commit c7317d4dc74bcb1d0e939c6b06a724fce1510a4e
parent adcd16c3f7588b4a28d37495f05e94278c9e3a1e
Author: kolya <kolya>
Date: Wed, 24 Sep 2008 01:48:31 +0000
always save and restore %fs, %gs to ensure old segment entries are never
accessible to user from the hidden CPU segment registers.
Diffstat:
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/trapasm.S b/trapasm.S
@@ -8,6 +8,8 @@ alltraps:
# Build trap frame.
pushl %ds
pushl %es
+ pushl %fs
+ pushl %gs
pushal
# Set up data segments.
@@ -24,6 +26,8 @@ alltraps:
.globl trapret
trapret:
popal
+ popl %gs
+ popl %fs
popl %es
popl %ds
addl $0x8, %esp # trapno and errcode
diff --git a/x86.h b/x86.h
@@ -135,21 +135,25 @@ struct trapframe {
uint eax;
// rest of trap frame
- ushort es;
+ ushort gs;
ushort padding1;
- ushort ds;
+ ushort fs;
ushort padding2;
+ ushort es;
+ ushort padding3;
+ ushort ds;
+ ushort padding4;
uint trapno;
// below here defined by x86 hardware
uint err;
uint eip;
ushort cs;
- ushort padding3;
+ ushort padding5;
uint eflags;
// below here only when crossing rings, such as from user to kernel
uint esp;
ushort ss;
- ushort padding4;
+ ushort padding6;
};