_END);
 	BUG_ON((pa % (PAGE_SIZE * PTRS_PER_PTE)) != 0);
 
 #ifndef __PAGETABLE_PMD_FOLDED
@@ -195,15 +200,14 @@ asmlinkage void __init setup_vm(void)
 			__pgprot(_PAGE_TABLE));
 	trampoline_pmd[0] = pfn_pmd(PFN_DOWN(pa), prot);
 
-	for (i = 0; i < (-PAGE_OFFSET)/PGDIR_SIZE; ++i) {
-		size_t o = (PAGE_OFFSET >> PGDIR_SHIFT) % PTRS_PER_PGD + i;
-
+	for (i = 0; i < (-linear_start)/PGDIR_SIZE; ++i) {
+		size_t o = (linear_start >> PGDIR_SHIFT) % PTRS_PER_PGD + i;
 		swapper_pg_dir[o] =
 			pfn_pgd(PFN_DOWN((uintptr_t)swapper_pmd) + i,
 				__pgprot(_PAGE_TABLE));
 	}
 	for (i = 0; i < ARRAY_SIZE(swapper_pmd); i++)
-		swapper_pmd[i] = pfn_pmd(PFN_DOWN(pa + i * PMD_SIZE), prot);
+		swapper_pmd[i] = pfn_pmd(PFN_DOWN(off + i * PMD_SIZE), prot);
 
 	swapper_pg_dir[(FIXADDR_START >> PGDIR_SHIFT) % PTRS_PER_PGD] =
 		pfn_pgd(PFN_DOWN((uintptr_t)fixmap_pmd),
@@ -215,11 +219,10 @@ asmlinkage void __init setup_vm(void)
 	trampoline_pg_dir[(PAGE_OFFSET >> PGDIR_SHIFT) % PTRS_PER_PGD] =
 		pfn_pgd(PFN_DOWN(pa), prot);
 
-	for (i = 0; i < (-PAGE_OFFSET)/PGDIR_SIZE; ++i) {
-		size_t o = (PAGE_OFFSET >> PGDIR_SHIFT) % PTRS_PER_PGD + i;
-
-		swapper_pg_dir[o] =
-			pfn_pgd(PFN_DOWN(pa + i * PGDIR_SIZE), prot);
+	for (i = 0; i < (-linear_start)/PGDIR_SIZE; ++i) {
+		size_t o = (linear_start >> PGDIR_SHIFT) % PTRS_PER_PGD + i;
+		swapper_pg_dir[o] = pfn_pgd(PFN_DOWN(off + i * PGDIR_SIZE),
+					    prot);
 	}
 
 	swapper_pg_dir[(FIXADDR_START >> PGDIR_SHIFT) % PTRS_PER_PGD] =
-- 
2.20.1