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mirror of https://github.com/speed47/spectre-meltdown-checker synced 2024-12-22 04:13:38 +01:00

feat: read/write msr now supports msr-tools or perl as dd fallback

This commit is contained in:
Stéphane Lesimple 2018-08-08 16:52:31 +02:00
parent f4592bf3a8
commit ab67a9221d

View File

@ -1499,18 +1499,39 @@ number_of_cpus()
# $2 - cpu index
write_msr()
{
# _msr must be in hex, in the form 0x1234:
_msr="$1"
# cpu index, starting from 0:
_cpu="$2"
if [ "$os" != Linux ]; then
cpucontrol -m "$1=0" "/dev/cpuctl$2" >/dev/null 2>&1; ret=$?
cpucontrol -m "$_msr=0" "/dev/cpuctl$_cpu" >/dev/null 2>&1; ret=$?
else
# for Linux
# convert to decimal
_msrindex=$(( $1 ))
if [ ! -w /dev/cpu/"$2"/msr ]; then
_msr=$(( _msr ))
if [ ! -w /dev/cpu/"$_cpu"/msr ]; then
ret=200 # permission error
# if wrmsr is available, use it
elif which wrmsr >/dev/null 2>&1 && [ "$SMC_NO_WRMSR" != 1 ]; then
_debug "write_msr: using wrmsr"
wrmsr $_msr 0 2>/dev/null; ret=$?
# or if we have perl, use it, any 5.x version will work
elif which perl >/dev/null 2>&1 && [ "$SMC_NO_PERL" != 1 ]; then
_debug "write_msr: using perl"
ret=1
perl -e "open(M,'>','/dev/cpu/$_cpu/msr') and seek(M,$_msr,0) and exit(syswrite(M,pack('H16',0)))"; [ $? -eq 8 ] && ret=0
# fallback to dd if it supports seek_bytes
elif dd if=/dev/null of=/dev/null bs=8 count=1 seek="$_msr" oflag=seek_bytes 2>/dev/null; then
_debug "write_msr: using dd"
dd if=/dev/zero of=/dev/cpu/"$_cpu"/msr bs=8 count=1 seek="$_msr" oflag=seek_bytes 2>/dev/null; ret=$?
else
dd if=/dev/zero of=/dev/cpu/"$2"/msr bs=8 count=1 seek="$_msrindex" oflag=seek_bytes 2>/dev/null; ret=$?
_debug "write_msr: got no wrmsr, perl or recent enough dd!"
return 201 # missing tool error
fi
fi
_debug "write_msr: for cpu $2 on msr $1 ($_msrindex), ret=$ret"
# normalize ret
[ "$ret" != 0 ] && ret=1
_debug "write_msr: for cpu $_cpu on msr $_msr, ret=$ret"
return $ret
}
@ -1531,12 +1552,27 @@ read_msr()
_msr_l="$(( _msr_l >> 24 & 0xFF )) $(( _msr_l >> 16 & 0xFF )) $(( _msr_l >> 8 & 0xFF )) $(( _msr_l & 0xFF ))"
read_msr_value="$_msr_h $_msr_l"
else
# for Linux
# convert to decimal
_msr=$(( _msr ))
if [ ! -r /dev/cpu/"$_cpu"/msr ]; then
return 200 # permission error
# if rdmsr is available, use it
elif which rdmsr >/dev/null 2>&1 && [ "$SMC_NO_RDMSR" != 1 ]; then
_debug "read_msr: using rdmsr"
read_msr_value=$(rdmsr -r $_msr 2>/dev/null | od -t u1 -A n)
# or if we have perl, use it, any 5.x version will work
elif which perl >/dev/null 2>&1 && [ "$SMC_NO_PERL" != 1 ]; then
_debug "read_msr: using perl"
read_msr_value=$(perl -e "open(M,'<','/dev/cpu/$_cpu/msr') and seek(M,$_msr,0) and read(M,\$_,8) and print" | od -An -t u1)
# fallback to dd if it supports skip_bytes
elif dd if=/dev/null of=/dev/null bs=8 count=1 skip="$_msr" iflag=skip_bytes 2>/dev/null; then
_debug "read_msr: using dd"
read_msr_value=$(dd if=/dev/cpu/"$_cpu"/msr bs=8 count=1 skip="$_msr" iflag=skip_bytes 2>/dev/null | od -t u1 -A n)
else
_debug "read_msr: got no rdmsr, perl or recent enough dd!"
return 201 # missing tool error
fi
read_msr_value=$(dd if=/dev/cpu/"$_cpu"/msr bs=8 count=1 skip="$_msr" iflag=skip_bytes 2>/dev/null | od -t u1 -A n)
if [ -z "$read_msr_value" ]; then
# MSR doesn't exist, don't check for $? because some versions of dd still return 0!
return 1
@ -1569,9 +1605,7 @@ check_cpu()
pstatus yellow UNKNOWN "is msr kernel module available?"
else
# the new MSR 'SPEC_CTRL' is at offset 0x48
# here we use dd, it's the same as using 'rdmsr 0x48' but without needing the rdmsr tool
# if we get a read error, the MSR is not there. bs has to be 8 for msr
# skip=9 because 8*9=72=0x48
# we check if we have it for all cpus
val=0
cpu_mismatch=0
for i in $(seq 0 "$idx_max_cpu")
@ -1598,6 +1632,9 @@ check_cpu()
elif [ $val -eq 200 ]; then
pstatus yellow UNKNOWN "is msr kernel module available?"
spec_ctrl_msr=-1
elif [ $val -eq 201 ]; then
pstatus yellow UNKNOWN "missing tool, install either msr-tools or perl"
spec_ctrl_msr=-1
else
spec_ctrl_msr=0
pstatus yellow NO
@ -1659,8 +1696,7 @@ check_cpu()
pstatus yellow UNKNOWN "is msr kernel module available?"
else
# the new MSR 'PRED_CTRL' is at offset 0x49, write-only
# here we use dd, it's the same as using 'wrmsr 0x49 0' but without needing the wrmsr tool
# if we get a write error, the MSR is not there
# we test if of all cpus
val=0
cpu_mismatch=0
for i in $(seq 0 "$idx_max_cpu")
@ -1833,8 +1869,7 @@ check_cpu()
pstatus yellow UNKNOWN "is msr kernel module available?"
else
# the new MSR 'ARCH_CAPABILITIES' is at offset 0x10a
# here we use dd, it's the same as using 'rdmsr 0x10a' but without needing the rdmsr tool
# if we get a read error, the MSR is not there. bs has to be 8 for msr
# we check if we have it for all cpus
val=0
val_cap_msr=0
cpu_mismatch=0
@ -1874,6 +1909,8 @@ check_cpu()
fi
elif [ $val -eq 200 ]; then
pstatus yellow UNKNOWN "is msr kernel module available?"
elif [ $val -eq 201 ]; then
pstatus yellow UNKNOWN "missing tool, install either msr-tools or perl"
else
pstatus yellow NO
fi