Commit f5a16b93 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: handle gcc generated __builtin_trap() 



gcc toggle -fisolate-erroneous-paths-dereference (default at -O2
onwards) isolates faulty code paths such as null pointer access, divide
by zero etc by emitting __builtin_trap()

Newer ARC gcc generates TRAP_S 5 instruction which needs to be handled
and treated like any other unexpected exception
  - user mode  : task terminated with a SEGV
  - kernel mode: die() called after register and stack dump

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 79435ac7

arch/arc/kernel/traps.c

+6 −0
Original line number Original line Diff line number Diff line
@@ -83,6 +83,7 @@ DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC) 
DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)

DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)

DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)

DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)

DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)

DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)

DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)





/*

/*

 * Entry Point for Misaligned Data access Exception, for emulating in software

 * Entry Point for Misaligned Data access Exception, for emulating in software
@@ -115,6 +116,8 @@ void do_machine_check_fault(unsigned long address, struct pt_regs *regs) 
 * Thus TRAP_S <n> can be used for specific purpose

 * Thus TRAP_S <n> can be used for specific purpose

 *  -1 used for software breakpointing (gdb)

 *  -1 used for software breakpointing (gdb)

 *  -2 used by kprobes

 *  -2 used by kprobes

 *  -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as

 *     -fno-isolate-erroneous-paths-dereference

 */

 */

void do_non_swi_trap(unsigned long address, struct pt_regs *regs)

void do_non_swi_trap(unsigned long address, struct pt_regs *regs)

{

{
@@ -134,6 +137,9 @@ void do_non_swi_trap(unsigned long address, struct pt_regs *regs) 
		kgdb_trap(regs);

		kgdb_trap(regs);

		break;

		break;





	case 5:

		do_trap5_error(address, regs);

		break;

	default:

	default:

		break;

		break;

	}

	}

arch/arc/kernel/troubleshoot.c

+3 −0
Original line number Original line Diff line number Diff line
@@ -163,6 +163,9 @@ static void show_ecr_verbose(struct pt_regs *regs) 
		else

		else

			pr_cont("Bus Error, check PRM\n");

			pr_cont("Bus Error, check PRM\n");

#endif

#endif

	} else if (vec == ECR_V_TRAP) {

		if (regs->ecr_param == 5)

			pr_cont("gcc generated __builtin_trap\n");

	} else {

	} else {

		pr_cont("Check Programmer's Manual\n");

		pr_cont("Check Programmer's Manual\n");

	}

	}

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