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Commit 3a3b5aa6 authored by Kevin Hao's avatar Kevin Hao Committed by Benjamin Herrenschmidt
Browse files

powerpc: Introduce function emulate_math() 



There are two invocations of do_mathemu() in traps.c. And the codes
in these two places are almost the same. Introduce a locale function
to eliminate the duplication. With this change we can also make sure
that in program_check_exception() the PPC_WARN_EMULATED is invoked for
the correctly emulated math instructions.

Signed-off-by: default avatarKevin Hao <haokexin@gmail.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 6761ee3d

arch/powerpc/kernel/traps.c

+34 −45
Original line number Diff line number Diff line
@@ -1055,11 +1055,41 @@ int is_valid_bugaddr(unsigned long addr) 
	return is_kernel_addr(addr);

}



#ifdef CONFIG_MATH_EMULATION

static int emulate_math(struct pt_regs *regs)

{

	int ret;

	extern int do_mathemu(struct pt_regs *regs);



	ret = do_mathemu(regs);

	if (ret >= 0)

		PPC_WARN_EMULATED(math, regs);



	switch (ret) {

	case 0:

		emulate_single_step(regs);

		return 0;

	case 1: {

			int code = 0;

			code = __parse_fpscr(current->thread.fpscr.val);

			_exception(SIGFPE, regs, code, regs->nip);

			return 0;

		}

	case -EFAULT:

		_exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);

		return 0;

	}



	return -1;

}

#else

static inline int emulate_math(struct pt_regs *regs) { return -1; }

#endif



void __kprobes program_check_exception(struct pt_regs *regs)

{

	enum ctx_state prev_state = exception_enter();

	unsigned int reason = get_reason(regs);

	extern int do_mathemu(struct pt_regs *regs);



	/* We can now get here via a FP Unavailable exception if the core

	 * has no FPU, in that case the reason flags will be 0 */
@@ -1125,7 +1155,6 @@ void __kprobes program_check_exception(struct pt_regs *regs) 
	if (!arch_irq_disabled_regs(regs))

		local_irq_enable();



#ifdef CONFIG_MATH_EMULATION

	/* (reason & REASON_ILLEGAL) would be the obvious thing here,

	 * but there seems to be a hardware bug on the 405GP (RevD)

	 * that means ESR is sometimes set incorrectly - either to
@@ -1134,22 +1163,8 @@ void __kprobes program_check_exception(struct pt_regs *regs) 
	 * instruction or only on FP instructions, whether there is a

	 * pattern to occurrences etc. -dgibson 31/Mar/2003

	 */

	switch (do_mathemu(regs)) {

	case 0:

		emulate_single_step(regs);

	if (!emulate_math(regs))

		goto bail;

	case 1: {

			int code = 0;

			code = __parse_fpscr(current->thread.fpscr.val);

			_exception(SIGFPE, regs, code, regs->nip);

			goto bail;

		}

	case -EFAULT:

		_exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);

		goto bail;

	}

	/* fall through on any other errors */

#endif /* CONFIG_MATH_EMULATION */



	/* Try to emulate it if we should. */

	if (reason & (REASON_ILLEGAL | REASON_PRIVILEGED)) {
@@ -1428,11 +1443,6 @@ void performance_monitor_exception(struct pt_regs *regs) 
#ifdef CONFIG_8xx

void SoftwareEmulation(struct pt_regs *regs)

{

	extern int do_mathemu(struct pt_regs *);

#if defined(CONFIG_MATH_EMULATION)

	int errcode;

#endif



	CHECK_FULL_REGS(regs);



	if (!user_mode(regs)) {
@@ -1440,31 +1450,10 @@ void SoftwareEmulation(struct pt_regs *regs) 
		die("Kernel Mode Software FPU Emulation", regs, SIGFPE);

	}



#ifdef CONFIG_MATH_EMULATION

	errcode = do_mathemu(regs);

	if (errcode >= 0)

		PPC_WARN_EMULATED(math, regs);



	switch (errcode) {

	case 0:

		emulate_single_step(regs);

		return;

	case 1: {

			int code = 0;

			code = __parse_fpscr(current->thread.fpscr.val);

			_exception(SIGFPE, regs, code, regs->nip);

			return;

		}

	case -EFAULT:

		_exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);

	if (!emulate_math(regs))

		return;

	default:

		_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);

		return;

	}

#else



	_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);

#endif

}

#endif /* CONFIG_8xx */