[PATCH] uml: skas0 stubs now check system call return values
Change syscall-stub's data to include a "expected retval".
Stub now checks syscalls retval and aborts execution of syscall list, if
retval != expected retval.
run_syscall_stub prints the data of the failed syscall, using the data pointer
and retval written by the stub to the beginning of the stack.
one_syscall_stub is removed, to simplify code, because only some instructions
are saved by one_syscall_stub, no host-syscall.
Using the stub with additional data (modify_ldt via stub)
is prepared also.
Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/sys-i386/stub.S b/arch/um/sys-i386/stub.S
index a0f9506..6a70d9a 100644
--- a/arch/um/sys-i386/stub.S
+++ b/arch/um/sys-i386/stub.S
@@ -2,24 +2,50 @@
.globl syscall_stub
.section .__syscall_stub, "x"
-syscall_stub:
- int $0x80
- mov %eax, UML_CONFIG_STUB_DATA
- int3
.globl batch_syscall_stub
batch_syscall_stub:
- mov $UML_CONFIG_STUB_DATA, %esp
-again: pop %eax
+ /* load pointer to first operation */
+ mov $(UML_CONFIG_STUB_DATA+8), %esp
+
+again:
+ /* load length of additional data */
+ mov 0x0(%esp), %eax
+
+ /* if(length == 0) : end of list */
+ /* write possible 0 to header */
+ mov %eax, UML_CONFIG_STUB_DATA+4
cmpl $0, %eax
jz done
+
+ /* save current pointer */
+ mov %esp, UML_CONFIG_STUB_DATA+4
+
+ /* skip additional data */
+ add %eax, %esp
+
+ /* load syscall-# */
+ pop %eax
+
+ /* load syscall params */
pop %ebx
pop %ecx
pop %edx
pop %esi
pop %edi
pop %ebp
+
+ /* execute syscall */
int $0x80
+
+ /* check return value */
+ pop %ebx
+ cmp %ebx, %eax
+ je again
+
+done:
+ /* save return value */
mov %eax, UML_CONFIG_STUB_DATA
- jmp again
-done: int3
+
+ /* stop */
+ int3