#include "param.h" #include "x86.h" #include "mmu.h" # the offset of cs in trapframe (i.e., tf->cs - tf) #define CSOFF 144 # vectors.S sends all traps here. .globl alltraps alltraps: # Build trap frame. push %r15 push %r14 push %r13 push %r12 push %r11 push %r10 push %r9 push %r8 push %rdi push %rsi push %rbp push %rdx push %rcx push %rbx push %rax cmpw $SEG_KCODE, CSOFF(%rsp) # compare to saved cs jz 1f swapgs 1:mov %rsp, %rdi # frame in arg1 call trap # Return falls through to trapret... .globl trapret trapret: cli cmpw $SEG_KCODE, CSOFF(%rsp) # compare to saved cs jz 1f swapgs 1:pop %rax pop %rbx pop %rcx pop %rdx pop %rbp pop %rsi pop %rdi pop %r8 pop %r9 pop %r10 pop %r11 pop %r12 pop %r13 pop %r14 pop %r15 add $16, %rsp # discard trapnum and errorcode iretq #PAGEBREAK! # syscall jumps here after syscall instruction .globl sysentry sysentry: # Build syscall frame. // load kernel stack address swapgs movq %rax, %gs:0 // save %rax in syscallno of cpu entry movq %rsp, %gs:8 // user sp movq %gs:16, %rax // proc entry movq %ss:0(%rax), %rax // load kstack from proc addq $(KSTACKSIZE), %rax movq %rax, %rsp movq %gs:0, %rax // restore rax push %gs:8 push %rcx push %r11 push %rax push %rbp push %rbx push %r12 push %r13 push %r14 push %r15 push %r9 push %r8 push %r10 push %rdx push %rsi push %rdi mov %rsp, %rdi # frame in arg1 call syscall # fall through to sysexit .globl sysexit sysexit: # to make sure we don't get any interrupts on the user stack while in # supervisor mode. insufficient? (see vunerability reports for sysret) cli pop %rdi pop %rsi pop %rdx pop %r10 pop %r8 pop %r9 pop %r15 pop %r14 pop %r13 pop %r12 pop %rbx pop %rbp pop %rax pop %r11 pop %rcx mov (%rsp),%rsp # switch to the user stack # there are two more values on the stack, but we don't care about them swapgs sysretq