Portable Native Client

Transcription

1 Portable Native Client David Sehr, Robert Muth, Jan Voung, David Meyer, Betul Buyukkurt, Karl Schimpf, Jason Kim, Rafael Espindola, Alan Donovan 1

2 Agenda Motivation Approach Developing Using PNaCl Safe Translation Status Ongoing Work 2

3 Motivation

4 A NaCl-Enabled Web Application Your favorite language Screened for malicious instructions System calls moderated by a virtualized OS Native Client Helper Performance within 5% of native code

5 Applications with NaCl Lego Star Wars Darkroom demo Nexuiz 5

6 Where Native Client Started OSX Windows Linux x

7 Where Native Client Started OSX Windows Linux x86-32 linux-like system calls gcc binutils newlib 7

8 Where We Went Next x86-32 ARM 8

9 Where We Went Next linux-like system calls llvm binutils newlib x86-32 ARM 9

10 What Developers Want x86-32 ARM x86-64 Only one porting effort 10

11 Approach 11

12 Application Life Cycle sources a.cc z.cc app.bc app.so library info lib.bc 12

13 Application Life Cycle sources a.cc z.cc app.bc app.so library info lib.bc LLVM bitcode is PNaCl s distribution format 13

14 Client side Native Client Helper translation engine myapp.so ELF x86, x64, or ARM NaCl sandbox

15 Developing Using PNaCl

16 Target Model Address space / data model ILP32 (sizeof(int) == sizeof(long) == sizeof(void*)) sizeof(va_list) == 24 1GB maximum total address space Stack pointer starts at the top of the address space Data types IEEE fp natural alignment (e.g., double is aligned 0mod8) Byte order Little Endian 16

17 Target Model C++ Exception Handling x86-32 Linux model varargs sizeof(va_list) == 24 Front end emits va_arg instruction setjmp Consistent jmp_buf size 17

18 Target Model Calling conventions Bitcode file is calling convention neutral Actual target convention determined by translator Concurrency and memory model Assume a least common denominator Store ordering within a thread Explicit synchronization across threads We expect people to use llvm atomic/barrier intrinsics where needed 18

19 Application Life Cycle sources a.cc z.cc app.so library info app.bc lib.bc gcc-like driver llvm-gcc front end LLVM s link-time optimization Produce smallest bitcode Expensive opts. off client 19

20 Safe Translation

21 Translating in a Sandbox The translator must run in the browser Malicious bitcode files are a potential attack vector 21

22 Translating in a Sandbox The translator must run in the browser Malicious bitcode files are a potential attack vector Translator phases are run as NaCl modules 22

23 Translator today myapp.bc Rapid code generation llc ld myapp.so 23

24 Translator goal myapp.bc llc ld myapp.so Know the platform (uarch) Can collect/use profiling data Webpage-specific specialization Can translate at invocation time install time asynchronously 24

25 Status 25

26 What s running? One bitcode file translates, validates, and runs on three architectures All of SPEC2000 int and the four C fp tests pass The translator is self-built and sandboxed llc and ld run as NaCl modules on x86-32 and 64 ARM getting close ARM ELF direct object generation passing most tests Still a bit of debugging on ARM self-build 26

27 What s running? Examples are running in Chromium (With a command-line flag for now) 27

28 Ongoing Work 28

29 Developer Tools LTO producing the smallest possible.bc files Improve gold plugin for marking symbols internal Gold/LTO as full linker without.bc to.o Collecting soname list for.so generation 29

30 Translator Direct.so generation Emission work for DT_NEEDED Translation time 30

31 Want to Learn More? (Follow Portable Native Client link) 31