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always save and restore %fs, %gs to ensure old segment entries are never

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accessible to user from the hidden CPU segment registers.
This commit is contained in:
kolya 2008-09-24 01:48:31 +00:00
parent adcd16c3f7
commit c7317d4dc7
2 changed files with 12 additions and 4 deletions
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4
trapasm.S
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@ -8,6 +8,8 @@ alltraps:
# Build trap frame. # Build trap frame.
pushl %ds pushl %ds
pushl %es pushl %es
pushl %fs
pushl %gs
pushal pushal
# Set up data segments. # Set up data segments.
@ -24,6 +26,8 @@ alltraps:
.globl trapret .globl trapret
trapret: trapret:
popal popal
popl %gs
popl %fs
popl %es popl %es
popl %ds popl %ds
addl $0x8, %esp # trapno and errcode addl $0x8, %esp # trapno and errcode

12
x86.h
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@ -135,21 +135,25 @@ struct trapframe {
uint eax; uint eax;
// rest of trap frame // rest of trap frame
ushort es; ushort gs;
ushort padding1; ushort padding1;
ushort ds; ushort fs;
ushort padding2; ushort padding2;
ushort es;
ushort padding3;
ushort ds;
ushort padding4;
uint trapno; uint trapno;
// below here defined by x86 hardware // below here defined by x86 hardware
uint err; uint err;
uint eip; uint eip;
ushort cs; ushort cs;
ushort padding3; ushort padding5;
uint eflags; uint eflags;
// below here only when crossing rings, such as from user to kernel // below here only when crossing rings, such as from user to kernel
uint esp; uint esp;
ushort ss; ushort ss;
ushort padding4; ushort padding6;
}; };