From: acevest <zhaoyanbai@126.com>
Date: Mon, 1 Nov 2021 08:33:17 +0000 (+0800)
Subject: 换种方式实现sysc bad number
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/zlib_tech.html?a=commitdiff_plain;h=6248bb9e75cb14510c577d5c98b87b07970aa5e7;p=kernel.git

换种方式实现sysc bad number
---

diff --git a/include/syscall.h b/include/syscall.h
index 5e8bd15..59b4a83 100644
--- a/include/syscall.h
+++ b/include/syscall.h
@@ -36,23 +36,21 @@ int _syscall4(int nr, unsigned long a, unsigned long b, unsigned long c, unsigne
 #define syscall3(nr, a, b, c) _syscall3(nr, (unsigned long)a, (unsigned long)b, (unsigned long)c)
 #define syscall4(nr, a, b, c, d) _syscall4(nr, (unsigned long)a, (unsigned long)b, (unsigned long)c, (unsigned long)d)
 
-enum
-{
-    SYSC_WRITE,
-    SYSC_REBOOT,
-    SYSC_FORK,
-    SYSC_CLONE,
-    SYSC_EXEC,
-    SYSC_WAIT,
-    SYSC_OPEN,
-    SYSC_READ,
-    SYSC_STAT,
-    SYSC_EXIT,
-    SYSC_PAUSE,
-    SYSC_TEST,
-    SYSC_DEBUG
-};
-
 #endif // ASM
 
+#define SYSC_WRITE (0)
+#define SYSC_REBOOT (1)
+#define SYSC_FORK (2)
+#define SYSC_CLONE (3)
+#define SYSC_EXEC (4)
+#define SYSC_WAIT (5)
+#define SYSC_OPEN (6)
+#define SYSC_READ (7)
+#define SYSC_STAT (8)
+#define SYSC_EXIT (9)
+#define SYSC_PAUSE (10)
+#define SYSC_TEST (11)
+#define SYSC_DEBUG (12)
+#define SYSC_BAD_NR (SYSC_NUM - 1)
+
 #endif //_SYSCALL_H
diff --git a/kernel/syscall.S b/kernel/syscall.S
index fdd9772..89996b8 100644
--- a/kernel/syscall.S
+++ b/kernel/syscall.S
@@ -48,8 +48,10 @@ syscall_entry:
     popl    %eax
 
     cmpl    $SYSC_NUM, %eax
-    jae     bad_sysc_nr
+    jb      .normal_syscall
+    mov     $SYSC_BAD_NR, %eax
 
+ .normal_syscall:
     call    *sysc_handler_table(,%eax,4)
 
 normal_syscall_exit:
@@ -66,10 +68,6 @@ syscall_exit:
     sti        /* sysenter have cleared IF, and sysexit will not set IF. */
     sysexit
 
-bad_sysc_nr:
-    call    sysc_bad_syscnr
-    jmp     syscall_exit
-
 ret_from_fork_user:
     xorl    %eax, %eax
     jmp     normal_syscall_exit
diff --git a/kernel/syscall.c b/kernel/syscall.c
index ef98edb..3c11103 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -90,14 +90,17 @@ void init_sysc_handler_table()
     _sysc_(SYSC_PAUSE, sysc_pause);
     _sysc_(SYSC_TEST, sysc_test);
     _sysc_(SYSC_DEBUG, sysc_debug);
+    _sysc_(SYSC_BAD_NR, sysc_bad_nr)
 }
 
-int sysc_bad_syscnr()
+int sysc_bad_nr()
 {
     int sysc_nr;
+
     asm(""
         : "=a"(sysc_nr));
+
     printk("bad syscall nr:%d\n", sysc_nr);
 
-    return 0;
+    return -1;
 }