diff options
Diffstat (limited to 'arch/mips/kernel/traps.c')
| -rw-r--r-- | arch/mips/kernel/traps.c | 101 |
1 files changed, 95 insertions, 6 deletions
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index b0c7f80e05e5..4f27cbfad1e5 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -47,6 +47,7 @@ #include <asm/mipsregs.h> #include <asm/mipsmtregs.h> #include <asm/module.h> +#include <asm/msa.h> #include <asm/pgtable.h> #include <asm/ptrace.h> #include <asm/sections.h> @@ -79,6 +80,7 @@ extern asmlinkage void handle_ov(void); extern asmlinkage void handle_tr(void); extern asmlinkage void handle_fpe(void); extern asmlinkage void handle_ftlb(void); +extern asmlinkage void handle_msa(void); extern asmlinkage void handle_mdmx(void); extern asmlinkage void handle_watch(void); extern asmlinkage void handle_mt(void); @@ -1074,6 +1076,76 @@ static int default_cu2_call(struct notifier_block *nfb, unsigned long action, return NOTIFY_OK; } +static int enable_restore_fp_context(int msa) +{ + int err, was_fpu_owner; + + if (!used_math()) { + /* First time FP context user. */ + err = init_fpu(); + if (msa && !err) + enable_msa(); + if (!err) + set_used_math(); + return err; + } + + /* + * This task has formerly used the FP context. + * + * If this thread has no live MSA vector context then we can simply + * restore the scalar FP context. If it has live MSA vector context + * (that is, it has or may have used MSA since last performing a + * function call) then we'll need to restore the vector context. This + * applies even if we're currently only executing a scalar FP + * instruction. This is because if we were to later execute an MSA + * instruction then we'd either have to: + * + * - Restore the vector context & clobber any registers modified by + * scalar FP instructions between now & then. + * + * or + * + * - Not restore the vector context & lose the most significant bits + * of all vector registers. + * + * Neither of those options is acceptable. We cannot restore the least + * significant bits of the registers now & only restore the most + * significant bits later because the most significant bits of any + * vector registers whose aliased FP register is modified now will have + * been zeroed. We'd have no way to know that when restoring the vector + * context & thus may load an outdated value for the most significant + * bits of a vector register. + */ + if (!msa && !thread_msa_context_live()) + return own_fpu(1); + + /* + * This task is using or has previously used MSA. Thus we require + * that Status.FR == 1. + */ + was_fpu_owner = is_fpu_owner(); + err = own_fpu(0); + if (err) + return err; + + enable_msa(); + write_msa_csr(current->thread.fpu.msacsr); + set_thread_flag(TIF_USEDMSA); + + /* + * If this is the first time that the task is using MSA and it has + * previously used scalar FP in this time slice then we already nave + * FP context which we shouldn't clobber. + */ + if (!test_and_set_thread_flag(TIF_MSA_CTX_LIVE) && was_fpu_owner) + return 0; + + /* We need to restore the vector context. */ + restore_msa(current); + return 0; +} + asmlinkage void do_cpu(struct pt_regs *regs) { enum ctx_state prev_state; @@ -1153,12 +1225,7 @@ asmlinkage void do_cpu(struct pt_regs *regs) /* Fall through. */ case 1: - if (used_math()) /* Using the FPU again. */ - err = own_fpu(1); - else { /* First time FPU user. */ - err = init_fpu(); - set_used_math(); - } + err = enable_restore_fp_context(0); if (!raw_cpu_has_fpu || err) { int sig; @@ -1183,6 +1250,27 @@ out: exception_exit(prev_state); } +asmlinkage void do_msa(struct pt_regs *regs) +{ + enum ctx_state prev_state; + int err; + + prev_state = exception_enter(); + + if (!cpu_has_msa || test_thread_flag(TIF_32BIT_FPREGS)) { + force_sig(SIGILL, current); + goto out; + } + + die_if_kernel("do_msa invoked from kernel context!", regs); + + err = enable_restore_fp_context(1); + if (err) + force_sig(SIGILL, current); +out: + exception_exit(prev_state); +} + asmlinkage void do_mdmx(struct pt_regs *regs) { enum ctx_state prev_state; @@ -2041,6 +2129,7 @@ void __init trap_init(void) set_except_vector(15, handle_fpe); set_except_vector(16, handle_ftlb); + set_except_vector(21, handle_msa); set_except_vector(22, handle_mdmx); if (cpu_has_mcheck) |