diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2018-04-29 15:20:11 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-05-03 13:55:50 +0200 |
| commit | b617cfc858161140d69cc0b5cc211996b557a1c7 (patch) | |
| tree | 64803e15cb79a0d535504ea9b873b7846f614c58 /include | |
| parent | 28a2775217b17208811fa43a9e96bd1fdf417b86 (diff) | |
prctl: Add speculation control prctls
Add two new prctls to control aspects of speculation related vulnerabilites
and their mitigations to provide finer grained control over performance
impacting mitigations.
PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature
which is selected with arg2 of prctl(2). The return value uses bit 0-2 with
the following meaning:
Bit Define Description
0 PR_SPEC_PRCTL Mitigation can be controlled per task by
PR_SET_SPECULATION_CTRL
1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is
disabled
2 PR_SPEC_DISABLE The speculation feature is disabled, mitigation is
enabled
If all bits are 0 the CPU is not affected by the speculation misfeature.
If PR_SPEC_PRCTL is set, then the per task control of the mitigation is
available. If not set, prctl(PR_SET_SPECULATION_CTRL) for the speculation
misfeature will fail.
PR_SET_SPECULATION_CTRL allows to control the speculation misfeature, which
is selected by arg2 of prctl(2) per task. arg3 is used to hand in the
control value, i.e. either PR_SPEC_ENABLE or PR_SPEC_DISABLE.
The common return values are:
EINVAL prctl is not implemented by the architecture or the unused prctl()
arguments are not 0
ENODEV arg2 is selecting a not supported speculation misfeature
PR_SET_SPECULATION_CTRL has these additional return values:
ERANGE arg3 is incorrect, i.e. it's not either PR_SPEC_ENABLE or PR_SPEC_DISABLE
ENXIO prctl control of the selected speculation misfeature is disabled
The first supported controlable speculation misfeature is
PR_SPEC_STORE_BYPASS. Add the define so this can be shared between
architectures.
Based on an initial patch from Tim Chen and mostly rewritten.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/nospec.h | 5 | ||||
| -rw-r--r-- | include/uapi/linux/prctl.h | 11 |
2 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/nospec.h b/include/linux/nospec.h index e791ebc65c9c..700bb8a4e4ea 100644 --- a/include/linux/nospec.h +++ b/include/linux/nospec.h @@ -55,4 +55,9 @@ static inline unsigned long array_index_mask_nospec(unsigned long index, \ (typeof(_i)) (_i & _mask); \ }) + +/* Speculation control prctl */ +int arch_prctl_spec_ctrl_get(unsigned long which); +int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl); + #endif /* _LINUX_NOSPEC_H */ diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index af5f8c2df87a..ebf057ac1346 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -207,4 +207,15 @@ struct prctl_mm_map { # define PR_SVE_VL_LEN_MASK 0xffff # define PR_SVE_VL_INHERIT (1 << 17) /* inherit across exec */ +/* Per task speculation control */ +#define PR_GET_SPECULATION_CTRL 52 +#define PR_SET_SPECULATION_CTRL 53 +/* Speculation control variants */ +# define PR_SPEC_STORE_BYPASS 0 +/* Return and control values for PR_SET/GET_SPECULATION_CTRL */ +# define PR_SPEC_NOT_AFFECTED 0 +# define PR_SPEC_PRCTL (1UL << 0) +# define PR_SPEC_ENABLE (1UL << 1) +# define PR_SPEC_DISABLE (1UL << 2) + #endif /* _LINUX_PRCTL_H */ |