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Fix RFLAGS-clobbering syscalls

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Justin C. Miller
2019-03-20 23:05:30 -07:00
parent 91cb00fde2
commit 866073ae8a
1 changed files with 19 additions and 12 deletions
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21
src/kernel/syscall.s
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@@ -12,18 +12,18 @@ syscall_handler_prelude:
mov rsp, [gs:0x00] mov rsp, [gs:0x00]
push 0x23 ; ss push 0x23 ; ss
push rsp push 0x00 ; rsp - to be filled
pushf push r11 ; rflags
push 0x2b ; cs push 0x2b ; cs
push rcx ; user rip push rcx ; user rip
push 0 ; bogus interrupt push 0 ; bogus error
push 0 ; bogus errorcode push 0 ; bogus vector
push_all push_all
inc qword [rel __counter_syscall_enter] inc qword [rel __counter_syscall_enter]
mov rax, [gs:0x08] mov rax, [gs:0x08]
mov [rsp + 0x98], rax mov [rsp + 0xa0], rax
mov rax, [rsp + 0x70] mov rax, [rsp + 0x70]
mov rdi, rsp mov rdi, rsp
@@ -37,11 +37,18 @@ syscall_handler_prelude:
inc qword [rel __counter_syscall_sysret] inc qword [rel __counter_syscall_sysret]
swapgs mov rax, [rsp + 0xa0]
mov [gs:0x08], rax
pop_all pop_all
add rsp, 16 ; ignore bogus interrupt / error add rsp, 16 ; ignore bogus interrupt / error
pop rcx ; user rip pop rcx ; user rip
add rsp, 32 ; ignore cs, flags, rsp, ss add rsp, 8 ; ignore cs
pop r11 ; flags
add rsp, 16 ; rsp, ss
mov [gs:0x00], rsp
mov rsp, [gs:0x08]
swapgs
o64 sysret o64 sysret