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

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Message-Id: <20190327213643.23789-5-logang@deltatee.com>
Date:   Wed, 27 Mar 2019 15:36:40 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Cc:     Stephen Bates <sbates@...thlin.com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Christoph Hellwig <hch@....de>,
        Albert Ou <aou@...s.berkeley.edu>,
        Logan Gunthorpe <logang@...tatee.com>,
        Anup Patel <anup.patel@....com>,
        Atish Patra <atish.patra@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Zong Li <zongbox@...il.com>, Mike Rapoport <rppt@...ux.ibm.com>
Subject: [PATCH 4/7] RISC-V: Update page tables to cover the whole linear mapping

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@...tatee.com>
Cc: Palmer Dabbelt <palmer@...ive.com>
Cc: Albert Ou <aou@...s.berkeley.edu>
Cc: Anup Patel <anup.patel@....com>
Cc: Atish Patra <atish.patra@....com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>
Cc: Zong Li <zongbox@...il.com>
Cc: Mike Rapoport <rppt@...ux.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