Overview
| Comment: | make crt behave as a C runtime launcher should; comment code thoroughly |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
f0f16493caf8ef1de1c32504d868442c |
| User & Date: | lexi on 2019-08-21 03:44:37 |
| Original Comment: | make crt behave properly, hopefully fixing segfault on nixos; comment code thoroughly |
| Other Links: | manifest | tags |
Context
|
2019-08-21
| ||
| 04:24 | modify build system to replace extremely fragile error code generation mechanism check-in: d77ef26adf user: lexi tags: trunk | |
| 03:44 | make crt behave as a C runtime launcher should; comment code thoroughly check-in: f0f16493ca user: lexi tags: trunk | |
| 03:10 | add assembly output flag to build.sh check-in: 06e32bd3b4 user: lexi tags: trunk | |
Changes
Modified kcore/boot.rt.c from [6007ea2ce5] to [a5bf4923b7].
1 1 #include <k/core.h> 2 2 extern stat entry(kenv); 3 3 4 -stat _boot(unsigned int argc, char** argv) { 4 +unsigned long long 5 +_boot(unsigned int argc, /* argument count */ 6 + char** argv, /* arguments */ 7 + char** envp /* environment */ ) { 5 8 kenv e = { 6 - // todo: determine terminal class and set term vs ansi correctly! 9 + /* TODO: determine terminal class and set term vs ansi correctly! */ 7 10 { {kiostream_term, 0}, {kiostream_term, 1} }, // chan std 8 11 { {kiostream_closed}, {kiostream_term, 2} }, // chan err 9 - argc, argv, 10 - null // no environment yet 12 + argc, argv, 13 + null // needs parsing 11 14 }; 12 15 return entry(e); 13 16 } 14 17
Modified kcore/boot.rt.x86.lin.64.s from [c4c48f7422] to [3c036595d7].
2 2 bits 64 3 3 %include "../arch/posix/x86.lin.64.s" 4 4 global _start:function 5 5 extern _boot 6 6 extern entry 7 7 8 8 _start: 9 - mov rbp, rsp 10 - mov rdi, [rbp + 0] ; argc 11 - lea rsi, [rbp + 8] ; argv 9 + mov rbp, 0 ; zero the stack base ptr. 10 + ; attempted fix for a difficult-to- 11 + ; reproduce bug 12 + 13 + mov rdi, 0 ; zero rdi - because argc 14 + ; is 32 bits long, we have to store 15 + ; its value in the lower half of rdi. 16 + ; this ensures that the upper half is 17 + ; zeroed as well. 18 + 19 + mov edi, [rsp + 0] ; sizeof arguments 20 + ; first argument to _boot(): argc 21 + ; this is a 32-bit signed(??) integer 22 + ; that is equal to the number of 23 + ; elements in argv (see below). it is 24 + ; not strictly necessary, because argv 25 + ; is per spec always null-terminated, 26 + ; but we pass it just in case. 27 + 28 + lea rsi, [rsp + 8] ; &arguments 29 + ; 2nd argument to _boot(): ptr to argv 30 + ; this points to an array of strings 31 + ; containing the program's command line 32 + ; arguments. _boot() does not need to 33 + ; parse this, but it does need to store 34 + ; it in the structure passed to main() 35 + 36 + lea rdx, [rsp + 16] ; &environment 37 + ; third argument to _boot(): ptr to envp 38 + ; this points to the list of environment 39 + ; variables for the running program. it 40 + ; is the responsibility of _boot to parse 41 + ; this list and arrange it into a set of 42 + ; legible and useful C arrays. 43 + 44 + mov rax, 0 ; zero out %rax 45 + ; this is required by the C ABI, and is 46 + ; reputedly necessary for compatibility 47 + ; with icc, intel's own proprietary C 48 + ; compiler. 49 + 50 + call _boot ; invoke the start function 51 + ; that will set up the runtime and 52 + ; construct the necessary structures 53 + ; that will be bassed to libc. 54 + 55 + ; boot has returned and left its 56 + ; return value in the register %rax. 57 + ; regardless of the size of the 58 + ; return value of main(), _boot always 59 + ; returns the system word length. 60 + 61 + mov sys.reg.1, sys.reg.ret ; fill in 62 + ; the return value as exit's argument 12 63 13 - call _boot 64 + mov sys.reg.0, sys.exit ; set %rax to 65 + ; the syscall number of exit 14 66 15 - mov sys.reg.1, sys.reg.ret 16 - mov sys.reg.0, sys.exit 17 - sys.call 67 + sys.call ; invoke the kernel