diff options
Diffstat (limited to 'arch/arm64/kernel/process.c')
| -rw-r--r-- | arch/arm64/kernel/process.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 9e773732520c..243fd247d04e 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -296,6 +296,10 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, if (IS_ENABLED(CONFIG_ARM64_UAO) && cpus_have_const_cap(ARM64_HAS_UAO)) childregs->pstate |= PSR_UAO_BIT; + + if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) + set_ssbs_bit(childregs); + p->thread.cpu_context.x19 = stack_start; p->thread.cpu_context.x20 = stk_sz; } @@ -336,6 +340,32 @@ void uao_thread_switch(struct task_struct *next) } /* + * Force SSBS state on context-switch, since it may be lost after migrating + * from a CPU which treats the bit as RES0 in a heterogeneous system. + */ +static void ssbs_thread_switch(struct task_struct *next) +{ + struct pt_regs *regs = task_pt_regs(next); + + /* + * Nothing to do for kernel threads, but 'regs' may be junk + * (e.g. idle task) so check the flags and bail early. + */ + if (unlikely(next->flags & PF_KTHREAD)) + return; + + /* If the mitigation is enabled, then we leave SSBS clear. */ + if ((arm64_get_ssbd_state() == ARM64_SSBD_FORCE_ENABLE) || + test_tsk_thread_flag(next, TIF_SSBD)) + return; + + if (compat_user_mode(regs)) + set_compat_ssbs_bit(regs); + else if (user_mode(regs)) + set_ssbs_bit(regs); +} + +/* * We store our current task in sp_el0, which is clobbered by userspace. Keep a * shadow copy so that we can restore this upon entry from userspace. * @@ -363,6 +393,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, contextidr_thread_switch(next); entry_task_switch(next); uao_thread_switch(next); + ssbs_thread_switch(next); /* * Complete any pending TLB or cache maintenance on this CPU in case |