Messages in this thread | | | From | "Misono, Tomohiro" <> | Subject | Question about dmesg/sysfs output when retpoline config is disabled | Date | Tue, 30 Jan 2018 13:52:46 +0900 |
| |
Hello,
I think dmesg/sysfs output messages are not suitable if retpoline config is off:
I intentionally compiled the kernel 4.15.0 with CONFIG_RETPOLINE=n for test and boot it with the following kernel command line option to check dmesg/sysfs:
(a) no command line option or "spectre_v2=on" or "spectre_v2=auto" $ dmesg | grep -i spectre [ 0.017714] Spectre V2 mitigation: Vulnerable: Minimal generic ASM retpoline $ cat /sys/devices/system/cpu/vulnerabilities/spectre_v2 Minimal generic ASM retpoline
(b) "spectre_v2=off" $ dmesg | grep -i spectre [ 0.017002] Spectre V2 mitigation: disabled on command line. $ cat /sys/devices/system/cpu/vulnerabilities/spectre_v2 Vulnerable
(c) "spectre_v2=retpoline" $ dmesg | grep -i spectre [ 0.018002] Spectre V2 mitigation: kernel not compiled with retpoline; no mitigation available! $ cat /sys/devices/system/cpu/vulnerabilities/spectre_v2 Vulnerable
I think the output of (c) is correct for this case, or are these outputs actually right?
Also, the output of (a) is the same with following condition: (1) CONFIG_RETPOLINE=n, and (2) CONFIG_RETPOLINE=y but the compiler did not support retpoline These cannot be distinguished unless option of (c) is explicitly used.
Regards, Tomohiro Misono
| |