diff options
Diffstat (limited to 'contrib/syslinux-4.02/gpxe/src/arch/i386/core/gdbidt.S')
| -rw-r--r-- | contrib/syslinux-4.02/gpxe/src/arch/i386/core/gdbidt.S | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/arch/i386/core/gdbidt.S b/contrib/syslinux-4.02/gpxe/src/arch/i386/core/gdbidt.S new file mode 100644 index 0000000..cd8b38a --- /dev/null +++ b/contrib/syslinux-4.02/gpxe/src/arch/i386/core/gdbidt.S @@ -0,0 +1,215 @@ +/* + * Interrupt Descriptor Table (IDT) setup and interrupt handlers for GDB stub. + */ + +#include <librm.h> + +#define SIZEOF_I386_REGS 32 +#define SIZEOF_I386_FLAGS 4 + +/**************************************************************************** + * Interrupt Descriptor Table + **************************************************************************** + */ + .section ".data16", "aw", @progbits + .globl idtr +idtr: +idt_limit: + .word idt_length - 1 +idt_base: + .long 0 + +/* IDT entries have the following format: + * offset_lo, segment selector, flags, offset_hi + * + * Since it is not possible to specify relocations in arbitrary + * expressions like (int_overflow & 0xffff), we initialise the + * IDT with entries in an incorrect format. + * + * The entries are shuffled into the correct format in init_librm(). + */ +#define IDT_ENTRY_EMPTY(name) .word 0, 0, 0, 0 +#define IDT_ENTRY_PRESENT(name) \ + .long int_##name; \ + .word 0x8e00, VIRTUAL_CS + +.align 16 +idt: + IDT_ENTRY_PRESENT(divide_error) + IDT_ENTRY_PRESENT(debug_trap) + IDT_ENTRY_EMPTY(non_maskable_interrupt) + IDT_ENTRY_PRESENT(breakpoint) + IDT_ENTRY_PRESENT(overflow) + IDT_ENTRY_PRESENT(bound_range_exceeded) + IDT_ENTRY_PRESENT(invalid_opcode) + IDT_ENTRY_EMPTY(device_not_available) + IDT_ENTRY_PRESENT(double_fault) + IDT_ENTRY_EMPTY(coprocessor_segment_overrun) + IDT_ENTRY_PRESENT(invalid_tss) + IDT_ENTRY_PRESENT(segment_not_present) + IDT_ENTRY_PRESENT(stack_segment_fault) + IDT_ENTRY_PRESENT(general_protection) + IDT_ENTRY_PRESENT(page_fault) +idt_end: + .equ idt_length, idt_end - idt + +/* The IDT entries are fixed up (once) in init_librm() */ +idt_fixed: + .byte 0 + +/**************************************************************************** + * idt_init (real-mode near call, 16-bit real-mode near return address) + * + * Initialise the IDT, called from init_librm. + * + * Parameters: + * %eax : IDT base address + * + * Destroys %ax, %bx, and %di. + **************************************************************************** + */ + .section ".text16", "ax", @progbits + .code16 + .globl idt_init +idt_init: + movl %eax, idt_base + addl $idt, idt_base + + /* IDT entries are only fixed up once */ + movb idt_fixed, %al + orb %al, %al + jnz 2f + movb $1, idt_fixed + + /* Shuffle IDT entries into the correct format */ + movb $(idt_length / 8), %al + movw $idt, %bx + or %al, %al + jz 2f +1: + movw 2(%bx), %di + xchg %di, 6(%bx) + movw %di, 2(%bx) + addw $8, %bx + dec %al + jnz 1b +2: + ret + +/**************************************************************************** + * Interrupt handlers + **************************************************************************** + */ + .section ".text", "ax", @progbits + .code32 + +/* POSIX signal numbers for reporting traps to GDB */ +#define SIGILL 4 +#define SIGTRAP 5 +#define SIGBUS 7 +#define SIGFPE 8 +#define SIGSEGV 11 +#define SIGSTKFLT 16 + +int_divide_error: + pushl $SIGFPE + jmp do_interrupt + +int_debug_trap: +int_breakpoint: + pushl $SIGTRAP + jmp do_interrupt + +int_overflow: +int_bound_range_exceeded: + pushl $SIGSTKFLT + jmp do_interrupt + +int_invalid_opcode: + pushl $SIGILL + jmp do_interrupt + +int_double_fault: + movl $SIGBUS, (%esp) + jmp do_interrupt + +int_invalid_tss: +int_segment_not_present: +int_stack_segment_fault: +int_general_protection: +int_page_fault: + movl $SIGSEGV, (%esp) + jmp do_interrupt + +/* When invoked, the stack contains: eflags, cs, eip, signo. */ +#define IH_OFFSET_GDB_REGS ( 0 ) +#define IH_OFFSET_GDB_EIP ( IH_OFFSET_GDB_REGS + SIZEOF_I386_REGS ) +#define IH_OFFSET_GDB_EFLAGS ( IH_OFFSET_GDB_EIP + 4 ) +#define IH_OFFSET_GDB_SEG_REGS ( IH_OFFSET_GDB_EFLAGS + SIZEOF_I386_FLAGS ) +#define IH_OFFSET_GDB_END ( IH_OFFSET_GDB_SEG_REGS + 6 * 4 ) +#define IH_OFFSET_SIGNO ( IH_OFFSET_GDB_END ) +#define IH_OFFSET_OLD_EIP ( IH_OFFSET_SIGNO + 4 ) +#define IH_OFFSET_OLD_CS ( IH_OFFSET_OLD_EIP + 4 ) +#define IH_OFFSET_OLD_EFLAGS ( IH_OFFSET_OLD_CS + 4 ) +#define IH_OFFSET_END ( IH_OFFSET_OLD_EFLAGS + 4 ) + +/* We also access the stack whilst still storing or restoring + * the register snapshot. Since ESP is in flux, we need + * special offsets. + */ +#define IH_OFFSET_FLUX_OLD_CS ( IH_OFFSET_OLD_CS - 44 ) +#define IH_OFFSET_FLUX_OLD_EFLAGS ( IH_OFFSET_OLD_EFLAGS - 40 ) +#define IH_OFFSET_FLUX_OLD_EIP ( IH_OFFSET_OLD_EIP - 36 ) +#define IH_OFFSET_FLUX_END ( IH_OFFSET_END - 20 ) +do_interrupt: + /* Store CPU state in GDB register snapshot */ + pushw $0 + pushw %gs + pushw $0 + pushw %fs + pushw $0 + pushw %es + pushw $0 + pushw %ds + pushw $0 + pushw %ss + pushw $0 + pushw IH_OFFSET_FLUX_OLD_CS + 2(%esp) + pushl IH_OFFSET_FLUX_OLD_EFLAGS(%esp) + pushl IH_OFFSET_FLUX_OLD_EIP(%esp) + pushl %edi + pushl %esi + pushl %ebp + leal IH_OFFSET_FLUX_END(%esp), %edi + pushl %edi /* old ESP */ + pushl %ebx + pushl %edx + pushl %ecx + pushl %eax + + /* Call GDB stub exception handler */ + pushl %esp + pushl (IH_OFFSET_SIGNO + 4)(%esp) + call gdbmach_handler + addl $8, %esp + + /* Restore CPU state from GDB register snapshot */ + popl %eax + popl %ecx + popl %edx + popl %ebx + addl $4, %esp /* Changing ESP currently not supported */ + popl %ebp + popl %esi + popl %edi + popl IH_OFFSET_FLUX_OLD_EIP(%esp) + popl IH_OFFSET_FLUX_OLD_EFLAGS(%esp) + popl IH_OFFSET_FLUX_OLD_CS(%esp) + popl %ss + popl %ds + popl %es + popl %fs + popl %gs + + addl $4, %esp /* drop signo */ + iret |