From af95bd2ba1d54b7b7ecbf18eb23731e4fa9688ee Mon Sep 17 00:00:00 2001
From: antifallobst <antifallobst@systemausfall.org>
Date: Tue, 18 Apr 2023 17:06:48 +0200
Subject: [PATCH] refactor (syscalls): improved syscall handling infrastructure

---
 kernel/inc/platform/syscall.h | 10 ++--
 kernel/src/platform/syscall.c | 95 +++++++++++++++++++++++------------
 2 files changed, 67 insertions(+), 38 deletions(-)

diff --git a/kernel/inc/platform/syscall.h b/kernel/inc/platform/syscall.h
index 14475a0..8c66fdd 100644
--- a/kernel/inc/platform/syscall.h
+++ b/kernel/inc/platform/syscall.h
@@ -7,11 +7,11 @@
 #include "utils/status.h"
 
 typedef enum {
-    SYSCALLS_FILES          = 0x00,
-    SYSCALLS_MEMORY         = 0x01,
-    SYSCALLS_PROC           = 0x02,
-    SYSCALLS_RUNTIME_LINKER = 0x02,
-    SYSCALLS_COMPATABILITY  = 0x02,
+    SYSCALLS_FILES          = 0x01,
+    SYSCALLS_MEMORY         = 0x02,
+    SYSCALLS_PROC           = 0x03,
+    SYSCALLS_RUNTIME_LINKER = 0x04,
+    SYSCALLS_COMPATABILITY  = 0x05,
 
     SYSCALLS_KERNEL         = 0xFF
 }syscall_group_E;
diff --git a/kernel/src/platform/syscall.c b/kernel/src/platform/syscall.c
index c40698e..fdf0cde 100644
--- a/kernel/src/platform/syscall.c
+++ b/kernel/src/platform/syscall.c
@@ -6,55 +6,84 @@
 #include "proc/scheduler.h"
 #include "drivers/fs/vfs.h"
 
+void syscall_handle_nx_fopen(cpu_state_T* state) {
+    // read arguments
+    uint64_t arg1 = state->rdi;
+
+    vfs_node_T *node = vfs_resolve_path(&g_root_fs, (string_t) arg1);
+    if (node == NULL) {
+        state->rax = STATUS_RESOURCE_NOT_AVAILABLE;
+        return;
+    }
+
+    log(LOG_DEBUG, "resolved file '%s' -> 0x%x", arg1, node);
+}
+
+
 cpu_state_T* syscall_handle(cpu_state_T* state) {
     cpu_state_T*    return_state = state;
     syscall_group_E group_id     = (state->rax & 0xFF00) >> 8;
 
-    if (group_id == SYSCALLS_KERNEL &&
-        scheduler_is_initialized() &&
-        scheduler_get_current_process()->id != PROCESS_KERNEL)
-    {
-        log(LOG_WARNING, "non kernel process[%d:%d] tried to perform a kernel syscall (permission denied)", scheduler_get_current_process(), scheduler_get_current_thread());
-        return return_state;
-    }
-
     // read arguments
     uint64_t arg1 = state->rdi;
-    uint64_t arg2 = state->rsi;
-    uint64_t arg3 = state->rdx;
-    uint64_t arg4 = state->rcx;
-    uint64_t ret  = STATUS_SUCCESS;
 
-    switch (state->rax) {
-        case SYSCALL_FILES_OPEN: {
-            vfs_node_T* node = vfs_resolve_path(&g_root_fs, (string_t)arg1);
-            if (node == NULL) {
-                ret = STATUS_RESOURCE_NOT_AVAILABLE;
-                break;
+    switch (group_id) {
+        case SYSCALLS_FILES: {
+
+            switch (state->rax) {
+                case SYSCALL_FILES_OPEN: {
+                    syscall_handle_nx_fopen(state);
+                    break;
+                }
+            }
+            break;
+        }
+
+        case SYSCALLS_MEMORY: {
+            break;
+        }
+
+        case SYSCALLS_PROC: {
+            break;
+        }
+
+        case SYSCALLS_RUNTIME_LINKER: {
+            break;
+        }
+
+        case SYSCALLS_COMPATABILITY: {
+            break;
+        }
+
+        case SYSCALLS_KERNEL: {
+
+            // check if the current Process is permitted to perform a kernel syscall
+            if (scheduler_is_initialized() &&
+                scheduler_get_current_process()->id != PROCESS_KERNEL)
+            {
+                log(LOG_WARNING, "non kernel process[%d:%d] tried to perform a kernel syscall (permission denied)", scheduler_get_current_process(), scheduler_get_current_thread());
+                state->rax = STATUS_PERMISSION_DENIED;
+                return return_state;
             }
 
-            log(LOG_DEBUG, "resolved file '%s' -> 0x%x", arg1, node);
+            switch (state->rax) {
+                case SYSCALL_KERNEL_SCHEDULER_START: {
+                    return_state = scheduler_start(state);
+                    break;
+                }
 
-            break;
-        }
-
-        case SYSCALL_KERNEL_SCHEDULER_START: {
-            return_state = scheduler_start(state);
-            break;
-        }
-        case SYSCALL_KERNEL_PANIC: {
-            panic(state, (string_t)arg1);
-            break;
+                case SYSCALL_KERNEL_PANIC: {
+                    panic(state, (string_t)arg1);
+                    break;
+                }
+            }
         }
 
         default: {
-            log(LOG_WARNING, "unhandled syscall: 0x%xw", state->rax);
+            log(LOG_WARNING, "unknown syscall group: 0x%xb", group_id);
             break;
         }
     }
 
-    // apply return value
-    state->rax = ret;
-
     return return_state;
 }
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