added sse_hvc_main_handler

Author: yuvraj1803

include/sse/sse.h

@@ -1,3 +1,23 @@
 #ifndef __SSE_H__
 #define __SSE_H__
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define SSE_FOPEN_HVC_NR        0
+#define SSE_FREAD_HVC_NR        1
+#define SSE_FWRITE_HVC_NR       2
+#define SSE_FSEEK_HVC_NR        3
+#define SSE_REWIND_HVC_NR       4
+#define SSE_FCLOSE_HVC_NR       5
+
+void sse_hvc_main_handler(uint16_t hvc_number);
+
+int  sse_hvc_fopen_handler(const char* filename, const char* mode);
+int  sse_hvc_fread_handler(char* buf, size_t size, size_t nmemb, int fd);
+int  sse_hvc_fwrite_handler(char* buf, size_t size, size_t nmemb, int fd);
+int  sse_hvc_fseek_handler(int fd, uint64_t offset, int pos);
+int  sse_hvc_rewind_handler(int fd);
+int  sse_hvc_fclose_handler(int fd);
+
 #endif

sse/sse.c

@@ -1 +1,118 @@
-#include "sse/sse.h"
+#include "sse/sse.h"
+#include "core/vm.h"
+#include "mm/paging.h"
+
+/*
+
++   So, basically when the guestOS calls the hypervisor, some args are placed in the general purpose registers. (x0-x7)
+
++   But when the context switches, these registers are put into VM structure's pt_regs.
+
++   So now, we need to access those args from pt_regs.
+
++   Also, the pointers passed from guest are in its IPA. Hence we need to find the page in physical memory as well.
+
++   Return value from the hypervisor is placed in 'x0' in pt_regs, so when context switch happens back to guest, it can view the return value as though nothing happened.
+
+*/
+
+extern struct vm* current;
+
+void sse_hvc_main_handler(uint16_t hvc_number){
+
+    struct pt_regs* vm_regs = (struct pt_regs*) get_vm_pt_regs(current);   // This is VM's state before context switch occured.
+
+    uint64_t x0 = vm_regs->regs[0];
+    uint64_t x1 = vm_regs->regs[1];
+    uint64_t x2 = vm_regs->regs[2];
+    uint64_t x3 = vm_regs->regs[3];
+
+
+    // temporary variables used inside switch statement.    
+    int return_val = -1;
+    char* filename_virt;
+    char* filename_phys;
+    char* mode_virt;
+    char* mode_phys;
+    char* buf_virt;
+    char* buf_phys;
+    size_t size, nmemb;
+    int fd;
+    int pos;
+    uint64_t offset;
+
+    switch(hvc_number){
+		case SSE_FOPEN_HVC_NR:
+
+            filename_virt = (char*)x0;
+            mode_virt     = (char*)x1;
+
+            filename_phys = (char*)ipa_to_phys(current, (uint64_t)filename_virt);
+            mode_phys     = (char*)ipa_to_phys(current, (uint64_t)mode_virt);
+
+			return_val = sse_hvc_fopen_handler(filename_phys, mode_phys);
+			break;
+		case SSE_FREAD_HVC_NR:
+
+            buf_virt    = (char*)x0;
+            size        = (size_t)x1;
+            nmemb       = (size_t)x2;
+            fd          = (int)x3;
+
+            buf_phys    = (char*)ipa_to_phys(current, (uint64_t)buf_virt);
+
+			return_val = sse_hvc_fread_handler(buf_phys, size, nmemb, fd);
+			break;
+		case SSE_FWRITE_HVC_NR:
+
+            buf_virt        = (char*)x0;
+            size            = (size_t)x1;
+            nmemb           = (size_t)x2;
+            fd              = (int)x3;
+
+            buf_phys        = (char*)ipa_to_phys(current, (uint64_t)buf_virt);
+
+			return_val = sse_hvc_fwrite_handler(buf_phys, size, nmemb, fd);
+			break;
+		case SSE_FSEEK_HVC_NR:
+            fd      = (int)x0;
+            offset  = (uint64_t)x1;
+            pos     = (int)x2;
+			return_val = sse_hvc_fseek_handler(fd, offset, pos);
+			break;
+		case SSE_REWIND_HVC_NR:
+
+            fd = (int)x0;
+			return_val = sse_hvc_rewind_handler(fd);
+			break;
+		case SSE_FCLOSE_HVC_NR:
+            fd = (int)x0;
+			return_val = sse_hvc_fclose_handler(x0);
+			break;
+	}
+
+    // now we place 'return_val' into VM's pt_regs so it can see it.
+    vm_regs->regs[0] = return_val;
+
+}
+
+int  sse_hvc_fopen_handler(const char* filename, const char* mode){
+
+    printf("file: %s Mode: %s\n", filename, mode);
+
+}
+int  sse_hvc_fread_handler(char* buf, size_t size, size_t nmemb, int fd){
+
+}
+int  sse_hvc_fwrite_handler(char* buf, size_t size, size_t nmemb, int fd){
+
+}
+int  sse_hvc_fseek_handler(int fd, uint64_t offset, int pos){
+
+}
+int  sse_hvc_rewind_handler(int fd){
+
+}
+int  sse_hvc_fclose_handler(int fd){
+
+}