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| author | Frans Kaashoek <kaashoek@mit.edu> | 2022-08-25 13:52:48 -0400 |
|---|---|---|
| committer | Frans Kaashoek <kaashoek@mit.edu> | 2022-08-25 13:52:48 -0400 |
| commit | 0c477a6c84091415efe2ac15509adc4b518bd7ea (patch) | |
| tree | 32cacc69f57fec08a7f543b6671c89cf7571d530 /kernel/syscall.c | |
| parent | 7d47335b4f955fd93d2acaef745add723bc7f7d0 (diff) | |
| parent | 3d6ce9b308399f8c49c13653bd4ac21ca2311f26 (diff) | |
| download | xv6-labs-2022-0c477a6c84091415efe2ac15509adc4b518bd7ea.tar.xz xv6-labs-2022-0c477a6c84091415efe2ac15509adc4b518bd7ea.zip | |
Merge branch 'riscv' into util
Diffstat (limited to 'kernel/syscall.c')
| -rw-r--r-- | kernel/syscall.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/syscall.c b/kernel/syscall.c index ee94696..ed65409 100644 --- a/kernel/syscall.c +++ b/kernel/syscall.c @@ -79,6 +79,7 @@ argstr(int n, char *buf, int max) return fetchstr(addr, buf, max); } +// Prototypes for the functions that handle system calls. extern uint64 sys_fork(void); extern uint64 sys_exit(void); extern uint64 sys_wait(void); @@ -101,6 +102,8 @@ extern uint64 sys_link(void); extern uint64 sys_mkdir(void); extern uint64 sys_close(void); +// An array mapping syscall numbers from syscall.h +// to the function that handles the system call. static uint64 (*syscalls[])(void) = { [SYS_fork] sys_fork, [SYS_exit] sys_exit, @@ -133,6 +136,8 @@ syscall(void) num = p->trapframe->a7; if(num > 0 && num < NELEM(syscalls) && syscalls[num]) { + // Use num to lookup the system call function for num, call it, + // and store its return value in p->trapframe->a0 p->trapframe->a0 = syscalls[num](); } else { printf("%d %s: unknown sys call %d\n", |