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[GDB] Add GDB stub for remote debugging
See http://etherboot.org/wiki/dev/gdbstub for documentation.
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,209 @@ | ||
| /* | ||
| * Interrupt Descriptor Table (IDT) setup and interrupt handlers for GDB stub. | ||
| */ | ||
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| #include <virtaddr.h> | ||
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| #define SIZEOF_I386_REGS 32 | ||
| #define SIZEOF_I386_FLAGS 4 | ||
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| /**************************************************************************** | ||
| * Interrupt Descriptor Table | ||
| **************************************************************************** | ||
| */ | ||
| .section ".data16" | ||
| .globl idtr | ||
| idtr: | ||
| idt_limit: | ||
| .word idt_length - 1 | ||
| idt_base: | ||
| .long 0 | ||
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| /* 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 | ||
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| .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 | ||
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| /* The IDT entries are fixed up (once) in init_librm() */ | ||
| idt_fixed: | ||
| .byte 0 | ||
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| /**************************************************************************** | ||
| * 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" | ||
| .code16 | ||
| .globl idt_init | ||
| idt_init: | ||
| movl %eax, idt_base | ||
| addl $idt, idt_base | ||
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| /* IDT entries are only fixed up once */ | ||
| movb idt_fixed, %al | ||
| orb %al, %al | ||
| jnz 2f | ||
| movb $1, idt_fixed | ||
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| /* 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 | ||
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| /**************************************************************************** | ||
| * Interrupt handlers | ||
| **************************************************************************** | ||
| */ | ||
| .section ".text" | ||
| .code32 | ||
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| /* 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 | ||
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| int_divide_error: | ||
| pushl $SIGFPE | ||
| jmp do_interrupt | ||
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| int_debug_trap: | ||
| int_breakpoint: | ||
| pushl $SIGTRAP | ||
| jmp do_interrupt | ||
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| int_overflow: | ||
| int_bound_range_exceeded: | ||
| pushl $SIGSTKFLT | ||
| jmp do_interrupt | ||
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| int_invalid_opcode: | ||
| pushl $SIGILL | ||
| jmp do_interrupt | ||
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| int_double_fault: | ||
| movl $SIGBUS, (%esp) | ||
| jmp do_interrupt | ||
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| int_invalid_tss: | ||
| int_segment_not_present: | ||
| int_stack_segment_fault: | ||
| int_general_protection: | ||
| int_page_fault: | ||
| movl $SIGSEGV, (%esp) | ||
| jmp do_interrupt | ||
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| /* 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 ) | ||
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| /* 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 */ | ||
| pushl %gs | ||
| pushl %fs | ||
| pushl %es | ||
| pushl %ds | ||
| pushl %ss | ||
| pushl IH_OFFSET_FLUX_OLD_CS(%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 | ||
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| /* Call GDB stub exception handler */ | ||
| pushl %esp | ||
| pushl (IH_OFFSET_SIGNO + 4)(%esp) | ||
| call gdbstub_handler | ||
| addl $8, %esp | ||
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| /* 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 | ||
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| addl $4, %esp /* drop signo */ | ||
| iret |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,51 @@ | ||
| #ifndef GDBMACH_H | ||
| #define GDBMACH_H | ||
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| /** @file | ||
| * | ||
| * GDB architecture specifics | ||
| * | ||
| * This file declares functions for manipulating the machine state and | ||
| * debugging context. | ||
| * | ||
| */ | ||
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| typedef uint32_t gdbreg_t; | ||
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| /* The register snapshot, this must be in sync with interrupt handler and the | ||
| * GDB protocol. */ | ||
| enum { | ||
| GDBMACH_EAX, | ||
| GDBMACH_ECX, | ||
| GDBMACH_EDX, | ||
| GDBMACH_EBX, | ||
| GDBMACH_ESP, | ||
| GDBMACH_EBP, | ||
| GDBMACH_ESI, | ||
| GDBMACH_EDI, | ||
| GDBMACH_EIP, | ||
| GDBMACH_EFLAGS, | ||
| GDBMACH_CS, | ||
| GDBMACH_SS, | ||
| GDBMACH_DS, | ||
| GDBMACH_ES, | ||
| GDBMACH_FS, | ||
| GDBMACH_GS, | ||
| GDBMACH_NREGS, | ||
| GDBMACH_SIZEOF_REGS = GDBMACH_NREGS * sizeof ( gdbreg_t ) | ||
| }; | ||
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| static inline void gdbmach_set_pc ( gdbreg_t *regs, gdbreg_t pc ) { | ||
| regs [ GDBMACH_EIP ] = pc; | ||
| } | ||
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| static inline void gdbmach_set_single_step ( gdbreg_t *regs, int step ) { | ||
| regs [ GDBMACH_EFLAGS ] &= ~( 1 << 8 ); /* Trace Flag (TF) */ | ||
| regs [ GDBMACH_EFLAGS ] |= ( step << 8 ); | ||
| } | ||
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| static inline void gdbmach_breakpoint ( void ) { | ||
| __asm__ __volatile__ ( "int $3\n" ); | ||
| } | ||
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| #endif /* GDBMACH_H */ |
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