arm64 can support multiple base page sizes. Instead of selecting a page size at compile time, as is done today, we will make it possible to select the desired page size on the command line. In this case PAGE_SHIFT and it's derivatives, PAGE_SIZE and PAGE_MASK (as well as a number of other macros related to or derived from PAGE_SHIFT, but I'm not worrying about those yet), are no longer compile-time constants. So the code base needs to cope with that. As a first step, introduce MIN and MAX variants of these macros, which express the range of possible page sizes. These are always compile-time constants and can be used in many places where PAGE_[SHIFT|SIZE|MASK] were previously used where a compile-time constant is required. (Subsequent patches will do that conversion work). When the arch/build doesn't support boot-time page size selection, the MIN and MAX variants are equal and everything resolves as it did previously. Additionally, introduce DEFINE_GLOBAL_PAGE_SIZE_VAR[_CONST]() which wrap global variable defintions so that for boot-time page size selection builds, the variable being wrapped is initialized at boot-time, instead of compile-time. This is done by defining a function to do the assignment, which has the "constructor" attribute. Constructor is preferred over initcall, because when compiling a module, the module is limited to a single initcall but constructors are unlimited. For built-in code, constructors are now called earlier to guarrantee that the variables are initialized by the time they are used. Any arch that wants to enable boot-time page size selection will need to select CONFIG_CONSTRUCTORS. These new macros need to be available anywhere PAGE_SHIFT and friends are available. Those are defined via asm/page.h (although some arches have a sub-include that defines them). Unfortunately there is no reliable asm-generic header we can easily piggy-back on, so let's define a new one, pgtable-geometry.h, which we include near where each arch defines PAGE_SHIFT. Ugh. ------- Most of the problems that need to be solved over the next few patches fall into these broad categories, which are all solved with the help of these new macros: 1. Assignment of values derived from PAGE_SIZE in global variables For boot-time page size builds, we must defer the initialization of these variables until boot-time, when the page size is known. See DEFINE_GLOBAL_PAGE_SIZE_VAR[_CONST]() as described above. 2. Define static storage in units related to PAGE_SIZE This static storage will be defined according to PAGE_SIZE_MAX. 3. Define size of struct so that it is related to PAGE_SIZE The struct often contains an array that is sized to fill the page. In this case, use a flexible array with dynamic allocation. In other cases, the struct fits exactly over a page, which is a header (e.g. swap file header). In this case, remove the padding, and manually determine the struct pointer within the page. 4. BUILD_BUG_ON() with values derived from PAGE_SIZE In most cases, we can change these to compare againt the appropriate limit (either MIN or MAX). In other cases, we must change these to run-time BUG_ON(). 5. Ensure page alignment of static data structures Align instead to PAGE_SIZE_MAX. 6. #ifdeffery based on PAGE_SIZE Often these can be changed to c code constructs. e.g. a macro that returns a different value depending on page size can be changed to use the ternary operator and the compiler will dead code strip it for the compile-time constant case and runtime evaluate it for the non-const case. Or #if/#else/#endif within a function can be converted to c if/else blocks, which are also dead code stripped for the const case. Sometimes we can change the c-preprocessor logic to use the appropriate MIN/MAX limit. Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- ***NOTE*** Any confused maintainers may want to read the cover note here for context: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@xxxxxxx/ arch/alpha/include/asm/page.h | 1 + arch/arc/include/asm/page.h | 1 + arch/arm/include/asm/page.h | 1 + arch/arm64/include/asm/page-def.h | 2 + arch/csky/include/asm/page.h | 3 ++ arch/hexagon/include/asm/page.h | 2 + arch/loongarch/include/asm/page.h | 2 + arch/m68k/include/asm/page.h | 1 + arch/microblaze/include/asm/page.h | 1 + arch/mips/include/asm/page.h | 1 + arch/nios2/include/asm/page.h | 2 + arch/openrisc/include/asm/page.h | 1 + arch/parisc/include/asm/page.h | 1 + arch/powerpc/include/asm/page.h | 2 + arch/riscv/include/asm/page.h | 1 + arch/s390/include/asm/page.h | 1 + arch/sh/include/asm/page.h | 1 + arch/sparc/include/asm/page.h | 3 ++ arch/um/include/asm/page.h | 2 + arch/x86/include/asm/page_types.h | 2 + arch/xtensa/include/asm/page.h | 1 + include/asm-generic/pgtable-geometry.h | 71 ++++++++++++++++++++++++++ init/main.c | 5 +- 23 files changed, 107 insertions(+), 1 deletion(-) create mode 100644 include/asm-generic/pgtable-geometry.h diff --git a/arch/alpha/include/asm/page.h b/arch/alpha/include/asm/page.h index 70419e6be1a35..d0096fb5521b8 100644 --- a/arch/alpha/include/asm/page.h +++ b/arch/alpha/include/asm/page.h @@ -88,5 +88,6 @@ typedef struct page *pgtable_t; #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #endif /* _ALPHA_PAGE_H */ diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h index def0dfb95b436..8d56549db7a33 100644 --- a/arch/arc/include/asm/page.h +++ b/arch/arc/include/asm/page.h @@ -6,6 +6,7 @@ #define __ASM_ARC_PAGE_H #include <uapi/asm/page.h> +#include <asm-generic/pgtable-geometry.h> #ifdef CONFIG_ARC_HAS_PAE40 diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h index 62af9f7f9e963..417aa8533c718 100644 --- a/arch/arm/include/asm/page.h +++ b/arch/arm/include/asm/page.h @@ -191,5 +191,6 @@ extern int pfn_valid(unsigned long); #include <asm-generic/getorder.h> #include <asm-generic/memory_model.h> +#include <asm-generic/pgtable-geometry.h> #endif diff --git a/arch/arm64/include/asm/page-def.h b/arch/arm64/include/asm/page-def.h index 792e9fe881dcf..d69971cf49cd2 100644 --- a/arch/arm64/include/asm/page-def.h +++ b/arch/arm64/include/asm/page-def.h @@ -15,4 +15,6 @@ #define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT) #define PAGE_MASK (~(PAGE_SIZE-1)) +#include <asm-generic/pgtable-geometry.h> + #endif /* __ASM_PAGE_DEF_H */ diff --git a/arch/csky/include/asm/page.h b/arch/csky/include/asm/page.h index 0ca6c408c07f2..95173d57adc8b 100644 --- a/arch/csky/include/asm/page.h +++ b/arch/csky/include/asm/page.h @@ -92,4 +92,7 @@ static inline unsigned long virt_to_pfn(const void *kaddr) #include <asm-generic/getorder.h> #endif /* !__ASSEMBLY__ */ + +#include <asm-generic/pgtable-geometry.h> + #endif /* __ASM_CSKY_PAGE_H */ diff --git a/arch/hexagon/include/asm/page.h b/arch/hexagon/include/asm/page.h index 8a6af57274c2d..ba7ad5231695f 100644 --- a/arch/hexagon/include/asm/page.h +++ b/arch/hexagon/include/asm/page.h @@ -139,4 +139,6 @@ static inline unsigned long virt_to_pfn(const void *kaddr) #endif /* ifdef __ASSEMBLY__ */ #endif /* ifdef __KERNEL__ */ +#include <asm-generic/pgtable-geometry.h> + #endif diff --git a/arch/loongarch/include/asm/page.h b/arch/loongarch/include/asm/page.h index e85df33f11c77..9862e8fb047a6 100644 --- a/arch/loongarch/include/asm/page.h +++ b/arch/loongarch/include/asm/page.h @@ -123,4 +123,6 @@ extern int __virt_addr_valid(volatile void *kaddr); #endif /* !__ASSEMBLY__ */ +#include <asm-generic/pgtable-geometry.h> + #endif /* _ASM_PAGE_H */ diff --git a/arch/m68k/include/asm/page.h b/arch/m68k/include/asm/page.h index 8cfb84b499751..4df4681b02194 100644 --- a/arch/m68k/include/asm/page.h +++ b/arch/m68k/include/asm/page.h @@ -60,5 +60,6 @@ extern unsigned long _ramend; #include <asm-generic/getorder.h> #include <asm-generic/memory_model.h> +#include <asm-generic/pgtable-geometry.h> #endif /* _M68K_PAGE_H */ diff --git a/arch/microblaze/include/asm/page.h b/arch/microblaze/include/asm/page.h index 8810f4f1c3b02..abc23c3d743bd 100644 --- a/arch/microblaze/include/asm/page.h +++ b/arch/microblaze/include/asm/page.h @@ -142,5 +142,6 @@ static inline const void *pfn_to_virt(unsigned long pfn) #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #endif /* _ASM_MICROBLAZE_PAGE_H */ diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h index 4609cb0326cf3..3d91021538f02 100644 --- a/arch/mips/include/asm/page.h +++ b/arch/mips/include/asm/page.h @@ -227,5 +227,6 @@ static inline unsigned long kaslr_offset(void) #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #endif /* _ASM_PAGE_H */ diff --git a/arch/nios2/include/asm/page.h b/arch/nios2/include/asm/page.h index 0722f88e63cc7..2e5f93beb42b7 100644 --- a/arch/nios2/include/asm/page.h +++ b/arch/nios2/include/asm/page.h @@ -97,4 +97,6 @@ extern struct page *mem_map; #endif /* !__ASSEMBLY__ */ +#include <asm-generic/pgtable-geometry.h> + #endif /* _ASM_NIOS2_PAGE_H */ diff --git a/arch/openrisc/include/asm/page.h b/arch/openrisc/include/asm/page.h index 1d5913f67c312..a0da2a9842241 100644 --- a/arch/openrisc/include/asm/page.h +++ b/arch/openrisc/include/asm/page.h @@ -88,5 +88,6 @@ static inline unsigned long virt_to_pfn(const void *kaddr) #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #endif /* __ASM_OPENRISC_PAGE_H */ diff --git a/arch/parisc/include/asm/page.h b/arch/parisc/include/asm/page.h index 4bea2e95798f0..2a75496237c09 100644 --- a/arch/parisc/include/asm/page.h +++ b/arch/parisc/include/asm/page.h @@ -173,6 +173,7 @@ extern int npmem_ranges; #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #include <asm/pdc.h> #define PAGE0 ((struct zeropage *)absolute_pointer(__PAGE_OFFSET)) diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h index 83d0a4fc5f755..4601c115b6485 100644 --- a/arch/powerpc/include/asm/page.h +++ b/arch/powerpc/include/asm/page.h @@ -300,4 +300,6 @@ static inline unsigned long kaslr_offset(void) #include <asm-generic/memory_model.h> #endif /* __ASSEMBLY__ */ +#include <asm-generic/pgtable-geometry.h> + #endif /* _ASM_POWERPC_PAGE_H */ diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h index 7ede2111c5917..e5af7579e45bf 100644 --- a/arch/riscv/include/asm/page.h +++ b/arch/riscv/include/asm/page.h @@ -204,5 +204,6 @@ static __always_inline void *pfn_to_kaddr(unsigned long pfn) #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #endif /* _ASM_RISCV_PAGE_H */ diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h index 16e4caa931f1f..42157e7690a77 100644 --- a/arch/s390/include/asm/page.h +++ b/arch/s390/include/asm/page.h @@ -275,6 +275,7 @@ static inline unsigned long virt_to_pfn(const void *kaddr) #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #define AMODE31_SIZE (3 * PAGE_SIZE) diff --git a/arch/sh/include/asm/page.h b/arch/sh/include/asm/page.h index f780b467e75d7..09533d46ef033 100644 --- a/arch/sh/include/asm/page.h +++ b/arch/sh/include/asm/page.h @@ -162,5 +162,6 @@ typedef struct page *pgtable_t; #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#include <asm-generic/pgtable-geometry.h> #endif /* __ASM_SH_PAGE_H */ diff --git a/arch/sparc/include/asm/page.h b/arch/sparc/include/asm/page.h index 5e44cdf2a8f2b..4327fe2bfa010 100644 --- a/arch/sparc/include/asm/page.h +++ b/arch/sparc/include/asm/page.h @@ -9,4 +9,7 @@ #else #include <asm/page_32.h> #endif + +#include <asm-generic/pgtable-geometry.h> + #endif diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h index 9ef9a8aedfa66..f26011808f514 100644 --- a/arch/um/include/asm/page.h +++ b/arch/um/include/asm/page.h @@ -119,4 +119,6 @@ extern unsigned long uml_physmem; #define __HAVE_ARCH_GATE_AREA 1 #endif +#include <asm-generic/pgtable-geometry.h> + #endif /* __UM_PAGE_H */ diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h index 52f1b4ff0cc16..6d2381342047f 100644 --- a/arch/x86/include/asm/page_types.h +++ b/arch/x86/include/asm/page_types.h @@ -71,4 +71,6 @@ extern void initmem_init(void); #endif /* !__ASSEMBLY__ */ +#include <asm-generic/pgtable-geometry.h> + #endif /* _ASM_X86_PAGE_DEFS_H */ diff --git a/arch/xtensa/include/asm/page.h b/arch/xtensa/include/asm/page.h index 4db56ef052d22..86952cb32af23 100644 --- a/arch/xtensa/include/asm/page.h +++ b/arch/xtensa/include/asm/page.h @@ -200,4 +200,5 @@ static inline unsigned long ___pa(unsigned long va) #endif /* __ASSEMBLY__ */ #include <asm-generic/memory_model.h> +#include <asm-generic/pgtable-geometry.h> #endif /* _XTENSA_PAGE_H */ diff --git a/include/asm-generic/pgtable-geometry.h b/include/asm-generic/pgtable-geometry.h new file mode 100644 index 0000000000000..358e729a6ac37 --- /dev/null +++ b/include/asm-generic/pgtable-geometry.h @@ -0,0 +1,71 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef ASM_GENERIC_PGTABLE_GEOMETRY_H +#define ASM_GENERIC_PGTABLE_GEOMETRY_H + +#if defined(PAGE_SHIFT_MAX) && defined(PAGE_SIZE_MAX) && defined(PAGE_MASK_MAX) && \ + defined(PAGE_SHIFT_MIN) && defined(PAGE_SIZE_MIN) && defined(PAGE_MASK_MIN) +/* Arch supports boot-time page size selection. */ +#elif defined(PAGE_SHIFT_MAX) || defined(PAGE_SIZE_MAX) || defined(PAGE_MASK_MAX) || \ + defined(PAGE_SHIFT_MIN) || defined(PAGE_SIZE_MIN) || defined(PAGE_MASK_MIN) +#error Arch must define all or none of the boot-time page size macros +#else +/* Arch does not support boot-time page size selection. */ +#define PAGE_SHIFT_MIN PAGE_SHIFT +#define PAGE_SIZE_MIN PAGE_SIZE +#define PAGE_MASK_MIN PAGE_MASK +#define PAGE_SHIFT_MAX PAGE_SHIFT +#define PAGE_SIZE_MAX PAGE_SIZE +#define PAGE_MASK_MAX PAGE_MASK +#endif + +/* + * Define a global variable (scalar or struct), whose value is derived from + * PAGE_SIZE and friends. When PAGE_SIZE is a compile-time constant, the global + * variable is simply defined with the static value. When PAGE_SIZE is + * determined at boot-time, a pure initcall is registered and run during boot to + * initialize the variable. + * + * @type: Unqualified type. Do not include "const"; implied by macro variant. + * @name: Variable name. + * @...: Initialization value. May be scalar or initializer. + * + * "static" is declared by placing "static" before the macro. + * + * Example: + * + * struct my_struct { + * int a; + * char b; + * }; + * + * static DEFINE_GLOBAL_PAGE_SIZE_VAR(struct my_struct, my_variable, { + * .a = 10, + * .b = 'e', + * }); + */ +#if PAGE_SIZE_MIN != PAGE_SIZE_MAX +#define __DEFINE_GLOBAL_PAGE_SIZE_VAR(type, name, attrib, ...) \ + type name attrib; \ + static int __init __attribute__((constructor)) __##name##_init(void) \ + { \ + name = (type)__VA_ARGS__; \ + return 0; \ + } + +#define DEFINE_GLOBAL_PAGE_SIZE_VAR(type, name, ...) \ + __DEFINE_GLOBAL_PAGE_SIZE_VAR(type, name, , __VA_ARGS__) + +#define DEFINE_GLOBAL_PAGE_SIZE_VAR_CONST(type, name, ...) \ + __DEFINE_GLOBAL_PAGE_SIZE_VAR(type, name, __ro_after_init, __VA_ARGS__) +#else /* PAGE_SIZE_MIN == PAGE_SIZE_MAX */ +#define __DEFINE_GLOBAL_PAGE_SIZE_VAR(type, name, attrib, ...) \ + type name attrib = __VA_ARGS__; \ + +#define DEFINE_GLOBAL_PAGE_SIZE_VAR(type, name, ...) \ + __DEFINE_GLOBAL_PAGE_SIZE_VAR(type, name, , __VA_ARGS__) + +#define DEFINE_GLOBAL_PAGE_SIZE_VAR_CONST(type, name, ...) \ + __DEFINE_GLOBAL_PAGE_SIZE_VAR(const type, name, , __VA_ARGS__) +#endif + +#endif /* ASM_GENERIC_PGTABLE_GEOMETRY_H */ diff --git a/init/main.c b/init/main.c index 206acdde51f5a..ba1515eb20b9d 100644 --- a/init/main.c +++ b/init/main.c @@ -899,6 +899,8 @@ static void __init early_numa_node_init(void) #endif } +static __init void do_ctors(void); + asmlinkage __visible __init __no_sanitize_address __noreturn __no_stack_protector void start_kernel(void) { @@ -910,6 +912,8 @@ void start_kernel(void) debug_objects_early_init(); init_vmlinux_build_id(); + do_ctors(); + cgroup_init_early(); local_irq_disable(); @@ -1360,7 +1364,6 @@ static void __init do_basic_setup(void) cpuset_init_smp(); driver_init(); init_irq_proc(); - do_ctors(); do_initcalls(); } -- 2.43.0
