diff options
Diffstat (limited to 'arch/mips/kernel/process.c')
| -rw-r--r-- | arch/mips/kernel/process.c | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index 85bff5d513e5..bf85cc180d91 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -25,6 +25,7 @@ #include <linux/completion.h> #include <linux/kallsyms.h> #include <linux/random.h> +#include <linux/prctl.h> #include <asm/asm.h> #include <asm/bootinfo.h> @@ -562,3 +563,98 @@ void arch_trigger_all_cpu_backtrace(bool include_self) { smp_call_function(arch_dump_stack, NULL, 1); } + +int mips_get_process_fp_mode(struct task_struct *task) +{ + int value = 0; + + if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS)) + value |= PR_FP_MODE_FR; + if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS)) + value |= PR_FP_MODE_FRE; + + return value; +} + +int mips_set_process_fp_mode(struct task_struct *task, unsigned int value) +{ + const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE; + unsigned long switch_count; + struct task_struct *t; + + /* Check the value is valid */ + if (value & ~known_bits) + return -EOPNOTSUPP; + + /* Avoid inadvertently triggering emulation */ + if ((value & PR_FP_MODE_FR) && cpu_has_fpu && + !(current_cpu_data.fpu_id & MIPS_FPIR_F64)) + return -EOPNOTSUPP; + if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre) + return -EOPNOTSUPP; + + /* FR = 0 not supported in MIPS R6 */ + if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6) + return -EOPNOTSUPP; + + /* Save FP & vector context, then disable FPU & MSA */ + if (task->signal == current->signal) + lose_fpu(1); + + /* Prevent any threads from obtaining live FP context */ + atomic_set(&task->mm->context.fp_mode_switching, 1); + smp_mb__after_atomic(); + + /* + * If there are multiple online CPUs then wait until all threads whose + * FP mode is about to change have been context switched. This approach + * allows us to only worry about whether an FP mode switch is in + * progress when FP is first used in a tasks time slice. Pretty much all + * of the mode switch overhead can thus be confined to cases where mode + * switches are actually occuring. That is, to here. However for the + * thread performing the mode switch it may take a while... + */ + if (num_online_cpus() > 1) { + spin_lock_irq(&task->sighand->siglock); + + for_each_thread(task, t) { + if (t == current) + continue; + + switch_count = t->nvcsw + t->nivcsw; + + do { + spin_unlock_irq(&task->sighand->siglock); + cond_resched(); + spin_lock_irq(&task->sighand->siglock); + } while ((t->nvcsw + t->nivcsw) == switch_count); + } + + spin_unlock_irq(&task->sighand->siglock); + } + + /* + * There are now no threads of the process with live FP context, so it + * is safe to proceed with the FP mode switch. + */ + for_each_thread(task, t) { + /* Update desired FP register width */ + if (value & PR_FP_MODE_FR) { + clear_tsk_thread_flag(t, TIF_32BIT_FPREGS); + } else { + set_tsk_thread_flag(t, TIF_32BIT_FPREGS); + clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE); + } + + /* Update desired FP single layout */ + if (value & PR_FP_MODE_FRE) + set_tsk_thread_flag(t, TIF_HYBRID_FPREGS); + else + clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS); + } + + /* Allow threads to use FP again */ + atomic_set(&task->mm->context.fp_mode_switching, 0); + + return 0; +} |