Downloaded 11 times
![libstd/rt/io/native/process.rs
#[cfg(unix)]
fn spawn_process_os(prog: &str, args: &[~str],
env: Option<~[(~str, ~str)]>, dir: Option<&Path>,
in_fd: c_int, out_fd: c_int, err_fd: c_int) -> SpawnProcessResult {
…
#[cfg(not(target_os = "macos"), not(windows))]
unsafe fn set_environ(envp: *c_void) {
extern {
static mut environ: *c_void;
}
environ = envp;
}
unsafe {
let pid = fork();
if pid < 0 {
fail!("failure in fork: {}", os::last_os_error());
} else if pid > 0 {
return SpawnProcessResult {pid: pid, handle: ptr::null()};
}
… // 25 lines of failure-handing code
}
7 November 2013
University of Virginia cs4414
3](https://image.slidesharecdn.com/class20-131107120929-phpapp01/75/Crossing-into-Kernel-Space-4-2048.jpg)
![Test Program
use std::libc::funcs::posix88::unistd::fork;
#[fixed_stack_segment]
fn main() {
let pid = unsafe { fork() } ;
println(fmt!("pid = %?", pid));
}
7 November 2013
University of Virginia cs4414
> rustc fork.rs
> ./fork
pid = 0i32
pid = 15039i32
$ ./fork
pid = 15043i32
pid = 0i32
4](https://image.slidesharecdn.com/class20-131107120929-phpapp01/75/Crossing-into-Kernel-Space-5-2048.jpg)
![use std::libc::funcs::posix88::unistd::fork;
> rustc -O -S fork.rs
> wc -l fork.S
72 fork.S
#[fixed_stack_segment]
fn main() { unsafe { fork() } ; }
.section
__TEXT,__text,regular,pure_instructio
ns
.align 4, 0x90
__ZN4main18h8b6694fe33a5855ag4
v0.0E:
.cfi_startproc
leaq -2097152(%rsp), %r11
cmpq %gs:816, %r11
ja LBB0_2
movabsq $2097152, %r10
movabsq $0, %r11
callq ___morestack
ret
LBB0_2:
pushq %rbp
Ltmp2:
.cfi_def_cfa_offset 16
Ltmp3:
.cfi_offset %rbp, -16
movq %rsp, %rbp
7 November 2013
Ltmp4:
.cfi_def_cfa_register %rbp
popq %rbp
jmp
_fork
.cfi_endproc
.globl _main
.align 4, 0x90
_main:
.cfi_startproc
cmpq %gs:816, %rsp
ja LBB1_2
movabsq $8, %r10
movabsq $0, %r11
callq ___morestack
ret
LBB1_2:
pushq %rbp
Ltmp7:
.cfi_def_cfa_offset 16
Ltmp8:
.cfi_offset %rbp, -16
movq %rsp, %rbp
University of Virginia cs4414
Ltmp9:
.cfi_def_cfa_register %rbp
movq %rsi, %rax
movq %rdi, %rcx
movq %rsi, %rax
movq %rdi, %rcx
leaq __ZN4main18h8b6694fe33a5855ag4v0.0E(%rip), %rsi
xorl %edi, %edi
movq %rcx, %rdx
movq %rax, %rcx
popq %rbp
jmp __ZN8unstable4lang5start17hf72eb8b3c3a0a9ac4v0.8E
.cfi_endproc
.section
__DATA,__data
.globl __rust_crate_map_toplevel
.align 4
__rust_crate_map_toplevel:
.long 1
.space 4
.quad __rust_mod_map
.quad __rust_crate_map_std_0.8_6c65cf4b443341b1
.quad 0
.zerofill __DATA,__bss,__rust_mod_map,16,3
.section
__TEXT,__const
.globl _rust_abi_version
.align 3
_rust_abi_version:
.quad 1
.subsections_via_symbols
5](https://image.slidesharecdn.com/class20-131107120929-phpapp01/75/Crossing-into-Kernel-Space-6-2048.jpg)
Uploaded byDavid Evans
Crossing into Kernel Space
The document discusses the Rust runtime and how it interfaces with the Linux kernel to spawn new processes. It covers how fork() is implemented at the libc level and how it ultimately triggers a system call by generating an interrupt. It also discusses entering supervisor mode in the kernel and recaps some PS3 benchmarking results.
More Related Content
Similar to Crossing into Kernel Space
More from David Evans
Crossing into Kernel Space
- 2. Plan for Today Betweenlibc and the kernel PS3 Benchmarking Results Project Time 7 November 2013 University of Virginia cs4414 1
- 3. Rust Runtime Recap run::Process::new(program, argv,options) spawn_process_os(prog, args, env, dir, in_fd, …) fork() Today libc: fork() linux kernel: fork syscall 7 November 2013 University of Virginia cs4414 2
- 4. libstd/rt/io/native/process.rs #[cfg(unix)] fn spawn_process_os(prog: &str,args: &[~str], env: Option<~[(~str, ~str)]>, dir: Option<&Path>, in_fd: c_int, out_fd: c_int, err_fd: c_int) -> SpawnProcessResult { … #[cfg(not(target_os = "macos"), not(windows))] unsafe fn set_environ(envp: *c_void) { extern { static mut environ: *c_void; } environ = envp; } unsafe { let pid = fork(); if pid < 0 { fail!("failure in fork: {}", os::last_os_error()); } else if pid > 0 { return SpawnProcessResult {pid: pid, handle: ptr::null()}; } … // 25 lines of failure-handing code } 7 November 2013 University of Virginia cs4414 3
- 5. Test Program use std::libc::funcs::posix88::unistd::fork; #[fixed_stack_segment] fnmain() { let pid = unsafe { fork() } ; println(fmt!("pid = %?", pid)); } 7 November 2013 University of Virginia cs4414 > rustc fork.rs > ./fork pid = 0i32 pid = 15039i32 $ ./fork pid = 15043i32 pid = 0i32 4
- 6. use std::libc::funcs::posix88::unistd::fork; > rustc-O -S fork.rs > wc -l fork.S 72 fork.S #[fixed_stack_segment] fn main() { unsafe { fork() } ; } .section __TEXT,__text,regular,pure_instructio ns .align 4, 0x90 __ZN4main18h8b6694fe33a5855ag4 v0.0E: .cfi_startproc leaq -2097152(%rsp), %r11 cmpq %gs:816, %r11 ja LBB0_2 movabsq $2097152, %r10 movabsq $0, %r11 callq ___morestack ret LBB0_2: pushq %rbp Ltmp2: .cfi_def_cfa_offset 16 Ltmp3: .cfi_offset %rbp, -16 movq %rsp, %rbp 7 November 2013 Ltmp4: .cfi_def_cfa_register %rbp popq %rbp jmp _fork .cfi_endproc .globl _main .align 4, 0x90 _main: .cfi_startproc cmpq %gs:816, %rsp ja LBB1_2 movabsq $8, %r10 movabsq $0, %r11 callq ___morestack ret LBB1_2: pushq %rbp Ltmp7: .cfi_def_cfa_offset 16 Ltmp8: .cfi_offset %rbp, -16 movq %rsp, %rbp University of Virginia cs4414 Ltmp9: .cfi_def_cfa_register %rbp movq %rsi, %rax movq %rdi, %rcx movq %rsi, %rax movq %rdi, %rcx leaq __ZN4main18h8b6694fe33a5855ag4v0.0E(%rip), %rsi xorl %edi, %edi movq %rcx, %rdx movq %rax, %rcx popq %rbp jmp __ZN8unstable4lang5start17hf72eb8b3c3a0a9ac4v0.8E .cfi_endproc .section __DATA,__data .globl __rust_crate_map_toplevel .align 4 __rust_crate_map_toplevel: .long 1 .space 4 .quad __rust_mod_map .quad __rust_crate_map_std_0.8_6c65cf4b443341b1 .quad 0 .zerofill __DATA,__bss,__rust_mod_map,16,3 .section __TEXT,__const .globl _rust_abi_version .align 3 _rust_abi_version: .quad 1 .subsections_via_symbols 5
- 7. Could actual callto kernel fork be a regular call? 7 November 2013 University of Virginia cs4414 6
- 8. Rust Runtime Entering theKernel run::Process::new(program, argv, options) spawn_process_os(prog, args, env, dir, in_fd, …) fork() libc: fork() linux kernel: fork syscall 7 November 2013 University of Virginia cs4414 7
- 9. Supervisor Mode Kernel codeneeds (or at least uses) special privileges! What would happen if user-level code could just jump into kernel code? 7 November 2013 University of Virginia cs4414 8
- 10. Entering the Kernel User-LevelCode … movl $SYS_fork,%eax int $0x80 int instruction generates an interrupt 7 November 2013 University of Virginia cs4414 9
- 11. Traditional PC Design Programmable Interrupt Controller CPU (PIC) Keyboard 7November 2013 Interval Timer University of Virginia cs4414 10
- 12. Page 2213 ofIntel x86 Manual: http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf Modern x86 Design: “APIC” = “Advanced PIC” 7 November 2013 University of Virginia cs4414 11
- 13. Page 2213 ofIntel x86 Manual: http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf What should generate a “Local Interrupt”? 7 November 2013 What should generate an “External Interrupt”? University of Virginia cs4414 12
- 14. 7 November 2013 Universityof Virginia cs4414 13
- 15. 7 November 2013 Universityof Virginia cs4414 14
- 16. 7 November 2013 Universityof Virginia cs4414 15
- 17. … movl $SYS_fork,%eax int $0x80 Programmable Interrupt Controller (PIC) 7 November2013 University of Virginia cs4414 Handling Syscall Interrupts CPU 16
- 18. 7 November 2013 Universityof Virginia cs4414 17
- 19. 7 November 2013 Universityof Virginia cs4414 18
- 20. Intel manual, p.146: 7 November 2013 University of Virginia cs4414 19
- 21. 7 November 2013 Universityof Virginia cs4414 20
- 22. Rust Runtime Running inSupervisor Mode run::Process::new(program, argv, options) spawn_process_os(prog, args, env, dir, in_fd, …) fork() int 0x80 libc: fork() jumps into kernel code sets supervisor mode linux kernel: fork syscall 7 November 2013 University of Virginia cs4414 21
- 23.
- 24. 13.2, 5701.3 Average ResponseTime (milliseconds) 6,000 5,000 9.7, 3908.1 4,000 217.1, 3902.7 reference zhtta 3,000 2,000 44.0, 989.7 39.8, 960.8 1,000 225.2, 531.3 5.5, 0.6 0 0 50 100 150 200 Total Duration (seconds) 5 November 2013 University of Virginia cs4414 23
- 25. 8pm Friday Rouss/Robertson HallRoom 120 7 November 2013 University of Virginia cs4414 24
- 26. Decoy Project! 7 November2013 University of Virginia cs4414 25
- 27. 7 November 2013 Universityof Virginia cs4414 26
- 28. 13.2, 5701.3 6,000 Average ResponseTime (milliseconds) Kiet, Mark, Tanmoy 5,000 9.7, 3908.1 4,000 217.1, 3902.7 reference zhtta 3,000 2,000 44.0, 989.7 39.8, 960.8 Hong, Jireh, Marshall Chris, Tong, Yicheng 1,000 225.2, 531.3 5.5, 0.6 0 0 Harriet, Kevin, Zeming 50 100 150 200 Total Duration (seconds) 5 November 2013 University of Virginia cs4414 27
- 29. Charge Find a teamand project! Decoy projects are only allowed in security classes. Sneaking around my house is no longer permitted. 7 November 2013 University of Virginia cs4414 28