Commit 304acb71 authored by Maciej W. Rozycki's avatar Maciej W. Rozycki Committed by Ralf Baechle
Browse files

MIPS: Set `si_code' for SIGFPE signals sent from emulation too 



Rework `process_fpemu_return' and move IEEE 754 exception interpretation
there, from `do_fpe'.  Record the cause bits set in FCSR before they are
cleared and pass them through to `process_fpemu_return' so as to set
`si_code' correctly too for SIGFPE signals sent from emulation rather
than those issued by hardware with the FPE processor exception only.

For simplicity `mipsr2_decoder' assumes `*fcr31' has been preinitialised
and only sets it to anything if an FPU instruction has been emulated,
which in turn is the only case SIGFPE can be issued for here.

Signed-off-by: default avatarMaciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9705/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 443c4403

arch/mips/include/asm/fpu_emulator.h

+2 −1
Original line number Diff line number Diff line
@@ -66,7 +66,8 @@ extern int do_dsemulret(struct pt_regs *xcp); 
extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,

				    struct mips_fpu_struct *ctx, int has_fpu,

				    void *__user *fault_addr);

int process_fpemu_return(int sig, void __user *fault_addr);

int process_fpemu_return(int sig, void __user *fault_addr,

			 unsigned long fcr31);

int mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,

		     unsigned long *contpc);

arch/mips/include/asm/mips-r2-to-r6-emul.h

+7 −2
Original line number Diff line number Diff line
@@ -84,11 +84,16 @@ extern void do_trap_or_bp(struct pt_regs *regs, unsigned int code, 


#ifndef CONFIG_MIPSR2_TO_R6_EMULATOR

static int mipsr2_emulation;

static inline int mipsr2_decoder(struct pt_regs *regs, u32 inst) { return 0; };

static inline int mipsr2_decoder(struct pt_regs *regs, u32 inst,

				 unsigned long *fcr31)

{

	return 0;

};

#else

/* MIPS R2 Emulator ON/OFF */

extern int mipsr2_emulation;

extern int mipsr2_decoder(struct pt_regs *regs, u32 inst);

extern int mipsr2_decoder(struct pt_regs *regs, u32 inst,

			  unsigned long *fcr31);

#endif /* CONFIG_MIPSR2_TO_R6_EMULATOR */



#define NO_R6EMU	(cpu_has_mips_r6 && !mipsr2_emulation)

arch/mips/kernel/mips-r2-to-r6-emul.c

+3 −1
Original line number Diff line number Diff line
@@ -898,8 +898,9 @@ 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

 */

int mipsr2_decoder(struct pt_regs *regs, u32 inst)

int mipsr2_decoder(struct pt_regs *regs, u32 inst, unsigned long *fcr31)

{

	int err = 0;

	unsigned long vaddr;
@@ -1168,6 +1169,7 @@ fpu_emul: 


		err = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 0,

					       &fault_addr);

		*fcr31 = current->thread.fpu.fcr31;



		/*

		 * We can't allow the emulated instruction to leave any of

arch/mips/kernel/traps.c

+83 −67
Original line number Diff line number Diff line
@@ -700,29 +700,60 @@ asmlinkage void do_ov(struct pt_regs *regs) 
	exception_exit(prev_state);

}



int process_fpemu_return(int sig, void __user *fault_addr)

int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31)

{

	if (sig == SIGSEGV || sig == SIGBUS) {

	struct siginfo si = { 0 };



	switch (sig) {

	case 0:

		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);

		return 1;



	case SIGBUS:

		si.si_addr = fault_addr;

		si.si_signo = sig;

		si.si_code = BUS_ADRERR;

		force_sig_info(sig, &si, current);

		return 1;



	case SIGSEGV:

		si.si_addr = fault_addr;

		si.si_signo = sig;

		if (sig == SIGSEGV) {

		down_read(&current->mm->mmap_sem);

		if (find_vma(current->mm, (unsigned long)fault_addr))

			si.si_code = SEGV_ACCERR;

		else

			si.si_code = SEGV_MAPERR;

		up_read(&current->mm->mmap_sem);

		} else {

			si.si_code = BUS_ADRERR;

		}

		force_sig_info(sig, &si, current);

		return 1;

	} else if (sig) {



	default:

		force_sig(sig, current);

		return 1;

	} else {

		return 0;

	}

}
@@ -730,7 +761,8 @@ static int simulate_fp(struct pt_regs *regs, unsigned int opcode, 
		       unsigned long old_epc, unsigned long old_ra)

{

	union mips_instruction inst = { .word = opcode };

	void __user *fault_addr = NULL;

	void __user *fault_addr;

	unsigned long fcr31;

	int sig;



	/* If it's obviously not an FP instruction, skip it */
@@ -760,6 +792,7 @@ static int simulate_fp(struct pt_regs *regs, unsigned int opcode, 
	/* Run the emulator */

	sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 1,

				       &fault_addr);

	fcr31 = current->thread.fpu.fcr31;



	/*

	 * We can't allow the emulated instruction to leave any of
@@ -767,12 +800,12 @@ static int simulate_fp(struct pt_regs *regs, unsigned int opcode, 
	 */

	current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X;



	/* If something went wrong, signal */

	process_fpemu_return(sig, fault_addr);



	/* Restore the hardware register state */

	own_fpu(1);



	/* Send a signal if required.  */

	process_fpemu_return(sig, fault_addr, fcr31);



	return 0;

}
@@ -782,7 +815,8 @@ static int simulate_fp(struct pt_regs *regs, unsigned int opcode, 
asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)

{

	enum ctx_state prev_state;

	siginfo_t info = {0};

	void __user *fault_addr;

	int sig;



	prev_state = exception_enter();

	if (notify_die(DIE_FP, "FP exception", regs, 0, regs_to_trapnr(regs),
@@ -791,9 +825,6 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) 
	die_if_kernel("FP exception in kernel code", regs);



	if (fcr31 & FPU_CSR_UNI_X) {

		int sig;

		void __user *fault_addr = NULL;



		/*

		 * Unimplemented operation exception.  If we've got the full

		 * software emulator on-board, let's use it...
@@ -810,6 +841,7 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) 
		/* Run the emulator */

		sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 1,

					       &fault_addr);

		fcr31 = current->thread.fpu.fcr31;



		/*

		 * We can't allow the emulated instruction to leave any of
@@ -819,35 +851,13 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) 


		/* Restore the hardware register state */

		own_fpu(1);	/* Using the FPU again.	 */



		/* If something went wrong, signal */

		process_fpemu_return(sig, fault_addr);



		goto out;

	} else {

		sig = SIGFPE;

		fault_addr = (void __user *) regs->cp0_epc;

	}



	/*

	 * 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)

		info.si_code = FPE_FLTINV;

	else if (fcr31 & FPU_CSR_DIV_X)

		info.si_code = FPE_FLTDIV;

	else if (fcr31 & FPU_CSR_OVF_X)

		info.si_code = FPE_FLTOVF;

	else if (fcr31 & FPU_CSR_UDF_X)

		info.si_code = FPE_FLTUND;

	else if (fcr31 & FPU_CSR_INE_X)

		info.si_code = FPE_FLTRES;

	else

		info.si_code = __SI_FAULT;

	info.si_signo = SIGFPE;

	info.si_errno = 0;

	info.si_addr = (void __user *) regs->cp0_epc;

	force_sig_info(SIGFPE, &info, current);

	/* Send a signal if required.  */

	process_fpemu_return(sig, fault_addr, fcr31);



out:

	exception_exit(prev_state);
@@ -1050,7 +1060,9 @@ asmlinkage void do_ri(struct pt_regs *regs) 
	if (mipsr2_emulation && cpu_has_mips_r6 &&

	    likely(user_mode(regs)) &&

	    likely(get_user(opcode, epc) >= 0)) {

		status = mipsr2_decoder(regs, opcode);

		unsigned long fcr31 = 0;



		status = mipsr2_decoder(regs, opcode, &fcr31);

		switch (status) {

		case 0:

		case SIGEMT:
@@ -1060,7 +1072,8 @@ asmlinkage void do_ri(struct pt_regs *regs) 
			goto no_r2_instr;

		default:

			process_fpemu_return(status,

					     &current->thread.cp0_baduaddr);

					     &current->thread.cp0_baduaddr,

					     fcr31);

			task_thread_info(current)->r2_emul_return = 1;

			return;

		}
@@ -1307,10 +1320,13 @@ asmlinkage void do_cpu(struct pt_regs *regs) 
	enum ctx_state prev_state;

	unsigned int __user *epc;

	unsigned long old_epc, old31;

	void __user *fault_addr;

	unsigned int opcode;

	unsigned long fcr31;

	unsigned int cpid;

	int status, err;

	unsigned long __maybe_unused flags;

	int sig;



	prev_state = exception_enter();

	cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;
@@ -1384,12 +1400,12 @@ asmlinkage void do_cpu(struct pt_regs *regs) 
	case 1:

		err = enable_restore_fp_context(0);



		if (!raw_cpu_has_fpu || err) {

			int sig;

			void __user *fault_addr = NULL;

			sig = fpu_emulator_cop1Handler(regs,

						       &current->thread.fpu,

						       0, &fault_addr);

		if (raw_cpu_has_fpu && !err)

			break;



		sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 0,

					       &fault_addr);

		fcr31 = current->thread.fpu.fcr31;



		/*

		 * We can't allow the emulated instruction to leave
@@ -1397,9 +1413,9 @@ asmlinkage void do_cpu(struct pt_regs *regs) 
		 */

		current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X;



			if (!process_fpemu_return(sig, fault_addr) && !err)

		/* Send a signal if required.  */

		if (!process_fpemu_return(sig, fault_addr, fcr31) && !err)

			mt_ase_fp_affinity();

		}



		break;

arch/mips/kernel/unaligned.c

+2 −2
Original line number Diff line number Diff line
@@ -1076,7 +1076,7 @@ static void emulate_load_store_insn(struct pt_regs *regs, 
		own_fpu(1);	/* Restore FPU state. */



		/* Signal if something went wrong. */

		process_fpemu_return(res, fault_addr);

		process_fpemu_return(res, fault_addr, 0);



		if (res == 0)

			break;
@@ -1511,7 +1511,7 @@ fpu_emul: 
		own_fpu(1);	/* restore FPU state */



		/* If something went wrong, signal */

		process_fpemu_return(res, fault_addr);

		process_fpemu_return(res, fault_addr, 0);



		if (res == 0)

			goto success;

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