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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-05 12:50:34 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-05 12:50:34 -0800 |
| commit | edaed168e135f8ec87b27b567a367cbb041f2243 (patch) | |
| tree | dc56708c4a2c6ace03c8a7211e941c8911a17092 /arch | |
| parent | 78f860135433a8bba406352fbdcea8e8980583bf (diff) | |
| parent | 71368af9027f18fe5d1c6f372cfdff7e4bde8b48 (diff) | |
| download | lwn-edaed168e135f8ec87b27b567a367cbb041f2243.tar.gz lwn-edaed168e135f8ec87b27b567a367cbb041f2243.zip | |
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86/pti update from Thomas Gleixner:
"Just a single change from the anti-performance departement:
- Add a new PR_SPEC_DISABLE_NOEXEC option which allows to apply the
speculation protections on a process without inheriting the state
on exec.
This remedies a situation where a Java-launcher has speculation
protections enabled because that's the default for JVMs which
causes the launched regular harmless processes to inherit the
protection state which results in unintended performance
degradation"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/speculation: Add PR_SPEC_DISABLE_NOEXEC
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 12 | ||||
| -rw-r--r-- | arch/x86/kernel/process.c | 12 |
2 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 01874d54f4fd..2da82eff0eb4 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -798,15 +798,25 @@ static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl) if (task_spec_ssb_force_disable(task)) return -EPERM; task_clear_spec_ssb_disable(task); + task_clear_spec_ssb_noexec(task); task_update_spec_tif(task); break; case PR_SPEC_DISABLE: task_set_spec_ssb_disable(task); + task_clear_spec_ssb_noexec(task); task_update_spec_tif(task); break; case PR_SPEC_FORCE_DISABLE: task_set_spec_ssb_disable(task); task_set_spec_ssb_force_disable(task); + task_clear_spec_ssb_noexec(task); + task_update_spec_tif(task); + break; + case PR_SPEC_DISABLE_NOEXEC: + if (task_spec_ssb_force_disable(task)) + return -EPERM; + task_set_spec_ssb_disable(task); + task_set_spec_ssb_noexec(task); task_update_spec_tif(task); break; default: @@ -885,6 +895,8 @@ static int ssb_prctl_get(struct task_struct *task) case SPEC_STORE_BYPASS_PRCTL: if (task_spec_ssb_force_disable(task)) return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE; + if (task_spec_ssb_noexec(task)) + return PR_SPEC_PRCTL | PR_SPEC_DISABLE_NOEXEC; if (task_spec_ssb_disable(task)) return PR_SPEC_PRCTL | PR_SPEC_DISABLE; return PR_SPEC_PRCTL | PR_SPEC_ENABLE; diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 90ae0ca51083..58ac7be52c7a 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -255,6 +255,18 @@ void arch_setup_new_exec(void) /* If cpuid was previously disabled for this task, re-enable it. */ if (test_thread_flag(TIF_NOCPUID)) enable_cpuid(); + + /* + * Don't inherit TIF_SSBD across exec boundary when + * PR_SPEC_DISABLE_NOEXEC is used. + */ + if (test_thread_flag(TIF_SSBD) && + task_spec_ssb_noexec(current)) { + clear_thread_flag(TIF_SSBD); + task_clear_spec_ssb_disable(current); + task_clear_spec_ssb_noexec(current); + speculation_ctrl_update(task_thread_info(current)->flags); + } } static inline void switch_to_bitmap(struct thread_struct *prev, |