diff --git a/arch/mips/include/asm/fpu_emulator.h b/arch/mips/include/asm/fpu_emulator.h index 355dc25172e7a91b7ccf3c959a4a8fbd05dbf390..c05369e0b8d60352dc1833880b026e15ac09ba17 100644 --- a/arch/mips/include/asm/fpu_emulator.h +++ b/arch/mips/include/asm/fpu_emulator.h @@ -63,6 +63,8 @@ do { \ extern int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx, int has_fpu, void *__user *fault_addr); +void force_fcr31_sig(unsigned long fcr31, void __user *fault_addr, + struct task_struct *tsk); int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31); int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn, @@ -81,4 +83,15 @@ static inline void fpu_emulator_init_fpu(void) set_fpr64(&t->thread.fpu.fpr[i], 0, SIGNALLING_NAN); } +/* + * Mask the FCSR Cause bits according to the Enable bits, observing + * that Unimplemented is always enabled. + */ +static inline unsigned long mask_fcr31_x(unsigned long fcr31) +{ + return fcr31 & (FPU_CSR_UNI_X | + ((fcr31 & FPU_CSR_ALL_E) << + (ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)))); +} + #endif /* _ASM_FPU_EMULATOR_H */ diff --git a/arch/mips/include/asm/switch_to.h b/arch/mips/include/asm/switch_to.h index ebb5c0f2f90daef7b2bcca348fb90df2b7530037..c0ae27971e3108093fdc3952969d15bb3bfd5f30 100644 --- a/arch/mips/include/asm/switch_to.h +++ b/arch/mips/include/asm/switch_to.h @@ -75,6 +75,22 @@ do { if (cpu_has_rw_llb) { \ } \ } while (0) +/* + * Check FCSR for any unmasked exceptions pending set with `ptrace', + * clear them and send a signal. + */ +#define __sanitize_fcr31(next) \ +do { \ + unsigned long fcr31 = mask_fcr31_x(next->thread.fpu.fcr31); \ + void __user *pc; \ + \ + if (unlikely(fcr31)) { \ + pc = (void __user *)task_pt_regs(next)->cp0_epc; \ + next->thread.fpu.fcr31 &= ~fcr31; \ + force_fcr31_sig(fcr31, pc, next); \ + } \ +} while (0) + /* * For newly created kernel threads switch_to() will return to * ret_from_kernel_thread, newly created user threads to ret_from_fork. @@ -85,6 +101,8 @@ do { if (cpu_has_rw_llb) { \ do { \ __mips_mt_fpaff_switch_to(prev); \ lose_fpu_inatomic(1, prev); \ + if (tsk_used_math(next)) \ + __sanitize_fcr31(next); \ if (cpu_has_dsp) { \ __save_dsp(prev); \ __restore_dsp(next); \ diff --git a/arch/mips/kernel/mips-r2-to-r6-emul.c b/arch/mips/kernel/mips-r2-to-r6-emul.c index 22dedd62818ad08d517de10a705da5cf2b9a5279..bd09853aecdfa1e567717cc35a9d19e786468391 100644 --- a/arch/mips/kernel/mips-r2-to-r6-emul.c +++ b/arch/mips/kernel/mips-r2-to-r6-emul.c @@ -899,7 +899,7 @@ static inline int mipsr2_find_op_func(struct pt_regs *regs, u32 inst, * mipsr2_decoder: Decode and emulate a MIPS R2 instruction * @regs: Process register set * @inst: Instruction to decode and emulate - * @fcr31: Floating Point Control and Status Register returned + * @fcr31: Floating Point Control and Status Register Cause bits returned */ int mipsr2_decoder(struct pt_regs *regs, u32 inst, unsigned long *fcr31) { @@ -1172,13 +1172,13 @@ int mipsr2_decoder(struct pt_regs *regs, u32 inst, unsigned long *fcr31) err = fpu_emulator_cop1Handler(regs, ¤t->thread.fpu, 0, &fault_addr); - *fcr31 = current->thread.fpu.fcr31; /* - * We can't allow the emulated instruction to leave any of - * the cause bits set in $fcr31. + * We can't allow the emulated instruction to leave any + * enabled Cause bits set in $fcr31. */ - current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X; + *fcr31 = res = mask_fcr31_x(current->thread.fpu.fcr31); + current->thread.fpu.fcr31 &= ~res; /* * this is a tricky issue - lose_fpu() uses LL/SC atomics diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c index fd3a9580661abaa18ae94fad360de0372eb7340e..a92994d60e91e4b768ac6570012ad64c1c86885d 100644 --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -79,16 +79,15 @@ void ptrace_disable(struct task_struct *child) } /* - * Poke at FCSR according to its mask. Don't set the cause bits as - * this is currently not handled correctly in FP context restoration - * and will cause an oops if a corresponding enable bit is set. + * Poke at FCSR according to its mask. Set the Cause bits even + * if a corresponding Enable bit is set. This will be noticed at + * the time the thread is switched to and SIGFPE thrown accordingly. */ static void ptrace_setfcr31(struct task_struct *child, u32 value) { u32 fcr31; u32 mask; - value &= ~FPU_CSR_ALL_X; fcr31 = child->thread.fpu.fcr31; mask = boot_cpu_data.fpu_msk31; child->thread.fpu.fcr31 = (value & ~mask) | (fcr31 & mask); diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index b9a910b208f99928350000931af04ef0c9da174d..3905003dfe2b918faa7acd39f350710c9ed6edd0 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -708,6 +708,32 @@ asmlinkage void do_ov(struct pt_regs *regs) exception_exit(prev_state); } +/* + * Send SIGFPE according to FCSR Cause bits, which must have already + * been masked against Enable bits. This is impotant as Inexact can + * happen together with Overflow or Underflow, and `ptrace' can set + * any bits. + */ +void force_fcr31_sig(unsigned long fcr31, void __user *fault_addr, + struct task_struct *tsk) +{ + struct siginfo si = { .si_addr = fault_addr, .si_signo = SIGFPE }; + + if (fcr31 & FPU_CSR_INV_X) + si.si_code = FPE_FLTINV; + else if (fcr31 & FPU_CSR_DIV_X) + si.si_code = FPE_FLTDIV; + else if (fcr31 & FPU_CSR_OVF_X) + si.si_code = FPE_FLTOVF; + else if (fcr31 & FPU_CSR_UDF_X) + si.si_code = FPE_FLTUND; + else if (fcr31 & FPU_CSR_INE_X) + si.si_code = FPE_FLTRES; + else + si.si_code = __SI_FAULT; + force_sig_info(SIGFPE, &si, tsk); +} + int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31) { struct siginfo si = { 0 }; @@ -718,27 +744,7 @@ int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31) return 0; case SIGFPE: - si.si_addr = fault_addr; - si.si_signo = sig; - /* - * Inexact can happen together with Overflow or Underflow. - * Respect the mask to deliver the correct exception. - */ - fcr31 &= (fcr31 & FPU_CSR_ALL_E) << - (ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)); - if (fcr31 & FPU_CSR_INV_X) - si.si_code = FPE_FLTINV; - else if (fcr31 & FPU_CSR_DIV_X) - si.si_code = FPE_FLTDIV; - else if (fcr31 & FPU_CSR_OVF_X) - si.si_code = FPE_FLTOVF; - else if (fcr31 & FPU_CSR_UDF_X) - si.si_code = FPE_FLTUND; - else if (fcr31 & FPU_CSR_INE_X) - si.si_code = FPE_FLTRES; - else - si.si_code = __SI_FAULT; - force_sig_info(sig, &si, current); + force_fcr31_sig(fcr31, fault_addr, current); return 1; case SIGBUS: @@ -802,13 +808,13 @@ static int simulate_fp(struct pt_regs *regs, unsigned int opcode, /* Run the emulator */ sig = fpu_emulator_cop1Handler(regs, ¤t->thread.fpu, 1, &fault_addr); - fcr31 = current->thread.fpu.fcr31; /* - * We can't allow the emulated instruction to leave any of - * the cause bits set in $fcr31. + * We can't allow the emulated instruction to leave any + * enabled Cause bits set in $fcr31. */ - current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X; + fcr31 = mask_fcr31_x(current->thread.fpu.fcr31); + current->thread.fpu.fcr31 &= ~fcr31; /* Restore the hardware register state */ own_fpu(1); @@ -834,7 +840,7 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) goto out; /* Clear FCSR.Cause before enabling interrupts */ - write_32bit_cp1_register(CP1_STATUS, fcr31 & ~FPU_CSR_ALL_X); + write_32bit_cp1_register(CP1_STATUS, fcr31 & ~mask_fcr31_x(fcr31)); local_irq_enable(); die_if_kernel("FP exception in kernel code", regs); @@ -856,13 +862,13 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) /* Run the emulator */ sig = fpu_emulator_cop1Handler(regs, ¤t->thread.fpu, 1, &fault_addr); - fcr31 = current->thread.fpu.fcr31; /* - * We can't allow the emulated instruction to leave any of - * the cause bits set in $fcr31. + * We can't allow the emulated instruction to leave any + * enabled Cause bits set in $fcr31. */ - current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X; + fcr31 = mask_fcr31_x(current->thread.fpu.fcr31); + current->thread.fpu.fcr31 &= ~fcr31; /* Restore the hardware register state */ own_fpu(1); /* Using the FPU again. */ @@ -1427,13 +1433,13 @@ asmlinkage void do_cpu(struct pt_regs *regs) sig = fpu_emulator_cop1Handler(regs, ¤t->thread.fpu, 0, &fault_addr); - fcr31 = current->thread.fpu.fcr31; /* * We can't allow the emulated instruction to leave - * any of the cause bits set in $fcr31. + * any enabled Cause bits set in $fcr31. */ - current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X; + fcr31 = mask_fcr31_x(current->thread.fpu.fcr31); + current->thread.fpu.fcr31 &= ~fcr31; /* Send a signal if required. */ if (!process_fpemu_return(sig, fault_addr, fcr31) && !err)