diff options
Diffstat (limited to 'arch/arm64/kernel/process.c')
| -rw-r--r-- | arch/arm64/kernel/process.c | 50 |
1 files changed, 33 insertions, 17 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index a47462def04b..71f788cd2b18 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -17,6 +17,7 @@ #include <linux/sched/task.h> #include <linux/sched/task_stack.h> #include <linux/kernel.h> +#include <linux/lockdep.h> #include <linux/mm.h> #include <linux/stddef.h> #include <linux/sysctl.h> @@ -44,6 +45,7 @@ #include <asm/alternative.h> #include <asm/arch_gicv3.h> #include <asm/compat.h> +#include <asm/cpufeature.h> #include <asm/cacheflush.h> #include <asm/exec.h> #include <asm/fpsimd.h> @@ -332,22 +334,27 @@ void arch_release_task_struct(struct task_struct *tsk) fpsimd_release_task(tsk); } -/* - * src and dst may temporarily have aliased sve_state after task_struct - * is copied. We cannot fix this properly here, because src may have - * live SVE state and dst's thread_info may not exist yet, so tweaking - * either src's or dst's TIF_SVE is not safe. - * - * The unaliasing is done in copy_thread() instead. This works because - * dst is not schedulable or traceable until both of these functions - * have been called. - */ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { if (current->mm) fpsimd_preserve_current_state(); *dst = *src; + /* We rely on the above assignment to initialize dst's thread_flags: */ + BUILD_BUG_ON(!IS_ENABLED(CONFIG_THREAD_INFO_IN_TASK)); + + /* + * Detach src's sve_state (if any) from dst so that it does not + * get erroneously used or freed prematurely. dst's sve_state + * will be allocated on demand later on if dst uses SVE. + * For consistency, also clear TIF_SVE here: this could be done + * later in copy_process(), but to avoid tripping up future + * maintainers it is best not to leave TIF_SVE and sve_state in + * an inconsistent state, even temporarily. + */ + dst->thread.sve_state = NULL; + clear_tsk_thread_flag(dst, TIF_SVE); + return 0; } @@ -361,13 +368,6 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context)); /* - * Unalias p->thread.sve_state (if any) from the parent task - * and disable discard SVE state for p: - */ - clear_tsk_thread_flag(p, TIF_SVE); - p->thread.sve_state = NULL; - - /* * In case p was allocated the same task_struct pointer as some * other recently-exited task, make sure p is disassociated from * any cpu that may have run that now-exited task recently. @@ -633,3 +633,19 @@ static int __init tagged_addr_init(void) core_initcall(tagged_addr_init); #endif /* CONFIG_ARM64_TAGGED_ADDR_ABI */ + +asmlinkage void __sched arm64_preempt_schedule_irq(void) +{ + lockdep_assert_irqs_disabled(); + + /* + * Preempting a task from an IRQ means we leave copies of PSTATE + * on the stack. cpufeature's enable calls may modify PSTATE, but + * resuming one of these preempted tasks would undo those changes. + * + * Only allow a task to be preempted once cpufeatures have been + * enabled. + */ + if (static_branch_likely(&arm64_const_caps_ready)) + preempt_schedule_irq(); +} |