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reading from/writing to non-existant MSRs via /dev/msr no longer crashes the system

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This commit is contained in:
aiju 2011-07-19 15:42:00 +02:00
parent eee8fc8f2a
commit 03d71535ec
4 changed files with 36 additions and 3 deletions
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6
sys/src/9/pc/devarch.c
View file

@ -397,7 +397,8 @@ archread(Chan *c, void *a, long n, vlong offset)
error(Ebadarg);
vp = a;
for(port = offset; port < offset+n; port += 8)
rdmsr(port, vp++);
if(tryrdmsr(port, vp++) < 0)
error(Ebadarg);
return n;
case Qioalloc:
@ -475,7 +476,8 @@ archwrite(Chan *c, void *a, long n, vlong offset)
error(Ebadarg);
vp = a;
for(port = offset; port < offset+n; port += 8)
wrmsr(port, *vp++);
if(trywrmsr(port, *vp++) < 0)
error(Ebadarg);
return n;
default:

4
sys/src/9/pc/fns.h
View file

@ -167,6 +167,10 @@ void trapenable(int, void (*)(Ureg*, void*), void*, char*);
void trapinit(void);
void trapinit0(void);
int tas(void*);
int tryrdmsr(int, vlong*);
void tryrdmsrbody(void);
int trywrmsr(int, vlong);
void trywrmsrbody(void);
uvlong tscticks(uvlong*);
ulong umbmalloc(ulong, int, int);
void umbfree(ulong, int);

21
sys/src/9/pc/l.s
View file

@ -691,6 +691,17 @@ TEXT rdmsr(SB), $0 /* model-specific register */
MOVL AX, 0(CX) /* lo */
MOVL DX, 4(CX) /* hi */
RET
TEXT tryrdmsr(SB), $0 /* model-specific register */
MOVL $0, BP
MOVL index+0(FP), CX
TEXT tryrdmsrbody(SB), $0
RDMSR
MOVL vlong+4(FP), CX /* &vlong */
MOVL AX, 0(CX) /* lo */
MOVL DX, 4(CX) /* hi */
MOVL BP, AX
RET
TEXT wrmsr(SB), $0
MOVL index+0(FP), CX
@ -699,6 +710,16 @@ TEXT wrmsr(SB), $0
WRMSR
RET
TEXT trywrmsr(SB), $0
MOVL $0, BP
MOVL index+0(FP), CX
MOVL lo+4(FP), AX
MOVL hi+8(FP), DX
TEXT trywrmsrbody(SB), $0
WRMSR
MOVL BP, AX
RET
/*
* Try to determine the CPU type which requires fiddling with EFLAGS.
* If the Id bit can be toggled then the CPUID instruction can be used

8
sys/src/9/pc/trap.c
View file

@ -463,7 +463,13 @@ trap(Ureg* ureg)
return;
}
}
if(vno == VectorGPF && !user &&
(ureg->pc == (ulong)(void*)tryrdmsrbody ||
ureg->pc == (ulong)(void*)trywrmsrbody)){
ureg->bp = -1;
ureg->pc += 2;
return;
}
dumpregs(ureg);
if(!user){
ureg->sp = (ulong)&ureg->sp;