Linux Kernel Architecture

Mauerer runapp01.tex V1 - 09/04/2008 6:08pm Page 1134

Appendix A: Architecture Specifics

A.7.8 AMD64

Even though the AMD64 architecture is very similar to its IA32 predecessor, a number of registers have

been added so that there are some differences as concerns the registers that must be saved during system

calls:

include/asm-x86/ptrace.h

struct pt_regs {

unsigned long r15;

unsigned long r14;

unsigned long r13;

unsigned long r12;

unsigned long rbp;

unsigned long rbx;

/* arguments: non interrupts/non tracing syscalls only save upto here*/

unsigned long r11;

unsigned long r10;

unsigned long r9;

unsigned long r8;

unsigned long rax;

unsigned long rcx;

unsigned long rdx;

unsigned long rsi;

unsigned long rdi;

unsigned long orig_rax;

/* end of arguments */

/* cpu exception frame or undefined */

unsigned long rip;

unsigned long cs;

unsigned long eflags;

unsigned long rsp;

unsigned long ss;

/* top of stack page */

};

The close ties between the two architectures are very apparent in the followingthread_structstructure

which has almost exactly the same layout as in IA32:

include/asm-x86_64/processor.h

struct thread_struct {

unsigned long rsp0;

unsigned long rsp;

unsigned long userrsp; /* Copy from PDA */

unsigned long fs;

unsigned long gs;

unsigned short es, ds, fsindex, gsindex;

/* Hardware debugging registers */

unsigned long debugreg0;

unsigned long debugreg1;

unsigned long debugreg2;

unsigned long debugreg3;

unsigned long debugreg6;

unsigned long debugreg7;

/* fault info */