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Implement fast syscall/sysret for sytem calls

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Justin C. Miller
2019-03-13 23:51:29 -07:00
parent 97e8f2c69a
commit f7558e3d18
9 changed files with 77 additions and 21 deletions
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27
src/kernel/syscall.s
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@@ -1,21 +1,44 @@
%include "push_all.inc"
extern __counter_syscall_enter
extern __counter_syscall_sysret
extern syscall_handler
extern isr_handler_return
global syscall_handler_prelude
syscall_handler_prelude:
push 0 ; ss, doesn't matter here
swapgs
mov [gs:0x08], rsp
mov rsp, [gs:0x00]
push 0x23 ; ss
push rsp
pushf
push 0 ; cs, doesn't matter here
push 0x2b ; cs
push rcx ; user rip
push 0 ; bogus interrupt
push 0 ; bogus errorcode
push_all_and_segments
inc qword [rel __counter_syscall_enter]
mov rax, [gs:0x08]
mov [rsp + 0x98], rax
mov rax, [rsp + 0x70]
mov rdi, rsp
call syscall_handler
mov rsp, rax
mov rax, [rsp + 0x90]
and rax, 0x3
cmp rax, 0x3
jne isr_handler_return
inc qword [rel __counter_syscall_sysret]
swapgs
pop_all_and_segments
add rsp, 16 ; ignore bogus interrupt / error
pop rcx ; user rip