diff options
Diffstat (limited to 'arch/arm64/kernel/process.c')
| -rw-r--r-- | arch/arm64/kernel/process.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 325c83b1a24d..de0ab08cb260 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -529,6 +529,27 @@ static void erratum_1418040_thread_switch(struct task_struct *prev, write_sysreg(val, cntkctl_el1); } +static void update_sctlr_el1(u64 sctlr) +{ + sysreg_clear_set(sctlr_el1, SCTLR_USER_MASK, sctlr); + + /* ISB required for the kernel uaccess routines when setting TCF0. */ + isb(); +} + +void set_task_sctlr_el1(u64 sctlr) +{ + /* + * __switch_to() checks current->thread.sctlr as an + * optimisation. Disable preemption so that it does not see + * the variable update before the SCTLR_EL1 one. + */ + preempt_disable(); + current->thread.sctlr_user = sctlr; + update_sctlr_el1(sctlr); + preempt_enable(); +} + /* * Thread switching. */ @@ -559,6 +580,9 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, * registers. */ mte_thread_switch(next); + /* avoid expensive SCTLR_EL1 accesses if no change */ + if (prev->thread.sctlr_user != next->thread.sctlr_user) + update_sctlr_el1(next->thread.sctlr_user); /* the actual thread switch */ last = cpu_switch_to(prev, next); |