Implement kernel brk

src/kernel/boot/kmain.c

@@ -28,7 +28,7 @@ void kmain(uint64_t multiboot_magic, void *multiboot_data)
     debug_info("Boot complete\n");
 
     debug_info("Mallocing\n");
-    uint64_t a = malloc(100);
+    void *a = malloc(100);
     debug_info("Malloced %x\n", a);
 
     PANIC("End of kernel function!");

src/kernel/include/memory.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #define KERNEL_OFFSET 0xFFFFFF8000000000
+#define KERNEL_BRK0   0xFFFFFFC000000000
 
 #define PAGE_PRESENT 0x001
 #define PAGE_WRITE 0x002
@@ -46,6 +47,9 @@
     int memcmp(const void *s1, const void *s2, size_t n);
     size_t strlen(const char *s);
 
+    // memory/kbrk.c
+    long kbrk(long brk, long, long, long, long, long);
+
     // Link.ld
     extern int kernel_start, kernel_end;
 

src/kernel/include/musl-glue.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#define SYSCALL_BRK 12
+
+typedef long (*syscall_handler)(long, long, long, long, long, long);
+
+// lib/musl-glue.c
+syscall_handler set_syscall_handler(long num, syscall_handler handler);

src/kernel/lib/musl-glue.c

@@ -1,22 +1,41 @@
+#include <musl-glue.h>
 #include <debug.h>
 
+syscall_handler syscall_handlers[440];
+
+syscall_handler set_syscall_handler(long num, syscall_handler handler)
+{
+    syscall_handler old = syscall_handlers[num];
+    syscall_handlers[num] = handler;
+    return old;
+}
+
 long syscall0(long num)
 {
     long retval = 0;
-    PANIC("Unknown syscall: %d()\n", num);
+    if(syscall_handlers[num])
+        retval = syscall_handlers[num](0, 0, 0, 0, 0, 0);
+    else
+        PANIC("Unknown syscall: %d()\n", num);
     return retval;
 }
 
 extern long syscall1(long num, long a1)
 {
     long retval = 0;
-    PANIC("Unknown syscall: %d(%x)\n", num, a1);
+    if(syscall_handlers[num])
+        retval = syscall_handlers[num](a1, 0, 0, 0, 0, 0);
+    else
+        PANIC("Unknown syscall: %d(%x)\n", num, a1);
     return retval;
 }
 
 extern long syscall2(long num, long a1, long a2)
 {
     long retval = 0;
+    if(syscall_handlers[num])
+        retval = syscall_handlers[num](a1, a2, 0, 0, 0, 0);
+    else
     PANIC("Unknown syscall: %d(%x, %x)\n", num, a1, a2);
     return retval;
 }
@@ -24,6 +43,9 @@ extern long syscall2(long num, long a1, long a2)
 extern long syscall3(long num, long a1, long a2, long a3)
 {
     long retval = 0;
+    if(syscall_handlers[num])
+        retval = syscall_handlers[num](a1, a2, a3, 0, 0, 0);
+    else
     PANIC("Unknown syscall: %d(%x, %x, %x)\n", num, a1, a2, a3);
     return retval;
 }
@@ -31,6 +53,9 @@ extern long syscall3(long num, long a1, long a2, long a3)
 extern long syscall4(long num, long a1, long a2, long a3, long a4)
 {
     long retval = 0;
+    if(syscall_handlers[num])
+        retval = syscall_handlers[num](a1, a2, a3, a4, 0, 0);
+    else
     PANIC("Unknown syscall: %d(%x, %x, %x, %x)\n", num, a1, a2, a3, a4);
     return retval;
 }
@@ -38,6 +63,9 @@ extern long syscall4(long num, long a1, long a2, long a3, long a4)
 extern long syscall5(long num, long a1, long a2, long a3, long a4, long a5)
 {
     long retval = 0;
+    if(syscall_handlers[num])
+        retval = syscall_handlers[num](a1, a2, a3, a4, a5, 0);
+    else
     PANIC("Unknown syscall: %d(%x, %x, %x, %x, %x)\n", num, a1, a2, a3, a4, a5);
     return retval;
 }
@@ -45,6 +73,9 @@ extern long syscall5(long num, long a1, long a2, long a3, long a4, long a5)
 extern long syscall6(long num, long a1, long a2, long a3, long a4, long a5, long a6)
 {
     long retval = 0;
-    PANIC("Unknown syscall: %d(%x, %x, %x, %x, %x, %x)\n", num, a1, a2, a3, a4, a5, a6);
+    if(syscall_handlers[num])
+        retval = syscall_handlers[num](a1, a2, a3, a4, a5, a6);
+    else
+        PANIC("Unknown syscall: %d(%x, %x, %x, %x, %x, %x)\n", num, a1, a2, a3, a4, a5, a6);
     return retval;
 }

src/kernel/memory/kbrk.c

@@ -0,0 +1,18 @@
+#include <memory.h>
+#include <debug.h>
+
+static long _brk = KERNEL_BRK0;
+
+long kbrk(long brk, long, long, long, long, long)
+{
+    if(brk)
+    {
+        while(_brk < brk) {
+            vmm_set_page(kernel_P4, _brk, pmm_alloc(), PAGE_WRITE | PAGE_PRESENT);
+            _brk += PAGE_SIZE;
+        }
+        return _brk;
+    } else {
+        return _brk;
+    }
+}

src/kernel/memory/memory.c

@@ -2,6 +2,7 @@
 #include <memory.h>
 #include <debug.h>
 #include <multiboot.h>
+#include <musl-glue.h>
 
 
 uint64_t kernel_P4;
@@ -37,4 +38,6 @@ void memory_init()
             pmm_free(p);
         }
     }
+
+    set_syscall_handler(SYSCALL_BRK, &kbrk);
 }