| 1 |
/* syscall.c - System call interface for Pactor64 */ |
| 2 |
#include "syscall.h" |
| 3 |
|
| 4 |
/* Syscall dispatch table */ |
| 5 |
typedef uint64_t (*syscall_fn_t)(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t); |
| 6 |
static syscall_fn_t syscall_table[MAX_SYSCALL]; |
| 7 |
|
| 8 |
/* Current heap break for brk() */ |
| 9 |
static uint64_t current_brk = 0; |
| 10 |
|
| 11 |
/* === Individual syscall implementations === */ |
| 12 |
|
| 13 |
static uint64_t sys_read(uint64_t fd, uint64_t buf, uint64_t count, |
| 14 |
uint64_t a3, uint64_t a4) { |
| 15 |
(void)buf; (void)count; (void)a3; (void)a4; |
| 16 |
if (fd == 0) return 0; /* stdin: no input yet */ |
| 17 |
return (uint64_t)-1; |
| 18 |
} |
| 19 |
|
| 20 |
static uint64_t sys_write(uint64_t fd, uint64_t buf, uint64_t count, |
| 21 |
uint64_t a3, uint64_t a4) { |
| 22 |
(void)a3; (void)a4; |
| 23 |
if (fd == 1 || fd == 2) { |
| 24 |
const char *str = (const char *)(uintptr_t)buf; |
| 25 |
for (uint64_t i = 0; i < count; i++) serial_putc(str[i]); |
| 26 |
return count; |
| 27 |
} |
| 28 |
return (uint64_t)-1; |
| 29 |
} |
| 30 |
|
| 31 |
static uint64_t sys_open(uint64_t path, uint64_t flags, uint64_t mode, |
| 32 |
uint64_t a3, uint64_t a4) { |
| 33 |
(void)path; (void)flags; (void)mode; (void)a3; (void)a4; |
| 34 |
kprintf("[syscall] open: not yet implemented\n"); |
| 35 |
return (uint64_t)-1; |
| 36 |
} |
| 37 |
|
| 38 |
static uint64_t sys_close(uint64_t fd, uint64_t a1, uint64_t a2, |
| 39 |
uint64_t a3, uint64_t a4) { |
| 40 |
(void)a1; (void)a2; (void)a3; (void)a4; |
| 41 |
if (fd <= 2) return 0; |
| 42 |
return (uint64_t)-1; |
| 43 |
} |
| 44 |
|
| 45 |
static uint64_t sys_exit(uint64_t status, uint64_t a1, uint64_t a2, |
| 46 |
uint64_t a3, uint64_t a4) { |
| 47 |
(void)a1; (void)a2; (void)a3; (void)a4; |
| 48 |
kprintf("\n[syscall] Process exited with status %d\n", status); |
| 49 |
/* Return to kernel shell instead of hanging */ |
| 50 |
return (uint64_t)-999; |
| 51 |
return 0; /* unreachable */ |
| 52 |
} |
| 53 |
|
| 54 |
static uint64_t sys_brk(uint64_t addr, uint64_t a1, uint64_t a2, |
| 55 |
uint64_t a3, uint64_t a4) { |
| 56 |
(void)a1; (void)a2; (void)a3; (void)a4; |
| 57 |
if (current_brk == 0) { current_brk = addr; return current_brk; } |
| 58 |
if (addr == 0) return current_brk; |
| 59 |
if (addr > current_brk) current_brk = addr; |
| 60 |
return current_brk; |
| 61 |
} |
| 62 |
|
| 63 |
/* Initialize the syscall interface */ |
| 64 |
void syscall_init(void) { |
| 65 |
for (int i = 0; i < MAX_SYSCALL; i++) syscall_table[i] = 0; |
| 66 |
|
| 67 |
syscall_table[SYS_READ] = sys_read; |
| 68 |
syscall_table[SYS_WRITE] = sys_write; |
| 69 |
syscall_table[SYS_OPEN] = sys_open; |
| 70 |
syscall_table[SYS_CLOSE] = sys_close; |
| 71 |
syscall_table[SYS_EXIT] = sys_exit; |
| 72 |
syscall_table[SYS_BRK] = sys_brk; |
| 73 |
|
| 74 |
/* STAR: kernel CS=0x08 (SS=0x10), user CS base=0x18 |
| 75 |
* SYSCALL: CS=STAR[63:48]=0x08, SS=STAR[63:48]+8=0x10 |
| 76 |
* SYSRET: CS=STAR[47:32]|3=0x1B, SS=(STAR[47:32]+8)|3=0x23 */ |
| 77 |
uint64_t star = ((uint64_t)0x0008 << 48) | ((uint64_t)0x0018 << 32); |
| 78 |
write_msr(MSR_STAR, star); |
| 79 |
write_msr(MSR_LSTAR, (uint64_t)(uintptr_t)syscall_entry); |
| 80 |
/* FMASK: clear IF and DF on SYSCALL entry */ |
| 81 |
write_msr(MSR_FMASK, (1 << 9) | (1 << 10)); |
| 82 |
|
| 83 |
kprintf("[syscall] Initialized SYSCALL interface\n"); |
| 84 |
kprintf("[syscall] STAR=0x%x LSTAR=0x%x\n", star, (uint64_t)(uintptr_t)syscall_entry); |
| 85 |
} |
| 86 |
|
| 87 |
/* Main syscall dispatcher - called from assembly */ |
| 88 |
uint64_t syscall_dispatch(uint64_t num, uint64_t arg1, uint64_t arg2, |
| 89 |
uint64_t arg3, uint64_t arg4, uint64_t arg5) { |
| 90 |
if (num >= MAX_SYSCALL || syscall_table[num] == 0) { |
| 91 |
kprintf("[syscall] Unimplemented syscall %d\n", num); |
| 92 |
return (uint64_t)-38; /* ENOSYS */ |
| 93 |
} |
| 94 |
return syscall_table[num](arg1, arg2, arg3, arg4, arg5); |
| 95 |
} |
| 96 |
|