diff options
| -rw-r--r-- | arch/mips/include/asm/mmu.h | 3 | ||||
| -rw-r--r-- | arch/mips/include/asm/mmu_context.h | 2 | ||||
| -rw-r--r-- | arch/mips/include/asm/processor.h | 11 | ||||
| -rw-r--r-- | arch/mips/kernel/process.c | 92 | ||||
| -rw-r--r-- | arch/mips/kernel/traps.c | 19 | ||||
| -rw-r--r-- | include/uapi/linux/prctl.h | 5 | ||||
| -rw-r--r-- | kernel/sys.c | 12 |
7 files changed, 144 insertions, 0 deletions
diff --git a/arch/mips/include/asm/mmu.h b/arch/mips/include/asm/mmu.h index c436138945a8..1afa1f986df8 100644 --- a/arch/mips/include/asm/mmu.h +++ b/arch/mips/include/asm/mmu.h @@ -1,9 +1,12 @@ #ifndef __ASM_MMU_H #define __ASM_MMU_H +#include <linux/atomic.h> + typedef struct { unsigned long asid[NR_CPUS]; void *vdso; + atomic_t fp_mode_switching; } mm_context_t; #endif /* __ASM_MMU_H */ diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h index 2f82568a3ee4..87f11072f557 100644 --- a/arch/mips/include/asm/mmu_context.h +++ b/arch/mips/include/asm/mmu_context.h @@ -132,6 +132,8 @@ init_new_context(struct task_struct *tsk, struct mm_struct *mm) for_each_possible_cpu(i) cpu_context(i, mm) = 0; + atomic_set(&mm->context.fp_mode_switching, 0); + return 0; } diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index f1df4cb4a286..9daa38608cd8 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -399,4 +399,15 @@ unsigned long get_wchan(struct task_struct *p); #endif +/* + * Functions & macros implementing the PR_GET_FP_MODE & PR_SET_FP_MODE options + * to the prctl syscall. + */ +extern int mips_get_process_fp_mode(struct task_struct *task); +extern int mips_set_process_fp_mode(struct task_struct *task, + unsigned int value); + +#define GET_FP_MODE(task) mips_get_process_fp_mode(task) +#define SET_FP_MODE(task,value) mips_set_process_fp_mode(task, value) + #endif /* _ASM_PROCESSOR_H */ diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index eb76434828e8..4677b4c67da6 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> @@ -550,3 +551,94 @@ 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; + + /* 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; +} diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index ad3d2031c327..d5fbfb51b9da 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -1134,10 +1134,29 @@ static int default_cu2_call(struct notifier_block *nfb, unsigned long action, return NOTIFY_OK; } +static int wait_on_fp_mode_switch(atomic_t *p) +{ + /* + * The FP mode for this task is currently being switched. That may + * involve modifications to the format of this tasks FP context which + * make it unsafe to proceed with execution for the moment. Instead, + * schedule some other task. + */ + schedule(); + return 0; +} + static int enable_restore_fp_context(int msa) { int err, was_fpu_owner, prior_msa; + /* + * If an FP mode switch is currently underway, wait for it to + * complete before proceeding. + */ + wait_on_atomic_t(¤t->mm->context.fp_mode_switching, + wait_on_fp_mode_switch, TASK_KILLABLE); + if (!used_math()) { /* First time FP context user. */ preempt_disable(); diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 89f63503f903..31891d9535e2 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -185,4 +185,9 @@ struct prctl_mm_map { #define PR_MPX_ENABLE_MANAGEMENT 43 #define PR_MPX_DISABLE_MANAGEMENT 44 +#define PR_SET_FP_MODE 45 +#define PR_GET_FP_MODE 46 +# define PR_FP_MODE_FR (1 << 0) /* 64b FP registers */ +# define PR_FP_MODE_FRE (1 << 1) /* 32b compatibility */ + #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index a8c9f5a7dda6..08b16bbdcdf0 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -97,6 +97,12 @@ #ifndef MPX_DISABLE_MANAGEMENT # define MPX_DISABLE_MANAGEMENT(a) (-EINVAL) #endif +#ifndef GET_FP_MODE +# define GET_FP_MODE(a) (-EINVAL) +#endif +#ifndef SET_FP_MODE +# define SET_FP_MODE(a,b) (-EINVAL) +#endif /* * this is where the system-wide overflow UID and GID are defined, for @@ -2215,6 +2221,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, case PR_MPX_DISABLE_MANAGEMENT: error = MPX_DISABLE_MANAGEMENT(me); break; + case PR_SET_FP_MODE: + error = SET_FP_MODE(me, arg2); + break; + case PR_GET_FP_MODE: + error = GET_FP_MODE(me); + break; default: error = -EINVAL; break; |