Hi.
I am trying to implement multi CPU x86 sistem call emulation in M5.
The idea is that every thread that is created in the program runs on
it's own CPU,
so that we don't need any thread scheduling.
The following program runs without the problems with my implementation:
int k = 0;
void f(long a){ k+= a; }
void g(long a){ k+= a; }
int main(){
long t1 = create_thread(&f, 5);
long t2 = create_thread(&g, 6);
join_thread(t1);
join_thread(t2);
printf("%d", k);
}
The implementation that I have wright now is:
I have implemented 3 new system calls in M5:
create_thread
join_thread
stop_thread.
create_thread(f, a):
- alocates a stack space for new thread
- and adds the code that will call the stop_thread system call when
function 'f' returns.
- sets program counter of the unactive cpu to point to address of 'f'
- activates inactive cpu
join_thread(t1):
- waits thread 't1' to be suspended or suspends parent thread
stop_thread():
- suspends itself.
When I run more complex examples that execute 'printf' or 'malloc' in
child thread,
the simulator stop executing program with the following error message:
Running clients... panic: Tried to access unmapped address 0.
@ cycle 132099500
[invoke:build/X86_SE/arch/x86/faults.cc, line 160]
Program aborted at cycle 132099500
Aborted
Can you give me any directions what can be the problem?
(I have the feeling that current sistem call emulation doesn't support
I/0 that execute from two different thread_conetexts)
Tnx,
Srdjan
P.S.
Longer log for the example were child thread calls malloc:
127311000: system.cpu2 T0 : @main+280 : CALL_NEAR_I : stupd
t7, SS:[rsp + 0xfffffffffffffff8] : MemWrite : D=0x00007fffffffeaa8
A=0x7fffffffeaa8
127311500: system.cpu2 T0 : @main+280 : CALL_NEAR_I : wrip ,
t7, t1 : IntAlu :
127312000: system.cpu2 T0 : @create_thread : PUSH_R : stupd rbp,
SS:[rsp + 0xfffffffffffffff8] : MemWrite : D=0x00007fffffffeaa0
A=0x7fffffffeaa0
127312500: system.cpu2 T0 : @create_thread+1 : MOV_R_R : mov rbp,
rbp, rsp : IntAlu : D=0x00007fffffffeaa0
127313000: system.cpu2 T0 : @create_thread+4 : SUB_R_I : limm t1,
0x20 : IntAlu : D=0x0000000000000020
127313500: system.cpu2 T0 : @create_thread+4 : SUB_R_I : sub rsp,
rsp, t1 : IntAlu : D=0x000000000000002c
127314000: system.cpu2 T0 : @create_thread+8 : MOV_M_R : st rdi,
SS:[rbp + 0xffffffffffffffe8] : MemWrite : D=0x00000000004005ea
A=0x7fffffffea88
127314500: system.cpu2 T0 : @create_thread+12 : MOV_M_R : st
rsi, SS:[rbp + 0xffffffffffffffe0] : MemWrite : D=0x0000000000d91c28
A=0x7fffffffea80
127315500: system.cpu2 T0 : @create_thread+16 : MOV_R_I : limm
eax, 0x111 : IntAlu : D=0x0000000000000111
127316000: system.cpu2 T0 : @create_thread+21 : MOV_R_M : ld
rdi, SS:[rbp + 0xffffffffffffffe8] : MemRead : D=0x00000000004005ea
A=0x7fffffffea88
127317000: system.cpu2 T0 : @create_thread+25 : MOV_R_M : ld
rsi, SS:[rbp + 0xffffffffffffffe0] : MemRead : D=0x0000000000d91c28
A=0x7fffffffea80
127317500: system.cpu2 T0 : @create_thread+29 : syscall eax
: IntAlu :
127318000: system.cpu2 T0 : @create_thread+31 : MOV_M_R : st
rax, SS:[rbp + 0xfffffffffffffff8] : MemWrite : D=0x0000000000cbb0d0
A=0x7fffffffea98
127318500: system.cpu0 T0 : @client_run : PUSH_R : stupd rbp,
SS:[rsp + 0xfffffffffffffff8] : MemWrite : D=0x00002aaaaabacfe9
A=0x2aaaaabacfe9
127319000: system.cpu2 T0 : @create_thread+35 : MOV_R_M : ld
rax, SS:[rbp + 0xfffffffffffffff8] : MemRead : D=0x0000000000cbb0d0
A=0x7fffffffea98
127319000: system.cpu0 T0 : @client_run+1 : MOV_R_R : mov rbp,
rbp, rsp : IntAlu : D=0x00002aaaaabacfe9
....
....
127339500: system.cpu2 T0 : @main+355 : CMP_R_M : sub t0,
rax, t1 : IntAlu : D=0x00000000000000b9
127340000: system.cpu2 T0 : @main+359 : JL_I : rdip t1,
%ctrl153, : IntAlu : D=0x000000000040367e
127340000: system.cpu0 T0 : @malloc+22 : MOV_R_P : ld rax,
DS:[t7 + 0x16fcab] : MemRead : D=0x0000000000000000 A=0x58a848
127340500: system.cpu0 T0 : @malloc+29 : TEST_R_R : and t0,
rax, rax : IntAlu : D=0x0000000000000050
127340500: system.cpu2 T0 : @main+359 : JL_I : limm t2,
0xffffffffffffffda : IntAlu : D=0xffffffffffffffda
127341000: system.cpu2 T0 : @main+359 : JL_I : wrip , t1, t2
: IntAlu :
127341000: system.cpu0 T0 : @malloc+32 : JZ_I : rdip t1,
%ctrl153, : IntAlu : D=0x000000000041aba2
127341500: system.cpu0 T0 : @malloc+32 : JZ_I : limm t2, 0x1e
: IntAlu : D=0x000000000000001e
127341500: system.cpu2 T0 : @main+323 : MOV_R_M : ld eax,
SS:[rbp + 0xffffffffffffffe4] : MemRead : D=0x0000000000000000
A=0x7fffffffeb34
127342000: system.cpu2 T0 : @main+326 : MOV_R_M : ld rdx,
SS:[rbp + 0xffffffffffffffc8] : MemRead : D=0x00007fffffffeab0
A=0x7fffffffeb18
127342000: system.cpu0 T0 : @malloc+32 : JZ_I : wrip , t1, t2
: IntAlu :
127343000: system.cpu2 T0 : @main+330 : CDQE_R : sexti rax,
rax, 0x1f : IntAlu : D=0x0000000000000000
END
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