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Diffstat (limited to 'mini-os/entry.S')
| -rw-r--r-- | mini-os/entry.S | 348 |
1 files changed, 348 insertions, 0 deletions
diff --git a/mini-os/entry.S b/mini-os/entry.S new file mode 100644 index 0000000000..a5a86543b0 --- /dev/null +++ b/mini-os/entry.S @@ -0,0 +1,348 @@ +/* + * linux/arch/i386/entry.S + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * Adjusted for XenoLinux use by K A Frasier + * Adjusted for Xen minimal os by R Neugebauer + */ + + +#include <os.h> + +EBX = 0x00 +ECX = 0x04 +EDX = 0x08 +ESI = 0x0C +EDI = 0x10 +EBP = 0x14 +EAX = 0x18 +DS = 0x1C +ES = 0x20 +ORIG_EAX = 0x24 +EIP = 0x28 +CS = 0x2C +EFLAGS = 0x30 +OLDESP = 0x34 +OLDSS = 0x38 + +CF_MASK = 0x00000001 +IF_MASK = 0x00000200 +NT_MASK = 0x00004000 + +/* Declare a globally-visible label */ +#define ENTRY(X) .globl X ; X : + +/* A Linux hangover. Just ignore it. */ +#define SYMBOL_NAME(X) X + +#define SAVE_ALL \ + cld; \ + pushl %es; \ + pushl %ds; \ + pushl %eax; \ + pushl %ebp; \ + pushl %edi; \ + pushl %esi; \ + pushl %edx; \ + pushl %ecx; \ + pushl %ebx; \ + movl $(__KERNEL_DS),%edx; \ + movl %edx,%ds; \ + movl %edx,%es; + +#define RESTORE_ALL \ + popl %ebx; \ + popl %ecx; \ + popl %edx; \ + popl %esi; \ + popl %edi; \ + popl %ebp; \ + popl %eax; \ +1: popl %ds; \ +2: popl %es; \ + addl $4,%esp; \ +3: iret; \ +.section .fixup,"ax"; \ +4: movl $0,(%esp); \ + jmp 1b; \ +5: movl $0,(%esp); \ + jmp 2b; \ +6: pushl %ss; \ + popl %ds; \ + pushl %ss; \ + popl %es; \ + pushl $11; \ + call do_exit; \ +.previous; \ +.section __ex_table,"a";\ + .align 4; \ + .long 1b,4b; \ + .long 2b,5b; \ + .long 3b,6b; \ +.previous + +ENTRY(divide_error) + pushl $0 # no error code + pushl $ SYMBOL_NAME(do_divide_error) + .align 4 +error_code: + pushl %ds + pushl %eax + xorl %eax,%eax + pushl %ebp + pushl %edi + pushl %esi + pushl %edx + decl %eax # eax = -1 + pushl %ecx + pushl %ebx + cld + movl %es,%ecx + movl ORIG_EAX(%esp), %esi # get the error code + movl ES(%esp), %edi # get the function address + movl %eax, ORIG_EAX(%esp) + movl %ecx, ES(%esp) + movl %esp,%edx + pushl %esi # push the error code + pushl %edx # push the pt_regs pointer + movl $(__KERNEL_DS),%edx + movl %edx,%ds + movl %edx,%es + call *%edi + addl $8,%esp + +# These are the tests Linux makes before exiting the OS back to userland. +# At these point preeemption may occur, or signals may get delivered. +ret_to_user_tests: +# cmpl $0,need_resched(%ebx) +# jne reschedule +# cmpl $0,sigpending(%ebx) +# je safesti + jmp safesti + + +ret_from_exception: + movb CS(%esp),%cl + test $2,%cl # slow return to ring 2 or 3 + jne ret_to_user_tests + RESTORE_ALL + +# A note on the "critical region" in our callback handler. +# We want to avoid stacking callback handlers due to events occurring +# during handling of the last event. To do this, we keep events disabled +# until weve done all processing. HOWEVER, we must enable events before +# popping the stack frame (cant be done atomically) and so it would still +# be possible to get enough handler activations to overflow the stack. +# Although unlikely, bugs of that kind are hard to track down, so wed +# like to avoid the possibility. +# So, on entry to the handler we detect whether we interrupted an +# existing activation in its critical region -- if so, we pop the current +# activation and restart the handler using the previous one. +ENTRY(hypervisor_callback) + pushl %eax + SAVE_ALL + movl EIP(%esp),%eax + cmpl $scrit,%eax + jb 11f + cmpl $ecrit,%eax + jb critical_region_fixup +11: push %esp + call do_hypervisor_callback + add $4,%esp + movl SYMBOL_NAME(HYPERVISOR_shared_info),%esi + xorl %eax,%eax + movb CS(%esp),%cl + test $2,%cl # slow return to ring 2 or 3 + jne ret_to_user_tests +safesti:btsl $31,4(%esi) # reenable event callbacks +scrit: /**** START OF CRITICAL REGION ****/ + cmpl %eax,(%esi) + jne 14f # process more events if necessary... + RESTORE_ALL +14: btrl %eax,4(%esi) + jmp 11b +ecrit: /**** END OF CRITICAL REGION ****/ +# [How we do the fixup]. We want to merge the current stack frame with the +# just-interrupted frame. How we do this depends on where in the critical +# region the interrupted handler was executing, and so how many saved +# registers are in each frame. We do this quickly using the lookup table +# 'critical_fixup_table'. For each byte offset in the critical region, it +# provides the number of bytes which have already been popped from the +# interrupted stack frame. +critical_region_fixup: + addl $critical_fixup_table-scrit,%eax + movzbl (%eax),%eax # %eax contains num bytes popped + mov %esp,%esi + add %eax,%esi # %esi points at end of src region + mov %esp,%edi + add $0x34,%edi # %edi points at end of dst region + mov %eax,%ecx + shr $2,%ecx # convert words to bytes + je 16f # skip loop if nothing to copy +15: subl $4,%esi # pre-decrementing copy loop + subl $4,%edi + movl (%esi),%eax + movl %eax,(%edi) + loop 15b +16: movl %edi,%esp # final %edi is top of merged stack + jmp 11b + +critical_fixup_table: + .byte 0x00,0x00 # cmpl %eax,(%esi) + .byte 0x00,0x00 # jne 14f + .byte 0x00 # pop %ebx + .byte 0x04 # pop %ecx + .byte 0x08 # pop %edx + .byte 0x0c # pop %esi + .byte 0x10 # pop %edi + .byte 0x14 # pop %ebp + .byte 0x18 # pop %eax + .byte 0x1c # pop %ds + .byte 0x20 # pop %es + .byte 0x24,0x24,0x24 # add $4,%esp + .byte 0x28 # iret + .byte 0x00,0x00,0x00,0x00,0x00 # btrl $31,4(%esi) + .byte 0x00,0x00 # jmp 11b + +# Hypervisor uses this for application faults while it executes. +ENTRY(failsafe_callback) +1: pop %ds +2: pop %es +3: pop %fs +4: pop %gs +5: iret +.section .fixup,"ax"; \ +6: movl $0,(%esp); \ + jmp 1b; \ +7: movl $0,(%esp); \ + jmp 2b; \ +8: movl $0,(%esp); \ + jmp 3b; \ +9: movl $0,(%esp); \ + jmp 4b; \ +10: pushl %ss; \ + popl %ds; \ + pushl %ss; \ + popl %es; \ + pushl $11; \ + call do_exit; \ +.previous; \ +.section __ex_table,"a";\ + .align 4; \ + .long 1b,6b; \ + .long 2b,7b; \ + .long 3b,8b; \ + .long 4b,9b; \ + .long 5b,10b; \ +.previous + +ENTRY(coprocessor_error) + pushl $0 + pushl $ SYMBOL_NAME(do_coprocessor_error) + jmp error_code + +ENTRY(simd_coprocessor_error) + pushl $0 + pushl $ SYMBOL_NAME(do_simd_coprocessor_error) + jmp error_code + +ENTRY(device_not_available) + pushl $-1 # mark this as an int + SAVE_ALL + #call SYMBOL_NAME(math_state_restore) + jmp ret_from_exception + +ENTRY(debug) + pushl $0 + pushl $ SYMBOL_NAME(do_debug) + jmp error_code + +ENTRY(int3) + pushl $0 + pushl $ SYMBOL_NAME(do_int3) + jmp error_code + +ENTRY(overflow) + pushl $0 + pushl $ SYMBOL_NAME(do_overflow) + jmp error_code + +ENTRY(bounds) + pushl $0 + pushl $ SYMBOL_NAME(do_bounds) + jmp error_code + +ENTRY(invalid_op) + pushl $0 + pushl $ SYMBOL_NAME(do_invalid_op) + jmp error_code + +ENTRY(coprocessor_segment_overrun) + pushl $0 + pushl $ SYMBOL_NAME(do_coprocessor_segment_overrun) + jmp error_code + +ENTRY(double_fault) + pushl $ SYMBOL_NAME(do_double_fault) + jmp error_code + +ENTRY(invalid_TSS) + pushl $ SYMBOL_NAME(do_invalid_TSS) + jmp error_code + +ENTRY(segment_not_present) + pushl $ SYMBOL_NAME(do_segment_not_present) + jmp error_code + +ENTRY(stack_segment) + pushl $ SYMBOL_NAME(do_stack_segment) + jmp error_code + +ENTRY(general_protection) + pushl $ SYMBOL_NAME(do_general_protection) + jmp error_code + +ENTRY(alignment_check) + pushl $ SYMBOL_NAME(do_alignment_check) + jmp error_code + +# This handler is special, because it gets an extra value on its stack, +# which is the linear faulting address. +ENTRY(page_fault) + pushl %ds + pushl %eax + xorl %eax,%eax + pushl %ebp + pushl %edi + pushl %esi + pushl %edx + decl %eax # eax = -1 + pushl %ecx + pushl %ebx + cld + movl %es,%ecx + movl ORIG_EAX(%esp), %esi # get the error code + movl ES(%esp), %edi # get the faulting address + movl %eax, ORIG_EAX(%esp) + movl %ecx, ES(%esp) + movl %esp,%edx + pushl %edi # push the faulting address + pushl %esi # push the error code + pushl %edx # push the pt_regs pointer + movl $(__KERNEL_DS),%edx + movl %edx,%ds + movl %edx,%es + call SYMBOL_NAME(do_page_fault) + addl $12,%esp + jmp ret_from_exception + +ENTRY(machine_check) + pushl $0 + pushl $ SYMBOL_NAME(do_machine_check) + jmp error_code + +ENTRY(spurious_interrupt_bug) + pushl $0 + pushl $ SYMBOL_NAME(do_spurious_interrupt_bug) + jmp error_code |