From mboxrd@z Thu Jan 1 00:00:00 1970 From: ard.biesheuvel@linaro.org (Ard Biesheuvel) Date: Mon, 11 May 2015 09:13:05 +0200 Subject: [PATCH 07/10] arm64: move kernel mapping out of linear region In-Reply-To: <1431328388-3051-1-git-send-email-ard.biesheuvel@linaro.org> References: <1431328388-3051-1-git-send-email-ard.biesheuvel@linaro.org> Message-ID: <1431328388-3051-8-git-send-email-ard.biesheuvel@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org This moves the primary mapping of the kernel Image out of the linear region. This is a preparatory step towards allowing the kernel Image to reside anywhere in physical memory without affecting the ability to map all of it efficiently. Signed-off-by: Ard Biesheuvel --- arch/arm64/include/asm/boot.h | 7 +++++++ arch/arm64/include/asm/memory.h | 19 ++++++++++++++++--- arch/arm64/kernel/head.S | 18 +++++++++++++----- arch/arm64/kernel/vmlinux.lds.S | 11 +++++++++-- arch/arm64/mm/init.c | 5 +++-- arch/arm64/mm/mmu.c | 10 +++++++++- 6 files changed, 57 insertions(+), 13 deletions(-) diff --git a/arch/arm64/include/asm/boot.h b/arch/arm64/include/asm/boot.h index 81151b67b26b..092d1096ce9a 100644 --- a/arch/arm64/include/asm/boot.h +++ b/arch/arm64/include/asm/boot.h @@ -11,4 +11,11 @@ #define MIN_FDT_ALIGN 8 #define MAX_FDT_SIZE SZ_2M +/* + * arm64 requires the kernel image to be 2 MB aligned and + * not exceed 64 MB in size. + */ +#define MIN_KIMG_ALIGN SZ_2M +#define MAX_KIMG_SIZE SZ_64M + #endif diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index f800d45ea226..050ede7cd1ee 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -24,6 +24,7 @@ #include #include #include +#include #include /* @@ -39,7 +40,12 @@ #define PCI_IO_SIZE SZ_16M /* - * PAGE_OFFSET - the virtual address of the start of the kernel image (top + * Offset below PAGE_OFFSET where to map the kernel Image. + */ +#define KIMAGE_OFFSET MAX_KIMG_SIZE + +/* + * PAGE_OFFSET - the virtual address of the base of the linear mapping (top * (VA_BITS - 1)) * VA_BITS - the maximum number of bits for virtual addresses. * TASK_SIZE - the maximum size of a user space task. @@ -49,7 +55,8 @@ */ #define VA_BITS (CONFIG_ARM64_VA_BITS) #define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1)) -#define MODULES_END (PAGE_OFFSET) +#define KIMAGE_VADDR (PAGE_OFFSET - KIMAGE_OFFSET) +#define MODULES_END KIMAGE_VADDR #define MODULES_VADDR (MODULES_END - SZ_64M) #define PCI_IO_END (MODULES_VADDR - SZ_2M) #define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE) @@ -77,7 +84,11 @@ * private definitions which should NOT be used outside memory.h * files. Use virt_to_phys/phys_to_virt/__pa/__va instead. */ -#define __virt_to_phys(x) (((phys_addr_t)(x) - PAGE_OFFSET + PHYS_OFFSET)) +#define __virt_to_phys(x) ({ \ + long __x = (long)(x) - PAGE_OFFSET; \ + __x >= 0 ? (phys_addr_t)(__x + PHYS_OFFSET) : \ + (phys_addr_t)(__x + PHYS_OFFSET + kernel_va_offset); }) + #define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET + PAGE_OFFSET)) /* @@ -113,6 +124,8 @@ extern phys_addr_t memstart_addr; /* PHYS_OFFSET - the physical address of the start of memory. */ #define PHYS_OFFSET ({ memstart_addr; }) +extern u64 kernel_va_offset; + /* * PFNs are used to describe any physical page; this means * PFN 0 == physical address 0. diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index c0ff3ce4299e..3050a4066db9 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -36,8 +36,6 @@ #include #include -#define __PHYS_OFFSET (KERNEL_START - TEXT_OFFSET) - #if (TEXT_OFFSET & 0xfff) != 0 #error TEXT_OFFSET must be at least 4KB aligned #elif (PAGE_OFFSET & 0x1fffff) != 0 @@ -58,6 +56,8 @@ #define KERNEL_START _text #define KERNEL_END _end +#define KERNEL_BASE (KERNEL_START - TEXT_OFFSET) + /* * Initial memory map attributes. @@ -235,7 +235,15 @@ section_table: ENTRY(stext) bl preserve_boot_args bl el2_setup // Drop to EL1, w20=cpu_boot_mode - adrp x24, __PHYS_OFFSET + + /* + * Before the linear mapping has been set up, __va() translations will + * not produce usable virtual addresses unless we tweak PHYS_OFFSET to + * compensate for the offset between the kernel mapping and the base of + * the linear mapping. We will undo this in map_mem(). + */ + adrp x24, KERNEL_BASE + KIMAGE_OFFSET + bl set_cpu_boot_mode_flag bl __create_page_tables // x25=TTBR0, x26=TTBR1 /* @@ -411,10 +419,10 @@ __create_page_tables: * Map the kernel image (starting with PHYS_OFFSET). */ mov x0, x26 // swapper_pg_dir - mov x5, #PAGE_OFFSET + ldr x5, =KERNEL_BASE create_pgd_entry x0, x5, x3, x6 ldr x6, =KERNEL_END // __va(KERNEL_END) - mov x3, x24 // phys offset + adrp x3, KERNEL_BASE // real PHYS_OFFSET create_block_map x0, x7, x3, x5, x6 /* diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 0b82c4c203fb..1f6d79eeda06 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -6,6 +6,7 @@ #include #include +#include #include #include #include @@ -96,7 +97,7 @@ SECTIONS *(.discard.*) } - . = PAGE_OFFSET + TEXT_OFFSET; + . = KIMAGE_VADDR + TEXT_OFFSET; .head.text : { _text = .; @@ -204,4 +205,10 @@ ASSERT(SIZEOF(.pgdir) <= ALIGNOF(.pgdir), ".pgdir size exceeds its alignment") /* * If padding is applied before .head.text, virt<->phys conversions will fail. */ -ASSERT(_text == (PAGE_OFFSET + TEXT_OFFSET), "HEAD is misaligned") +ASSERT(_text == (KIMAGE_VADDR + TEXT_OFFSET), "HEAD is misaligned") + +/* + * Make sure the memory footprint of the kernel Image does not exceed the limit. + */ +ASSERT(_end - _text + TEXT_OFFSET <= MAX_KIMG_SIZE, + "Kernel Image memory footprint exceeds MAX_KIMG_SIZE") diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 373ea02bdb96..3909a5fe7d7c 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -164,9 +164,10 @@ void __init arm64_memblock_init(void) * with the linear mapping. */ const s64 linear_region_size = -(s64)PAGE_OFFSET; + u64 dram_base = memstart_addr - KIMAGE_OFFSET; - memblock_remove(0, memstart_addr); - memblock_remove(memstart_addr + linear_region_size, ULLONG_MAX); + memblock_remove(0, dram_base); + memblock_remove(dram_base + linear_region_size, ULLONG_MAX); memblock_enforce_memory_limit(memory_limit); diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 32ce481d90bf..c5c8d0f886e9 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -50,6 +50,8 @@ u64 idmap_t0sz = TCR_T0SZ(VA_BITS); struct page *empty_zero_page; EXPORT_SYMBOL(empty_zero_page); +u64 kernel_va_offset __read_mostly; + pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { @@ -436,6 +438,9 @@ static unsigned long __init bootstrap_region(struct bootstrap_pgtables *reg, * Bootstrap the linear ranges that cover the start of DRAM and swapper_pg_dir * so that the statically allocated page tables as well as newly allocated ones * are accessible via the linear mapping. + * Since@this point, PHYS_OFFSET is still biased to redirect __va() + * translations into the kernel text mapping, we need to apply an + * explicit va_offset to calculate linear virtual addresses. */ static void __init bootstrap_linear_mapping(unsigned long va_offset) { @@ -465,7 +470,10 @@ static void __init map_mem(void) { struct memblock_region *reg; - bootstrap_linear_mapping(0); + bootstrap_linear_mapping(KIMAGE_OFFSET); + + kernel_va_offset = KIMAGE_OFFSET; + memstart_addr -= KIMAGE_OFFSET; /* map all the memory banks */ for_each_memblock(memory, reg) { -- 1.9.1