bionic: modify syscall to use 6 registers to pass parameter.
Kernel allows to use 6 registers(exclude eax) to pass parameter.
But in syscall's implementation, it only uses five registers.
It will lead to error when 6 parameters passed.
Change-Id: I92d663194e6334c3847f0c0c257ca3b9dee0edef
Author: Jin Wei <wei.a.jin@intel.com>
Signed-off-by: Xiaokang Qin <xiaokang.qin@intel.com>
Signed-off-by: Beare, Bruce J <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 30838
diff --git a/libc/arch-x86/bionic/syscall.S b/libc/arch-x86/bionic/syscall.S
index 8370f0b..49d6f8d 100644
--- a/libc/arch-x86/bionic/syscall.S
+++ b/libc/arch-x86/bionic/syscall.S
@@ -1,15 +1,13 @@
/*
* Generic syscall call.
- * Upon entry
- * %eax: system call number
- * %ebx: arg0 to system call
- * %ecx: arg..
- * %edx: arg..
- * %esi: arg..
- * %edi: arg..
- * We push these (to save them) load them up with the
- * values from the calling frame (not all will actually be valid)
- * and make the syscall.
+ * Upon entry:
+ * %eax: system call number - caller save
+ * %ebx: arg0 to system call - callee save
+ * %ecx: arg1 - caller save
+ * %edx: arg2 - caller save
+ * %esi: arg3 - callee save
+ * %edi: arg4 - callee save
+ * %ebp: arg5 - callee save
*/
#include <sys/linux-syscalls.h>
@@ -20,26 +18,37 @@
.align 4
syscall:
+ # Push the callee save registers.
push %ebx
push %esi
push %edi
- mov 16(%esp),%eax
- mov 20(%esp),%ebx
- mov 24(%esp),%ecx
- mov 28(%esp),%edx
- mov 32(%esp),%esi
- mov 36(%esp),%edi
+ push %ebp
+ # Load all the arguments from the calling frame.
+ # (Not all will be valid, depending on the syscall.)
+ mov 20(%esp),%eax
+ mov 24(%esp),%ebx
+ mov 28(%esp),%ecx
+ mov 32(%esp),%edx
+ mov 36(%esp),%esi
+ mov 40(%esp),%edi
+ mov 44(%esp),%ebp
+
+ # Make the system call.
int $0x80
+ # Error?
cmpl $-4095, %eax
jb 1f
+ # Yes, so set errno.
negl %eax
pushl %eax
call __set_errno
addl $4, %esp
orl $-1, %eax
1:
+ # Restore the callee save registers.
+ pop %ebp
pop %edi
pop %esi
pop %ebx