diff options
Diffstat (limited to 'payloads/libpayload/arch/x86/exception_asm.S')
| -rw-r--r-- | payloads/libpayload/arch/x86/exception_asm.S | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/payloads/libpayload/arch/x86/exception_asm.S b/payloads/libpayload/arch/x86/exception_asm.S new file mode 100644 index 0000000000..c56a7a0bab --- /dev/null +++ b/payloads/libpayload/arch/x86/exception_asm.S @@ -0,0 +1,291 @@ +/* + * This file is part of the libpayload project. + * + * Copyright 2013 Google Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. 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. + * 3. 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. + */ + + .align 4 + .global exception_stack_end +exception_stack_end: + .long 0 + +/* Some temporary variables which are used while saving exception state. */ +vector: + .long 0 +error_code: + .long 0 +old_esp: + .long 0 +old_eax: + .long 0 + + .align 8 + +/* + * Each exception vector has a small stub associated with it which sets aside + * the error code, if any, records which vector we entered from, and calls + * the common exception entry point. Some exceptions have error codes and some + * don't, so we have a macro for each type. + */ + + .macro stub num +exception_stub_\num: + movl $0, error_code + movl $\num, vector + jmp exception_common + .endm + + .macro stub_err num +exception_stub_\num: + popl error_code + movl $\num, vector + jmp exception_common + .endm + + stub 0 + stub 1 + stub 2 + stub 3 + stub 4 + stub 5 + stub 6 + stub 7 + stub_err 8 + stub 9 + stub_err 10 + stub_err 11 + stub_err 12 + stub_err 13 + stub_err 14 + stub 15 + stub 16 + stub_err 17 + stub 18 + stub 19 + stub 20 + stub 21 + stub 22 + stub 23 + stub 24 + stub 25 + stub 26 + stub 27 + stub 28 + stub 29 + stub_err 30 + stub 31 + +exception_common: + /* + * Save off the stack pointer and old eax value and install the + * exception stack. eax points to the old stack which has the + * exception ip, cs, and flags. + */ + mov %esp, old_esp + addl $12, old_esp + mov %eax, old_eax + mov %esp, %eax + mov exception_stack_end, %esp + + /* + * Push values onto the top of the exception stack to form an + * exception state structure. + */ + pushl vector + pushl error_code + pushl %gs + pushl %fs + pushl %es + pushl %ds + pushl %ss + pushl 4(%eax) + pushl 8(%eax) + pushl (%eax) + pushl %edi + pushl %esi + pushl %ebp + pushl old_esp + pushl %ebx + pushl %edx + pushl %ecx + pushl old_eax + + /* + * Call the C exception handler. It will find the exception state on + * the exception stack. Not passing parameters means we don't have to + * worry about what ABI is being used. + */ + call exception_handler + + /* + * Restore state from the exception state structure, including any + * changes that might have been made. + */ + popl old_eax + popl %ecx + popl %edx + popl %ebx + popl old_esp + + mov old_esp, %eax + subl $12, %eax + + popl %ebp + popl %esi + popl %edi + popl (%eax) + popl 8(%eax) + popl 4(%eax) + popl %ss + popl %ds + popl %es + popl %fs + popl %gs + + mov %eax, %esp + mov old_eax, %eax + + /* Return from the exception. */ + iretl + +/* + * We need segment selectors for the IDT, so we need to know where things are + * in the GDT. We set one up here which is pretty standard and largely copied + * from coreboot. + */ + .align 8 +gdt: + /* selgdt 0, unused */ + .word 0x0000, 0x0000 + .byte 0x00, 0x00, 0x00, 0x00 + + /* selgdt 8, unused */ + .word 0x0000, 0x0000 + .byte 0x00, 0x00, 0x00, 0x00 + + /* selgdt 0x10, flat 4GB code segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x9b, 0xcf, 0x00 + + /* selgdt 0x18, flat 4GB data segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x93, 0xcf, 0x00 +gdt_end: + +/* GDT pointer for use with lgdt */ +gdt_ptr: + .word gdt_end - gdt - 1 + .long gdt + + /* + * Record the target and construct the actual entry at init time. This + * is necessary because the linker doesn't want to construct the entry + * for us. + */ + .macro interrupt_gate target + .long \target + .long \target + .endm + + .align 8 + .global idt +idt: + interrupt_gate exception_stub_0 + interrupt_gate exception_stub_1 + interrupt_gate exception_stub_2 + interrupt_gate exception_stub_3 + interrupt_gate exception_stub_4 + interrupt_gate exception_stub_5 + interrupt_gate exception_stub_6 + interrupt_gate exception_stub_7 + interrupt_gate exception_stub_8 + interrupt_gate exception_stub_9 + interrupt_gate exception_stub_10 + interrupt_gate exception_stub_11 + interrupt_gate exception_stub_12 + interrupt_gate exception_stub_13 + interrupt_gate exception_stub_14 + interrupt_gate exception_stub_15 + interrupt_gate exception_stub_16 + interrupt_gate exception_stub_17 + interrupt_gate exception_stub_18 + interrupt_gate exception_stub_19 + interrupt_gate exception_stub_20 + interrupt_gate exception_stub_21 + interrupt_gate exception_stub_22 + interrupt_gate exception_stub_23 + interrupt_gate exception_stub_24 + interrupt_gate exception_stub_25 + interrupt_gate exception_stub_26 + interrupt_gate exception_stub_27 + interrupt_gate exception_stub_28 + interrupt_gate exception_stub_29 + interrupt_gate exception_stub_30 + interrupt_gate exception_stub_31 +idt_end: + +/* IDT pointer for use with lidt */ +idt_ptr: + .word idt_end - idt - 1 + .long idt + + .global exception_init_asm +exception_init_asm: + /* Save eax so we can use it as a temporary variable. */ + pushl %eax + + /* Install the GDT. */ + lgdt gdt_ptr + /* Load the segment registers from it. */ + ljmp $0x10, $1f +1: movl $0x18, %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %ss + movl %eax, %fs + movl %eax, %gs + + /* + * Loop over the entries which start out as two copies of the target + * address. We can turn them into real interrupt gates by selectively + * replacing certain bit fields. + */ + movl $idt, %eax +1: + andl $0x0000ffff, (%eax) + orl $0x00100000, (%eax) + andl $0xffff0000, 4(%eax) + orl $0x0000ee00, 4(%eax) + addl $8, %eax + cmp $idt_end, %eax + jne 1b + + /* Install the IDT. */ + lidt idt_ptr + + /* Restore eax and return to the caller. */ + popl %eax + ret |