--- /dev/null
+/*
+ * linux/boot/head.S
+ *
+ * Copyright (C) 1991, 1992, 1993 Linus Torvalds
+ */
+
+/*
+ * head.S contains the 32-bit startup code.
+ *
+ * NOTE!!! Startup happens at absolute address 0x00001000, which is also where
+ * the page directory will exist. The startup code will be overwritten by
+ * the page directory. [According to comments etc elsewhere on a compressed
+ * kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
+ *
+ * Page 0 is deliberately kept safe, since System Management Mode code in
+ * laptops may need to access the BIOS data stored there. This is also
+ * useful for future device drivers that either access the BIOS via VM86
+ * mode.
+ */
+
+/*
+ * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
+ */
+ .text
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/page_types.h>
+#include <asm/boot.h>
+#include <asm/asm-offsets.h>
+#include <asm/bootparam.h>
+
+ __HEAD
+ENTRY(startup_32)
+#ifdef CONFIG_EFI_STUB
+ jmp preferred_addr
+
+ /*
+ * We don't need the return address, so set up the stack so
+ * efi_main() can find its arguments.
+ */
+ENTRY(efi_pe_entry)
+ add $0x4, %esp
+
+ call 1f
+1: popl %esi
+ subl $1b, %esi
+
+ popl %ecx
+ movl %ecx, efi32_config(%esi) /* Handle */
+ popl %ecx
+ movl %ecx, efi32_config+8(%esi) /* EFI System table pointer */
+
+ /* Relocate efi_config->call() */
+ leal efi32_config(%esi), %eax
+ add %esi, 88(%eax)
+ pushl %eax
+
+ call make_boot_params
+ cmpl $0, %eax
+ je fail
+ movl %esi, BP_code32_start(%eax)
+ popl %ecx
+ pushl %eax
+ pushl %ecx
+ jmp 2f /* Skip efi_config initialization */
+
+ENTRY(efi32_stub_entry)
+ add $0x4, %esp
+ popl %ecx
+ popl %edx
+
+ call 1f
+1: popl %esi
+ subl $1b, %esi
+
+ movl %ecx, efi32_config(%esi) /* Handle */
+ movl %edx, efi32_config+8(%esi) /* EFI System table pointer */
+
+ /* Relocate efi_config->call() */
+ leal efi32_config(%esi), %eax
+ add %esi, 88(%eax)
+ pushl %eax
+2:
+ call efi_main
+ cmpl $0, %eax
+ movl %eax, %esi
+ jne 2f
+fail:
+ /* EFI init failed, so hang. */
+ hlt
+ jmp fail
+2:
+ movl BP_code32_start(%esi), %eax
+ leal preferred_addr(%eax), %eax
+ jmp *%eax
+
+preferred_addr:
+#endif
+ cld
+ /*
+ * Test KEEP_SEGMENTS flag to see if the bootloader is asking
+ * us to not reload segments
+ */
+ testb $KEEP_SEGMENTS, BP_loadflags(%esi)
+ jnz 1f
+
+ cli
+ movl $__BOOT_DS, %eax
+ movl %eax, %ds
+ movl %eax, %es
+ movl %eax, %fs
+ movl %eax, %gs
+ movl %eax, %ss
+1:
+
+/*
+ * Calculate the delta between where we were compiled to run
+ * at and where we were actually loaded at. This can only be done
+ * with a short local call on x86. Nothing else will tell us what
+ * address we are running at. The reserved chunk of the real-mode
+ * data at 0x1e4 (defined as a scratch field) are used as the stack
+ * for this calculation. Only 4 bytes are needed.
+ */
+ leal (BP_scratch+4)(%esi), %esp
+ call 1f
+1: popl %ebp
+ subl $1b, %ebp
+
+/*
+ * %ebp contains the address we are loaded at by the boot loader and %ebx
+ * contains the address where we should move the kernel image temporarily
+ * for safe in-place decompression.
+ */
+
+#ifdef CONFIG_RELOCATABLE
+ movl %ebp, %ebx
+ movl BP_kernel_alignment(%esi), %eax
+ decl %eax
+ addl %eax, %ebx
+ notl %eax
+ andl %eax, %ebx
+ cmpl $LOAD_PHYSICAL_ADDR, %ebx
+ jge 1f
+#endif
+ movl $LOAD_PHYSICAL_ADDR, %ebx
+1:
+
+ /* Target address to relocate to for decompression */
+ addl $z_extract_offset, %ebx
+
+ /* Set up the stack */
+ leal boot_stack_end(%ebx), %esp
+
+ /* Zero EFLAGS */
+ pushl $0
+ popfl
+
+/*
+ * Copy the compressed kernel to the end of our buffer
+ * where decompression in place becomes safe.
+ */
+ pushl %esi
+ leal (_bss-4)(%ebp), %esi
+ leal (_bss-4)(%ebx), %edi
+ movl $(_bss - startup_32), %ecx
+ shrl $2, %ecx
+ std
+ rep movsl
+ cld
+ popl %esi
+
+/*
+ * Jump to the relocated address.
+ */
+ leal relocated(%ebx), %eax
+ jmp *%eax
+ENDPROC(startup_32)
+
+ .text
+relocated:
+
+/*
+ * Clear BSS (stack is currently empty)
+ */
+ xorl %eax, %eax
+ leal _bss(%ebx), %edi
+ leal _ebss(%ebx), %ecx
+ subl %edi, %ecx
+ shrl $2, %ecx
+ rep stosl
+
+/*
+ * Adjust our own GOT
+ */
+ leal _got(%ebx), %edx
+ leal _egot(%ebx), %ecx
+1:
+ cmpl %ecx, %edx
+ jae 2f
+ addl %ebx, (%edx)
+ addl $4, %edx
+ jmp 1b
+2:
+
+/*
+ * Do the decompression, and jump to the new kernel..
+ */
+ /* push arguments for decompress_kernel: */
+ pushl $z_run_size /* size of kernel with .bss and .brk */
+ pushl $z_output_len /* decompressed length, end of relocs */
+ leal z_extract_offset_negative(%ebx), %ebp
+ pushl %ebp /* output address */
+ pushl $z_input_len /* input_len */
+ leal input_data(%ebx), %eax
+ pushl %eax /* input_data */
+ leal boot_heap(%ebx), %eax
+ pushl %eax /* heap area */
+ pushl %esi /* real mode pointer */
+ call decompress_kernel /* returns kernel location in %eax */
+ addl $28, %esp
+
+/*
+ * Jump to the decompressed kernel.
+ */
+ xorl %ebx, %ebx
+ jmp *%eax
+
+#ifdef CONFIG_EFI_STUB
+ .data
+efi32_config:
+ .fill 11,8,0
+ .long efi_call_phys
+ .long 0
+ .byte 0
+#endif
+
+/*
+ * Stack and heap for uncompression
+ */
+ .bss
+ .balign 4
+boot_heap:
+ .fill BOOT_HEAP_SIZE, 1, 0
+boot_stack:
+ .fill BOOT_STACK_SIZE, 1, 0
+boot_stack_end:
Code Review / kvmfornfv.git / blobdiff