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Commit df270051 authored by Ralf Baechle's avatar Ralf Baechle
Browse files

[MIPS] Fix handling of trap and breakpoint instructions 



With fixes and cleanups from Atsushi Nemoto (anemo@mba.ocn.ne.jp).

Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent cf85c109

arch/mips/kernel/traps.c

+37 −52
Original line number Diff line number Diff line
@@ -675,35 +675,24 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31) 
	force_sig_info(SIGFPE, &info, current);

}



asmlinkage void do_bp(struct pt_regs *regs)

static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,

	const char *str)

{

	unsigned int opcode, bcode;

	siginfo_t info;



	if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))

		goto out_sigsegv;



	/*

	 * There is the ancient bug in the MIPS assemblers that the break

	 * code starts left to bit 16 instead to bit 6 in the opcode.

	 * Gas is bug-compatible, but not always, grrr...

	 * We handle both cases with a simple heuristics.  --macro

	 */

	bcode = ((opcode >> 6) & ((1 << 20) - 1));

	if (bcode < (1 << 10))

		bcode <<= 10;

	char b[40];



	/*

	 * (A short test says that IRIX 5.3 sends SIGTRAP for all break

	 * insns, even for break codes that indicate arithmetic failures.

	 * Weird ...)

	 * A short test says that IRIX 5.3 sends SIGTRAP for all trap

	 * insns, even for trap and break codes that indicate arithmetic

	 * failures.  Weird ...

	 * But should we continue the brokenness???  --macro

	 */

	switch (bcode) {

	case BRK_OVERFLOW << 10:

	case BRK_DIVZERO << 10:

		die_if_kernel("Break instruction in kernel code", regs);

		if (bcode == (BRK_DIVZERO << 10))

	switch (code) {

	case BRK_OVERFLOW:

	case BRK_DIVZERO:

		scnprintf(b, sizeof(b), "%s instruction in kernel code", str);

		die_if_kernel(b, regs);

		if (code == BRK_DIVZERO)

			info.si_code = FPE_INTDIV;

		else

			info.si_code = FPE_INTOVF;
@@ -713,12 +702,34 @@ asmlinkage void do_bp(struct pt_regs *regs) 
		force_sig_info(SIGFPE, &info, current);

		break;

	case BRK_BUG:

		die("Kernel bug detected", regs);

		die_if_kernel("Kernel bug detected", regs);

		force_sig(SIGTRAP, current);

		break;

	default:

		die_if_kernel("Break instruction in kernel code", regs);

		scnprintf(b, sizeof(b), "%s instruction in kernel code", str);

		die_if_kernel(b, regs);

		force_sig(SIGTRAP, current);

	}

}



asmlinkage void do_bp(struct pt_regs *regs)

{

	unsigned int opcode, bcode;



	if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))

		goto out_sigsegv;



	/*

	 * There is the ancient bug in the MIPS assemblers that the break

	 * code starts left to bit 16 instead to bit 6 in the opcode.

	 * Gas is bug-compatible, but not always, grrr...

	 * We handle both cases with a simple heuristics.  --macro

	 */

	bcode = ((opcode >> 6) & ((1 << 20) - 1));

	if (bcode >= (1 << 10))

		bcode >>= 10;



	do_trap_or_bp(regs, bcode, "Break");

	return;



out_sigsegv:
@@ -728,7 +739,6 @@ out_sigsegv: 
asmlinkage void do_tr(struct pt_regs *regs)

{

	unsigned int opcode, tcode = 0;

	siginfo_t info;



	if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))

		goto out_sigsegv;
@@ -737,32 +747,7 @@ asmlinkage void do_tr(struct pt_regs *regs) 
	if (!(opcode & OPCODE))

		tcode = ((opcode >> 6) & ((1 << 10) - 1));



	/*

	 * (A short test says that IRIX 5.3 sends SIGTRAP for all trap

	 * insns, even for trap codes that indicate arithmetic failures.

	 * Weird ...)

	 * But should we continue the brokenness???  --macro

	 */

	switch (tcode) {

	case BRK_OVERFLOW:

	case BRK_DIVZERO:

		die_if_kernel("Trap instruction in kernel code", regs);

		if (tcode == BRK_DIVZERO)

			info.si_code = FPE_INTDIV;

		else

			info.si_code = FPE_INTOVF;

		info.si_signo = SIGFPE;

		info.si_errno = 0;

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

		force_sig_info(SIGFPE, &info, current);

		break;

	case BRK_BUG:

		die("Kernel bug detected", regs);

		break;

	default:

		die_if_kernel("Trap instruction in kernel code", regs);

		force_sig(SIGTRAP, current);

	}

	do_trap_or_bp(regs, tcode, "Trap");

	return;



out_sigsegv: