[PATCH 0/5] Small cleanup for mm/init.c and address conversion macros

[PATCH 0/5] Small cleanup for mm/init.c and address conversion macros

[Alexandre Ghiti]

The first patch allows to have only one definition of the address
conversion macros for all kernel types.

The following patches bring small cleanups to mm/init.c and the last
patch makes the size of the DTB early mapping consistent between 32-bit
and 64-bit kernels.

Alexandre Ghiti (5)
  riscv: Introduce va_kernel_pa_offset for 32-bit kernel
  riscv: Get rid of map_size parameter to create_kernel_page_table
  riscv: Use __maybe_unused instead of #ifdefs around variable
    declarations
  riscv: Simplify BUILTIN_DTB device tree mapping handling
  riscv: Move early fdt mapping creation in its own function

 arch/riscv/include/asm/page.h |  15 +----
 arch/riscv/mm/init.c          | 121 +++++++++++++++-------------------
 2 files changed, 54 insertions(+), 82 deletions(-)

-- 
2.30.2


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[PATCH 1/5] riscv: Introduce va_kernel_pa_offset for 32-bit kernel

[Alexandre Ghiti]

va_kernel_pa_offset was only used for 64-bit as the kernel mapping lies
in the linear mapping for 32-bit kernel and then only the offset between
the PAGE_OFFSET and the kernel load address is needed.

But this distinction complexifies the code with #ifdefs and especially
with a separate definition of the address conversions macros.

Simplify the code by defining this variable for both 32-bit and 64-bit.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/riscv/include/asm/page.h | 15 ++-------------
 arch/riscv/mm/init.c          |  3 ---
 2 files changed, 2 insertions(+), 16 deletions(-)

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 10dc063868f6..adf5b4671684 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -91,10 +91,8 @@ struct kernel_mapping {
 	uintptr_t size;
 	/* Offset between linear mapping virtual address and kernel load address */
 	unsigned long va_pa_offset;
-#ifdef CONFIG_64BIT
 	/* Offset between kernel mapping virtual address and kernel load address */
 	unsigned long va_kernel_pa_offset;
-#endif
 	unsigned long va_kernel_xip_pa_offset;
 #ifdef CONFIG_XIP_KERNEL
 	uintptr_t xiprom;
@@ -105,11 +103,11 @@ struct kernel_mapping {
 extern struct kernel_mapping kernel_map;
 extern phys_addr_t phys_ram_base;
 
-#ifdef CONFIG_64BIT
 #define is_kernel_mapping(x)	\
 	((x) >= kernel_map.virt_addr && (x) < (kernel_map.virt_addr + kernel_map.size))
+
 #define is_linear_mapping(x)	\
-	((x) >= PAGE_OFFSET && (x) < kernel_map.virt_addr)
+	((x) >= PAGE_OFFSET && (!IS_ENABLED(CONFIG_64BIT) || (x) < kernel_map.virt_addr))
 
 #define linear_mapping_pa_to_va(x)	((void *)((unsigned long)(x) + kernel_map.va_pa_offset))
 #define kernel_mapping_pa_to_va(y)	({						\
@@ -133,15 +131,6 @@ extern phys_addr_t phys_ram_base;
 	is_linear_mapping(_x) ?							\
 		linear_mapping_va_to_pa(_x) : kernel_mapping_va_to_pa(_x);	\
 	})
-#else
-#define is_kernel_mapping(x)	\
-	((x) >= kernel_map.virt_addr && (x) < (kernel_map.virt_addr + kernel_map.size))
-#define is_linear_mapping(x)	\
-	((x) >= PAGE_OFFSET)
-
-#define __pa_to_va_nodebug(x)  ((void *)((unsigned long) (x) + kernel_map.va_pa_offset))
-#define __va_to_pa_nodebug(x)  ((unsigned long)(x) - kernel_map.va_pa_offset)
-#endif /* CONFIG_64BIT */
 
 #ifdef CONFIG_DEBUG_VIRTUAL
 extern phys_addr_t __virt_to_phys(unsigned long x);
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 4ebe7e19c2b8..9668867e2702 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -559,11 +559,8 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 	kernel_map.phys_addr = (uintptr_t)(&_start);
 	kernel_map.size = (uintptr_t)(&_end) - kernel_map.phys_addr;
 #endif
-
 	kernel_map.va_pa_offset = PAGE_OFFSET - kernel_map.phys_addr;
-#ifdef CONFIG_64BIT
 	kernel_map.va_kernel_pa_offset = kernel_map.virt_addr - kernel_map.phys_addr;
-#endif
 
 	pfn_base = PFN_DOWN(kernel_map.phys_addr);
 
-- 
2.30.2


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[PATCH 2/5] riscv: Get rid of map_size parameter to create_kernel_page_table

[Alexandre Ghiti]

The kernel must always be mapped using PMD_SIZE, and this is already the
case, this just simplifies create_kernel_page_table.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/riscv/mm/init.c | 30 +++++++++++-------------------
 1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 9668867e2702..e35df3e1c9a3 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -501,36 +501,35 @@ static __init pgprot_t pgprot_from_va(uintptr_t va)
 #endif
 
 #ifdef CONFIG_XIP_KERNEL
-static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size,
+static void __init create_kernel_page_table(pgd_t *pgdir,
 					    __always_unused bool early)
 {
 	uintptr_t va, end_va;
 
 	/* Map the flash resident part */
 	end_va = kernel_map.virt_addr + kernel_map.xiprom_sz;
-	for (va = kernel_map.virt_addr; va < end_va; va += map_size)
+	for (va = kernel_map.virt_addr; va < end_va; va += PMD_SIZE)
 		create_pgd_mapping(pgdir, va,
 				   kernel_map.xiprom + (va - kernel_map.virt_addr),
-				   map_size, PAGE_KERNEL_EXEC);
+				   PMD_SIZE, PAGE_KERNEL_EXEC);
 
 	/* Map the data in RAM */
 	end_va = kernel_map.virt_addr + XIP_OFFSET + kernel_map.size;
-	for (va = kernel_map.virt_addr + XIP_OFFSET; va < end_va; va += map_size)
+	for (va = kernel_map.virt_addr + XIP_OFFSET; va < end_va; va += PMD_SIZE)
 		create_pgd_mapping(pgdir, va,
 				   kernel_map.phys_addr + (va - (kernel_map.virt_addr + XIP_OFFSET)),
-				   map_size, PAGE_KERNEL);
+				   PMD_SIZE, PAGE_KERNEL);
 }
 #else
-static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size,
-					    bool early)
+static void __init create_kernel_page_table(pgd_t *pgdir, bool early)
 {
 	uintptr_t va, end_va;
 
 	end_va = kernel_map.virt_addr + kernel_map.size;
-	for (va = kernel_map.virt_addr; va < end_va; va += map_size)
+	for (va = kernel_map.virt_addr; va < end_va; va += PMD_SIZE)
 		create_pgd_mapping(pgdir, va,
 				   kernel_map.phys_addr + (va - kernel_map.virt_addr),
-				   map_size,
+				   PMD_SIZE,
 				   early ?
 					PAGE_KERNEL_EXEC : pgprot_from_va(va));
 }
@@ -539,7 +538,6 @@ static void __init create_kernel_page_table(pgd_t *pgdir, uintptr_t map_size,
 asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 {
 	uintptr_t __maybe_unused pa;
-	uintptr_t map_size;
 #ifndef __PAGETABLE_PMD_FOLDED
 	pmd_t fix_bmap_spmd, fix_bmap_epmd;
 #endif
@@ -564,15 +562,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 
 	pfn_base = PFN_DOWN(kernel_map.phys_addr);
 
-	/*
-	 * Enforce boot alignment requirements of RV32 and
-	 * RV64 by only allowing PMD or PGD mappings.
-	 */
-	map_size = PMD_SIZE;
-
 	/* Sanity check alignment and size */
 	BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
-	BUG_ON((kernel_map.phys_addr % map_size) != 0);
+	BUG_ON((kernel_map.phys_addr % PMD_SIZE) != 0);
 
 	pt_ops.alloc_pte = alloc_pte_early;
 	pt_ops.get_pte_virt = get_pte_virt_early;
@@ -609,7 +601,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 	 * us to reach paging_init(). We map all memory banks later
 	 * in setup_vm_final() below.
 	 */
-	create_kernel_page_table(early_pg_dir, map_size, true);
+	create_kernel_page_table(early_pg_dir, true);
 
 #ifndef __PAGETABLE_PMD_FOLDED
 	/* Setup early PMD for DTB */
@@ -725,7 +717,7 @@ static void __init setup_vm_final(void)
 
 #ifdef CONFIG_64BIT
 	/* Map the kernel */
-	create_kernel_page_table(swapper_pg_dir, PMD_SIZE, false);
+	create_kernel_page_table(swapper_pg_dir, false);
 #endif
 
 	/* Clear fixmap PTE and PMD mappings */
-- 
2.30.2


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[PATCH 3/5] riscv: Use __maybe_unused instead of #ifdefs around variable declarations

[Alexandre Ghiti]

This allows to simplify the code and make it more readable.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/riscv/mm/init.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index e35df3e1c9a3..6b29c5791555 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -538,9 +538,7 @@ static void __init create_kernel_page_table(pgd_t *pgdir, bool early)
 asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 {
 	uintptr_t __maybe_unused pa;
-#ifndef __PAGETABLE_PMD_FOLDED
-	pmd_t fix_bmap_spmd, fix_bmap_epmd;
-#endif
+	pmd_t __maybe_unused fix_bmap_spmd, fix_bmap_epmd;
 
 	kernel_map.virt_addr = KERNEL_LINK_ADDR;
 
-- 
2.30.2


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[PATCH 4/5] riscv: Simplify BUILTIN_DTB device tree mapping handling

[Alexandre Ghiti]

__PAGETABLE_PMD_FOLDED defines a 2-level page table that is only used in
32-bit kernel, so there is no need to check for CONFIG_64BIT in #ifndef
__PAGETABLE_PMD_FOLDED and vice-versa.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/riscv/mm/init.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 6b29c5791555..1b30ad7e3ebc 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -614,18 +614,14 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 			   pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
 	dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 1));
 #else /* CONFIG_BUILTIN_DTB */
-#ifdef CONFIG_64BIT
 	/*
 	 * __va can't be used since it would return a linear mapping address
 	 * whereas dtb_early_va will be used before setup_vm_final installs
 	 * the linear mapping.
 	 */
 	dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
-#else
-	dtb_early_va = __va(dtb_pa);
-#endif /* CONFIG_64BIT */
 #endif /* CONFIG_BUILTIN_DTB */
-#else
+#else /* __PAGETABLE_PMD_FOLDED */
 #ifndef CONFIG_BUILTIN_DTB
 	/* Create two consecutive PGD mappings for FDT early scan */
 	pa = dtb_pa & ~(PGDIR_SIZE - 1);
@@ -635,13 +631,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 			   pa + PGDIR_SIZE, PGDIR_SIZE, PAGE_KERNEL);
 	dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PGDIR_SIZE - 1));
 #else /* CONFIG_BUILTIN_DTB */
-#ifdef CONFIG_64BIT
-	dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
-#else
 	dtb_early_va = __va(dtb_pa);
-#endif /* CONFIG_64BIT */
 #endif /* CONFIG_BUILTIN_DTB */
-#endif
+#endif /* __PAGETABLE_PMD_FOLDED */
 	dtb_early_pa = dtb_pa;
 
 	/*
-- 
2.30.2


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[PATCH 5/5] riscv: Move early fdt mapping creation in its own function

[Alexandre Ghiti]

The code that handles the early fdt mapping is hard to read and does not
create the same mapping size depending on the kernel:

- for 64-bit, 2 PMD entries are used which amounts to a 4MB mapping
- for 32-bit, 2 PGDIR entries are used which amounts to a 8MB mapping

So keep using 2 PMD entries for 64-bit and use only one PGD entry for
32-bit needed to cover 4MB. Move that into a new function called
create_fdt_early_page_table which, using the same naming as
create_kernel_page_table.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/riscv/mm/init.c | 76 +++++++++++++++++++++++---------------------
 1 file changed, 40 insertions(+), 36 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 1b30ad7e3ebc..e2c8f188ad95 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -228,6 +228,7 @@ 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 trampoline_pg_dir      ((pgd_t *)XIP_FIXUP(trampoline_pg_dir))
@@ -308,7 +309,6 @@ static void __init create_pte_mapping(pte_t *ptep,
 static pmd_t trampoline_pmd[PTRS_PER_PMD] __page_aligned_bss;
 static pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
 static pmd_t early_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
-static pmd_t early_dtb_pmd[PTRS_PER_PMD] __initdata __aligned(PAGE_SIZE);
 
 #ifdef CONFIG_XIP_KERNEL
 #define trampoline_pmd ((pmd_t *)XIP_FIXUP(trampoline_pmd))
@@ -394,6 +394,7 @@ static void __init create_pmd_mapping(pmd_t *pmdp,
 #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot)	\
 	create_pte_mapping(__nextp, __va, __pa, __sz, __prot)
 #define fixmap_pgd_next		fixmap_pte
+#define create_pmd_mapping(__pmdp, __va, __pa, __sz, __prot)
 #endif
 
 void __init create_pgd_mapping(pgd_t *pgdp,
@@ -535,9 +536,44 @@ static void __init create_kernel_page_table(pgd_t *pgdir, bool early)
 }
 #endif
 
+/*
+ * Setup a 4MB mapping that encompasses the device tree: for 64-bit kernel,
+ * 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)
+{
+#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);
+
+	if (IS_ENABLED(CONFIG_64BIT)) {
+		create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA,
+				   pa, PMD_SIZE, PAGE_KERNEL);
+		create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA + PMD_SIZE,
+				   pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
+	}
+
+	dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 1));
+#else
+	/*
+	 * For 64-bit kernel, __va can't be used since it would return a linear
+	 * mapping address whereas dtb_early_va will be used before
+	 * setup_vm_final installs the linear mapping. For 32-bit kernel, as the
+	 * kernel is mapped in the linear mapping, that makes no difference.
+	 */
+	dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
+#endif
+
+	dtb_early_pa = dtb_pa;
+}
+
 asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 {
-	uintptr_t __maybe_unused pa;
 	pmd_t __maybe_unused fix_bmap_spmd, fix_bmap_epmd;
 
 	kernel_map.virt_addr = KERNEL_LINK_ADDR;
@@ -601,40 +637,8 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 	 */
 	create_kernel_page_table(early_pg_dir, true);
 
-#ifndef __PAGETABLE_PMD_FOLDED
-	/* Setup early PMD for DTB */
-	create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA,
-			   (uintptr_t)early_dtb_pmd, PGDIR_SIZE, PAGE_TABLE);
-#ifndef CONFIG_BUILTIN_DTB
-	/* Create two consecutive PMD mappings for FDT early scan */
-	pa = dtb_pa & ~(PMD_SIZE - 1);
-	create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA,
-			   pa, PMD_SIZE, PAGE_KERNEL);
-	create_pmd_mapping(early_dtb_pmd, DTB_EARLY_BASE_VA + PMD_SIZE,
-			   pa + PMD_SIZE, PMD_SIZE, PAGE_KERNEL);
-	dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PMD_SIZE - 1));
-#else /* CONFIG_BUILTIN_DTB */
-	/*
-	 * __va can't be used since it would return a linear mapping address
-	 * whereas dtb_early_va will be used before setup_vm_final installs
-	 * the linear mapping.
-	 */
-	dtb_early_va = kernel_mapping_pa_to_va(XIP_FIXUP(dtb_pa));
-#endif /* CONFIG_BUILTIN_DTB */
-#else /* __PAGETABLE_PMD_FOLDED */
-#ifndef CONFIG_BUILTIN_DTB
-	/* Create two consecutive PGD mappings for FDT early scan */
-	pa = dtb_pa & ~(PGDIR_SIZE - 1);
-	create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA,
-			   pa, PGDIR_SIZE, PAGE_KERNEL);
-	create_pgd_mapping(early_pg_dir, DTB_EARLY_BASE_VA + PGDIR_SIZE,
-			   pa + PGDIR_SIZE, PGDIR_SIZE, PAGE_KERNEL);
-	dtb_early_va = (void *)DTB_EARLY_BASE_VA + (dtb_pa & (PGDIR_SIZE - 1));
-#else /* CONFIG_BUILTIN_DTB */
-	dtb_early_va = __va(dtb_pa);
-#endif /* CONFIG_BUILTIN_DTB */
-#endif /* __PAGETABLE_PMD_FOLDED */
-	dtb_early_pa = dtb_pa;
+	/* Setup early mapping for FDT early scan */
+	create_fdt_early_page_table(early_pg_dir, dtb_pa);
 
 	/*
 	 * Bootime fixmap only can handle PMD_SIZE mapping. Thus, boot-ioremap
-- 
2.30.2


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Re: [PATCH 0/5] Small cleanup for mm/init.c and address conversion macros

[Palmer Dabbelt]

On Fri, 23 Jul 2021 06:01:23 PDT (-0700), alex@ghiti.fr wrote:
> The first patch allows to have only one definition of the address
> conversion macros for all kernel types.
>
> The following patches bring small cleanups to mm/init.c and the last
> patch makes the size of the DTB early mapping consistent between 32-bit
> and 64-bit kernels.
>
> Alexandre Ghiti (5)
>   riscv: Introduce va_kernel_pa_offset for 32-bit kernel
>   riscv: Get rid of map_size parameter to create_kernel_page_table
>   riscv: Use __maybe_unused instead of #ifdefs around variable
>     declarations
>   riscv: Simplify BUILTIN_DTB device tree mapping handling
>   riscv: Move early fdt mapping creation in its own function
>
>  arch/riscv/include/asm/page.h |  15 +----
>  arch/riscv/mm/init.c          | 121 +++++++++++++++-------------------
>  2 files changed, 54 insertions(+), 82 deletions(-)

Thanks, these are on for-next.  There were some minor merge conflicts, 
let me know if I missed anything.

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