Index: boot/Makefile.common =================================================================== --- boot/Makefile.common (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/Makefile.common (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -250,5 +250,5 @@ COMPONENTS = \ - $(KERNEL_PATH)/kernel.bin \ + $(KERNEL_PATH)/kernel.elf \ $(INIT_TASKS) \ $(INITRD).img Index: boot/Makefile.grub =================================================================== --- boot/Makefile.grub (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/Makefile.grub (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -85,5 +85,5 @@ for module in $(MODULES) ; do \ echo " echo 'Loading $$module'" >> $(BOOT_CONFIG) ; \ - if [ "$$module" = "kernel.bin" ] ; then \ + if [ "$$module" = "kernel.elf" ] ; then \ echo " $(MULTIBOOT_CMD) /boot/$$module" >> $(BOOT_CONFIG) ; \ else \ Index: boot/arch/arm32/Makefile.inc =================================================================== --- boot/arch/arm32/Makefile.inc (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/arm32/Makefile.inc (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -107,3 +107,4 @@ generic/src/gzip.c \ generic/src/tar.c \ + generic/src/kernel.c \ generic/src/payload.c Index: boot/arch/arm32/src/main.c =================================================================== --- boot/arch/arm32/src/main.c (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/arm32/src/main.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -50,4 +50,5 @@ #include #include +#include static void clean_dcache_poc(void *address, size_t size) @@ -104,6 +105,8 @@ clean_dcache_poc(boot_pt, PTL0_ENTRIES * PTL0_ENTRY_SIZE); + uintptr_t entry = check_kernel((void *) PA2KA(BOOT_OFFSET)); + printf("Booting the kernel...\n"); - jump_to_kernel((void *) PA2KA(BOOT_OFFSET), &bootinfo); + jump_to_kernel((void *) entry, &bootinfo); } Index: boot/arch/ia64/Makefile.inc =================================================================== --- boot/arch/ia64/Makefile.inc (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/ia64/Makefile.inc (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -61,4 +61,5 @@ generic/src/tar.c \ generic/src/gzip.c \ + generic/src/kernel.c \ generic/src/payload.c Index: boot/arch/ia64/include/arch/arch.h =================================================================== --- boot/arch/ia64/include/arch/arch.h (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/ia64/include/arch/arch.h (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -36,4 +36,5 @@ #define LOADER_ADDRESS 0x4400000 #define KERNEL_ADDRESS 0x4800000 +#define KERNEL_VADDRESS 0xe000000004800000 #define STACK_SIZE 8192 Index: boot/arch/ia64/src/main.c =================================================================== --- boot/arch/ia64/src/main.c (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/ia64/src/main.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -44,4 +44,5 @@ #include #include +#include #define DEFAULT_MEMORY_BASE 0x4000000ULL @@ -182,5 +183,11 @@ (uintptr_t) kernel_start, NULL); - printf("Booting the kernel ...\n"); - jump_to_kernel(&bootinfo, kernel_start); + uintptr_t entry = check_kernel(kernel_start); + + // FIXME: kernel's entry point is linked at a different address than + // where it is run from. + entry = entry - KERNEL_VADDRESS + KERNEL_ADDRESS; + + printf("Booting the kernel at %p...\n", (void *) entry); + jump_to_kernel(&bootinfo, (void *) entry); } Index: boot/arch/mips32/Makefile.inc =================================================================== --- boot/arch/mips32/Makefile.inc (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/mips32/Makefile.inc (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -88,3 +88,4 @@ generic/src/gzip.c \ generic/src/tar.c \ + generic/src/kernel.c \ generic/src/payload.c Index: boot/arch/mips32/src/main.c =================================================================== --- boot/arch/mips32/src/main.c (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/mips32/src/main.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -40,4 +40,5 @@ #include #include +#include static bootinfo_t *bootinfo = (bootinfo_t *) PA2KA(BOOTINFO_OFFSET); @@ -78,5 +79,7 @@ } - printf("Booting the kernel ... \n"); - jump_to_kernel((void *) PA2KA(BOOT_OFFSET), bootinfo); + uintptr_t entry = check_kernel(kernel_start); + + printf("Booting the kernel...\n"); + jump_to_kernel((void *) entry, bootinfo); } Index: boot/arch/ppc32/Makefile.inc =================================================================== --- boot/arch/ppc32/Makefile.inc (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/ppc32/Makefile.inc (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -76,3 +76,4 @@ generic/src/gzip.c \ generic/src/tar.c \ + generic/src/kernel.c \ generic/src/payload.c Index: boot/arch/ppc32/_link.ld.in =================================================================== --- boot/arch/ppc32/_link.ld.in (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/ppc32/_link.ld.in (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -6,5 +6,4 @@ loader_start = .; *(BOOTSTRAP); - *(REALMODE); *(.text); } Index: boot/arch/ppc32/src/asm.S =================================================================== --- boot/arch/ppc32/src/asm.S (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/ppc32/src/asm.S (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -152,7 +152,4 @@ FUNCTION_END(jump_to_kernel) -.section REALMODE, "ax" - -.align PAGE_WIDTH SYMBOL(real_mode) Index: boot/arch/ppc32/src/main.c =================================================================== --- boot/arch/ppc32/src/main.c (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/ppc32/src/main.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -42,4 +42,5 @@ #include #include +#include #define BALLOC_MAX_SIZE 131072 @@ -68,6 +69,4 @@ printf(" %p|%p: real mode trampoline\n", &real_mode, real_mode_pa); printf(" %p|%p: boot info structure\n", &bootinfo, bootinfo_pa); - printf(" %p|%p: kernel entry point\n", - (void *) PA2KA(BOOT_OFFSET), (void *) BOOT_OFFSET); printf(" %p|%p: loader entry point\n", (void *) LOADER_ADDRESS, loader_address_pa); @@ -144,6 +143,7 @@ } + uintptr_t entry = check_kernel_translated(inflate_base, 0); + printf("Booting the kernel...\n"); - jump_to_kernel(bootinfo_pa, transtable_pa, pages, real_mode_pa, - PA2KA(BOOT_OFFSET)); + jump_to_kernel(bootinfo_pa, transtable_pa, pages, real_mode_pa, entry); } Index: boot/arch/riscv64/Makefile.inc =================================================================== --- boot/arch/riscv64/Makefile.inc (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/riscv64/Makefile.inc (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -30,5 +30,4 @@ BFD_OUTPUT = $(BFD_NAME) BFD_ARCH = riscv -BFD = binary BITS = 64 @@ -51,3 +50,4 @@ generic/src/gzip.c \ generic/src/tar.c \ + generic/src/kernel.c \ generic/src/payload.c Index: boot/arch/riscv64/include/arch/asm.h =================================================================== --- boot/arch/riscv64/include/arch/asm.h (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/riscv64/include/arch/asm.h (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -36,5 +36,5 @@ extern char pt_page[]; -extern _Noreturn void jump_to_kernel(uintptr_t); +extern _Noreturn void jump_to_kernel(uintptr_t, uintptr_t); #endif Index: boot/arch/riscv64/src/asm.S =================================================================== --- boot/arch/riscv64/src/asm.S (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/riscv64/src/asm.S (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -125,5 +125,6 @@ csrw mstatus, t0 - li ra, PA2KA(BOOT_OFFSET) + /* Entry point address is in a1. */ + mv ra, a1 csrw mepc, ra Index: boot/arch/riscv64/src/main.c =================================================================== --- boot/arch/riscv64/src/main.c (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/riscv64/src/main.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -42,4 +42,5 @@ #include #include +#include static bootinfo_t bootinfo; @@ -88,5 +89,7 @@ extract_payload(&bootinfo.taskmap, load_addr, end, kernel_addr, NULL); + uintptr_t entry = check_kernel(load_addr); + printf("Booting the kernel...\n"); - jump_to_kernel(PA2KA(&bootinfo)); + jump_to_kernel(PA2KA(&bootinfo), entry); } Index: boot/arch/sparc64/Makefile.inc =================================================================== --- boot/arch/sparc64/Makefile.inc (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/sparc64/Makefile.inc (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -72,3 +72,4 @@ generic/src/gzip.c \ generic/src/tar.c \ + generic/src/kernel.c \ generic/src/payload.c Index: boot/arch/sparc64/src/main.c =================================================================== --- boot/arch/sparc64/src/main.c (revision d59718e246e2f30ad97e0364fac7e75455fcb7d1) +++ boot/arch/sparc64/src/main.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -43,4 +43,5 @@ #include #include +#include /* The lowest ID (read from the VER register) of some US3 CPU model */ @@ -257,6 +258,8 @@ sun4u_smp(); + uintptr_t entry = check_kernel((void *) KERNEL_ADDRESS); + printf("Booting the kernel ...\n"); - jump_to_kernel(bootinfo.physmem_start | BSP_PROCESSOR, &bootinfo, subarch, - (void *) KERNEL_ADDRESS); -} + jump_to_kernel(bootinfo.physmem_start | BSP_PROCESSOR, &bootinfo, + subarch, (void *) entry); +} Index: boot/generic/include/kernel.h =================================================================== --- boot/generic/include/kernel.h (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) +++ boot/generic/include/kernel.h (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -0,0 +1,37 @@ +/* + * Copyright (c) 2018 Jiří Zárevúcky + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * - The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef BOOT_ELF_H_ +#define BOOT_ELF_H_ + +#include + +uintptr_t check_kernel_translated(void *, uintptr_t); +uintptr_t check_kernel(void *); + +#endif Index: boot/generic/src/kernel.c =================================================================== --- boot/generic/src/kernel.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) +++ boot/generic/src/kernel.c (revision bf05c7451aebfdd5f9d9f9cba5cc3d3190368378) @@ -0,0 +1,162 @@ +/* + * Copyright (c) 2018 Jiří Zárevúcky + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * - The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include +#include +#include +#include +#include + +// FIXME: elf_is_valid is a duplicate of the same-named libc function. + +// TODO: better kernel ELF loading +// +// Currently the boot loader is very primitive. It loads the ELF file as +// a contiguous span starting at a predefined offset, and then checks load +// segments in it to make sure they are correctly positioned. Ideally, this +// should change to a more flexible loader that actually loads based on the +// kernel's ELF segments. There would still be some restrictions however. +// ELF vaddr and paddr fields offer some flexibility in their interpretation, +// so I propose the following scheme, to correctly express everything various +// architectures require: +// +// - in vaddr and paddr fields, addresses numerically in the lower half are +// interpreted as physical addresses, addresses in the upper half are +// interpreted as virtual addresses. +// +// - If vaddr is a virtual address, the segment is mapped into the kernel's +// virtual address space at vaddr. +// +// - If vaddr is a physical address, it must be the same as paddr. +// Loader loads the segment at the given physical address, but does not +// map it into the kernel's virtual address space. Symbols defined in this +// segment are only accessible with paging disabled. +// +// - If paddr is a physical address, the loader must load the segment at +// physical address paddr, or die trying. +// +// - If paddr is a virtual address, it must be the same as vaddr. +// Loader may allocate the physical location arbitrarily. +// +// - If the kernel is a Position Independent Executable, all this is +// irrelevant, paddr must be the same as vaddr, vaddr is always the +// virtual address offset, and loader can choose the virtual address +// base arbitrarily within some predefined constraints. We might want +// to support PIE kernel on architectures that need some code at fixed +// physical address. In that case, the "real mode" code should probably +// be in a separate ELF file from the rest of kernel. +// + +/** + * Checks that the ELF header is valid for the running system. + */ +static bool elf_is_valid(const elf_header_t *header) +{ + // TODO: check more things + // TODO: debug output + + if (header->e_ident[EI_MAG0] != ELFMAG0 || + header->e_ident[EI_MAG1] != ELFMAG1 || + header->e_ident[EI_MAG2] != ELFMAG2 || + header->e_ident[EI_MAG3] != ELFMAG3) { + return false; + } + + if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || + header->e_machine != ELF_MACHINE || + header->e_ident[EI_VERSION] != EV_CURRENT || + header->e_version != EV_CURRENT || + header->e_ident[EI_CLASS] != ELF_CLASS) { + return false; + } + + if (header->e_phentsize != sizeof(elf_segment_header_t)) { + return false; + } + + if (header->e_type != ET_EXEC && header->e_type != ET_DYN) { + return false; + } + + if (header->e_phoff == 0) { + return false; + } + + return true; +} + +uintptr_t check_kernel(void *start) +{ + return check_kernel_translated(start, (uintptr_t) start); +} + +/** + * Checks that the kernel ELF image is valid, and returns the entry point + * address. We check that the image's load addresses match the actual location. + * + * @param start Pointer to the start of the ELF file in memory. + * @param actual_addr Start address where the kernel is moved after the check + * but before it is executed. + * + * @return Entry point address in *kernel's* address space. + */ +uintptr_t check_kernel_translated(void *start, uintptr_t actual_addr) +{ + elf_header_t *header = (elf_header_t *) start; + + if (!elf_is_valid(header)) { + printf("Kernel is not a valid ELF image.\n"); + halt(); + } + + elf_segment_header_t *phdr = + (elf_segment_header_t *) ((uintptr_t) start + header->e_phoff); + + /* Walk through PT_LOAD headers, to find out the size of the module. */ + for (int i = 0; i < header->e_phnum; i++) { + if (phdr[i].p_type != PT_LOAD) + continue; + + uintptr_t expected = actual_addr + phdr[i].p_offset; + uintptr_t got = phdr[i].p_paddr; + if (expected != got) { + printf("Incorrect kernel load address. " + "Expected: %p, got %p\n", + (void *) expected, (void *) got); + halt(); + } + + if (phdr[i].p_filesz != phdr[i].p_memsz) { + printf("Kernel's memory size is greater than its file" + " size. We don't currently support that.\n"); + halt(); + } + } + + return (uintptr_t) header->e_entry; +}