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https://github.com/speed47/spectre-meltdown-checker
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refactor: rewrite read_cpuid to get more common code parts between BSD and Linux
This commit is contained in:
Stéphane Lesimple
parent
0919f5c236
commit
7a4ebe8009
@ -755,10 +755,19 @@ load_cpuid()
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read_cpuid()
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{
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# leaf is the value of the eax register when calling the cpuid instruction:
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_leaf="$1"
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_bytenum="$2"
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_and_operand="$3"
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# eax=1 ebx=2 ecx=3 edx=4:
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_register="$2"
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# number of bits to shift the register right to:
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_shift="$3"
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# mask to apply as an AND operand to the shifted register value
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_mask="$4"
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# wanted value (optional), if present we return 0(true) if the obtained value is equal, 1 otherwise:
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_wanted="$5"
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# in any case, the read value is globally available in $read_cpuid_value
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read_cpuid_value=''
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if [ ! -e /dev/cpu/0/cpuid ] && [ ! -e /dev/cpuctl0 ]; then
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# try to load the module ourselves (and remember it so we can rmmod it afterwards)
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load_cpuid
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@ -768,61 +777,39 @@ read_cpuid()
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# Linux
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# we need _leaf to be converted to decimal for dd
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_leaf=$(( _leaf ))
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if [ "$opt_verbose" -ge 3 ]; then
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dd if=/dev/cpu/0/cpuid bs=16 skip="$_leaf" iflag=skip_bytes count=1 >/dev/null 2>/dev/null
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_debug "cpuid: reading leaf$_leaf of cpuid on cpu0, ret=$?"
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_debug "cpuid: leaf$_leaf eax-ebx-ecx-edx: $( dd if=/dev/cpu/0/cpuid bs=16 skip="$_leaf" iflag=skip_bytes count=1 2>/dev/null | od -x -A n)"
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fi
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# getting proper byte of edx on leaf$_leaf of cpuinfo in decimal
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_reg_byte=$(dd if=/dev/cpu/0/cpuid bs=16 skip="$_leaf" iflag=skip_bytes count=1 2>/dev/null | dd bs=1 skip="$_bytenum" count=1 2>/dev/null | od -t u1 -A n | awk '{print $1}')
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_debug "cpuid: leaf$_leaf byte $_bytenum: $_reg_byte (decimal)"
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_reg_bit=$(( _reg_byte & _and_operand ))
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_debug "cpuid: leaf$_leaf byte $_bytenum & $_and_operand = $_reg_bit"
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[ "$_reg_bit" -eq 0 ] && return 1
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# $_reg_bit is > 0, so the bit was found: return true (aka 0)
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return 0
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_cpuid=$(dd if=/dev/cpu/0/cpuid bs=16 skip="$_leaf" iflag=skip_bytes count=1 2>/dev/null | od -A n -t u4)
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elif [ -e /dev/cpuctl0 ]; then
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# BSD
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_cpuid=$(cpucontrol -i "$_leaf" /dev/cpuctl0 2>/dev/null | awk '{print $4,$5,$6,$7}')
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# cpuid level 0x1: 0x000306d4 0x00100800 0x4dfaebbf 0xbfebfbff
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_debug "cpuid: got $_cpuid for leaf $_leaf"
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if [ "$_bytenum" -lt 4 ]; then
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_reg_byte=$(echo "$_cpuid" | awk '{print $1}')
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_debug "cpuid: $_bytenum is part of EAX ($_reg_byte)"
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elif [ "$_bytenum" -lt 8 ]; then
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_reg_byte=$(echo "$_cpuid" | awk '{print $2}')
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_debug "cpuid: $_bytenum is part of EBX ($_reg_byte)"
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elif [ "$_bytenum" -lt 12 ]; then
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_reg_byte=$(echo "$_cpuid" | awk '{print $3}')
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_debug "cpuid: $_bytenum is part of ECX ($_reg_byte)"
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elif [ "$_bytenum" -lt 16 ]; then
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_reg_byte=$(echo "$_cpuid" | awk '{print $4}')
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_debug "cpuid: $_bytenum is part of EDX ($_reg_byte)"
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else
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_warn "read_cpuid: error in the program, please report to the developer ($_leaf/$_bytenum/$_and_operand)"
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exit 1
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fi
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_bytenum=$(( _bytenum % 4 ))
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case "$_bytenum" in
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0) _reg_byte=0x$(echo "$_reg_byte" | cut -c9-10) ;;
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1) _reg_byte=0x$(echo "$_reg_byte" | cut -c7-8) ;;
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2) _reg_byte=0x$(echo "$_reg_byte" | cut -c5-6) ;;
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3) _reg_byte=0x$(echo "$_reg_byte" | cut -c3-4) ;;
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*) exit 8;
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esac
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_debug "cpuid: wanted byte is $_reg_byte"
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# convert to decimal
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_reg_byte=$(( _reg_byte ))
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_debug "cpuid: decimal value is $_reg_byte"
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_reg_bit=$(( _reg_byte & _and_operand ))
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_debug "cpuid: leaf$_leaf byte $_bytenum & $_and_operand = $_reg_bit"
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[ "$_reg_bit" -eq 0 ] && return 1
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# $_reg_bit is > 0, so the bit was found: return true (aka 0)
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return 0
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return 2
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fi
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return 2
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_debug "cpuid: leaf$_leaf on cpu0, eax-ebx-ecx-edx: $_cpuid"
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[ -z "$_cpuid" ] && return 2
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# get the value of the register we want
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_reg=$(echo "$_cpuid" | awk '{print $'"$_register"'}')
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# Linux returns it as decimal, BSD as hex, normalize to decimal
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_reg=$(( _reg ))
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# shellcheck disable=SC2046
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_debug "cpuid: wanted register ($_register) has value $_reg aka "$(printf "%08x" "$_reg")
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_reg_shifted=$(( _reg >> _shift ))
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# shellcheck disable=SC2046
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_debug "cpuid: shifted value by $_shift is $_reg_shifted aka "$(printf "%x" "$_reg_shifted")
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read_cpuid_value=$(( _reg_shifted & _mask ))
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# shellcheck disable=SC2046
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_debug "cpuid: after AND $_mask, final value is $read_cpuid_value aka "$(printf "%x" "$read_cpuid_value")
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if [ -n "$_wanted" ]; then
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_debug "cpuid: wanted $_wanted and got $read_cpuid_value"
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if [ "$read_cpuid_value" = "$_wanted" ]; then
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return 0
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else
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return 1
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fi
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fi
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return 0
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}
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dmesg_grep()
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@ -1312,13 +1299,15 @@ write_msr()
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return $ret
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}
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# $1 - msr number
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# $2 - cpu index
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read_msr()
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{
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# _msr must be in hex, in the form 0x1234:
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_msr="$1"
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# cpu index, starting from 0:
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_cpu="$2"
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read_msr_value=''
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if [ "$os" != Linux ]; then
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_msr=$(cpucontrol -m "$1" "/dev/cpuctl$2" 2>/dev/null); ret=$?
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_msr=$(cpucontrol -m "$_msr" "/dev/cpuctl$_cpu" 2>/dev/null); ret=$?
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[ $ret -ne 0 ] && return 1
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# MSR 0x10: 0x000003e1 0xb106dded
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_msr_h=$(echo "$_msr" | awk '{print $3}');
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@ -1328,14 +1317,15 @@ read_msr()
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read_msr_value="$_msr_h $_msr_l"
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else
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# convert to decimal
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_msrindex=$(( $1 ))
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if [ ! -r /dev/cpu/"$2"/msr ]; then
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_msr=$(( _msr ))
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if [ ! -r /dev/cpu/"$_cpu"/msr ]; then
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return 200 # permission error
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fi
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if ! dd if=/dev/cpu/"$2"/msr bs=8 count=1 skip="$_msrindex" iflag=skip_bytes >/dev/null 2>&1; then
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read_msr_value=$(dd if=/dev/cpu/"$_cpu"/msr bs=8 count=1 skip="$_msr" iflag=skip_bytes 2>/dev/null | od -t u1 -A n)
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if [ -z "$read_msr_value" ]; then
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# MSR doesn't exist, don't check for $? because some versions of dd still return 0!
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return 1
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fi
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read_msr_value=$(dd if=/dev/cpu/"$2"/msr bs=8 count=1 skip="$_msrindex" iflag=skip_bytes 2>/dev/null | od -t u1 -A n)
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fi
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_debug "read_msr: MSR=$1 value is $read_msr_value"
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return 0
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@ -1402,7 +1392,7 @@ check_cpu()
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_info_nol " * CPU indicates IBRS capability: "
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# from kernel src: { X86_FEATURE_SPEC_CTRL, CPUID_EDX,26, 0x00000007, 0 },
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read_cpuid 0x7 15 4; ret=$?
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read_cpuid 0x7 4 26 1 1; ret=$?
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if [ $ret -eq 0 ]; then
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pstatus green YES "SPEC_CTRL feature bit"
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cpuid_spec_ctrl=1
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@ -1469,7 +1459,7 @@ check_cpu()
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_info_nol " * CPU indicates IBPB capability: "
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# CPUID EAX=0x80000008, ECX=0x00 return EBX[12] indicates support for just IBPB.
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read_cpuid 0x80000008 5 16; ret=$?
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read_cpuid 0x80000008 2 12 1 1; ret=$?
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if [ $ret -eq 0 ]; then
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pstatus green YES "IBPB_SUPPORT feature bit"
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elif [ "$cpuid_spec_ctrl" = 1 ]; then
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@ -1493,7 +1483,7 @@ check_cpu()
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_info_nol " * CPU indicates STIBP capability: "
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# A processor supports STIBP if it enumerates CPUID (EAX=7H,ECX=0):EDX[27] as 1
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read_cpuid 0x7 15 8; ret=$?
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read_cpuid 0x7 4 27 1 1; ret=$?
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if [ $ret -eq 0 ]; then
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pstatus green YES
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elif [ $ret -eq 2 ]; then
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@ -1505,8 +1495,8 @@ check_cpu()
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_info " * Enhanced IBRS (IBRS_ALL)"
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_info_nol " * CPU indicates ARCH_CAPABILITIES MSR availability: "
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cpuid_arch_capabilities=-1
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# A processor supports STIBP if it enumerates CPUID (EAX=7H,ECX=0):EDX[27] as 1
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read_cpuid 0x7 15 32; ret=$?
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# A processor supports the ARCH_CAPABILITIES MSR if it enumerates CPUID (EAX=7H,ECX=0):EDX[29] as 1
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read_cpuid 0x7 4 29 1 1; ret=$?
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if [ $ret -eq 0 ]; then
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pstatus green YES
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cpuid_arch_capabilities=1
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