diff options
Diffstat (limited to 'libhurd-mm/ia32-exception-entry.S')
| -rw-r--r-- | libhurd-mm/ia32-exception-entry.S | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/libhurd-mm/ia32-exception-entry.S b/libhurd-mm/ia32-exception-entry.S index 6b23c9f..f511563 100644 --- a/libhurd-mm/ia32-exception-entry.S +++ b/libhurd-mm/ia32-exception-entry.S @@ -116,9 +116,9 @@ after_adjust: normal mode. To return to normal mode, we need to restore the saved - registers, including the saved EAX, saved ESP and saved EIP. - On x86, there is no way to atomically restore ESP and EIP from - user code. The solution we use is: + registers, including the saved general registers, saved ESP + and saved EIP. On x86, there is no way to atomically restore + ESP and EIP from user code. The solution we use is: - save the saved EIP on the user stack - restore the saved ESP minus 4 @@ -132,15 +132,15 @@ after_adjust: kernel can transition us back to activated mode. But this raises another problem: the IP and SP that the kernel - see are not those that return us to user code. As this code + sees are not those that return us to user code. As this code relies on the exception stack, a nested stack will leave us in an inconsistent state. (This can also happen if we receive a message before returning to user code.) To avoid this, we register our restore to normal mode function with the kernel. - If the kernel transitions us back to activated while the EIP - is in this range, then it does not save the EIP and ESP and - invokes the exception handler with the interrupt_in_transition - flag set. */ + If the kernel transitions us back to activated mode while the + EIP is in this range, then it does not save the EIP and ESP + and invokes the exception handler with the + interrupt_in_transition flag set. */ /* Reset the activation bit. */ and $0xfffffffe, MODE(%edx) @@ -262,8 +262,8 @@ _exception_handler_end: /* Remove our exception frame, which is at the top of the exception frame stack. */ - mov EF_NEXT(%edx), %ecx - lock mov %ecx, EXCEPTION_STACK(%eax) + mov EF_NEXT(%eax), %ecx + lock mov %ecx, EXCEPTION_STACK(%edx) popl %eax popl %ecx |